Flexible office space With shallow-plan floor plates measuring 30 脳 13.8 m, the office wing combines open-plan and cellular offices. The structural grid of internal columns is arranged asymmetrically, with the narrower side of each floor allocated to cellular offices and the wider side to open-plan offices.
The BRE has a policy of weaning its specialist researchers out of their individual offices and into interactive groups. Tom Harvey, an early occupant of the building, comments: "People tended to move out of the cellular offices into the open plan. What made it easier to do so was the pleasantness of the building."
Comfort
Stable internal environment
Despite its lack of air-conditioning or refrigerant cooling, the building provides a stable, comfortable internal environment throughout the year. Monitoring the building during its first year of occupation, James Fisher of the BRE's energy division found that 87% of occupants were satisfied with overall comfort in winter and 69% in summer. The same respondents recorded comfort satisfaction levels of only 37% in winter and 18% in summer about their previous offices .
In terms of comfort levels, the building performed better than expected. Temperature levels within the offices exceeded 25掳C for less than 2% of occupied hours 鈥� three times better than the performance target. Only the top floor suffered from temperatures over 28掳C, but this was for just 0.2% of occupied hours, whereas the performance target was 1%. When external temperatures regularly peaked at 34掳C one week in August, the internal temperature on the first floor never rose above 27掳C. Other comfort factors, such as humidity, ventilation and air quality, all performed well.
Steve Moncrieff, head of the BRE's facilities team, confirms: "It's the only building out of the 74 at Garston where staff don't phone up to say they're too hot or too cold. We've had only one complaint about cold mornings, and this turned out to be a software problem in the building management system, which we were able to put right."
Many elements help cool the building. Natural cross ventilation of fresh air operates day and night during hot spells, enhanced by solar-powered stacks that suck up air on the south side. South-facing windows are shaded by projecting banks of glass louvres that tilt automatically with the changing angle of the sun, and exposed precast concrete floors help stabilise swings in temperature and humidity. The exposed S-shaped floor beams link up to form an undulating ceiling that increases the heat-absorbing surface, and ducts above the downward curves of the floor slab channel fresh air from high-level windows deep into the office interiors, whether office doors are shut or not.
Underfloor cooling fed through a heat exchanger by water at a fairly constant 10掳 drawn from a 70 m deep borehole directly beneath also cools the building. The borehole system had not been commissioned during Fisher's monitoring period and so should suppress high temperatures better in future, but the heat load from occupants and equipment was underestimated as the building was not fully occupied.
The 100-seat multipurpose hall is also cooled by natural ventilation and borehole cooling, but boosted by fans. "On a hot summer day, it feels air-conditioned inside," says Mike Clift, the client's representative for the building project.
Ample daylight
Lots of daylight is provided by large windows taking up 40% of external elevations. On the south side, obscure glass louvres automatically adjust to block out sunlight and glare, while letting the daylight in. A sophisticated artificial lighting system, installed by Philips, adjusts automatically when daylight fades.
Handy user environmental controls
One of the true innovations of the building is that controls for each user are encapsulated in a personal, hand-held remote control. Occupants are provided with a "mouse-pad" on which the operating instructions are printed.
The remote control can override the central computerised building management system in the user's immediate vicinity.
It controls ventilation, by opening and shutting high-level windows; solar shading, by adjusting the angles of external louvres; the heat emitted from perimeter radiators, and the intensity of artificial lighting. Yet, although the control is easy to use, it has had teething troubles (see Maintainability).
Noisy open-plan space
About the only persistent complaint from occupants is the spread of noise within the open-plan offices. Occupants find the noise of others talking intrusive, and this is accentuated by the lack of acoustic ceilings and of any background hum of air-conditioning or traffic. This problem has recently been tackled by rearranging storage cabinets to act as acoustic baffles between groups.
Delight
Landmark architecture
One of the original aims of the demonstration project was to bring it to the attention of a wide audience by means of eye-catching architectural imagery.
Feilden Clegg's design achieves this objective with its distinctive front facade of adjustable glass louvres and row of large rooftop flues in polished stainless steel. The RIBA regional award-winning design counteracts many people's interpretation of low-energy buildings as mean-spirited brick boxes with tiny windows.
On the other hand, the front facade has been criticised for its disjointed character, with three unrelated sections featuring, from right to left, a bank of adjustable glass louvres, an entrance recess in second-hand brick with a galvanised steel canopy and a large black glass panel of photovoltaic cells.
Although not spectacular, the interiors have a pleasant, spacious feel, with generous views out and ample headroom. Their most distinctive features are the ceilings 鈥� undulating floor slabs on the lower floors and pitched timber-lined roof on the top floor.
Maintainability
Low energy consumption As intended, the building uses little gas and electricity from the mains. Even so, during the first year, energy use was 29% higher than the target, which was to cut consumption to 66% of the DETR best-practice benchmark. It was discovered that air was leaking through the timber ceilings on the top floor and the joints between the boards have since been sealed. However, virtually any shallow-plan office on a landscaped campus could operate comfortably without energy-guzzling air-conditioning.
An additional benefit of the green strategy has been that only two boilers and two heat exchangers are needed to heat and cool the 2000 m2 building, housed in a compact 30 m2 plant that accounts for less than 2% of total floor space, whereas a conventional plant would have eaten up 7% of floor space.
Uncoordinated controls
The building has had its fair share of teething troubles 鈥� which is only to be expected in a building with an array of technical innovations 鈥� mainly concerning the remote control that integrated controls to the building management system, heating, lighting, windows and the adjustable louvres.
Bob Maxim, the BRE's M&E manager, explains the problem. "The system was set up so that signals from the remote control would have to go round the five components in a loop, but occasionally the signal would jump the loop and the whole system would go out of sync and need resetting. The manufacturers were protective about their own bit and passed the blame. In the end, we had to get all five companies round a table for a troubleshooting session, but this took a good few months to organise." Another criticism from facilities manager Moncrieff is that the window controls are housed under the raised access floors where they can only be reached by moving furniture, carpet and access panels. "It would make our job easier if controls were placed on panels below the windows," he says. "We ended up drawing colour-coded bands on the carpets to mark where the controls are." Finally, there are insufficient motors to open and shut the windows. One motor was installed to drive three windows but this caused delays in their operation. Moncrieff now plans to install one motor for each opening window.
Easy maintenance
Aside from the problems of the high-tech environmental controls, the new building is easy to maintain, claims Moncrieff. "The building management system is complex because of the many interfaces between controls. But the actual moving parts in the building are not complex.
"The operations and maintenance manuals were fairly well drawn up by the design consultants," he adds. "It has been easy to develop them into a planned maintenance programme." In advanced low-energy buildings, the delicate moving parts tend to be on the outside, where they are vulnerable to the elements, wear and tear and vandalism. The new BRE building has the good fortune to be located on a secure and well-tended private estate and, after two years of operation, it is too early to comment on the long-term durability of the delicate adjustable louvres and stainless steel flues.
Defects in recycled materials
Recycled building materials were used extensively in the new BRE building: aggregate from crushed concrete, second-hand London stock bricks and hardwood parquet flooring salvaged from London's County Hall. But one year after installation, the parquet started to lift and had to be replaced. "We never discovered what the problem was," says Clift. "The old parquet could have laid out in the weather too long, or the original fixing dowels could have broken off, or the new adhesive could have been incompatible with the remaining traces of the old bitumen."
