Are ECO schools causing your pupils to fall asleep?
A simple heating system has caught the attention of the school building market, thanks not only to its industrial-scale energy saving credentials, but also its ability to deliver fresh air. Andrew Brewster, engineer at CA Group, explains.
Research has been conducted by the University of Reading, which shows a direct association between the environmental conditions in classrooms and pupils’ cognitive performance. The results of the research showed that the thermal and air quality conditions in classrooms was inadequate for teaching activities during about 35% of school hours.
In the classrooms where
the research was conducted, it was found that CO2 intensity was up to 3.5 times the existing recommended average levels of 1500ppm. High fresh air supply rates are needed if the concentration of pupils is not to be impaired.
The study concluded that, as schools make a bid to reduce their energy consumption, it should not be at the expense of the concentration of pupils and teachers. For this reason, the school building market has been looking to more environmentally conscious building products in order to reduce its energy consumption and carbon emissions.
A proven, renewable technology known as the perforated Transpired Solar Collector (pTSC), under the brand name SolarWall, is holding its own when it comes to green credentials. With solar energy conversion rates up to 80% and payback periods as low as 3 years on new build and up to 7 years on retrofit, it is becoming a popular choice. The system is 100% recyclable at the end of its useful life and has been proven to provide significant reductions in both annual CO2 and energy emissions, whilst still providing a constant supply of fresh heated air into the building without extensive heating costs.
The principle of the SolarWall is simple. Installed as an additional skin to a building’s southerly facing elevation (where solar gain is greatest), the system consists of a coated, profiled steel sheet with thousands of tiny perforations uniformly spaced across the full face of the collector, which, unless viewed closely, are unnoticeable.
SolarWall uses the sun’s energy to heat a fine boundary layer of external surface air, which is drawn through the perforations into a purposely designed air cavity, heating the external air by as much as 30°C above its ambient temperature. This heated, fresh air can then be used as building ventilation or as heated air to provide some or all of the building’s heating requirements.
First developed in the late 1970s by Canadian firm Conserval Engineering Inc., SolarWall has undergone rigorous testing procedures, which saw many years of experimentation leading up to today’s proven version. Early versions of solar air heating systems were primarily based on what is known as the ‘back-pass’ technology and consisted of an un-perforated collector. These systems however, were demonstrated to be inefficient and incapable of capturing the external thermal boundary layer, which has been proven to contain 60% of the total thermal energy generated by the collector.
Having proved that the success lay in the perforated plate technology, Conserval set about marketing the product in a number of sectors such as education, health, industrial, agricultural plus many more. At first it was used in the United States and Canada for major organisations including Boeing, the Ford Motor Company, General Motors, Wal-Mart, the US & Canadian Governments and even the Antarctic Survey. Education projects in the US have a similar need to the ones in Europe, with many educational establishments utilising this technology to keep heating costs low and their student attention spans high. More recently, SolarWall has been utilised on industrial and commercial buildings in the UK and the focus is now shifting onto Education.
- A SolarWall at Seaquam School
In 2006, Durham-based CA Group became the licence holder to manufacture and market the product in the UK. The SolarWall system has probably been the focus of more testing and monitoring by independent bodies worldwide than any other solar heating product. Having invested in the perforated Transpired Solar Collector (pTSC), however, CA Group chose to undertake even more research to prove to sceptical members of the building industry exactly how SolarWall works and why it is so effective.
A conclusive report by BSRIA (Building Services Research and Information Association) in May 2007, demonstrates the effectiveness of the perforated Transpired Solar Collector (pTSC) during daylight hours. CA Group invited BSRIA to begin a year long rigorous testing process of SolarWall to examine savings on gas heating in a UK climate. The BSRIA monitoring commenced three months prior to the installation of the SolarWall at CA’s premises in Evenwood and was conducted over twelve months following the installation.
The full report shows that SolarWall produces ‘a significant amount of heat’, increasing air temperature by up to 28oC, as it is drawn through the collector. Exactly a 50% reduction in heat cost savings was observed over the 12-month monitoring period, versus the previous 12 months, taking into account ‘degree-days’. These findings were supported by a further report conducted by architects Battle McCarthy, which proved once again that SolarWall could contribute over 50% of a building’s heating requirement, CO2-free.
With an impressive catalogue of case studies proving the reliability of theproduct providing in excess of 20% of buildings’ total energy needs, together with the proof in RETscreen v3.1, which uses empirical data obtained from dynamic testing to show how SolarWall performs on live projects.
A number of projects have now been completed in the UK, the most recent being a 268m2 SolarWall installation for Jaguar / Land Rover’s new training academy, which is proving extremely successful in reducing CO2 emissions and drastically cutting their heating costs. The positive reputation of the perforated Transpired Solar Collector (pTSC) is se to continue growing.
Above The Jaguar Traning Acadamy’s SolarWall® system
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*Article reproduced by kind permission of Local Authority Building & Maintenance magazine.
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