dr. congxiao shang room no.: 01 37p email: [email protected] section 3: thermal comfort env-2d02...
TRANSCRIPT
Dr Congxiao Shang
Room No 01 37PEmail cshangueaacuk
Section 3 Thermal Comfort
ENV-2D02 (2006)Energy Conservation ndash power point versions of lectures
31 IntroductionMain objective To examine whether an environment is thermally comfortable at minimum energy consumption
No two people will react the same in a given environment
If all individual have the same clothing that when the temperature is at the optimum 25 --- too cold 25 ---- too hot
Voting is normally done on the ASHRAE scale ranging from -3 for too cold to +3 for too hot
People who vote with values lt-2 or gt +2 are those who are at the extremes
3 very hot
25
2 hot
15
1 slightly warm
05
0 neutral
-05
-1 slightly cool
-15
-2 cold
-25
-3 very cold
Extremes
Extremes
31 Introduction
The number of people voting at particular values follows a Gaussian (normal) distribution which has its peak at a mean vote of zero at an optimum setting
If we respond only to complaints from those who are feeling too cold or too hot then we are likely to find that more people will be dissatisfied as the curve will be shifted to hotter or colder end
people who are too cold complain more actively than the other way with the consequence that the temperature is often kept unnecessarily high
3 very hot
25
2 hot
15
1 slightly warm
05
0 neutral
-05
-1 slightly cool
-15
-2 cold
-25
-3 very cold
Extremes
Extremes
Main objective To examine whether an environment is thermally comfortable at minimum energy consumption
31 Introduction
Bear in mind for every 1oC the energy requirement rises by 8-10 (in the UK)
So We need to be objective in any response to complaints by investigating the overall situation - not just the immediate problem of one or two complainants
32 Thermal Comfort TheoryThe perception of thermal comfort for an individual depends on maintaining a balance between heat produced by body and heat losses Heat generated by body depending on metabolic rate --------H
Heat lost through respiration ----------------------------------R 1 Exhaust air is warmer than air taken in AND 2 it is more moist - latent heat of evaporation
Heat lost through evaporation from skin (sweat) -----------------E
So net heat generated by body is (Q) from metabolic
Q = H - R - E
32 Thermal Comfort Theory
To maintain a balance this heat of value Q must be ldquoremovedrdquo by radiation (Qr) and convection (Qc) from the clothing in an actual environment as follows
Net heat generated by body is (Q)
Q = H - R - E = Qr + Qc
If Q gt Qr + Qc
Q lt Qr + Qc
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
31 IntroductionMain objective To examine whether an environment is thermally comfortable at minimum energy consumption
No two people will react the same in a given environment
If all individual have the same clothing that when the temperature is at the optimum 25 --- too cold 25 ---- too hot
Voting is normally done on the ASHRAE scale ranging from -3 for too cold to +3 for too hot
People who vote with values lt-2 or gt +2 are those who are at the extremes
3 very hot
25
2 hot
15
1 slightly warm
05
0 neutral
-05
-1 slightly cool
-15
-2 cold
-25
-3 very cold
Extremes
Extremes
31 Introduction
The number of people voting at particular values follows a Gaussian (normal) distribution which has its peak at a mean vote of zero at an optimum setting
If we respond only to complaints from those who are feeling too cold or too hot then we are likely to find that more people will be dissatisfied as the curve will be shifted to hotter or colder end
people who are too cold complain more actively than the other way with the consequence that the temperature is often kept unnecessarily high
3 very hot
25
2 hot
15
1 slightly warm
05
0 neutral
-05
-1 slightly cool
-15
-2 cold
-25
-3 very cold
Extremes
Extremes
Main objective To examine whether an environment is thermally comfortable at minimum energy consumption
31 Introduction
Bear in mind for every 1oC the energy requirement rises by 8-10 (in the UK)
So We need to be objective in any response to complaints by investigating the overall situation - not just the immediate problem of one or two complainants
32 Thermal Comfort TheoryThe perception of thermal comfort for an individual depends on maintaining a balance between heat produced by body and heat losses Heat generated by body depending on metabolic rate --------H
Heat lost through respiration ----------------------------------R 1 Exhaust air is warmer than air taken in AND 2 it is more moist - latent heat of evaporation
Heat lost through evaporation from skin (sweat) -----------------E
So net heat generated by body is (Q) from metabolic
Q = H - R - E
