A self-build sustainable house on the outskirts of York has pushed the boundaries of carbon-neutral living with the help of a Mitsubishi Electric Ecodan air source heat pump.
Chris Gibbins, a former business analyst, set out to build a house for his young family made from straw bales, and has allied this highly sustainable material with a raft of other energy efficient measures in his mission to produce an exemplar in sustainable house building.
“Straw has all the right properties,” says Chris Gibbins. “It’s thermally insulating, it’s a waste product, there is no carbon produced – in fact it locks up carbon – so from every angle it’s a great product to use.”
A four-day course on building with the material at the Centre for Alternative Technology in Wales gave Chris the skills required to start his project.
The four-bedroom, three-storey property in the East Riding of Yorkshire has allied under-floor insulation, loft insulation, high-grade windows, photovoltaic roof panels and solar thermal with an 8.5kW Ecodan air source heat pump.
“We were faced with the choice of using either oil or electric because there is no gas in the village,” explains Chris.
“Originally, we thought we might be able to get away without heating the house at all, but we have had over a month at -13ºC, and the house wouldn’t remain warm at that temperature for that length of time. So we installed the heat pump as a background source to ensure that we achieved the right level of comfort throughout the winter period. In addition we need to look to the future because if we decide to sell the house the buyer will expect a certain level of heating throughout the property.”
“The whole house is incredibly efficient,” says Chris Wilde of Yorkshire Energy Systems, who installed the Ecodan unit. “Despite the fact that it is quite a large house we have installed a very modest size pump, as that is all that will be required to achieve the desired level of heating.”
Ecodan is accredited under the Microgeneration Certification Scheme and is therefore among the many features of this project that qualify for the Government’s Renewable Heat Incentive (RHI).
The RHI pays participants of the scheme that generate and use renewable energy to heat their buildings. By increasing the generation of heat from renewable energy sources (instead of fossil fuels), the RHI helps the UK reduce greenhouse gas emissions and meet targets for reducing the effects of climate change .
Although air source heat pumps remain relatively new, Ecodan has been on the UK market now for over seven years and has already proved itself as an efficient way of heating homes. It can achieve level 4 of the Code for Sustainable Homes, and even higher when used in conjunction with other improvements such as photovoltaics or solar thermal.
In this installation, the Ecodan unit provides all of the space heating and also makes a contribution to the hot water; Chris Gibbins hopes that the RHI income from this, in conjunction with the installation of other renewable energy technologies, will bring him close to covering all of his energy costs.