Nearly Passive in Somerset

On the way back from the Homebuilding & Renovating show, I pop into a development of near Passive Houses in Chewton Mendip. There I meet the project manager Arthur Bland who shows me around the terrace of three houses, which have been commissioned by the Waldegrave estate and are going to be rented out on completion.

It turns out that this project has been driven by Arthur and his interest in low energy housing and Arthur is a big thermal mass fan. He chose to work with Logix, one of our more innovative ICF businesses, and he assembled a crew to work with him. He particularly liked Logix because their formwork is manufactured in the South-west and therefore if he needed something extra he wouldn’t have to wait six weeks for it to arrive from overseas. “I went on their training course, I went and visited two sites and then I just got going with it,” he said. “I picked up local builders to work with me; some were brilliant at it, others couldn’t get their heads around it at all.”

There were problems with the site. For a start, building control had identified a radon issue, which had to be managed. Arthur chose to use Eco Slab which, he said, was a brilliant solution, very easy to use and no mechanical handling required and, because it gives a ventilated sub-slab, all it needed was a gas barrier installed above to meet the requirements. Arthur also went for a poured Quad Lock intermediate floor, specifically to increase thermal mass — there is a hell of a lot of concrete in these homes. All around, the fabric is designed to have U values equivalent to Passivhaus standards, with extra insulation added where the proprietary systems didn’t quite get there.

I had been told that these were another example of no heat homes, but it transpired that this wasn’t really true. What they did each have in their airing cupboards was £6,000 worth of Genvex Combi, a bit of kit I hadn’t come across before. This machine is a hybrid between a mechanical ventilation unit with heat recovery (MVHR), and an air source heat pump (ASHP), which also supplies 185litres of domestic hot water. It’s a beast, but it’s a quiet beast. One of the oft-heard criticisms of ASHP is that it is noisy, but these units ran with a barely discernable hum at the standard setting. Even on full blast setting, it made less noise than a gas boiler.

It’s a neat idea. On the other hand, it’s electric heating, which doesn’t sound too great an idea. But to be fair, this is also pretty close to the standard set up in a German Passivhaus, where they usually have something called a post-heater added to the MVHR system. Arthur said that without the unit on, the houses were settling at an internal temperature of around 12°C (it’s been fairly chilly recently), but when I visited they were holding a temperature of 17°C. None were yet occupied.

What I don’t yet know is how much energy these machines are using, though Arthur promises to let me know when he has some figures.

Wolfgang Feist, Mr Passivhaus

I joined a throng of about 250 people gathered last night in central London to hear a 40 minute lecture by Wolfgang Feist, Mr Passivhaus. In the obscurantist world of energy efficient building design, Feist is the nearest thing you will get to a superstar and this was the first time he had spoken in public in the UK. He spoke in excellent English and held the stage with his presentation, although in truth, for those who already know about the Passivhaus movement, there wasn’t anything particularly new to be gleaned. In any event, he was preaching to the converted, although in the bar afterwards it was suggested to me that I wasn’t wholly on board. Oh dear, what is it with me?

A few snippets I did glean. Feist and his family actually live in the oft-photographed original Passivhaus terrace built in Darmstadt in 1991. This is where the story started. His average energy consumption for space heating in this house is just 9kWh/m2/a; the Passivhaus standard is 15kWh/m2/a. In fact he showed a fascinating slide showing that though 15kWh/m2/a is the hoped for energy consumption in a Passivhaus, the range of outcomes measured at 32 Passivhauses on an estate in Hanover was between 4kWh/m2/a and 25kWh/m2/a. “if people like to keep the internal room temepartures at 25°C, then the energy use is going to be high. But then it’s still going to be much lower than on conventional homes.” He showed that such a range of outcomes was fairly typical across any group of homes studied.

He also said he was proud of the fact that were now over 40 Passiv Schools in Germany: schools of course help to disseminate the principles of low energy design because they are used by so many people.

Finally, he invited everyone to the next PassivHaus annual conference in Frankfurt in April 17/18 next year.

The talk was put on by the AECB, who also used the spot to promote their CarbonLite standard which is closely based on PassivHaus principles. What wasn’t explained was why the AECB should be supporting a different standard. Perhaps it will all become clearer to me in time.

