ng your ootprint Anne Brewer of Dorking Meeting writes from her experience at home
and easier to install being just a large box fixed to an outside wall. Microgeneration, who install HeatKing air source heat pumps, suggested additionally an extra solar panel and a Torrent Solar thermal store. This splendid new invention replaces both hot and cold water tanks, accepts input from solar panels, heat pumps and boilers, and supplies hot water for taps and radiators. So the solar contributes to central heating on bright winter days. The cost was around £13,000. We warranted a £2,400 Government grant but failed to get the application in and approved before work started – be warned! We took the plunge but had the thermal store equipped to accept input from a log burning stove with back boiler in case the system was inadequate during really cold weather. The system went live in October and is doing fine! The heat pump runs intermittently but makes a noise, which might annoy neighbours, but fortunately that side of our house overlooks
farmland. It doesn’t bother us indoors and won’t be needed in the summer, as the solar will supply all our hot water. The thermal store is cleverly designed, so hot water is unaffected by the central heating demands of a cold day and maximum use is made of input from the solar panels. Our thermal store is in the attic but could be sited in a garage or airing cupboard where your hot water cylinder used to be. Our airing cupboard was too small – usual problem! On recent dull days with no solar input the heat pump coped admirably producing hot water at 47°C and keeping the house comfortable at 15°C – we were already acclimatised to a low temperature! The pump only activated for about fifteen minutes an hour so could cope with a higher load, but it wouldn’t be suitable if you like a really warm house, as efficiency drops off with increasing differential between input and output temperature, which is why they are recommended for use with underfloor heating, which gives a warmer house at a
lower output temperature. It will work with outside temperatures down to -15°C. As we redecorated the kitchen using plant-based paints, we congratulated ourselves on our household’s nearly zero energy footprint. Even the old oil burner had gone, via Freecycle, to a restaurant owner planning to run it on used chip oil! Then something we read questioned the green credentials of heat pumps even if run on renewable electricity – such electricity is in short supply it said and should not be wasted on heating. Oh dear! An efficient log burner with a back boiler will reduce our dependence on electricity so that is our next project. What then? We could invest in a wind turbine or solar PV to generate our own electricity but you need an ideal site for the former to be effective and the latter is rather costly. I’ve a feeling that more effort to reduce our other areas of energy consumption is what the planet needs from us now – in my case more use of my bicycle!
Sources of information Anne found useful and suppliers mentioned: Centre for Alternative Technology Information Sheets. 01654 705989; www.cat.org.uk Energy Saving Trust: 0854 727 7200; www.est.org.uk Green Building Bible. Third edition. Published 2006 by Green Building Press. www.greenbuilding.co.uk Walk Cheerfully, Step Lightly. January 2006 edition. Published by Quaker Green Action. Ecotricity: www.ecotricity.com/thefriend; 0800 0326 100 quoting ‘The Friend magazine’ (see also back page) Good Energy: 0845 456 1640; www.good-energy.co.uk Green Building Store. Mail order supplies. 01484 854898; www.greenbuildingstore.co.uk Microgeneration: 0845 434 8084; www.microgeneration.com Okofen wood pellet boilers: the organic energy company, 0845 458 4076; www.organicenergy.co.uk
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