Solar and earth storage heating system for zero carbon homes

Sensemaking / Solar and earth storage heating system for zero carbon homes

This system combines solar photovoltaics, an underground Earth Energy Bank and a heat pump system for warmth all-year round.

By Sara Ver-Bruggen / 08 Jul 2014

A new building concept that generates solar energy and stores it in the ground for use during the winter could help the UK Government to meet its target for all new homes to be zero carbon from 2016.

The system is based around an array of hybrid photovoltaic and thermal (PVT) solar panels, and an underground earth energy bank (EEB) and heat pump to store and retrieve excess heat generated during the summer months. The EBB, situated beneath the house, is constructed by drilling a series of boreholes using a standard fence post fixture. Polyethylene (PE) piping and bentonite are used to create good thermal contact.

Caplin Homes, the UK sustainable construction company that developed the system, has set up a venture with Newform Energy, which supplies the hybrid solar panels, in order to provide it to the construction sector. “The joint venture, Zero Carbon Solution, will act as a one-stopsource for house builders and commercial developers, providing all the technologies and expertise needed for the solar homes, including heat pumps, the EEB and the PVT solar collectors”, explains Michael Goddard, a director at Caplin Homes.

The system adds about 8% on to the build cost for self-builders, and 10% for commercial builders, though these percentages should be lower in two years’ time. The return on investment is estimated to be around seven years.

De Montfort University has been monitoring the performance of Caplin’s pilot project, Great Glen, a five-bedroom solar house in Leicestershire which was recently sold to a private buyer. So far, results have shown that the building is able to achieve a mainly stable temperature throughout the winter heating season – drawing on stored energy and whatever the sun can offer. Average temperatures in the bedrooms during winter 2013 and spring 2014 reached 19°C, and 20°C and 21°C in the lounge and kitchen, respectively. An immersion heater is installed at the property, but Caplin Homes insists it is purely for emergencies.

“The solar home saves carbon and also assists in reducing energy running costs”, says Tassos Kougionis, Technical Manager at the Zero Carbon Hub, which works with government and industry to raise building standards and supports the UK construction industry’s transition to building zero carbon homes. “We were particularly impressed with the way the different systems were working in tandem to increase the overall efficiency.”

A further 12 projects are in the pipeline for 2014, including two three-bedroom pitch-roofed homes, more standard housing as well as an office, targeting the architect-designed self-build, lowrise commercial and volume commercial housing markets.

Photo credit: BedZed 2007/Tom Chance/FlickR

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