University challenge

Summer 2002 was a new beginning for the University of Newcastle upon Tyne. A large-scale restructuring programme had just got underway in a bid to place it among the top UK universites for teaching and research. An ongoing development and investment programme in the university's infrastructure was also about to be instigated with massive capital investment made in a number of flagship schemes. Foremost among these was the £12 million Devonshire building, built to house the newly formed Institute for Research on Environment and Sustainability (IRES). If ever a building was crying out to reflect the ethos of an organisation, this was it.

From the outset the team behind the project committed itself to delivering a building that would 'achieve the highest possible standards of environmental and sustainable design', while at the same time ushering into the university a new way of working. Gone was the traditional cellularised layout that allowed scientists and researchers to hide away and in its place was an open and transparent environment encouraging interaction and better communication.

Consulting engineers White Young Green took over from Battle McCarthy to develop the scheme for RIBA Stage D, working with the original architects, local practice The Dewjoc Partnership. The resulting five-storey (plus ground) building is split into three masses:an open plan write up area, central atrium and research laboratories (see figure 1).

The scheme changed radically from Stage C to D. In addition to shaving £2 million off the build costs, discussions between the design team and user groups revealed the building needed to run much more densely than originally planned – and potentially on a 24/7 basis. The latter had a major influence particularly in terms of air loads, resulting from the need to have 100% operability at any one time for the labs and fume cupboards, a massive jump from the 30% originally planned. This was in conjunction with reducing the building height, with slab-to-slab heights down from an initial 4200 mm to 3900 mm.

The architectural aim was for a design that would maximise the amount of natural daylight. A steel frame construction is used with precast concrete floor slabs and a mix of cedar, terracotta tiles and metal panel cladding. Glazing accounts for around 70% of the south facade, which enhances natural light entering the office spaces. With this in mind external shading was introduced as an integral part of the design. Automatic motorised brise soleil are installed on the south elevation which feature horizontal aerofoil blades from floors one to five. A series of sensors mounted on the support frame allow these to track the sun's azimuth, eliminating direct solar glare. Behind this shading clear low-e glazing is used – to maximise daylighting – while solar reflective glass is used on the east and west returns.

Energy targets
The client was committed to achieving a BREEAM 'Excellent' rating for the building. Early on Battle McCarthy carried out an assessment checklist based on BREEAM for Offices 2002 which, although not strictly true to the building's intended use, set the tone for what had to be achieved. In a similar vein they also set energy targets, which aimed to better best practice when measured against ECON 19.

"Obviously that's for offices," says Chris Carter, senior mechanical engineer with White Young Green. "We looked at it and did some simulation work using IES and for the office areas we think we are going to be 30% better than best practice. Overall for the building there is no real best practice target set, but we hope, even including the laboratories, we might beat the ECON 19 as if it was a whole office." The building operates on a mixed-mode basis. The open-plan offices on the south side rely on single sided natural ventilation via motorised windows, these have a stroke length governed to 150 mm to take account of exposure on the upper floors. The offices from the first floor up are open to the central atrium, while transfer ducts allow air from the enclosed ground floor spaces to feed into the central atrium. In addition to the transfer ducts 100 W fans provide a means of purging the rooms. These are manually operated on an ad hoc basis by the occupants based on their comfort.

Conditions in the atrium are effectively uncontrolled. Two displacement terminals at either end bleed in fresh air depending on CO2 levels. The original strategy to naturally vent the space using rooflights was dropped after cfd analysis highlighted potential problems with draughts generated by the stack effect – enough to cause papers to be "ripped off" desks – leading instead to a high level mechanical extract being adopted. Predictions are for a peak temperature in the space of around 26°C, with around 90% recirculation during winter months.

For the laboratories the design team opted for a constant air volume system, opposed to a more conventional vav set up. This was driven by the use of low velocity fume cupboards which operate with a face velocity of 0·25 m/s (independent of the height of the sash), half the speed of more conventional units. "With the new Part L2 insulation requirements and the internal heat gains we were finding that the air volumes that were required for cooling exceeded the air volumes required for the fume cupboards," explains Paul Newby, regional director with WYG. At twice the cost, the payback of the low velocity cupboards comes in the ability to reduce duct sizes, plant capacity, building height and running costs. Importantly for the project it allowed energy consumption to be significantly reduced and enabled the 100% operability level to be met. Reheaters are installed within the bulkhead of each lab with air delivered via sock diffusers, selected over a more traditional grille set up in order to reduce the risk of breaking the containment across the face of the fume cabinet. "Air comes out of the socks at low velocity, if you put the air in using a grille system we envisaged you may break the flow because it is such a low velocity," says Cartwright. In a further bid to reduce energy a shut-off damper in the supply air duct can be closed off if the lab is out of use, ie no experiments are being run.

At 3900 mm the slab to slab height is relatively low for laboratories of these densities. The strategy used – with supply ducts feeding in from the atrium side and extract running straight out through the external wall and up to rooflevel – avoids issues of crossovers and allows the void depth to be brought down from 800 mm to 500 mm.

