mitigation of summer thermal environment in …...the purpose of this study is to analyze the...
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29JR EAST Technical Review-No.28
Special edition paper
Measurement of the thermal environment of 17 stations in the greater Tokyo area carried out in fiscal 20121) revealed that the behavior of the difference in inside and outside temperature of over-track station concourses and overpasses could be roughly classified into three patterns. In line with this measurement, we investigated factors causing deterioration of the thermal environment and countermeasures to those. In fiscal 2013, we carried out measurements at 14 stations in the greater Tokyo area including under-viaduct stations where we had not yet measured. At those stations, passengers and station personnel pointed out that the temperature there was obviously high. We then analyzed the results of the two years of measurements together, aiming to set forth guidelines with which individual stations can decide on the level of need for improvement of the thermal environment and the effective measures to make that improvement. We see those guidelines as a bottom-up tool for simple diagnosis of the problem and improvement of thermal environment by renovation of stations. The presumed improvement measure is a passive method where air conditioning is used as little as possible and natural energy such as outdoor wind and insolation is controlled in a structural manner.
Outline of the Measurements2The measurements were carried out at stations in the greater Tokyo area from August to January in fiscal 2012 and 2013.
2.1 Target StationsMeasurement was done at 31 stations in the greater Tokyo area of different size and structure (17 stations in fiscal 2012 and 14 stations in fiscal 2013). The station space was divided at places where the space structure (ceiling height, shape, etc.) changes between overpass zone (15 overpasses) used for movement directly to the tracks and concourse zone (45 concourses) used for other purposes. For stations assumed to have multiple spaces with different characteristics, we divided the station into two or more zones and conducted measurement in each zone (Table 1).
Introduction1
2.2 Measurement of Temperature and HumidityWe measured and recorded the change over time of temperature and humidity in intervals of 10 minutes at a point each in 60 zones of 31 stations (30 zones of 17 stations in fiscal 2012 and 30 zones of 14 stations in fiscal 2013). The points of measurement were the places around the center of individual zones where a typical thermal environment was expected to be seen. The measurement device (espec Thermo Recorder RSW-20) was fixed to a guide sign (approx. 3.0 m above floor) or wall (approx. 0.5 m above floor), and its sensor was located 15 cm or greater from the device body. For outdoor temperature, we referred to the measurement values of outdoor temperature in 10-minute intervals at the meteorological observatories2) nearest to individual stations.
2.3 Measurement of CO2 ConcentrationTo identify the ventilation characteristics within stationhouses, we measured CO2 concentration. This was done in fiscal 2012 only.
2.4 Number of Passengers Passing Through Ticket GatesTo identify actual usage of stations and the relationship between number of station users and thermal environment of individual zones, we analyzed the numbers of the passengers passing through
Mitigation of Summer Thermal Environment in Railroad Stations
•Keywords: Station, Semi-outdoor environment, Measurement, Temperature and humidity, Thermal environment
The purpose of this study is to analyze the thermal comfort in urban train station and to set forth guidelines for effective improvement. From the survey results, average daily fluctuation patters of indoor and outdoor temperature difference were categorized into 4 types: mountain type, valley type, other type 1 (constant), and other type 2 (elevates in evening). First, the mountain type is affected largely by solar radiation and can frequently be found at bridge type structures above track, such as overpasses. The valley type can be found at crowded concourses at which ventilation is poor, and it depends on rush hour when many people are gathered. More importantly, survey results show that unacceptable thermal comfort time decreases at well-ventilated areas, such as near large windows and places where the point of measurement is close to the outside.
As a result, we reached the conclusion that there we need useful guidelines to improve thermal comfort. These guidelines consider characteristics of the number of users, because users can experience higher improvement effects at crowded stations during unacceptable thermal comfort time. Therefore, these guideline help to diagnose the problem easily and to renovate stations by passive methods as much as possible.
