Wolseley showcases the way to a sustainable future
Wolseley’s Sustainable Building Centre positively bristles with renewable technologies. Visible in this photo are louvres with embedded solar photo-voltaics, two Passivent Airscoops to deliver natural ventilation and, on the roof towards the top right, solar photo-voltaic and solar thermal panels.
Never can so many sustainable technologies been gathered together into one building as in Wolseley’s Sustainable Building Centre. Ken Sharpe jumped at the opportunity to be shown over it.Over the last few years, construction-materials distributor Wolseley has built up a portfolio of sustainable building products and now offers a very wide range of such products, many of them relating to building services. To demonstrate a whole host of sustainable products that those in the industry can visit and see in a building environment, Wolseley has recently opened its 630 m2 Sustainable Building Center at Leamington Spa, built at a cost of £3.2 million, to provide a living, interactive centre for decisions makers throughout the construction industry. Nigel Sibley, managing director of Wolseley UK, says, ‘We have long been an advocate of sustainable building products and construction methods, working with leading architects, developers and contractors to encourage the specification and use of energy-efficient materials in all types of buildings. ‘Wolseley has made a significant investment which reflects our belief that sustainable products will move from “niche” to “norm” in the construction industry. The opening of the Sustainable Building Center moves the eco-debate decisively forward, from talk to implementation.’ The project was the brainchild of Tim Pollard, generally regarded as Wolseley’s environmental champion. He admits, ‘The idea was all my own fault. It is a building that you would never actually build, but a project to show a huge number of sustainable products. The carbon footprint of this building is meaningless.’ Interest from the industry is very high, and there were more than a hundred visits to the building by customers and other interested groups even before it opened. Since then groups of up to 40 people have visited on an almost daily basis. Tim Pollard was appointed project manager for the building, which was designed by ECD Architects with Fulcrum Consulting as services engineers.
Natural daylight is carried into the building by these Glidevale Sunscoops. Note, too, the green roof.
Two of the most interesting demonstrations for building-services engineers are the ground-source heat pump and solar thermal systems. Energy is extracted from the ground by Uponor horizontal collectors laid at a depth of a metre. Because the soil on this site contains sharp stones, the collectors are covered in 10 cm of sand. This type of collector typically provides 10 to 18 W/m2. The lower figure would apply if the heat pump runs all day. The higher figure would be typical of a system running a few hours a day. When sized to 75 to 80% of the peak load, around 15 W/m2 could be drawn from the collector. Energy from the ground coils is upgraded by a Worcester Greenstore heat pump. An underfloor heating system from Uponor is laid inside the ground floor, which achieves comfort with 15 to 40% less energy than other systems. Among the reasons are the way people perceive radiant heat and there being no draughts. Air convection is lower, and the heat is where the people are, not above head height. The floor areas of the building have a double layer of Rockfloor insulation to minimise heat loss and cold bridging. Unifoil aluminium foil insulation is laid on top of the Rockfloor insulation. It has a high thermal resistance and a high reflective performance to increase the efficiency of the underfloor heating by focusing the output into the room. Uponor collectors in the ground also help provide cooling. Water at a flow/return temperature of 10/16°C serves a Unico modular air-movement system to deliver cool air to an office space. This is yet another example of a demonstration technology, because natural ventilation by opening windows provides enough cooling. The sustainable building centre has two examples of increasingly popular solar-thermal technology. Tim Pollard tells us, ‘Solar thermal is now a volume product and a business that is worth several million pounds a year to Wolseley.’ There are two different solar thermal systems on the southern-facing roof, both of which feed into cylinders on the ground flow and are expected to meet 60% of the building’s requirement for domestic hot water. One system has two Vaillant auroTHERM Plus flat-pate collectors with 4 mm-thick glass with a special coating to minimise reflections. There are also two Worcester Greenskies solar panels. The DHW system has three heat stores — two from Vaillant and one from Megatech. The Megatech cylinder provides hot water for distribution. One of the two Vaillant auroSTOR stainless-steel cylinders collects heat from the Worcester panel and the other collects heat from the Vaillant panel. The Worcester collectors are used for preheat, and the Vaillant collectors to raise the temperature to 55°C when possible. The temperature off this collector on a day in early July was a very adequate 74°C. The use of renewable energy from the Sun is also demonstrated by two solar photo-voltaic systems. One solar PV array consists of eight Romag 146Wp glass-glass laminates supplied by Solar Century mounted on the roof. It has a peak output of 1170 W under standard test conditions. The second solar array consists of 18 Sharp 167Wp PV modules mounted in the louvres that shade the facade. It has a maximum power output of 3 kW, also under standard test conditions. The two arrays are expected to produce 2700 kWh a year, which is converted from DC to AC by inverters and used by the building as much as possible. Any surplus is exported to the National Grid. Separate displays for each solar PV system show the amount of electricity being generated and the total output since they were switched on. One line on each display shows the amount of carbon dioxide saved by not using mains electricity. Natural ventilation is represented by two Passivent Airscoops on the upper floor, both with dampers to control the amount of ventilation. Tim Pollard says of them, ‘They have exceeded my expectations, simply because of the potential for overheating with the extensive area of glazing — even with coated glass and solar shading.’ The Airscoops deliver displacement ventilation driven by external wind forces to deliver air into the building and extract it. In the ground-floor gallery, Passivent Window Aircool units draw in fresh air from outside. The internal used and warm air rises by natural convection and is exhausted through high-level automatic opening windows. A digital controller monitors the temperature indoors and outdoors adjusts the Aircool louvres to increase or decrease airflow as required. Both Passivent systems can operate 24 hours a day to provide free cooling at night. The use of natural daylight is demonstrated by Glidevalde Sunscoops on the roof of the northern wing. They gather sunlight through a lens and carry it down into the building through a tube with a highly reflective coating to deliver 95% of the collected light to the room below. If required, Sunscoops can be fitted with low-energy lamps to provide light when sunlight is not available. Artificial lighting is also designed and controlled for maximum efficiency. Downlighters use LEDs, which Tim Pollard says is almost mandatory. These Philips downlighters use 13 W LED as opposed to 50 W halogen lamps. They also have a life of 50 000 h, compared with a thousand hours for halogen lamps — with important implications on maintenance costs. Finally, the price of LEDs continues to fall, and they are now only about 30% more expensive than halogen. Other luminaires are from Cooper Lighting & Security with lamps from Philips. Lighting controls include motion sensors and daylight sensors to turn lights on and off and dim them according to available daylight. Exploiting thermal mass is widely regarded as a key aspect of sustainable buildings, and several techniques can be seen. In particular, the first floor uses the Cobiax system from Hanson, which reduces concrete mass by 35% but still provides substantial thermal mass. This precast concrete product was developed in Switzerland and is made under licence in the UK. Cobiax is designed to remove the non-working dead load in concrete slabs while maintaining biaxial strength. This is achieved by placing hollow plastic spheres between the upper and lower static reinforcement of the concrete slab to replace concrete where it is has no structural benefit, reducing weight by up to 35% compared to a solid slab of the same load-bearing capacity. The thickness of Cobiax slabs ranges from 240 to over 600 mm. A Cobiax flat slab does not require beams. Soffits are flat and unobstructed, and the cost of installing services is substantially reduced. Thermal mass is also provided by phase-change materials in the ceilings of the lecture theatre, office and meeting room. Micronal Smartboard resembles plasterboard and can be installed and finished in the same way. Micronal Smartboard contains microscopically small polymer spheres containing a storage medium of waxes. This wax melts at 23°C, absorbing heat, and sets at 18°C, when it gives up heat. Peak temperatures during the day can be reduced, and the temperature will not fall so much overnight. With water described by CIBSE president John Swaffield as ‘the new carbon’, it is very appropriate that Wolseley’s Sustainable Building Center should incorporate water harvesting, ways of reducing water consumption and the management of water run-off. The rainwater harvesting is based on the Titan Envireau system, which collects rainwater