natvent bre energy efficient office of the future presentation of the building presentation of the...

NatVent

BRE Energy Efficient Office of the Future

Presentation Presentation of the buildingof the building

Building Building conceptconcept

ConclusionsConclusions

The Energy The Energy Efficient OfficeEfficient Office

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Design IssueDesign Issue

MonitoringMonitoring

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WinterWinter

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Building presentation (1...)

The building was designed by Architects Fielden Clegg Design.

The building has three storeys in two blocks connected by an atrium at the west wall of the building. The main axis is running east-west.

The ground and first floor contain open plan and cellular offices. The second floor is a large open plan office.

On the ground floor there is a large lecture theatre to the north. This is connected to the main building by a circulating zone containing toilets and a display area.

The building was designed by Architects Fielden Clegg Design.

The building has three storeys in two blocks connected by an atrium at the west wall of the building. The main axis is running east-west.

The ground and first floor contain open plan and cellular offices. The second floor is a large open plan office.

On the ground floor there is a large lecture theatre to the north. This is connected to the main building by a circulating zone containing toilets and a display area.

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Building presentation (2|)

NLecture theatre

Plan view of ground floorPlan view of ground floor

Atrium

Circ

ula

tion

zo

ne

Main building

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The Design Issue The design brief called for ‘outstanding energy performance’. The

Performance Specification, a key element of the building brief, dictates performance targets for energy consumption and carbon dioxide (CO2 ) emissions. The targets (47 kWh/m² for gas - 36 kWh/m² for electricity - 34 kg/m² CO2 emission) represent a 30% improvement on current best practice and were to be met by:

avoiding or minimising the use of air-conditioning maximising the benefits of the building fabric in terms of reducing the heating and

cooling loads minimising the use of artificial lighting while actively exploiting daylight applying the appropriate level of automatic and user control

However, energy efficiency is only acceptable within the parameters of a comfortable and healthy working environment. The internal design conditions for thermal comfort were:

For winter: 18°C minimum internal temperature For summer:

– 25°C is not to be exceeded for more than 5% and – 28°C is not to be exceeded for more than 1% of the year

The design brief called for ‘outstanding energy performance’. The Performance Specification, a key element of the building brief, dictates performance targets for energy consumption and carbon dioxide (CO2 ) emissions. The targets (47 kWh/m² for gas - 36 kWh/m² for electricity - 34 kg/m² CO2 emission) represent a 30% improvement on current best practice and were to be met by:

avoiding or minimising the use of air-conditioning maximising the benefits of the building fabric in terms of reducing the heating and

cooling loads minimising the use of artificial lighting while actively exploiting daylight applying the appropriate level of automatic and user control

However, energy efficiency is only acceptable within the parameters of a comfortable and healthy working environment. The internal design conditions for thermal comfort were:

For winter: 18°C minimum internal temperature For summer:

– 25°C is not to be exceeded for more than 5% and – 28°C is not to be exceeded for more than 1% of the year

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The building concept (1...) natural ventilation

Natural ventilation has been utilised to minimise the use of fans.

The ground and 1st floors are stack driven using solar towers on the southern façade. The 2nd floor has cross ventilation via openable windows. (see next slides..)

Voids in the ceiling slab act as ducts bringing air in from outside and exhausting air out to ventilation stacks.

Natural ventilation has been utilised to minimise the use of fans.

The ground and 1st floors are stack driven using solar towers on the southern façade. The 2nd floor has cross ventilation via openable windows. (see next slides..)

Voids in the ceiling slab act as ducts bringing air in from outside and exhausting air out to ventilation stacks.

Natural ventilation is used to: Improve the thermal comfort:

Intensive (night) ventilation can be applied to cool down the thermal mass (exposed ceilings) of the building.

Control the IAQ:

The occupants can open windows to control the IAQ

Natural ventilation is used to: Improve the thermal comfort:

Intensive (night) ventilation can be applied to cool down the thermal mass (exposed ceilings) of the building.

Control the IAQ:

The occupants can open windows to control the IAQ

exposed ceilingsexposed ceilings

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The building concept (2...) ventilation strategy

Voids in the ceiling slabVoids in the ceiling slab

Stack ventilation on hot still summer’s day

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The building concept (3...) ventilation strategy

Cross ventilation on windy summer’s day

Many ventilation openings are automatically

controlled. However can override the

automatic settings for windows

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The building concept (4|) shading and lighting

Solar gains are reduced by moveable external louvres on the South side of the building. These louvres improve the thermal summer comfort, but also control glare while still allowing daylight.