*Frontier Service Development Laboratory, Research and Development Center of JR East Group
Kiyoshi Sakamoto*Yoshiki Ikeda*
T-1 68,000 KM-1 88,100T-2 68,000 KM-2 130,300T-3 25,200 KM-3 88,100U-1 24,600 OI-1 85,400U-2 24,600 OI-2 97,600U-3 24,600 OM-1 106,500I-1 45,400 OM-2 61,200
MJ-1 60,100 SH-1 222,400MJ-2 60,100 SH-2 106,800NP-1 25,200 SH-3 329,200NP-2 66,500 TM-2 248,400SJ-1 47,200 TM-3 120,800SJ-2 28,700 YR-1 132,500
C-1 20,700 YR-2 48,400Y-1 54,900 YR-3 37,200
Y-2 95,400 AK-1 -O-1 100,800 AK-2 -O-2 100,800 AK-3 -O-3 82,300 AK-4 -
SG-1 121,500 KA-1 67,200MG-1 101,100 KS-1 78,100SN-1 48,800 KS-2 21,300
NS-1 20,300 KS-3 21,300NS-2 20,300 TA-1 130,700SS-1 71,600 KE-1 89,100SS-2 71,600 OG-1 42,300K-1 53,300 OG-2 108,300K-2 53,300 NO-1 82,100H-1 69,900 E-1 148,400
MK-1
OverpassOverpass
ConcourseOverpassOverpassOverpassOverpass
ConcourseConcourseOverpassOverpassOverpassOverpass
OverpassConcourse
ConcourseConcourseConcourseConcourseConcourseConcourseConcourse
ConcourseConcourseConcourseConcourseConcourseConcourseOverpass
Concourse
OverpassConcourseOverpass
ConcourseConcourseConcourseConcourse
ConcourseConcourseConcourseConcourseConcourseConcourse
ConcourseConcourse
ConcourseConcourseConcourseConcourseConcourseConcourseConcourse
ConcourseConcourseConcourseOverpass
ConcourseConcourseConcourse
Concourse125,700 E-2
Under-viaduct
Under-viaductUnder-viaduct
Over-trackOver-trackOver-trackOver-track
Under-viaductOver-trackOver-track
Over-trackUnder-viaductUnder-viaductOver-track
Under-viaductUnder-viaductOver-track
Over-track 97,800
Measurement in fiscal 2012 Measurement in fiscal 2013
Measurementpoint
Stationstructure
Measurementlocation
No. of passengerspassing through
ticket gates(persons/day)
Measurementpoint
Stationstructure
Measurementlocation
No. of passengerspassing through
ticket gates(persons/day)
Over-trackOver-trackOver-trackOver-trackOver-trackOver-track
Over-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-track
Over-trackOver-trackOver-trackOver-trackOver-trackOver-track
Over-track
Over-trackOver-trackOver-trackOver-trackOver-trackOver-track
Over-trackOver-trackOver-trackOver-trackOver-trackOver-trackOver-track
Over-track
Opencut
Opencut
Aboveground
Table 1 Overview of Measurement Zones
30 JR EAST Technical Review-No.28
Special edition paper
stations that should be given priority in improvement of the thermal environment. In this paper, we assessed using the thermal acceptability zone, which shows the acceptable limit of the thermal environment by station users. Based on the regression curves of the standard new effective temperature (SET*) and the ratio of persons who replied unacceptable in not air-conditioned stations as obtained in measurements by Nakano et al.3), it is assumed that the thermal acceptability zone in stations in the greater Tokyo area is 18.5 to 32 ºC. We thus set the upper limit of thermal acceptability in summer of station users at SET* 32 ºC. SET* is the perceived temperature that can be obtained from the six factors of air temperature, radiation temperature, air velocity, humidity,
the ticket gates nearest to the zones where measurement was carried out. For the analysis, we used data on a weekday (Thursday) and a holiday (Sunday) in September of each fiscal year.
2.5 Analysis PeriodFor analysis, we looked at the periods from August 1 to September 20, 2012 and August 1 to September 22, 2013 as summer seasons in which daily average temperature at the Tokyo District Meteorological Observatory exceeded 25 ºC. As the average change over time of outdoor temperature on summer days in fiscal 2012 and 2013 was similar to each other, we regarded the thermal environment of each fiscal year as equivalent for analysis.
