BRE Energy Efficient Office of the Future

Transcription

1 BRE Energy of the Future

2 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. 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.

3 presentation (2 ) Lecture theatre N Plan view of ground floor Circulation zone Main building Atrium

4 The! The design brief called for outstanding energy performance. The Performance Specification, a key element brief, dictates performance targets for energy consumption and carbon dioxide (CO 2 ) emissions. The targets (47 kwh/m² for gas - 36 kwh/m² for electricity - 34 kg/m² CO 2 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 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

5 The building (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 is used to: " Improve the thermal comfort: Intensive (night) ventilation can be applied to cool down the thermal mass (exposed ceilings). " Control the IAQ: The occupants can open windows to control the IAQ exposed ceilings

6 The building (2...) ventilation strategy Stack ventilation on hot still summer s day Voids in the ceiling slab

7 The building (3...) ventilation strategy Cross ventilation on windy summer s day Many ventilation openings are automatically controlled. However can override the automatic settings for windows

8 The building (4 ) shading and lighting! Solar gains are reduced by moveable external louvres on the South side. 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. External louvres Lighting: control sensor

9 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. Atrium! The following parameters were measured: Open plan Room 1 Room 2 Corridor zone Ventilation stacks " Internal and external CO 2 concentration as an indicator of IAQ. " Fresh air flow rates and local wind speed and direction. " External air and internal air and globe temperatures. N

10 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 CO 2 -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 rate (1/h) Room 2 ach Room 1 ach, air change rate in the monitored rooms :00 1/8/98 19:00 1/12/98 23:00 16/01/1998 Date/Time 3:00 21/01/1998 7:00 25/01/ :00 29/01/1998

11 monitoring (2...) CO 2 -concentrations! CO 2 concentrations are generally below the limit of 1200 ppm. The IAQ is acceptable! Increased levels of CO 2 coincide with occupancy. Carbon dioxide (ppm) , carbon dioxide concentration in the monitored rooms. External CO 2 Room 2 CO 2 Room 1 CO :00 1/8/98 19:00 1/12/98 23:00 16/01/1998 Date/Time 3:00 21/01/1998 7:00 25/01/ :00 29/01/1998

12 monitoring (3 ) temperatures! Temperatures were between 2 to 5 o C above the design minimum temperature (18 C).! There was little difference between air and globe temperatures. Temperature (degc) air and globe temperatures in the monitored rooms. Room 1 globe temp Room 2 globe temp External temp 0 15:38:26 14/01/ :38:26 17/01/98 7:38:26 21/01/98 Date/Time 16:29:28 24/01/98 0:29:28 28/01/98

13 monitoring (1...) air change rates! 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 Rate (1/h) Room 1 Room 2 air change rates in the monitored offices. 0 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

14 monitoring (2...) CO 2 -concentrations! CO 2 concentrations were generally below 1000 ppm. The IAQ is acceptable Carbon dioxide concentration (ppm) External Room 1 Room 2 carbon dioxide concentrations in monitored rooms. 0 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

15 monitoring (3 ) temperatures! The 28 C design maximum temperature was not exceeded.! The 25 C lower design temperature was exceeded on some occasions. Air Temperature (degc) External air temps Room 1 air temps Room 2 air temps air temperatures in the monitored rooms /7/ /8/ /8/ /8/ /8/ /8/ /8/ /8/97 17 Date/Time

16 (1...)! Indoor Climate: " Adequate ventilation is provided. " Internal air quality is acceptable. " Comfortable internal temperatures are achieved.! 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. over, 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.

17 (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. Air Temperature degc one weeks external and internal air temperatures during August Office External /08 07/08 08/08 09/08 10/08 11/08 12/08 13/08 Date/Time

18 Find more information on the PROBE building in the following documents: \Reports \ Reports \Summary Reports\gb1summ.pdf " global presentation s (±4p./building) " contents: building description - ventilation strategy and technology - winter and summer monitoring results - conclusions \Reports \ 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: OR run the installation file ar32e301(1).exe in the directory \Installation