Queens BuildingOctober 2006

Roderic Bunn revisits De Montfort University's Queens Building, an award-winning project considered a trailblazer of passive solar design. How is it performing a decade on?

Completed in late 1993, the Queens Building at De Montfort University was lauded at the time for being the first in a new generation of low energy, naturally ventilated buildings. In 1996, it was subject to a post-occupancy analysis under the PROBE project. Ten years later, BSRIA has returned to see how the Queens Building has fared since the PROBE investigation.

Design description and history

The original brief for the Queens Building called for innovative solutions that would reflect the creative nature of the then-new university. The architects were Short-Ford Associates and environmental engineers Max Fordham LLP, backed-up by a team of advisers, such as Cambridge Architectural Research on the stack-effect chimneys, and Bristol University on the physics of airflow.

The result was a highly insulated, thermally-massive envelope with mostly shallow-plan floor plates and generous ceiling heights. The 10 000 m2 building is L-shaped, with the south-facing wing comprising a full-height engineering laboratory, and a four-storey east wing containing a complex arrangement of laboratories, classrooms and offices. The wing is separated by a long, winding lightwell that connects to two auditoriums.

The building is almost exclusively naturally ventilated: cross-ventilation for the narrow wings, and chimney stack-assisted for the main building. The top floors are ventilated by motorised ridge windows.

Results of the original PROBE survey

The PROBE research team found that the commissioning period was compressed into a six-week window before the start of term in October 1993. Unresolved defects meant that the building operated for the first two years with problems in critical mechanical and control systems. For example, motors and actuators serving the rooflights were not properly commissioned, with the result that many motors burned out trying to drive the actuators past their stops.

The building's thermal massing and natural ventilation seemed to be effective at maintaining a comfortable environment, although the occupant survey conducted by Building Use Studies (BUS) showed dissatisfaction with high summertime temperatures, particularly on the third floor, and stuffiness in both winter and summer.

The PROBE researchers found that even copious amounts of daylight were not enough to displace electric lighting. This appeared to be a failing of the control systems and the building's users. Noise was the greatest cause for concern, largely stemming from the open-plan areas that were alien to academic researchers who were used to private labs and offices.

The building's low energy claims were largely borne out in practice. Based on a treated floor area of 8400 m2, gas and electricity consumption was 143 kWh/m2/y and 52 kWh/m2/y respectively. This compared favourably with the Energy Efficiency Offices' low target consumption for university buildings of 185 kWh/m2/y and 75 kWh/m2/y respectively.

Ten years on

In the last ten years some parts of the building have changed dramatically while other zones are much as they were in 1993.

The desk-based staff of the Institute of Energy and Sustainable Design (IESD) now occupy the former M&E laboratory, while the double-height, single space of the heavy engineering laboratory has been separated by a mezzanine floor with laboratories on the first floor. The smaller engineering facility on the ground floor now shares space with media units and TV studios.

Energy performance data has been gathered by IESD staff, who have taken an active interest in improving their own space while keeping a keen watch on other parts of the building.

Based in what was the M&E lab, the IESD staff enjoy a large, double-height space that has single-sided natural ventilation with stack-assisted exhaust through motorised rooflights. The copious daylighting from the west-facing elevation came with a glare penalty with low angle sun, something which didn't bother the previous occupants. Full-height blinds with beaded pull-cords have been installed, and the IESD staff use them regularly.

The IESD has replaced the motors for the rooflights. The original motors burned out shortly after they were first installed.

"The Queens Building was one of the first of the new generation of naturally ventilated buildings, and engineers weren't sure how powerful the motors had to be, or how far they should drive open the windows," explained the IESD's Dr Malcolm Cook. "As a result the motors were under too much strain."

A decade might seem an inordinately long time for failed motors to be replaced, but the engineering staff weren't bothered by the leaky rooflights, being able to both move around, and be warmed by large, heat-generating machinery. Today, the IESD staff can open and close the rooflight vents via wall-mounted switches.

The windows serving the IESD offices are mostly manually openable, with a few fitted with new motorised actuators to facilitate night cooling. Once a new bms is commissioned, the motorised openings will enable the IESD to introduce a night-cooling regime.

The pivot mechanism for the manually-openable windows has two settings: open and closed, with no intermediate position. This might have been acceptable for a machine shop, but sedentary staff require finer control. IESD staff have improvised ways of wedging the windows, finding that different-sized rolls of Sellotape give different rates of ventilation.

The third floor of the Queens Building was originally designed as an open-plan drawing studio, with copious amounts of daylight from glazed ventilators in the roof gables, and large, triangular windows on the east-facing elevation.

Drawing boards went out of fashion very early on, and the space was subsequently used by other departments. Today, it is home to banks of computers for student use. As in the machine shop, the motors serving the ridge ventilators soon burned out. Previous occupants of the space found ways to wedge open the ventilators, but at the time of writing the vents were found to be closed and the power turned off.