Characteristics of Thermal Environment in Station Space3
We computed the average values of indoor and outdoor temperature at the same time on sunny weekdays in the analysis periods and observed the trend in variation of indoor and outdoor air temperature and changes in temperature difference. Based on the results and on past reserarch,1) we defined patterns of the thermal environment in individual stations. Table 2 shows the definitions and characteristics of the difference in indoor and outdoor air temperature, and Fig. 1 shows the average change over time of indoor air temperature and the change over time of difference between indoor and outdoor air temperature on sunny weekdays.
Past research1) classified measurement points where the difference between indoor and outdoor air temperature is large in the daytime as having a mountain type pattern, and we classified as being mountain type this time many measurement zones in overpasses where roof material was exposed without ceiling panels and space volume was relatively small. The valley type pattern where the difference between indoor and outdoor air temperature was large in the morning and at night was seen in concourses where many passengers come and go. Many of the under-viaduct stations where measurement was done for the first time were classified as having a valley type pattern. We further classified the “other” type measurement points into the following two patterns based on the difference between indoor and outdoor air temperature.(1) “Other (constant)” typeThis is the type where the difference between indoor and outdoor air temperature was constant. Zones both in overpasses and concourses fell under this type. In those zones, change over time of the difference between indoor and outdoor air temperature differed depending on the day, showing a mixed pattern of mountain type and valley type. When averaged, the trend was seen as constant. There were zones where the difference between indoor and outdoor air temperature was always more than 3 ºC and zones where that difference was always smaller than 1 ºC. This type was often observed in stations used by many passengers and having membrane roof and top lights.(2) “Other (high at night)” typeThis is the type where the difference between indoor and outdoor air temperature became larger after 15:00. While it was the same as in the valley type where the indoor temperature remained high even after the outdoor temperature fell at night, the difference between indoor and outdoor air temperature became smaller from midnight to early morning. Thus, there is a possibility that ventilation at night is greater than in zones of the valley type.
Assessment of Thermal Environment Level of Stations4
As there are some stations where the difference between indoor and outdoor air temperature greatly differs from that of stations even in the same pattern type, some criteria is needed to choose
Pattern type
Mountain
Valley
Constant
Greaterin evening
Difference smallerin early morning/at night,
greater in daytime
Difference greaterin early morning/at night,
smaller in daytime
Difference constant all day
Differencegreater after 15:00
Oth
ers
Characteristics DefinitionNo. of
measurementpoints
12
24
19
5
(Ave. of A and B) - C≥ 1.0
(Ave. of A and B) - C≤ 1.5
A. Average difference in early morning (4:30 - 5:00)B: Average difference late at night (1:00 - 1:30)C: Average difference in daytime (12:00 - 12:59)
Mountaintype
Valleytype
Other, Constant type
Other, Greaterin evening type
VVV
Tem
p. d
iffer
ence
[ºC
]
Indo
or te
mp.
[ºC
]
Tem
p. d
iffer
ence
[ºC
]
Indo
or te
mp.
[ºC
]
Tem
p. d
iffer
ence
[ºC
]
Indo
or te
mp.
[ºC
]
Tem
p. d
iffer
ence
[ºC
]
Indo
or te
mp.
[ºC
]
Fig. 1 Average Change Over Time of Difference Between Indoor and Outdoor Air Temperature (left) and Indoor of Air Temperature (right)
Table 2 Characteristics and Definitions of Patterns of Difference Between Indoor and Outdoor Air Temperature
31JR EAST Technical Review-No.28
Special edition paper
metabolic level (level of activity), and amount of clothing. Table 3 shows the calculation conditions of SET* in this study.
We made an analysis mainly from the following two perspectives.(1) Ratio of persons who did not accept the thermal environment
To take into account the variation characteristics for the number of users of individual stations, we found the number of users in the thermally unacceptable time slots when SET* 32 ºC is exceeded and standardized by dividing by the number of users of individual stations daily.
