Located on Crompton Street in Paddington, London, the Little Venice Sports Centre forms part of a major regeneration initiative by Westminster City Council to improve local recreation and community amenities. Designed by LCE Architects, the £4.5m project includes a sports hall, a dance/exercise studio, a fitness suite, a teaching/IT area, and a small drop-in library. In addition to providing state-of-the-art leisure facilities, the 1800 square metre building also incorporates a wide range of sustainable technologies, including natural lighting and ventilation, high levels of insulation, solar thermal panels, recycled flooring and a sedum roof. Forming a key aspect of the environmental approach is the use of Monodraught Sunpipes and Windcatchers. The former ensure good levels of glare- and shadow-free daylighting – essential prerequisites for a safe and comfortable indoor sporting environment. The latter provide an effective and ecological source of ventilation, which, compared to installing and maintaining air conditioning or mechanical ventilation systems, is highly cost effective.
Rather than update the existing facilities at individual sites, Westminster City Council chose to invest in a new, centralised sports building that would serve the surrounding primary schools, some secondary schools and other groups within the community. The project also had to double as a community centre and be inherently flexible. LCE Architects was appointed in March 2005, following the preparation of a strategic outline proposal. Work started on site in February 2008, with completion in July 2009. Funding for the project included £1.8m from the Big Lottery Fund, Sport England, Skills Active, and John Lyon’s Charity Trust.
Replacing the former Westminster Children’s Sports Centre, the two-storey building is situated in a conservation area bounded by Queen Anne-style tenement blocks to the west, St Mary’s Gardens to the south and a Queen Anne-style school to the north-west. Taking advantage of the sloping topography, the ten-metre high sports hall is partly buried in the eastern boundary of the site. Steep grass berms further reduce the scale of this timber-clad element when viewed from St Mary’s Gardens. The hidden nature of the site entrance off Crompton Street is countered by a visually striking single-storey structure that projects from the main volume and is clad with an inclined flush-fitting aluminium rainscreen. The curvilinear form swells outwards to signify the main entrance/reception, bringing visitors into the building on axis with an internal street running north-south.
Intended to aid navigation and orientation, the 3.7 metre wide central street doubles as an assembly/waiting area and is equipped with recessed benches and sports lockers. To the east is the sports hall, which is large enough to accommodate four badminton courts. Internally the space is lined with birch-faced plywood panels incorporating open staggered joints to improve acoustic performance and to minimise visual distraction. To the west is the changing block and dance studio. Sandwiched between these elements and forming an incision in the building envelope is a timber-lined feature staircase. Lit from above by a translucent polycarbonate roof, the stair leads to a viewing gallery overlooking the sports hall. The first floor is given over to a 30-station fitness suite and a generous teaching/IT space. The former has a stripped-back industrial aesthetic in keeping with the technical fitness equipment, while the latter is equipped with movement analysis software, designed to help athletes improve their agility and technique.
Architect Mark Hewitt says the environmental strategy with regards to lighting was based on the recommendations of Sport England. The organisation advocates good levels of natural daylight for indoor facilities coupled with the effective control of glare and shadow (as a means of ensuring safe and distraction-free play). The team rejected the use of large windows or rooflights incorporating brise soleil early on for reasons of cost and complexity. Instead, they specified Monodraught Sunpipes for the sports hall, dance studio and teaching space. Designed to provide an even, diffuse light, the low-maintenance devices are used in combination with energy-efficient dimmable luminaires.
The decision to naturally ventilate the building posed a significant problem: concerns over noise, glare and security meant that the number of windows employed throughout the building was severely restricted. As a consequence, it was impossible to achieve the necessary levels of cross ventilation using opening lights alone. The solution was to use Monodraught Windcatchers. The roof-mounted ‘topdown’ ventilators are designed to catch the wind from any direction, bringing it down into the building via a series of external louvres, internal turning vanes and a damper control system that regulates the rate of the flow. Simultaneously, warm internal air rises and exits through the same route as a form of displacement ventilation.
Windcatcher specification
Windcatchers were chosen to ventilate the 5820 cubic metre sports hall, 830 cubic metre dance studio and 710 cubic metre fitness suite for several of reasons. First and most importantly, the units can be designed and sized to meet the exact needs of the spaces without relying on external elements, such as opening windows and vents. Second, they can provide effective night-time cooling, without the security risk of having to leave windows open. Third, the units are inherently reliable, containing few moving parts (none externally). Last but not least, the ventilators can be bespoke designed. This particularly appealed to the design team, who envisaged a streamlined conical form in keeping with the curving sedum roof. In addition, Mark Hewitt says the decision to use Windcatchers in place of a mechanical ventilation system significantly reduced the size of the plant room – from an anticipated 90 square metres to 50 – resulting in substantial space and equipment savings.
