Shredded paper

We opened the house up for visitors last weekend as part of International passivhaus open days. It was nice to see friends as well enthusiats from further afield, so thanks everyone who made the effort despite the damp weather conditions – hope mince pies & mulled wine helped. I think it was quite interesting for the visitors to see our house under construction (warts and all) rather than a finished article. We received very positive comments, and some potential builders are now considering going down the ‘passivhaus’ route, or using more sustainable materials in construction.

This week we’ve had the whole roof insulated with recycled cellulose. The roof structure consists of 400mm deep timber I-joists, so the choice of insulation was quite critical in terms of achieving the right thermal performance and filling the gaps fully between individual joists. I am a fan of recycled cellulose, as it’s a sustainable product (imagine all those tabloids finally put to a good use!), it can moderate moisture movement, it fills every nook and cranny when installed and it greatly helps with acoustics – especially in our case as we’re using tin roof as a finish. Cellulose was pumped into individual bays between I-joists through small holes in the airtightness membrane.  These were meticulously taped up after the installation to maintain proper function of airtightness layer. Timber battens to underside of membrane will form an independent service zone, so any installations will not compromise the airtightness.

We are expecting the first blower door test next week – this will give us an early indication of where we are with overall airtightness performance. Anyone wants to place a bet?

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Shredded paper

Wood stove

Last week was quite eventful. Mike’s team finished the tin roof, started with installation of airtightness membrane to underside of roof structure and we had a wood stove installed.

Being a passivhaus with low space heating requirements, our house won’t need much heat to keep it comfortably warm, so putting a wood stove in is a bit of a luxury rather than necessity. The intention is that it will provide bulk of the space heating, topped up with towel rail in bathrooms. For simplicity, we have not coupled it with back boiler to heat water (hot water will be generated via heater with air source heat pump). There have been a couple of technical challenges to overcome – airtightness and air supply. We have used Morso S11-42 stove (with optional airtightness kit) in combination with Poujoulat Efficience triple wall flue to give us a completely room-sealed system. The external cavity of the flue supplies fresh air in from outside directly to the stove, and the inner flue takes the hot air out. This ‘pipe in a pipe’ system also means that there is only one penetration through the building fabric. The flue came with a proprietary airtightness plate with a flexible seal, the airtightness membrane will be taped to it.

It was exciting to see the first fire lit – installation crew from Poujoulat (flue) and Prince&Pugh Knighton (stove) did a great job. Will just have to be careful with keeping the fire under control with all that exposed straw inside!

We will be opening the house up as part of international passivhaus open days on 11 and 12 November – follow this link for more information.

Wood stove