(2) Passive effectiveness index In the time slots when outdoor air temperature and humidity is high, we cannot expect to improve the indoor environment by ventilation. We hence defined a certain ratio (A/B) as the passive effectiveness index. Here, A is the number of the persons who did not accept the thermal environment in the time slots in which the indoor SET* was lower than 32 ºC when outdoor and indoor temperature and humidity are equal to each other, and B is the number of those persons for the whole day. The larger the passive effectiveness index of a station is, the more effective improvement of ventilation of such station using outdoor air (outdoor wind) is. Fig. 2 shows the ratio of users in thermally unacceptable time slots and the passive effectiveness index, both at each measurement point.The measurement points at which the ratio of the users in
the thermally unacceptable time slots was greater than 50% included O-2, SJ-1, O-3, MK-1, H-1, SN-1, and E-1. Those excluded measurement points in overpasses of simple structure and specification without ceiling material. Those measurement points were classified as having valley type and other type patterns. With some exceptions, the passive effectiveness index was high at the measurement points at which the ratio of the users in thermally unacceptable time slots was high. In contrast, at and around measurement points where no thermally unacceptable time slots were recorded, there was a station structure that facilitates ventilation. Such structure features include large openings for ventilation and short distance from the measurement point to the outdoors.
Analysis of Factors Causing Deterioration of Thermal Environment5
5.1 Effect of InsolationFig. 3 shows the weather and the maximum differences between indoor and outdoor air temperature on sunny weekdays and cloudy weekdays and the temperature difference between on sunny days and cloudy days. There were seven measurement points at which the maximum temperature difference between on sunny days and cloudy days was larger than 1.5 ºC, often observed at measurement points having a mountain type pattern in overpasses.
At those measurement points, insolation possibly had a great effect due to the lack of ceiling material and the roof surface being exposed to sunlight. We therefore recommend improvement to shield sunlight and to add ceiling material.
5.2 Effect of Insufficient VentilationFig. 4 shows the relationship between the indoor CO2 concentration and the ratio of the thermally unacceptable time slots. A larger the ratio of thermally unacceptable time slots was seen when the indoor CO2 concentration was larger, mainly at measurement points in concourses classified as having a valley type pattern or other type pattern. Thermal stagnation possibly occurs in zones with insufficient ventilation.
Examination of Improvement Measures6
Nakano et al.3) showed that the direction of outdoor prevailing wind around stations in the greater Tokyo area is often parallel to the track. In this context, we defined the area of openings in contact with outdoor air on walls at a right angle to the track as the area of the ventilation opening, and the area overlapping such openings on two opposing walls as the area of the effective ventilation opening. We further defined the area of effective ventilation opening divided by the area of the walls as the ratio of effective ventilation opening (Fig. 5). To show the relationship between structure of a station and its indoor thermal environment, we analyzed the correlation between the ratio of effective ventilation opening and the ratio of thermally unacceptable time slots. Fig. 6 shows that correlation separately for 0% and other ratios of effective ventilation opening. At the measurement points in the overpass and concourse of over-track stations, we found a tendency for the ratio of thermally unacceptable time slots to decrease as the ratio of the effective ventilation opening increased. This could be because indoor thermal stagnation was solved by inducing ventilation at the measurement points with a high ratio of effective ventilation opening. We saw, in contrast, little correlation at measurement points in concourses of under-viaduct stations and at points of 0% ratio of the effective ventilation opening. Those measurement points were located in stations that had no measurement points at opposing openings and in large-scale stations with no walls around the measurement points. We think that the tendency of improvement can be identified for spaces between openings in overpasses and concourses of over-track stations based on the ratio of the effective ventilation opening.
Creation of Guidelines for Improvement of Thermal Environment of Stations7
Based on the results of evaluation of the thermal environment and analysis of patterns in the difference between indoor and outdoor air temperature of individual measurement points, we created design guidelines for thermal environment of stations (diagnosis flow, Fig. 7).
