Product design
Solar flair
The Aerogel Solar Collector is a flat plate solar- air heater incorporating translucent granular aerogel insulation in the cover, designed to improve the efficiency of heat recovery systems in Passivhaus refurbishments. It was conceptualised and developed by IED Member, Dr Mark Dowson, an Engineering Doctorate researcher sponsored by Brunel University and Buro Happold engineers.
A full-scale prototype was successfully installed on a 1960s end terrace house in South-East London as part of the Technology Strategy Board’s Retrofit for the Future competition. In-situ testing has found that during cold sunny conditions, peak outlet temperatures up to 45°C were observed, preheating the dwelling’s fresh air supply up to 30°C, facilitating internal temperatures of 21-22°C without auxiliary heating. The predicted financial and embodied CO2 payback for a range of cover thicknesses is 7-13 years and 0-1 years, respectively. Efficiency up to 60% and a financial payback period as low as 4.5 years is possible through an optimised design.
Innovation This prototype is the UK’s first solar-air collector installation incorporating translucent granular aerogel insulation in the cover. Aerogel is a unique nano-porous translucent insulation material with the best insulating properties of any solid. It effectively blocks heat transfer by convection, conduction and long-wave thermal radiation. Meanwhile, it is highly transparent to light and short-wave solar radiation, making it an ideal material to incorporate into the cover of high-performance solar collectors. Compared to conventional single- or double-glazed
Product design innovation for housing refurbishments.
collectors, the heat losses through an aerogel cover will be significantly reduced providing higher operational efficiencies, particularly at low ambient temperatures during the peak heating season.
Project team This prototype was designed and installed as part of a collaborative effort. Detailed development of the prototype was lead by Dr Mark Dowson, working with Colin Biggs (technical director of Nuaire Ltd), Dr Jeremy Richings (technical director of Permarock Products Ltd) and Richard Lowe (technical services manager at Xtralitre Ltd). The refurbishment team included Buro Happold, Fraser Brown Mackenna Architects, Martin- Arnold Associates, Gallions Housing Association and Axis Europe contractors. Monitoring equipment was installed by BSRIA and MD electrical.
Design and installation The solar collector cover thickness was selected to achieve a Passivhaus U-value below 0.8 W/m2K, and the system was sized to provide supply-air temperatures of 30°C. The timber and aluminium framing was incorporated into the property’s external south facing wall, integrated alongside the external cladding scheme, with a fire break around the perimeter. Inside the cavity is a black perforated aluminium sheet to harness solar radiation transmitted through the cover and transfer the energy to the air. The prototype is connected to the extract side of the dwelling’s whole house mechanical ventilation with heat recovery system (MVHR), due to the design team not wanting to pass the dwelling’s fresh
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