Gable wall – external ly insulated – Udireco rendered 170mm recycled woodfibre. Front and back walls – internally insulated (bought but not yet fitted) 27mm Spacetherm glued to Fermacel board. Outrigger – tbc.
This took ages to work out, trying to marry up recyclability with embodied energy and while avoiding pervasive toxins, environmental degradation and derivatives of fossil fuels. Originally we were going to use Foamglas externally on the gable and internally on the front and back but the price was very high for what it is, and while the product is recycled, it is from a very high grade feedstock. Also this would have meant the whole house became entirely vapour sealed which splits commentators as to how bad this is.
Once deciding on breathability as key there are very few choices – mineral wool or wood fibre with either lime or diffusion open polymer render. They are pretty closely matched on embodied energy and toxicity. The tip to the balance was from sequestered carbon, the benign properties of wood fibre over glass, and UDI’s sustainability efforts through the entire product – glues, etc combined with the service from them and their UK agents Back to Earth. This produced a U-value of 0.2W/m/K
Breathable internal insulation is not advised here in the UK, internal insulation can cause issue anyway as the internal surface of the brickwork under the insulation will most likely be below dewpoint for much of the year so any water vapour there will turn into water so the strategies deployed are usually to prevent it getting there in the first place or ventilating the space between the lining and the masonry.
Add to this the fact that we want to keep the original plasterwork details – nothing spectacular, but part of the character of the place and our choices are very limited. The plaster is quite deep so we’ve got about 40mm to play with. The desire to avoid fossil fuels and foams becomes a prohibition internally as most of these materials would add considerably to the toxic load in a fire. Spacetherm uses aerogel impregnated into a mat, glued to a board it has the highest insulating properties after vacuum insulating panels – 0.13 W/m2/K and while high in embodied energy very little is used it is non toxic and enabels the walls to reach a U-value of 0.38 without thickening the wall. Its key disadvantage is cost, but it can be fixed directly to the wall with no framing or glueing so the cost of the material should be offset by the ease of installation. The boards have a built in vapour barrier and the mat itself is hygrophobic so with so little space in which vapour can gather the problem of interstitial condensation should be minimised.
The price of the Spacetherm is so high that where there are no plaster details left and window reveals can be adapted there is still room for another solution. As this is a pilot the intention is to try out a breathing internal wall insulation. There are 2 wood fibre solutions out there.
Recycled slates on TLX Gold vapour permeable multifoil sarking overall, over either formaldehyde free glasswool to 350mm, high density glass-fibre batts on Spacetherm or Thermafleece sheep’s wool between built up rafters, underdrawn with plasterboard
There are 3 configurations to the the roof insulation once past the covering:
The remaining floorspace above the attic rooms, in which we have simply topped up the glasswool, down the middle we have used some unwanted rigid insulation to create a crawlway now the insulation is so deep, to get to the solar plumbing. U-value 0.1 W/m2/K
The main slope of the roof has had the rafters built up to accommodate 200mm Thermafleece and is then underdrawn with 10mm plasterboard and skim with no vapour barrier, so fully vapour permeable. U-value 0.143 W/m2/K
The area under the half gable and dormers where space is at a premium has 100mm Hi-Cav 32 rigid glass wool batts, at the time of installation formaldehyde free was not available but to get the highest insulation value for the smallest thickness this is undrawn with 27mm of Spacetherm on Fermacel board which is vapour impermeable. U-value 0.148 W/m2/K
Triple, argon filled,coated glazing units in FSC hardwood double sealed timber frames and a feature frameless oriel window of double, argon filled, coated glazing units.
The triple glazing units came from Floatglass in Wythenshawe. The timber came in the same shipment as the bathroom timber and was made up by local joiners.
The special doubles for the oriel came from Cheadle Glass after Hansen glass tripled the price from their first and second estimates once it came to ordering. They were then sent to Structural Glazing in Telford for gluing.
97% recycled plastic gutters.
Swish have just brought these out, they use recycled plastic for most of the piece but with a think skin of new plastic on top. So far only the actual gutter and pipe are made this way the rest of the fittings are still new plastic. But overlall this seemed a most resource efficient solution over alternatives like zinc, cast iron or aluminium.
New flooring, eaves and verge boards – FSC certified, UK grown Douglas fir.
This took a while to source, but in the end found from a company called Inwood that grows it to make their laminated timber structural beams with grown on a Sussex plantation.
We moved out of Hulme after 20 years as we had outgrown our flat, price restricted us to a pretty run down house backing on to the pizza shop. It had been separately let rooms before we returned it to a family house. The order of the works below is the order we had to do it in to minimise the health hazards.
We have occasional days when you can have a look at the work we’ve done and talk to us about how to do it to your own home – the next one is on March 16th, books here: Superhome website
All the paints and finishes use no fossil fuel products. VOC’s were avoided.
We have tried a suite of natural paints to make sure that we minimise the toxicity of the internal environment and maximise where necessary the vapour permeability. Floors are finished with Polyx oil in low traffic areas, but we have found it is just not robust enough for heavy traffic so used Danish Oil in high traffic areas and just made sure we ventilated well for a bit.
Fully recycled/recyclable kitchen
The kitchen will use unglued/backed stainless steel for the worktop, the doors will be from recycled school worktops
Once the debate over feed in tariffs has settled down we’ll look at seeing how much further we get the house to full neutrality – there’s not enough roof space left to get all the way but we’ll see.