Airtemperature
Radiationtemperature
Relativehumidity
Measuredvalue
Regarded tobe same as air
temperatureMeasured
value
Air velocity Metaboliclevel
Amount ofclothing
0.1 [m/s] 1.6 [met] 0.5 [clo]
Ratio of users in thermallyunacceptable time slots
Ratio of users in thermally unacceptable time slotsat the condition of outdoor temperature SET*32 ºC or lower
Passive effectivenessindex (A/B)
Rat
io o
f use
rs [%
]
Pas
sive
effe
ctiv
enes
s in
dex
[%]
OI-1
Val
.
YR
-1 V
al.
YR
-3 V
al.
KA
-1 V
al.
KS
-1 V
al.
KS
-2 V
al.
KE
-1 O
th.
OG
-2 V
al.
NO
-1 O
th.
E-2
Val
.
OM
-1 V
al.
Y-1
Val
.
KS
-3 O
th.
SS
-1 O
th.
SH
-1 O
th.
SS
-2 O
th.
NS
-2 V
al.
YR
-2 V
al.
Y-2
Oth
.
OG
-1 M
nt.
MG
-1 V
al.
C-1
Mnt
.
SH
-3 O
th.
OM
-2 O
th.
TB-3
Oth
.
NS
-1 V
al.
K-1
Oth
.
U-1
Oth
.
SH
-2 O
th.
KM
-3 O
th.
TM-2
Oth
.
U-3
Mnt
.
KM
-1 O
th.
K-2
Oth
.
OI-2
Val
.
MJ-
2 O
th.
SG
-1- V
al.
KM
-2 O
th.
SJ-
2 M
nt.
O-1
Oth
.
NP
-2 M
nt.
TA-1
Oth
.
TM-3
Oth
.
MJ-
1 M
nt.
NP
-1 M
nt.
I-1 M
Mnt
.
U-2
Mnt
.
TB-1
Mnt
.
E-1
Val
.
SN
-1 V
al.
TB-2
Mnt
.
H-1
Oth
.
MK
-1 O
th.
O-3
Val
.
SJ-
1 V
al.
O-2
Val
.
Table 3 SET* Calculation Conditions
Fig. 2 Ratio of Users in Thermally Unacceptable Time Slots at Individual Measurement Points
32 JR EAST Technical Review-No.28
Special edition paper
Step 1: Pick out stations that have problems in their thermal environment based on measurement results of indoor temperature and humidity and data on the number of passengers passing through the ticket gates.
Step 2: Find the factors causing deterioration of the thermal environment based on analysis of the pattern of the difference between indoor and outdoor air temperature. In each pattern, the factors that have the most impact are insolation and insufficient ventilation amount.
Step 3: Determine the measures for improvement. We suggested shielding sunlight and adding ceiling material for the mountain type pattern, increasing the ratio of effective ventilation opening for stations with valley and other type patterns with a high passive effectiveness index, and introducing air-conditioning and other equipment for stations of those patterns with a low passive effectiveness index.
Conclusion8We carried out measurement of the thermal environment at stations in the greater Tokyo area and classified the measurement zones of the stations into patterns for indoor thermal environment. The results revealed that the difference between indoor and outdoor air temperature could be roughly divided into four patterns.
Based on the measurement results, we evaluated the thermal environment level of individual measurement points. As the improvement effect users can feel would be greater at stations with a larger number of users in the thermally unacceptable time slots, we applied an evaluation method taking into account the variation characteristics of the number of users per station.
Finally we created guidelines for improvement of the thermal environment of stations (diagnosis flow), taking account of the measurement results and the investigation of factors that cause deterioration of the indoor thermal environment. The guidelines consist of three steps, assuming improvement will be accomplished by a passive system as much as possible.
Afterward9When making an effort to improve the thermal environment of a station, it can be presumed that the guidelines for improvement of the thermal environment of stations (diagnosis flow) we created in this article cannot be applied as-is due to the restrictions in workability or the balance between budget and construction costs required. We think, however, that it would still be effective to make use of the guidelines as a reference to decide the priority of improvement. We are planning to propose the study results of this paper to the Tokyo Branch Office, which is considering development of a thermal environment improvement plan.