Solving the Housing Crisis

Remember the 3 million new homes that were needed by 2020? It wasn’t so long ago that this target was being spoken about seriously. Well, today a study by AA Insurance has found that a) 70% of UK homeowners have never had a lodger, but b) that 20% of these are now considering it. At least I think that’s what the figures mean. Let’s assume this is so.

There are around 25 million homes in the UK. So 70% of this is 17 million, give or take. Now if 20% of these 17 million (that’s 3.5million) are now actively thinking of taking a lodger, that will create 3.5million new bedrooms. That’s probably not far short of the number of bedrooms built in creating 3 million homes, as around 90% of these were envisaged as being rabbit-hutch style singleton flats.

So the credit crunch appears to have solved the housing shortage already, without so much as a brick having been laid. And all within 12 months.

On Eco Slab

This is me at the Harrogate Homebuilding & Renovating show standing on an Eco Slab.

What is an Eco Slab? Well, I hadn’t seen one before but the fact that it was being demonstrated on the stand of Logix, one of our best known ICF suppliers, gives you a clue. Because what ICFs are to walls (i.e polystyrene moulds), Eco Slabs are to floors.

• You level the hardcore base
• You cover the floor with 1m square eco slabs, which have little polystrene legs
• You then pour a re-inforced concrete slab. The thicker the concrete, the wider the achievable span.

Will it catch on? I’m not sure. What you end up with is a hybrid which is not quite a solid slab (because there is air beneath the eco slab) and yet not quite a suspended floor (because the legs of the eco slabs rest on the ground). Does it require ventilation, as a suspended floor would? Not sure. And if not, then why not just build a solid slab? Off to the website to find out more but the website just shows up as a blank page in all my browsers, which doesn’t inspire confidence in the company behind it.

But it certainly supports a 15 stone blogger, and his Costa Coffee latte.

Windfarms: a small proposal

Interesting conversation last night with Anna Stanford, head of communications at RES, who I met at the Inbuilt birthday party last night. RES are behind the Wadlow windfarm development, which is local to me and which had been stalled in interminable planning negotiations.

I asked her why RES didn’t offer some sort of financial inducement to the locals in order to get them onside. She said it was not possible because it would be regarded as bribery: the planning system expressly forbids it — or at least I think that was the gist of what she was saying. Technically, it would be feasible, for a 13 unit windfarm, such as the Wadlow one, would produce far more power than the surrounding parishes would ever need, and the financial model would still stack up because wind energy, albeit in its subsidised form, is very profitable and it would still be profitable if, say, 10% of the profit, or the power drawn from one of the turbines, was used to pay the electricity bills of homes within a mile or so.

There are various models you could work on to make it fair: for instance if you were within 1000m, you would get all your electricity paid for up to a certain amount, and if you were within 2000m you would get 50%. And so on. That way the community wouldn’t just have a windfarm dumped on them, which is what the system demands at present, but rather it could sell its wind energy potential on the open market.

The reason this can’t be done essentially boils down to a problem with definitions of ownership. No one can own wind energy — it’s a common good. But surely if organisations like RES are able to obtain rights to harvest some of this energy, they should pay compensation to anyone that they might inconvenience along the way.

All things being equal, most parishes would probably rather not pay host to a windfarm built on an industrial scale, so why shouldn’t the ones that do receive some benefit?

Meanwhile, here is an image of part of a wind farm I came across in Lanjaron in Spain two weeks ago. It’s located on the edge of the Sierra Nevada, easily visible on the road between Granada and the Med. Anyone who says a windfarm is an eyesore ought to go view this one: it is simply stunning. The road into Lanjaron weaves its way around numerous hairpins and it zigzags around several of the giant turbines. At one point you appear to be travelling through the blades themselves: they seem unbelievably close and powerful. For a brief moment, you can almost dream that the future may be benign afterall.

Ten Worst Home Improvements

I keep coming across this table on the Times website and then it keeps disappearing from view. Today I spotted it again on its Money Central site, so I thought I’d grab it and blog it, so that at least I can find it again when I next want to refer to it.


It’s both very funny and very depressing — maybe a sign of the times. It suggests that there is no point bothering doing anything ever, as all it does is waste money. Just clean everything and keep the surfaces painted.

Can things really be that bad? Where do these figures come from? It seems the research was carried out by the Abbey and it was widely quoted during the summer by a variety of media — try keying abbey research home improvements into your search engine — but I can find nothing on any Abbey site. If anybody can point me at the original document, I’d appreciate it.