Pumping heat

Great incentive:  It's unusual to feel that the government is doing something right but with the Renewable Heat Incentive, they certainly seem to be heading in the right direction in so far as encouraging renewable heat sources are concerned.

Heat pumps away!  Suddenly heat pumps seem a very sensible investment with the proposed incentives of about 7.5 pence returned to the householder per kilowatt hour of electricity expended to power them. So we're going for an 8.5kW Ecodan air source heat pump supplied by Ice Energy.We ordered the pump a few days ago and the first tranche of bits and pieces - the hot water storage tank and various other control devices to be installed by a plumber - are due to arrive later this week. Then it's up to us to modify the antiquated house heating system, currently powered by oil, so that it is ready for the actual installation and commissioning of the pump itself. We've found a plumber who is reputed to be very good and who has actual experience of air source heat pumps. He's paying us a preliminary visit tomorrow during which we can decide what we need to do and what we perhaps ought to do. Because the output water temperature of the ASHP is lower than that of an oil boiler, some radiators may need to be changed to a larger size.

The long road: So this is another step along the long and difficult road to carbon neutrality. The pump does, of course, use electricity but its coefficient of performance is around 3 (depending on the outside air temperature). That means we get 3kW of heat for every 1kW of electricity used. It becomes carbon neutral if we either buy our electricity from a supplier like Good Energy or generate some of it ourselves. We've rejected the wind turbine option for the obvious reason of lack of wind so we're now looking seriously at photovoltaics. The British government are offering major incentives in the form of feed-in tariffs which for us would 'generate' 41.3 pence for every kilowatt hour our PV array generates, either for us or which is fed into the national grid. It is really beginning to make sense to invest money in these technologies... much safer than stock markets.

Going down; going up!

Passive solar project continues...

Going down: At last, the digging out and barrowing on tons of boulders, stones and earth are over. The deepest part of all was the foundation for the 'dwarf' wall which will support the conservatory structure. Here (right), Val is checking the base level of the foundation trench with the water level (see previous post). Fortunately, because the ground is so hard and stony - thanks to glaciers 14,000 years ago - foundations can be minimal.


Going up: From this point on, it's up! First the foundations, then the base part of the dwarf wall which I've arranged so that the top of the blocks is exactly the same height as the finished floor level inside the structure. At least I hope I have. Val and I have treble checked levels, measurements and angles, all of which are made more complex by the front wall of the old farmhouse (to which the conservatory will attach) along which nothing is true; neither vertical nor plane.



Attention to insulation: The picture (above left) shows me, on a hot day wearing my sombrero, setting out the first double line of blocks. I'm using a sheet of Ecotherm insulation to ensure that the wall cavity is wide enough to hold these sheets when I build the rest of it. I intend to have 50mm of this high-quality insulation within the wall cavity and another 50mm attached to the inside and covered finally with plasterboard. I've found from my experience of building our holiday eco-cottage that insulation pays massive dividends. I shall also be insulating the floor. On the right (above), I'm pouring what seemed to be the thousandth barrowload of concrete - it's hard work! - to form the floor slab, 100mm thick. Underneath it is the black polythene damp proof membrane which we've lapped up the wall of the old house (which has neither foundations nor damp proof course) and over the first block of the dwarf wall. The damp course must always be above final outside ground level, of course.


Sub-floor complete! I finished pouring the final load of concrete just the day before it started to rain, the first rain for about 5 weeks. I'd worked 5 days previously, about 3-4 hours each day, making concrete, barrowing it and pouring it into 'cells' formed by pieces of timber. The top of each timber Val and I had carefully levelled (water level again) to ensure that the top of the levelled and tamped concrete would be about 100mm below the finished floor level. This leaves room for the underfloor insulation. As I write now, the concrete slab is flooded with water from all the lovely rain.


The next step: The conservatory frame arrives on a lorry in 3 days, complete with all the double glazed low-e glass ready to be installed when the frame is up. When the rain stops, I'll get on with building the rest of the dwarf wall at which point the excitement starts: will the frame fit? are my measurements correct? how long will it take? Already, the pressure's on... we've got our table and chairs on the new concrete floor (photo 3 behind) and look forward to having the finished structure which, we hope, will solve many of our old house's heating and insulation problems. We are, in short, fed up of living in a permanently frigid house. (It's frigid because there's no proper insulation and we refuse to run oil-fired heating except for an hour or so in the early morning.) The conservatory will help immensely because I intend to arrange for surplus heat to be ducted into the old house, effectively using the walls as a heat store. How effective this will be we can't be sure but it certainly will be better than the way things are now!