In the implementation and analysis of the survey, we received great help and advice from Mr. Junta Nakano, Associate Professor, Department of Architecture and Building Engineering, School of Engineering, Tokai University; and Mr. Daiki Kawamata, Mr. Ken Unno, Mr. Shun Kato, Ms. Eriko Kuzuu, and Mr. Naoki Ikeda, Master’s Course of the Department of Architecture, Creative Science and Engineering Graduate School, Waseda University. We would like to express our gratitude to those people for their cooperation.
Reference:1) Ken Unno et al., “Mitigation of Summer Thermal Environment in
Railroad Stations : Part 1 and 2 [in Japanese]”, Proceedings of the Annual Convention of Architectural Institute of Japan, D-2 (2013)
2) Japan Meteorological Agency: http://www.jma.go.jp/jma/indexe.html3) Junta Nakano et al., “Field Survey on Thermal Comfort in Railroad
Stations : Part 1 to 32 [in Japanese]”, Proceedings of the Annual Convention of Architectural Institute of Japan, D-2 (2005, 2006, 2007, 2008, 2009, 2010)
Sunny day Cloudy day Difference betweenon sunny day and cloudy day
Diff
eren
ce [º
C]
U-3
Mnt
.
MK
-1 O
th.
SJ-
1 V
al.
E-1
Val
.
MJ-
2 O
th.
T-3
Oth
.
Y-1
Val
.
K-2
Oth
.
U-1
Oth
.
O-3
Val
.
SG
-1- V
al.
SN
-1 V
al.
K-1
Oth
.
MG
-1 V
al.
NS
-1 V
al.
C-1
M
SS
-1 O
th.
SS
-2 O
th.
O-2
Val
.
NS
-2 V
al.
MJ-
1 M
nt.
OG
-1 M
nt.
NP
-2 M
nt.
NP
-1 M
nt.
I-1 M
nt.
AK
-4 M
nt.
T-2
Mnt
.
U-2
Mnt
.
SJ-
2 M
nt.
T-1
Mnt
.
Indoor CO2 concentration [ppm] Effective ventilation opening [%]
Rat
io o
f the
rmal
ly u
nacc
epta
ble
time
slot
s [%
]
Overpass
Over-track station, Overpass Over-track station, ConcourseOver-track station, Overpass (0) Over-track station, Concourse (0)Under-viaduct station, ConcourseLinearity (over-track station, overpass)
Linearity (over-track station, concourse)Concourse
Linearity (concourse)
Effective ventilationopening area
Ventilationopening area
Image of calculation of effective ventilation opening areaEffective ventilationopening area [m2]
Zone wall area [m2] Ratio of effective
ventilation opening [%] × 100=
Measurement ofindoor temperature & humidity
No. of passengers passingthrough ticket gates
Valley type
Passive effectiveness index
High
Possibility of increasingeffective ventilation
opening area
Mountain typeOther
(constant type)Other
(greater in evening)
Pattern analysis ofdifference between indoorand outdoor temperature
■Step 1Determination of stations with high priority for improvement
■Step 2Sorting Out of Factors Causing Deterioration of Thermal Environment
■Step 3Diagnosis of Effective Improvement Measures
<Thermal comfort zone>Ratio of persons not accepting
at SET* 32 ºC or higher
Shielding sunlightFinish ceiling, etc.
Install opening
Consider introducingair conditioning
and other equipment
Consider introducing ofair conditioning
and other equipment
Low
LowHigh
Ratio of effectiveventilation opening
“Give priority to stationswith higher ratio”
Fig. 3 Maximum Difference Between Indoor and Outdoor Air Temperature on Sunny and Cloudy Days
Fig. 6 Correlation Between Effective Ventilation Opening and Ratio of
Thermally Unacceptable Time Slots
Fig. 5 Image of Calculation of Effective Ventilation Opening Area
Fig. 4 Correlation Between Indoor CO2 Concentration and Ratio of Thermally
Unacceptable Time Slots
Fig. 7 Guidelines for Improvement of Thermal Environment of Stations (Diagnosis Flow)