1st Insulation arrives

Today we took delivery of the first batch of insulation - 140mm Rockwool Flexi for the walls. Tomorrow we expect the 60mm woodfibre board - 'Pavatherm Plus' - to be delivered, which will be used as an outer cladding to the timber frame walls. This is where we depart from conventional timber frame construction where the cladding adds additional insulation and reduces 'thermal bridging' through the timber studs in the frame.
The wall design is based on a detail developed for timber frame buildings by the AECB to meet their Silver standard for energy efficiency and we will add detail drawings alongside photos when the insulation is fitted.

Winter sun, first snow...

It was a chilly, raw weekend, and we certainly felt it in the caravan! I just couldn't get my feet warm the whole weekend, so on Sunday afternoon took a stroll around the fields to capture progress 'from a distance' on ECF2 after so much time focussing on the nitty gritty detail.

What I saw took me back to our architectural brief for a building which had a 'sense of place' in this special landscape, a home which looked as if it belongs to its surroundings. With that in mind and seeing the entire 'mass' of the building through the scaffolding, I felt we were well on our way to realising that brief.
When starting out on this project we were keen to build a contemporary house which was simple in form, yet followed the lines of a traditional highland 'long-house' design.
An architectural practice which has pioneered this design code is Dualchas based in Skye (http://www.dualchas.co.uk/), not least as a reaction to kit house designs that have been more 'urban-American' than 'traditional Scottish' which have popped up in the Scottish landscape in recent years. We were quite taken by Dualchas's work at the time, whilst at the same time needed a local practice we could 'get involved with' in our house design and which knew what worked for the National Park where we live.

Heat Pump: Part 2 - ground loop installed!

Amongst the generous mix of mud, scaffolding and construction materials we're relieved to have the 300m of 40mm diameter heat pump 'collector' pipe safely buried 1.4m underground. This photo from the upper scaffolding shows the end result in the middle distance which should re-vegitate over next spring.

We are very fortunate in having an ideal location for this collector system, being on gently sloping ground with a high water table. This will ensure that that low grade 'heat' taken out of the ground will be quickly replenished by this water movement under the ground at pipe level, with heat transfer aided by the sand used to protect the pipe aganst sharp rocks when backfilled.

Heat Pump: Part 1 - ground loop

As previously mentioned we have opted to use a ground source heat pump to provide both space and hot water heating. With no mains gas, an adjacent field and the opportunity to design a well insulated house from scratch with underfloor heating, the heat pump was the lowest carbon and lowest running cost option for East Cambusmoon.
For anyone considering a heat pump for their own house there aren't that many situations where it is the most cost effective and efficient choice, and certainly if you have the luxury of a mains gas supply a high efficiency gas boiler, coupled with say solar thermal panels will likely be a lower capital cost and running cost option than a heat pump doing both. If not on mains gas, then the costs need to be compared to LPG or oil and the decision will largely depend on the type of heating distribution system you already have, ie. radiators or underfloor heating. For the same heat input to a room, radiators need to be run at a higher temperature than underfloor heating simply because the heat emitter is concentrated into a relatively small wall hung panel, rather than the entire surface area of the floor. The problem with heat pumps is that their efficiency rapidly decreases in proportion to the heating medium temperature, such that running small radiaors from a heat pump is a bad idea. This can be alleviated to a certain extend by increasing the size of radiators so they can be run at a lower temperature.
Then there's the heat collection system, in our case this being a 300m length of 40mm diameter pipe buried 1.4m underground. This particular aspect of our build was a separate 'client item' from the main build contract so Debs, me, Stewart the digger driver and £60k's worth of band new JCB set to for four days of hard graft to get this pipe buried in the ground to in such a way as to absolutely maximise every joule of energy that could be sucked out of it .....which of course would be continuously be replenished by the sun. In effect, a huge solar panel!
In designing the collector system, we followed the heat pump manufacturer's (http://www.nibe.com/) advice on pipe depth, separaton and layout. Our supplier (http://www.ecoliving.info/) also offered advice on site and once certain of our plan, we got cracking! We ended up digging three 40m trenches, each 2m wide and 1.5m deep at 4m centres. We also imported 35 tonnes of sand to cover the pipe below and above to avoid the possiblity of damage from sharp rocks when backfilling and to ensure good contact with the ground. Bfore covering and backfilling, the pipe was pressure tsted and to finish off, fed into the house via the 'slow bend' duct pipes already built in to the floor slab.