There seems little effective ventilation in the space. With a lack of thermal mass in the roof, heat from the computers and hot air rising up from low levels, the former drawing studio is a hot space in summer.

Auditoriums

The hemispherical auditoriums sit side-by-side along the north-west elevation, with the second auditorium rotated through 180°, ostensibly as a space-saving manoeuvre. Both rely on buoyancy-driven ventilation, with incoming air tempered by traversing a concrete plenum beneath the seating and extracted through tall, insulated chimneys. The strategy has worked well for the auditorium that is orientated with its raked seating backing onto the road, but has arguably failed for the other auditorium.

Some incoming air for auditorium 1.12 traverses a convoluted route to reach the seating plenum, but the greater proportion takes the line of least resistance, entering the space directly past heating coils set into the perimeter wall. The incoming air is simply not in contact with the heating coils long enough to raise its temperature, and a lack of turbulent flow creates serious stratification problems. The result can lead to an 8°C difference between the upper and lower seating areas. Malcolm Cook thinks that blanking off a section of the supply grille may encourage better mixing.

Heavy engineering wing

The former heavy engineering hall has undergone a significant change of use, a reflection of the University's shift away from engineering to maths, chemistry and media studies.

The installation of a mezzanine, internal solid walls and partitions on the first floor to create laboratories required a complete rethink of the ventilation strategy.

Originally, fresh air entered the ground floor machine hall via ventilated buttresses.

Today, this air now crosses the machine hall and enters a central corridor via a series of transfer grilles. Extract is then out through the original ridge ventilators.

The only way the first floor laboratories could be ventilated was by knocking vents at first floor level into the ventilated buttresses, and relying on enough natural buoyancy to drive the ventilation through the ridge ventilators.

In practice, the laboratories do not seem to get enough air, and conditions are noticeably uncomfortable. The wing has also undergone further changes of use since the ventilation system was reconfigured, and in places it seems unable to cope.

Occupants of the labs also suffer glare from the apex windows, way beyond their reach, and currently they have no blinds or other mechanism by which to control it.

Energy consumption

In 1996, gas and electricity consumption was 143 kWh/m2/y and 52 kWh/m2/y respectively. In 2004, the energy figures were 176 kWh/m2/y for gas and 87 kWh/m2/y for electricity - close to the original EEO benchmark but still heading the wrong way.

While the increase in electrical use may be a combination of more computers and a change of use of the engineering wing, the relatively inefficient electric feature lighting in the main concourse has also defaulted to on, despite very good daylighting. Lighting control in many open plan areas and laboratories also seems non-existent or nonsensical in operation. (In one lab, the fluorescent lights were on in the daylit perimeter, but off in the central area.) A notable exception is the offices for the IESD where a daylight-linked dimming system has been installed.

The increase in gas consumption is largely attributable to problems with the heating system. Three major problems were resolved in 2005: re-zoning of the heating system so that demand for heat in one area of the building doesn't bring on the heating in others, extra pipework to create new heating zones, and the replacement of seized two and three-port valves. Energy figures for 2005 may show an improvement.

Occupant satisfaction survey

The BSRIA revisit to the Queens Building was conducted in early August 2006. Ostensibly the holiday season, over 50 permanent members of staff were working in the building. An occupant survey was carried out by Building Use Studies. Forty five BUS questionnaires were completed (compared to 75 in 1996).

In general terms, satisfaction with temperature in both summer and winter is the same, although occupants perceive the air in winter to be better. Productivity has improved by around four percent, but the building still suffers a minus score as it did in 1996. Lighting and noise scores are better.

Levels of occupant satisfaction are very dependent on location. For example, the relatively high occupant satisfaction in the refurbished IESD offices is not matched by those occupying the new laboratories.

Conclusions

Does the building deserve its iconic status?

History records that the architecture of the Queens Building has ploughed a lonely design furrow. Given that so much of the building's ventilation and daylighting is determined by its bricks and mortar, the Queens Building is rather stuck in a time warp. It's difficult to improve or alter it, apart from changes to heating circuits and replacements of valves and motors. Elements such as these are not fit-and-forget - they are critical to the building's operation, energy efficiency and occupant comfort.

The saving grace of the Queens Building is that its occupants seem willing to forgive the building's transgressions on comfort and lack of user control in the belief that they are working in a building worthy of being loved for its very idiosyncrasies.

BSRIA acknowledges the help of the Institute of Energy and Sustainable Development, and Adrian Leaman of Building Use Studies for use of the BUS occupant satisfaction survey.

For more information contact Roderic Bunn at BSRIA:

T: 01344 465516
E: roderic.bunn@bsria.co.uk