Phase change materials – the way of the future?

New research on phase change materials (PCMs) suggests a useful application to energy efficiency in the home. Professor Mohammed Farid, of Auckland University’s Department of Chemical and Materials Engineering, has found that significant electricity savings could be made through the use of PCMs in the walls of houses.

PCMs are substances that can store and release huge amounts of heat energy by melting and solidifying at particular temperatures. To accommodate the liquid state of the PCMs, Professor Farid’s team microencapsulated them and then mixed the microcapsules with building material. Two small huts were built – one with the PCM mix and another without – and the indoor temperatures were compared. The difference between the two huts was significant – the PCM hut took between three and five hours longer to drop to 17˚C at night due to its walls slowly releasing the heat absorbed during the day. The technology can also help keep houses cool in hot temperatures – the PCMs can store coolness at night and absorb heat during the day.

In a recent New Zealand Herald article Professor Farid commented that the technology is not limited to capturing external heat and coolness – it can also create peak load shifting. Heating or air-conditioning can be switched off for extended periods with little change in indoor temperature. This would allow electricity to be used during low peak periods, thereby reducing electricity bills.

PCMs are particularly well suited to New Zealand’s mild weather and some modern buildings already utilise the technology. However, PCMs are unlikely to become commonplace in residential construction until their cost comes down.

Click here to access Professor Farid’s article in the journal Energy (note there is a paywall).

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