Improving the energy efficiency of the nation’s housing stock is one of the priorities as the UK strives to meet its climate and energy targets in 2020 and beyond.
Help could be at hand as new research shows how a soil additive used by millions of amateur and professional gardeners could slash the cost of the most effective form of building insulation.
Brunel University London academic Dr. Harjit Singh and colleagues have conducted lab experiments which show that vacuum insulation panels can be made with a core of perlite — the volcanic ore popcorn used in horticulture to improve drainage and water retention.
These panels are usually made by surrounding a core of fumed silica with metallised PET envelope.
According to Dr. Singh, the initial cost savings from switching to perlite are estimated to be at least 30%.
Using perlite also has a number of other advantages, he explained. Perlite has a significantly lower embodied energy content than fumed silica. Perlite is manufactured at less than 1000°C whereas making fumed silica requires much higher temperatures, up to 3000°C.
In terms of performance vacuum panels are five to eight times more effective a form of insulation than rock wool or solid foam panels. When you consider 43% of the UK’s CO2 emissions are from buildings the potential significance of a switch to vacuum insulation panels is obvious.
The technology holds particular promise when it comes to retro-fitting insulation to existing buildings, said Dr. Singh.
Perlite-based panels less than 2cm thick perform as well as 100mm of solid foam so the new technique opens up the real possibility of insulating the 2.3 million UK homes with solid walls but from the inside, he concluded.
Dr. Singh is also investigating other potential ways of using the technology, including making small panels and embedding them in a flexible framework to make insulating wallpaper.
Details of the study have been published in the journal Energy and Buildings.