Researchers have developed an innovative heat-storing material that can retain and release heat according to specific temperature requirements which could change the way we heat and cool our buildings.
A team of scientists from Nottingham University based at the Ningbo campus in China (UNNC), have developed the heat-storing material that overcomes the problem of how to release energy quickly.

The composite substance, created at the university's Centre for Sustainable Energy Technologies (CSET) could be used to regulate building temperature more effectively than similar existing materials that release heat more slowly.

The new material can be manufactured cheaply and has the potential of delivering considerable energy savings and could lead to more efficient LED lights and solar panels, as well as reducing the cost and energy use of air conditioning by absorbing heat from a room.

Project leader and CSET director Prof Jo Darkwa told The Engineer that these 'phase-changing materials' tend to consist of small particles of a substance that absorbs heat surrounded or 'micro-encapsulated' in a coating.

The inner material draws in heat above a certain temperature and eventually melts (changes phase) but is held in place by the coating. When the external temperature drops, the material re-solidifies and begins emitting its heat.

Professor Darkwa said: 'There are quite a few of these materials on the market but they all have limitations. When it comes to releasing the heat in a short period there is a time lag, which is not very good. In the past when we've tried to improve on the thermal response, you lose some capacity to store the original amount of energy.

'The challenge was how to overcome these two barriers, making it more responsive but retaining its original abilities. We've been able to do that and manufacture samples at very low cost and using local material.'

Although the research team would not reveal the method for making the material more responsive or the exact ingredients of the composite, they would divulge it included a metallic component, a second material and an adhesive.

The researchers say they want to develop the material further so that it could be applied to existing buildings as a spray or wallpaper, opening the possibility for home retrofitting.

They also hope to find a way to change the temperature at which the material starts absorbing heat once it has been applied, something which is currently fixed during the manufacturing process.

Because of its cooling ability, the material could be used in electronics, lighting and photovoltaic solar panels, which can all become very hot and lose efficiency as they do so. The centre has formed partnerships with large LED and solar companies to look at applying the technology in this way.

Darkwa added that the university has had particular success in developing sustainable building methods in China because the government was so keen to reduce the large carbon footprint associated with the huge amount of building going on across the country.