The rooftop terminals have been neatly grouped in two silos. However there was concern amongst the design team that the exhaust gases from these could wash back down into the office spaces. "Conventionally you would have said take them 5 m up to be sure you don't get any dispersal back down into the offices but the height of the roofline was a planning issue," says Cartwright. Prevailing wind conditions are generally south-westerly but north-easterly winds also occur. A worst case contaminant and dispersal scenario was looked at using cfd to make sure there was no spillage and recirculation, resulting in a drop in height to 2·5 m above the pitch of the roof.

Heating and cooling
Predictions for the building are for a year round cooling load. Exposed multi service active chilled beams are installed in the open plan office spaces, with recessed units in the cellularised offices. The 6 m long Halton units were tailored to meet the needs of the project and incorporate T5 downlights with both pir and daylight sensors. Fresh tempered air is supplied onto the back of the units which are controlled by temperature sensors within the spaces. Circulating pumps to the beams are shut down in the event of the windows opening and the facility to have a night purge on the building is available.

Buried alongside the building is a 20 000 litre plastic rainwater collection tank which is fed via the roof's siphonic system. Water from this is used to flush wcs and urinals with the overflow spilling into an adjacent 40 000 litre geothermal heat sink tank. Initially geothermal piles were considered as a means of providing a first free level of cooling for the building, but ground conditions were unfavourable and the concept of the tank was developed. This contains coils connected via a heat exchanger to the chilled beam cooling water circuit, effectively acting as a large connection for heat exchange between the water and the ground, as well as the rainwater overflow replenishing the tank. Estimates put the potential cooling figure at 195 kWh, however the valve arrangement and the demand from the building will govern this – if the demand is there the cooling source will be used up within an hour. Tank temperatures are continually monitored and a bypass facility exists should they start to rise to a level that could cause bacterial growth.

In addition to the return from the chilled beams, heat from the cold rooms (equipped with water cooled rather than air-cooled condensers) is also dumped into the same cooling circuit. If insufficient heat is rejected from the cooling water circuit, it is reclaimed to the domestic hot water circuit and used as a pre-heat. Any further excess heat is taken out using a dry air cooler while a fully modulating air-cooled chiller acts as a safeguard and also supply cooling to the ahus serving the laboratories.

The demand for domestic hot water is high due to the laboratories – peak demand is around 8 kg/s. Two fully modulating condensing boilers are installed to meet the domestic hot water load. The majority of the hot water circuits work at 45°C/35°C to maximise the condensing, with the main heating circuit to the ahus running at 75°C/55°C.

Recycled plastic pipework has been used on all the main circuits, with the exception of those in the plant room and the branches off to the beams. This was a first for the university. "It's more expensive to buy but cheaper to put in, and has the added benefit that you don't have to insulate it," says Nick Purdie, project development officer for the University.

The future
One of the goals for the building's design was to change working practices within the university. "The whole emphasis on the research institute going in here is a new way of working," says Purdie. "Hence the spaces are more open, you can see people, see into the labs." A poster session held early on in the project emphasised the diversity of research undertaken within the various departments and importantly allowed academics an insight into the work of their colleagues and the chance to develop new alliances. "That is where this building is coming from, you get these scientists working next to each other. It's a new way of working for them and a cultural change."

The migration of researchers from their current location into the Devonshire building was due to take place over Easter, this follows an eight week commissioning period. Educating occupants in how to use the building was recognised early on by the university and occupants of the building will be involved in an induction programme to understand the building and its operation and systems. "It's all very well designing a building to be low energy but if you don't put that across to people using it on a day-by-day basis it defeats the object, so education is huge part of this building," says Newby. This also extends to other areas such as waste strategies. Recycling points are going to be established on each floor – no individual waste bins will be provided.

Plans to accurately monitor the building's performance have been put in place, influenced by both the university's commitments and the impending EU directive on energy labelling. "The university doesn't just want to look at the energy coming into the building, they want to know exactly where it is going around the building" says Newby. Heat meters are fitted on the flow and return heating and cooling pipework on each floor and all labs and write-up areas have their own lighting and power distribution boards with meters. Part of the base electrical load for these areas is being met from a pv installation made feasible by a DTI grant, which provided 60% of the cost of the installation. The majority of the panels – BP Solar thin film technology – sit on the curve of the south facing roof and will generate a peak electrical load of 24·9 kW from 296 panels covering a total area of 184 m².

With an ongoing development programme the university is keen to maximise the feedback it can get from the project. "We'll be doing various evaluations once we've got users in, three to six months afterwards followed by a post occupancy evaluation," says Purdie. "Also we'll be sitting down with the design team and the constructors and have a session on where we could have done better. There are lessons to be learnt."

For WYG the project still holds some unknowns. Whereas traditionally it would commit early on as to how it would envisage a building operating, with the Devonshire building things were less predictable. "We know 90% how it is going to operate," says Newby. "But until people actually start to use it, until we actually see how the characteristics of use affect the services we'll be tweaking it. And the university accepts that. It's a live building and part of the learning experience for everybody is how it is going to operate in the end."