Sunday evening, and another week of trying to sort out the minutiae of the specification, especially Airtightness. I shall be dreaming about the gap between the windows and the walls soon. We now have more figures and I have started a master list of all the costs, divided into five types: already paid, definite quotation, best quotation so far, estimate and guess! Not too many guesses but we need to sort out plumbing soon.

This is because Building Control wants our SAP rating ASAP. This is a measure of the energy efficiency of a house and all new houses have to have at least an idea of it before they get built and then a realistic evaluation once they are built. To get a SAP rating you have to say what sort of heating system you will have. To know for certain that we can do without a central heating system we need to know about Airtightness - this word is capitalised on purpose because of its looming importance in the scheme of things. A super-insulated house doesn't lose much heat through the walls, so heat loss through the cracks between elements is concomitantly more significant. And unless we can be sure that we won't lose a lot of heat through the gaps and cracks, we need to make provisions for a (central) heating system. The mantra is 'Build tight, ventilate right'. So we make a tight cosy frame then put in controlled ventilation to keep the air fresh. Most houses in this country ventilate themselves in an uncontrolled way through accidental gaps. The governement wants all new houses to be 'zero carbon' by 2016, which means that we'll soon all hear a lot more about Airtightness (and its close relation Thermal Bridging).

For timber frame, the Canadians know how to do this best. There are a lot of 'passive houses' in Germany and Austria, meaning houses which do not need extra heating except for the normal activity in a house: cooking, washing, fridges, body heat; but these are mainly masonry based. All new timber framed Canadian houses achieve better airtightness than the vast majority of UK houses and those built to the Canadian R2000 standard are extremely airtight. So I have been researching on Google Canada, also the UK's Building Research Establishment publications, and we had a long discussion with the timber frame company. Definitely a case of the devil (or the angel) in the details.

We may put just the pipework for a central heating system in so that if the worst comes to the worst and we get cold over the winter we can attach a boiler at one end and radiators at the other. Problem is, we haven't got natural gas, and bottled gas and oil are expensive. Also all fossil fuels of course. A bloke came to see us who is an expert in biomass, in this case woodchip boilers, so we could always go down that road, but they are quite expensive and we'd like to see if we can do it the passive house way first.

I have talked to so many people about this issue over the last couple of weeks. But there have been other developments. We've chosen the brickie to put in the plinth walls. We've also had a lot of quotes for windows and I think we can go up to triple-glazed with argon fill and still stay in budget. And we've got three quotes for all the timber for the house, having measured what we need. And R is a whizz with thinking through the tiny details and making lovely drawings of them. I think he dreams about staircase nosings and whether a wheelchair can get past the bottom of the stairs (long story).

I said that I would talk about Maharishi Sthapatya Veda in this blog, but I don't think that I can do better than the official sites, so here are a couple of links:
www.sthapatyaveda.com
vedicarchitecture.org
The house styles on these sites are definitely American, but MSV allows for all building styles and materials specifications so there is a great variety. The best site for UK homes is:
www.msvhomes.co.uk

I've been told by my dad to post blogs more often, so, as I always do what I'm told, expect them more frequently in future! More pics soon as the house starts going up (approx end of June).