32 Thermal Comfort Theory
To maintain a balance this heat of value Q must be ldquoremovedrdquo by radiation (Qr) and convection (Qc) from the clothing in an actual environment as follows
Net heat generated by body is (Q)
Q = H - R - E = Qr + Qc
If Q gt Qr + Qc
Q lt Qr + Qc
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
31 Introduction
The number of people voting at particular values follows a Gaussian (normal) distribution which has its peak at a mean vote of zero at an optimum setting
If we respond only to complaints from those who are feeling too cold or too hot then we are likely to find that more people will be dissatisfied as the curve will be shifted to hotter or colder end
people who are too cold complain more actively than the other way with the consequence that the temperature is often kept unnecessarily high
3 very hot
25
2 hot
15
1 slightly warm
05
0 neutral
-05
-1 slightly cool
-15
-2 cold
-25
-3 very cold
Extremes
Extremes
Main objective To examine whether an environment is thermally comfortable at minimum energy consumption
31 Introduction
Bear in mind for every 1oC the energy requirement rises by 8-10 (in the UK)
So We need to be objective in any response to complaints by investigating the overall situation - not just the immediate problem of one or two complainants
32 Thermal Comfort TheoryThe perception of thermal comfort for an individual depends on maintaining a balance between heat produced by body and heat losses Heat generated by body depending on metabolic rate --------H
Heat lost through respiration ----------------------------------R 1 Exhaust air is warmer than air taken in AND 2 it is more moist - latent heat of evaporation
Heat lost through evaporation from skin (sweat) -----------------E
So net heat generated by body is (Q) from metabolic
Q = H - R - E
32 Thermal Comfort Theory
To maintain a balance this heat of value Q must be ldquoremovedrdquo by radiation (Qr) and convection (Qc) from the clothing in an actual environment as follows
Net heat generated by body is (Q)
Q = H - R - E = Qr + Qc
If Q gt Qr + Qc
Q lt Qr + Qc
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
31 Introduction
Bear in mind for every 1oC the energy requirement rises by 8-10 (in the UK)
So We need to be objective in any response to complaints by investigating the overall situation - not just the immediate problem of one or two complainants
32 Thermal Comfort TheoryThe perception of thermal comfort for an individual depends on maintaining a balance between heat produced by body and heat losses Heat generated by body depending on metabolic rate --------H
Heat lost through respiration ----------------------------------R 1 Exhaust air is warmer than air taken in AND 2 it is more moist - latent heat of evaporation
Heat lost through evaporation from skin (sweat) -----------------E
So net heat generated by body is (Q) from metabolic
Q = H - R - E
32 Thermal Comfort Theory
To maintain a balance this heat of value Q must be ldquoremovedrdquo by radiation (Qr) and convection (Qc) from the clothing in an actual environment as follows
Net heat generated by body is (Q)
Q = H - R - E = Qr + Qc
If Q gt Qr + Qc
Q lt Qr + Qc
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
32 Thermal Comfort TheoryThe perception of thermal comfort for an individual depends on maintaining a balance between heat produced by body and heat losses Heat generated by body depending on metabolic rate --------H
Heat lost through respiration ----------------------------------R 1 Exhaust air is warmer than air taken in AND 2 it is more moist - latent heat of evaporation
Heat lost through evaporation from skin (sweat) -----------------E
So net heat generated by body is (Q) from metabolic
Q = H - R - E
32 Thermal Comfort Theory
To maintain a balance this heat of value Q must be ldquoremovedrdquo by radiation (Qr) and convection (Qc) from the clothing in an actual environment as follows
Net heat generated by body is (Q)
Q = H - R - E = Qr + Qc
If Q gt Qr + Qc
Q lt Qr + Qc
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
32 Thermal Comfort Theory
To maintain a balance this heat of value Q must be ldquoremovedrdquo by radiation (Qr) and convection (Qc) from the clothing in an actual environment as follows
Net heat generated by body is (Q)
Q = H - R - E = Qr + Qc
If Q gt Qr + Qc
Q lt Qr + Qc
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
33 Factors affecting thermal comfort
a) The air temperatureb) The mean radiant temperaturec) The relative humidityd) The level of clothinge) The activity level (Kcalhr-1m-2)
f) The air velocity
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a buildingWe should consider the position you are in the room for measurement
