The Ground Source Heat Pump Reinvented
Peter McKeown – 30th March 2013
I have always struggled a little bit with where ground source heating fits into the renewable energy mix. I know it is one of the most efficient forms of renewable heating, but with the lower output temperatures making it difficult to install for older properties (without significant improvements in insulation) – however when a property is really well insulation (such as in new build) the cost is hard to justify when compared to air source heating (particularly for the average sized home).
A new build 4 or 5 bed house in the UK at some 2000 square feet over two stories, can have a heat loss as low as 6 to 8 kWp. An air source heat pump for this can be supplied for as little as £2300 – with installation being as little as £500 (assuming that all you require us to do is connect the heat pump and the controllers to supplied pipework). The annual cost of providing heating through this system can be as little as £400 per year. Whilst a ground source heat pump can perhaps save you £50 per annum off this but it may costs as much as twice as much to supply, and perhaps 10 times as much to install (with ground works and heating pipes). Therefore if a ground source heating system costs you £10,000 compared to as little as £3000 it will need to be a lot more efficient to recover the extra £7000 you lay it in the initial capital costs. With running costs of £400 per year with an air source heat pump this is very difficult to attain over even a 25 year plus expected life span of the system.
In my mind – ground source heating was only really practical in the very large new homes or pubic/commercial spaces where heating demand is a lot higher that it is in the typical new build house in the UK.
And then – along come Kensa Engineering with their re-invention of the ground source heat pump for the residential marketplace in the form of the Shoebox Heat Pump.
This is the most innovative GSHP on the market (as they claim) and completely redefines the economics of installing ground source heating in new build properties. Designed for small units with heat demand of up to 3 kW (see above that is likely to be most attached or semi-detached 3 or 4 bed houses in the UK – without the improvements upon current building regulations that are easily achievable). And it overcomes some of the major drawbacks that architects and end users sometimes quote with air source units – where to site the outdoor unit and how to ensure that they do not present a noise nuisance!
Kensa have rather cleverly designed a small compact and virtually silent indoor unit (that fits in the typical kitchen cupboard) which attaches to communal ground heating pipes – meaning that developers or architects can design a scheme where there are many heat pumps sharing the same ground loop from which heat is extracted. This removes one of the other drawbacks in district heating – the apportionment of heating costs, as in many cases each unit is therefore completely independent of each other in terms of running costs (they only pay for the electricity used by the heat pump unit that is within their own home), and are free to disconnect and seek other sources of heat (not sure why they would but they could).
With per unit costs as low as £3190 we know have a ground source heating system that can compete with air source on cost and with better “aesthetics” and no noise concerns there is now a UK company offering perhaps one of the most innovative and efficient heating system to the new build sector. Also as a district heating system the Shoebox is currently eligible for the commercial RHI system and so benefiting from an income stream available to each homeowner in the development.