A fully integrated, intelligent and efficient lighting system has been installed which automatically compensates for daylight levels and occupancy, controlling each light separately. In this way the internal gains of lighting are minimised and linked to the available daylight. Reducing the internal gains of lighting is an important step toward summer comfort in office buildings.

Solar gains are reduced by moveable external louvres on the South side of the building. These louvres improve the thermal summer comfort, but also control glare while still allowing daylight.

A fully integrated, intelligent and efficient lighting system has been installed which automatically compensates for daylight levels and occupancy, controlling each light separately. In this way the internal gains of lighting are minimised and linked to the available daylight. Reducing the internal gains of lighting is an important step toward summer comfort in office buildings.

Lighting: control sensor

Lighting: control sensor

External louvres

External louvres

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Monitoring the building The building was

monitored in summer and winter.

Two rooms on the 1st floor were monitored. The rooms were used normally by occupant.

Night cooling was utilised during the summer months.

The building was monitored in summer and winter.

Two rooms on the 1st floor were monitored. The rooms were used normally by occupant.

Night cooling was utilised during the summer months.

Room 1 Room 2

Open plan

Ventilation stacks

Corridor zone

AtriumN

The following parameters were measured: Internal and external CO2 concentration as an indicator of IAQ. Fresh air flow rates and local wind speed and direction. External air and internal air and globe temperatures.

The following parameters were measured: Internal and external CO2 concentration as an indicator of IAQ. Fresh air flow rates and local wind speed and direction. External air and internal air and globe temperatures.

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Winter monitoring (1...) air change rates

Air change rates are similar in both rooms. Higher ventilation rates coincide with periods of occupancy. There is some correlation of air change rate with wind speed and direction. Air change rates were adequate in both rooms: the CO2 -concentrations are not too

high (see next slide) and the air supply is almost zero outside the office hours (reduction of ventilation losses).

Air change rates are similar in both rooms. Higher ventilation rates coincide with periods of occupancy. There is some correlation of air change rate with wind speed and direction. Air change rates were adequate in both rooms: the CO2 -concentrations are not too

high (see next slide) and the air supply is almost zero outside the office hours (reduction of ventilation losses).

Winter, air change rate in the monitored rooms.

0

1

2

3

4

5

6

7

8

9

10

15:001/8/98

19:001/12/98

23:0016/01/1998

3:0021/01/1998

7:0025/01/1998

11:0029/01/1998

Date/Time

Air

ch

ang

e ra

te (

1/h

)

Room 2 ach

Room 1 ach

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CO2 concentrations are generally below the limit of 1200 ppm. The IAQ is acceptable

Increased levels of CO2 coincide with occupancy.

CO2 concentrations are generally below the limit of 1200 ppm. The IAQ is acceptable

Increased levels of CO2 coincide with occupancy.

Winter monitoring (2...) CO2-concentrations

Winter, carbon dioxide concentration in the monitored rooms.

0

200

400

600

800

1000

1200

1400

1600

15:001/8/98

19:001/12/98

23:0016/01/1998

3:0021/01/1998

7:0025/01/1998

11:0029/01/1998

Date/Time

Car

bo

n d

ioxi

de

(pp

m)

External CO2

Room 2 CO2

Room 1 CO2

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Temperatures were between 2 to 5oC above the design minimum temperature (18°C).

There was little difference between air and globe temperatures.

Temperatures were between 2 to 5oC above the design minimum temperature (18°C).

There was little difference between air and globe temperatures.

Winter monitoring (3|) temperatures

air and globe temperatures in the monitored rooms.

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0

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10

15

20

25

15:38:2614/01/98

23:38:2617/01/98

7:38:2621/01/98

16:29:2824/01/98

0:29:2828/01/98

Date/Time

Tem

per

atu

re (

deg

C) Room 1 globe temp

Room 2 globe temp

External temp

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Air change rates in room 1 were higher than those in room 2, possibly due to poor mixing as a result of opening windows.

Again higher ventilation rates coincide with occupancy. Air change rates were adequate during occupied periods. Both offices were closed and locked at night and so did not benefit from night

ventilation.

Air change rates in room 1 were higher than those in room 2, possibly due to poor mixing as a result of opening windows.

Again higher ventilation rates coincide with occupancy. Air change rates were adequate during occupied periods. Both offices were closed and locked at night and so did not benefit from night

ventilation.

Summer monitoring (1...) air change rates

air change rates in the monitored offices.