Different walls have different surface temperatures eg internal walls external walls windows etc The mean radiant temperature is different at different points for measurements in the building
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
33 Factors affecting thermal comfortAt a specific area the mean radiant temperature within the area is measured with a Globe Thermometer and is related to the exchange of heat between a person and hisher surroundings
However within a building
As an approximation the AVERAGE MEAN radiant temperature within a room may be estimated by the following ( surface areas x surface temperatures) total surface area
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
34 Calculation of average mean radiant temperature
It is actually a mean temporal mean spatial MRT
Example
Office Size 3m x 3m x 3m (typical of UEA)
Windows 2m high and full width of one wall
Internal surface temperature of windows 8oC
The external wall 18oC
The air-temperature 20oC
What is AMRT
3m 3m
3m2m
5 3 3 20 1 3 18 2 3 8
6 3 3
334
1818 56
x x x x x x x
x xCo
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
34 Calculation of average mean radiation temperature
double glazing
3m 3m
3m2m
How about with double glazing
The internal surface temperature of the windows would rise to around 14oC and the AMRT is1944oC rather than 1856oC
From the previous example a rise of 1oC in AMRT Rise of Mean Vote by around 011
Therefore There will be improvement through double glazing in this room Alternatively we could reduce the air temperature slightly to get the same equivalent comfort level
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Computation of thermal comfort level
Actual Thermal Comfort Votes ndash For the analysis of a particular environment Thermal comfort experiments need to be done at particular conditions for a large number of individuals
Predicted Mean Vote (PMV)
1 Computer prediction with Fangerrsquos Equations
2 Manual use of the charts
CLO level from thermal comfort clothing chart
Their activity level
Air temperature
Humidity
Wind speed
Mean radiant temperture
A controlled environment
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Computation of thermal comfort levelCharts and tables for PMV at specific conditions were produced according to both experimental data and Fangerrsquos Equations
1) select table for appropriate metabolic rate indicated by activity level2) select appropriate clothing level sub-table3) now read of vote value corresponding to air (dry-bulb) temperature and air velocity (ms) corresponding to wind speed
Now how to obtain the PMV via the tables for other environments5) Use the Humidity correction chart which gives the correction for each 1 variation in humidity from 506) Repeat for the Mean Radiant Temperature Correction chart ie for each 1oC that the MRT differs from the air (dry bulb) temperature7) Apply these corrections to the basic value to obtain the corrected PMV (predicted Mean Vote)8) Use further chart to estimate proportion of people likely to be dissatisfied with thermal environment
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Thermal Comfort - ExampleAn office is 3m x 3m x 3m high with an external wall which is has a large 2m high window on the full width of the external wall facing North
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Internal air in the building T = 195degC air velocity = 0
The mean radiant T at a workers desk- 17degC near the external wall - 185degC on the other sides of the room and - 20degC in a similar south facing room
An office worker wearing clothing with a CLO value of 10 and has an activity level of 60 kcal hr-1m-2 complains of being too cold
What action would you take
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Air Temp degC PMV
18 -075
20 -032
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
- Estimate Predicted Mean Vote (PMV)- Consider Strategies
At 60 kcal hr-1m-2
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Thermal Comfort - ExampleAir Temp degC PMV
18 -075
20 -032
Known values
Air Temperature ordmC
By linear interpolation
Predicted Mean Vote at 195 degC =
-075 + (195 - 18) [-032- (-075)] (20-18) = - 043
PM
V
18 2019195
-075
-032
21
A
BC
Crsquo Brsquo
At 60 kcal hr-1m-2
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Thermal Comfort - Example
Activity Level KcalHr-1m-2
MR
T
Co
rrec
tio
n
1006050
006
012
The same people at different activity levels may feel comfortable at different temp
The corrections for MRT difference
At 50 kcal hr-1m-2 correction is + 012 At 100 kcal hr-1m-2 correction is + 006
Hence the correction at 60 kcal hr-1m-2
012 ndash (60-50) x [(012-006) (100-50)] = 011
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