from the roof, filters out leaves and debris and stores it in an underground tank. A pump draws off water and passes it through a series of filters for a variety of non-potable uses. When stored water is not available, the system automatically switches to mains water to ensure a constant supply. Tim Pollard explains that the size of the catchment area, usually the roof of the building, and the amount of rainfall in the area will determine how much water is harvested. Independently monitored typical domestic installations show that nearly all non-potable household requirements can be met, approximately halving the consumption of mains water. Potential non-potable applications include landscape irrigation, washing vehicles, flushing toilets and laundry. Numerous ways of reducing water consumption are shown in the toilets and washrooms. Twyford Galerie Flushwise WC suites have a dual flush of 4/2.6 litres, compared with the 6/4 litres of most modern suites. The design of the bowl enables it to operate effectively with such a low water use. Major savings in water, and energy, are demonstrated by the Mira Eco shower handset — which reduces water consumption by up to 75%. The handset uses a Venturi principle to mix air with the water to create a water spray made up of large droplets with air bubbles. The droplets explode on impact to produce great coverage using much less water. Wash basins are fitted with Saracen taps with infra-red beams beneath the spout to control operation. Male toilets have Armitage Aridian waterless urinals, which are described as hygienic and economic to maintain. They incorporate a cartridge that requires replacing about every 7000 uses. One of the requirements for planning permission was that this previously brownfield site with a factory making car parts should return no more water to the drains than the vacant site. Water harvesting makes a contribution by approximately halving the consumption of mains water, but site drainage is more important. The site drainage incorporates a SUDS (sustainable urban drainage system) to eliminate the storm surge caused by the rapid ingress of rainwater into drainage systems causing a backup and, ultimately, flooding. Wolseley’s site has a soakaway to the east of the building using Marley’s Waterloc. This modular product has four cells per cubic metre to provide attenuation and infiltration, slowly releasing storm water to the drainage system. Hard surfaces use Marshall’s Priora permeable paving. Water can be drained directly into the ground, recharging the ground water and also controlling the run-off of surface water at source. The rate at which water runs off the building itself is slowed down by a green sedum roof. Such green roofs can retain up to 90% of rainwater and slow down and control water run-off to reduce the load on the drainage system. Accumulated moisture can also evaporate. Not normally used in the day-to-day operation of the building is a Baxi Multi Heat domestic biomass boiler. It is fuelled by wood pellets supplied by Jeld-Wen, which supplied the wooden window frames used in the building. They are made from the waste material that is a by-product of window manufacture. Once the boiler has been ignited manually, full output is reached in 10 to 30 minutes. Operation is then automatic, with an electronic control unit to regulate the flow of fuel and air for combustion. During continuous operation, output can be modulated to 30%. When the temperature has been achieved, the blower is switched off, and the control switches to firing at intervals. In the interval setting, the fire is maintained by introducing a small quantity of fuel at long intervals and briefly running the blower. The fuel silo holds about a week’s supply, and so efficient is combustion that the ash holder needs emptying only once a week. Since very many of the materials and equipment in the Sustainable Building Center qualify for Enhanced Capital Allowances, it is tempting to speculate on how much of its cost Wolseley would be able to offset against tax in the first year. All the company would tell us is that it does take advantage of Enhanced Capital Allowances. Wolseley intends, however, that the building will have a more significant effect on its figures than just reducing its tax bill. Tim Pollard says quite simply, ‘The viability of this project was measured in terms of potential sales.’ Natural daylight is carried into the building by these Glidevale Sunscoops. Note, too, the green roof. One aspect of water management is the harvesting of rainwater for non-potable purposes. Energy for the underfloor heating system is extracted from the ground using Uponor horizontal collectors. 170 sustainable technologies are incorporated in Wolseley’s £3.2 million Sustainable Building Center at Leamington, the first building of its kind in the UK, providing a living, interactive centre for decision makers throughout the construction industry.