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15

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25

30

31/7/97 15:24 2/8/97 17:19 6/8/97 13:53 8/8/97 15:57 10/8/97 17:52 13/8/97 10:22 15/8/97 12:26

Date/Time

Air

Ch

ang

e R

ate

(1/h

)

Room 1

Room 2

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Summer monitoring (2...) CO2-concentrations

CO2 concentrations were generally below 1000 ppm. The IAQ is acceptable CO2 concentrations were generally below 1000 ppm. The IAQ is acceptable

carbon dioxide concentrations in monitored rooms.

0

300

600

900

31/7/97 15:21 2/8/97 17:16 6/8/97 13:50 8/8/97 15:54 10/8/97 17:49 13/8/97 10:19 15/8/97 12:23

Date/Time

Car

bo

n d

ioxi

de

con

cen

trat

ion

(p

pm

)

ExternalRoom 1Room 2

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The 28°C design maximum temperature was not exceeded. The 25°C lower design temperature was exceeded on some occasions.

The 28°C design maximum temperature was not exceeded. The 25°C lower design temperature was exceeded on some occasions.

Summer monitoring (3|) temperatures

air temperatures in the monitored rooms.

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26

28

30

31/7/97 16 2/8/97 08 4/8/97 00 7/8/97 10 9/8/97 02 10/8/97 18 12/8/97 10 14/8/97 17

Date/Time

Air

Tem

per

atu

re (

deg

C)

External air tempsRoom 1 air temps

Room 2 air temps

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Conclusions (1...)

Winter Indoor Climate: Adequate ventilation is provided. Internal air quality is acceptable. Comfortable internal temperatures are achieved.

Summer Indoor Climate Adequate ventilation is provided. Comfortable temperatures are maintained though the lower design

temperature was sometimes exceeded during warm spells.

The building has external louvres to reduce the solar gains. Moreover, the building makes use of night cooling. Cooler night time air is drawn in via the openable windows and ceiling voids. Fans in the ventilation towers can be used to assist purging. Ground water cooling can also be used.

Winter Indoor Climate: Adequate ventilation is provided. Internal air quality is acceptable. Comfortable internal temperatures are achieved.

Summer Indoor Climate Adequate ventilation is provided. Comfortable temperatures are maintained though the lower design

temperature was sometimes exceeded during warm spells.

The building has external louvres to reduce the solar gains. Moreover, the building makes use of night cooling. Cooler night time air is drawn in via the openable windows and ceiling voids. Fans in the ventilation towers can be used to assist purging. Ground water cooling can also be used.

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Conclusions (2|)

The good solar control and combination of high thermal mass and night ventilation did result in lower temperatures and helped maintain comfort. By using ground water cooling the lower design temperature (25°C) could be met.

The good solar control and combination of high thermal mass and night ventilation did result in lower temperatures and helped maintain comfort. By using ground water cooling the lower design temperature (25°C) could be met.

one weeks external and internal air temperatures during August 1997.

15

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31

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06/08 07/08 08/08 09/08 10/08 11/08 12/08 13/08

Date/Time

Air

Te

mp

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ture

de

gC

Office

External

More information...

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Find more information on the PROBE building in the following documents:

\Reports \Monitoring Reports \Summary Reports\gb1summ.pdf global presentation of the buildings (4p./building) contents: building description - ventilation strategy and technology -

winter and summer monitoring results - conclusions

\Reports \Monitoring Reports \Detailed Reports\gb1det.pdf detailed reports of all 19 monitoring campaigns (20p./campaign) contents: monitoring set up - analysis of results - conclusions

Find more information on the PROBE building in the following documents:

\Reports \Monitoring Reports \Summary Reports\gb1summ.pdf global presentation of the buildings (4p./building) contents: building description - ventilation strategy and technology -

winter and summer monitoring results - conclusions

\Reports \Monitoring Reports \Detailed Reports\gb1det.pdf detailed reports of all 19 monitoring campaigns (20p./campaign) contents: monitoring set up - analysis of results - conclusions

You can read and print pdf-files with the Acrobat® Reader ®3.0. Program. This program is free.

Download it from the Acrobat web site: www.adobe.com OR run the installation file ar32e301(1).exe in the directory \Installation

You can read and print pdf-files with the Acrobat® Reader ®3.0. Program. This program is free.

Download it from the Acrobat web site: www.adobe.com OR run the installation file ar32e301(1).exe in the directory \Installation

natvent bre energy efficient office of the future presentation of the building presentation of the...

Documents

building brief

building fabric

natvent presentation

energy consumption

energy efficiency

design brief

future presentation

outstanding energy performance