35 Thermal Comfort - Example
Window
N
3
3
2
1
20ordmC
17ordmC
(195ordmC)
185
ordmC
185
ordmC3
Hence
ACTION-Moving the desk to the other side of the room or better still to a south facing office
- By complaining an office worker must be voting a PMV lt -2 and yet the above PMV is only slightly negative suggesting that the person always feels cold and should be encouraged to wear an extra sweater( Increasing the CLO value to 125 will increase the vote by about 03)
In North facing Office near window
PMV = - 043 + 011 (17-195 ) = - 069on other side of officePMV = - 043 + 011 (185 -195 ) = - 054in south facing officePMV = - 043 + 011 (20-195) = - 037
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
Thermal Comfort Study Arts 301 25th January 2006 Sample Size 26
Metabolic Rate Clo Actual PMV Actual Predicted MRT Dry Wet
all data 58 115 028 022 263 480 213 203 1630905 70 116 071 060 769 950 220 202 1620930 55 115 017 012 000 360 215 202 1630945 50 117 -001 -014 000 160 205 204 164
males 58 117 030females 58 116 023
unknown sex 58 115 048front of class 58 079 042
middle 58 121 016window 58 125 049
dissatisfied Hot represent people voting +2 or morePredictions are reasonable for large numbers eg gt100
Vote dissatisfied Hot
Time seated Activity Level (Kcalhr-1m-2) ~ 5 minutes 70 ~ 15 minutes 60 ~ 30 minutes 55 ~ 60 minutes 50 ~ 90 minutes 45 gt 2 hours 40
80 Kcalhr-1m-2 for a person who is standing
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
-05
00
05
10
15
20
25
all data 0905 0930 0945
Vot
e
-5
0
5
10
15
20
25
Tem
per
atu
re
Actual PMVMRT DryWet
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
36 Thermal comfort summeryThermal Comfort measurements may be used to assess a given environment and are a useful additional aspect of Energy ManagementThe level of comfort may be predicted using Fangers Equations however you should note the following
It is difficult to accurately assess metabolic rate and there is a tendency to underestimate value for people who are seated unless they have been in the particular Environment and at the particular activity level for at least an hour
Fangers Theory strictly applies only to individuals having the same clothing but taking the mean values of a large number of votes should give the same as Fangerrsquos
If actual votes are available then we can still use Thermal Comfort Tables made under standard conditions or the computer to assess the effects of changes in the Environmental Conditions on the mean VOTE
Rarely is actual thermal comfort data used in Energy Management Decisions - responses are usually made for those who feel too cold without identifying the real problem
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
Correction charts for the increment of PMV for each 1 variation in humidity from 50
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
Correction charts for the increment of predicted mean vote for each 1oC variation of mean radiant temperature from the air (dry-bulb) temperature
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
PMV (predicted mean vote)
bull It represents on a thermal sensation scale of the mean vote of a large population of people exposed to a certain environment
bull It is derived from the physics of heat transfer combined with an empirical fit to sensation
bull It establishes a thermal strain based on steady-state heat transfer between the body and the environment and assigns a comfort vote to that amount of strain
bull The PMV equation for thermal comfort is an empirical equation for predicting the mean vote on a ordinal category rating scale of thermal comfort of a population of people (not required here)
bull PMV gt 0 towards hot discomfort PMV lt 0 towards cold discomfort
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-
Note Thermal comfort- Clothing (ldquoCLOrdquo)
ndash 1048708 ldquoCLOrdquo is a CLOthing insulation unit (Icl)
ndash 1048708 1 clo = 0155 m2 degCW
ndash 1048708 Lowest clo value is 0 (naked body)
ndash 1048708 Highest practical clo value = 4 clo (Eskimo clothing fur pants coat hood gloves etc)
ndash 1048708 Summer clothing ~ 06 clo
ndash 1048708 Winter clothing ~ 1 clo
- Section 3 Thermal Comfort
- 31 Introduction
- Slide 3
- Slide 4
- 32 Thermal Comfort Theory
- Slide 6
- 33 Factors affecting thermal comfort
- Slide 8
- Slide 9
- 34 Calculation of average mean radiant temperature
- 34 Calculation of average mean radiation temperature
- 35 Computation of thermal comfort level
- Slide 13
- 35 Thermal Comfort - Example
- Slide 15
- Slide 16
- Slide 17
- Slide 18
- Slide 19
- Slide 20
- 36 Thermal comfort summery
- Slide 22
- Slide 23
- PMV (predicted mean vote)
- Note Thermal comfort- Clothing (ldquoCLOrdquo)
-