The decision to use Windcatchers was taken early on, allowing the architect and environmental engineer Ingleton Wood to work closely with Monodraught. The starting point for the natural ventilation strategy was BS5925, The Code of Practice for Ventilation Principles. But instead of basing the design on the suggested ventilation rate of eight litres of fresh air per second per person (8l/s/p), Monodraught set a target rate of 12l/s/p in order to more effectively control heat gain and limit carbon dioxide build-up.
Detailed analysis undertaken by the manufacturer revealed that heat gains of 21kW, 18kW and 9kW would have to be ventilated from the sports hall, fitness suite and dance studio respectively. Unsurprisingly, people accounted for the highest heat gains (up to 12kW in the hall) with the remainder made up of lighting, solar, structural and equipment gains. In order to manage the anticipated heat build up, Monodraught advised 1.3 air changes per hour (ac/hr) in the sports hall using three 1700x1000mm oval Wind-catchers; 11.5 ac/hr in the fitness suite using two 1700x1000mm oval Sola-boost units; and 4.5 ac/hr in the dance studio using five Windcatchers of the same size and shape. The ventilators are sized to provide the desired ventilation rate at a wind speed of 2-3 metres per second. The average wind speed across the UK is around 4-4.5m/s, so this gives a high degree of assurance that the required air change rates will be achieved even at low wind speeds.
The Sola-boost Windcatchers specified for the fitness suite closely resemble the oval ventilators used elsewhere, except for a 40W polycrystalline solar panel mounted on the truncated top capping. This powers a high-efficiency, ultra-quiet DC fan that can import up to 260l/s of additional fresh air down into the building or extract stale, warm air. The aim is to ensure best performance even on hot sunny days with little or no wind.
Installation and commissioning
The roofing subcontractor formed structural apertures before fitting 150mm high steel aprons to each void. Installation was carried out by the manufacturer following completion of the preparatory work. The ventilators are bolted to the aprons, with the damper control assemblies and grey powder-coated eggcrate diffuser grilles suspended from the steel roof structure using a system of unistrut support frames and drop rods. External weatherproofing is provided by rain-trap louvres and a GRP skirt which dresses over the metal upstand. All the windcatchers were specified in a light grey finish.
The Windcatchers are automatically controlled via the building management system (BMS). The units are connected to the system using wall-mounted combined temperature and carbon dioxide sensors located approximately 1.5 metres from the floor. Readings taken from the sensors determine the degree by which the dampers on the units are opened or closed. During summer operation the dampers commence opening at 16°C and then continue to open by increments of 20 per cent with each additional degree-rise in temperature. With regards to carbon dioxide, the sensors are set at 1500ppm. If this level is reached, the dampers automatically open for 20 minutes before returning to their pre-set position.
Night-time cooling can be used in the summer by automatically opening the dampers between midnight and 6am. This saturates the building with cool air, making it fresh for the start of the next day. The programme can be run with a minimum temperature limit to ensure the building is not over-cooled. During the winter months the dampers can be closed or set to five per cent open to provide trickle ventilation. A manual override located on the sensor allows staff to fine-tune comfort levels and/or respond to unseasonal weather conditions.
Sunpipe specification
Alongside the Windcatchers, sixteen 750mm diameter Sunpipes were installed in the sports hall, with nine 530mm diameter units split between the dance studio and skills active hub. The devices comprise a silverised mirror-finish aluminium tube that intensifies and reflects daylight and sunlight from the roof down into the building. At the top of the fitting is a UV-protected polycarbonate diamond dome. At the base is a three-piece ceiling diffuser designed to provide an even spread of light. Installed by Monodraught, each unit is fixed to a steel upstand and fitted with a brushed nylon condensation trap positioned between the dome and the collar. Among the advantages offered by Sunpipes are their effectiveness in both sunny and overcast conditions, their non-glare properties, and their ability to save energy and cost.
Project team
Architect: LCE Architects; structural engineer: Richard Jackson; qs: Huntley Cartwright; m&e, project manager, CDM coordinator, party wall surveyor: Ingleton Wood; contractor: Crispin & Borst; client: Westminster City Council; photos: Duncan McNeil.
Selected subcontractors and suppliers
Passive stack vents, lightpipes: Monodraught; Finnforest ThermoWood cladding and carpentry: Nicholson Carpentry; Bailey Eaves Systems aluminium cladding: Star Ceilings; Forticrete Medici polished masonry and blockwork: Heritage brickwork; steel frame: W.S.Britland; floors: Metaldeck; roof: Hardy Sherwood; polycarbonate cladding: Solex Manufacturing; rooflights: Naturalight Systems; Bauder green roof: Accurate Roofing; revolving door, internal shutter: Kaba Door Systems; security barriers: Boon Edam; windows, integral blinds to glazed screens: Alucraft; security shutters: Charter Specialist Security; platform lift: Metro Lifts; ironmongery: John Planck.
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