£6k v £60k

Spent yesterday at the UK's first PassivHaus Conference, ably hosted by Alexis Rowell of Cutting the Carbon, who had hired Islington Town Hall Assembly Rooms, and also arranged a number of site visits in the afternoon session. Well organised, too, with around 250 people in attendance. Lots of familiar faces there, and buckets of enthusiasm for PassivHaus as a concept.

We also had a visit from Chris Huhne, the Coalition's minister for Energy and Climate Change, who made a 15 minute speech and answered a few questions from the floor. I thought he spoke quite well, but I heard one or two rather more negative comments from fellow participants. He bigged up the Green Deal, saying that it would be coming into effect with the forthcoming Energy Bill, which he expected to pass into law by next summer, and that he wanted every home in the UK to benefit from it between now and 2050 in "just one visit."

No figures were put on the Green Deal, but the indications are that it will be a soft loan of around £6,000, which can be paid off via the anticipated savings from lower fuel bills. The question is, will it work?

Now you can do a certain amount for £6,000, but it doesn't deliver a low-energy retrofit. Earlier in the day, I had visited 89 Culford Road, a Victorian terrace house nearby which has been given the PassivHaus treatment. This involved gutting the place, putting in a steel cage and rehanging all the floors, adding copious amounts of internal insulation, replacing all the windows, and threading in an MVHR system. The clients ended up with a stunning conversion (really lovely house, guys), but it had cost them an arm and a leg. Robert Cohen (the owner) told us that he thought the costs were around £60,000 just for the energy efficiency measures: seeing the house is just 120m2 in floor area, that's a gob smacking amount of money.

I don't know whether Chris Huhne was aware of this project, but he did refer to a similar scheme he had recently visited in Liverpool which had cost, in total, over £100,000. I expect this was one of the Retrofit for the Future projects which are being carried out all over the country at the moment, average spend about £120,000 per unit. No way, said Huhne, is that a realistic amount to spend on a retrofit. For once, my sympathies were with the politician.

But, on the other hand, £6k doesn't buy very much in terms of energy saving. Indeed, it may cause more problems than it solves for, without a coherent ventilation strategy, many amateur attempts at dry lining and draft proofing simply end up with pools of condensation and black mould. £6k puts us into that territory.

Now it may be that when the Green Deal is finally revealed, it will have one or two added elements that address these problems. Chris Huhne kept referring to a series of disasters which had happened to the Australian version of the Green Deal, where cowboy builders had been caught nailing through electricity cables and, as a result, the scheme has been derided in the Australian press. "We don't want that happening here," he said. At this point, he sounded like a true politician: afraid, very afraid.

But if £6k is too little, and £60k is too much, then the challenge must be to work out how to make robust alterations that cost somewhere in between. For a start, it might help us to define exactly what the hoped-for outcome should be. PassivHaus is great at using minimal energy to deliver even temperatures and really comfortable surroundings — shirtsleeves all winter — but in reality very few UK homes can achieve this level of comfort, even with a heat load ten times the PassivHaus standard. So it may be that we have to aim lower: say, looking for retrofits that manage to avoid condensation and mould problems and can guarantee residents a basic temperature, like 16°C, through most of the building, on a minimal heat load. Hair shirt heating. Anything above that would be classed as a luxury.

PassivHaus is already addressing these problems — to an extent — by introducing a lower standard for retrofits, known as EnerPHit, which is based on a much easier to achieve heating metric of 25kWh/m2/a. Whether this hits the sweet spot for the UK retrofit market remains to be seen, but EnerPHit still requires dramatic airtightness improvement and MVHR, so the likes of Chris Huhne will probably not be banging on the door just yet. MVHR can be difficult to incorporate into a new build, but in a retrofit it can be next to impossible to find the space to run all the ducting, without going through a total gutting process at costs which make demolition and rebuilding begin to look like the cheaper option.

This is all good stuff, close to the nitty gritty of what this blog is all about. My feeling is that this government (just like the last one) is all at sea on the retrofit debate, and is about to throw a large amount of money at it without really understanding the issues. As yet, I am not convinced that the PassivHaus standard is the solution for the UK retrofit market, but I am bowled over by the enthusiasm of the UK standard bearers. If anyone is going to sort out this conundrum, it's this lot. Count me in.