I'm puzzled how he achieves a heating cost of only £60/annum if he's using a passive stack. Wouldn't you need a MVHR arrangement t oachive that?

What does he back the claim that 'organic' insulation is more expensive then fibreglass with? The loose fill newspaper/wood fiber fills are pretty competative.

Triple glazing is definitly not more expensive the double glazing. He's just used the wrong supplier!

He's claiming a high level of airtightness. Yet a passive stack is suffienct ventilation? This sounds a bit confusing...

What does he use for heating? As both condensing and biomass boiler as no good according to the author.

On what basis is underfloor more efficient/cheaper to run the radiators?

The article comes across as very negative as he spends so much time telling us what he didn't do and why he didn't do it so it appears a little too unbalanced I feel. Would want to see much more detail on what he did do. How does his DHW system work for example. What lighting systems has he got, etc.

Any claim that this house is (nearly) zero carbon needs a lot more data to back it up.

If you publish it then please fix the typos and make the keys to the graphs (p28) legible and put meaningful time marks on the x axis.

(Not written by tony in disguise is it? :) )

I'm not sure what he says about the maximum cavity width being 200mm is correct. Isn't it the case that they used 250 or even 300mm at BedZed? Either what he says about the two skins acting independently structurally is wrong or it doesn't matter.

I also think he should explain why he is using lightweight blocks with boards dabbed on for his inner skin, meaning the only serious thermal mass in a 3 storey house is in the ground floor slab. Presumably there is some reason for this but it doesn't sound like a very good strategy to me, particularly when he has invested in half a Cotswold hillside of thermal mass on the outside where it is only any good for looking at...

Overall I liked the article, it is worth being read.

As with any project what is rejected and why is important. I liked seeing his decision making in the article, but like ted I would of still liked a bit more of what he actually did. Maybe you can drop some of the stuff that has no references (e.g. the condenser boiler bullets) and replace it with a little more on what went into the house.

What heating did he choose?

Am I right that his internal temperature in winter dropped to 14c. Is this an acceptable temperature?

I think it is a very provocative article, intended to advertise the project and to promote the design philosophy used. Putting that to one side, I found myself agreeing with quite a lot of the content, though like others here, I think the Author has got some things just plain wrong. Eg, taking cavity insulation down to formation level is a great idea-using an insulant which, shall we say, underperforms when wet, is not!

I think you should publish the article, and maybe start a topic here where Mike Hillard could be invited to explain a little more, and to also give us some more references, and to show us the data which will be coming on stream soon. The proof will ultimately lie with the data, whether the building performs as stated or not. In any event, developments like this are to be comended.

Just the sort of article we need.

I wouldn't use passive stack ventilation. as Paul says.

Thermal mass missing/wasted and it will be very air leaky as blobbed and dobbed. The bellows effect will tend to cool it too.

Like the reasoned approach even if I disagree with some things

Don't like the big conservatory

Do very much like the insulation going down well below the floor -- I would have used batts loose fill tends to move arround, settle and miss bits on installation.

Overall I enjoyed it.

Some rather questionable logic in places, and it seems a good part of the evidence that he does supply is anecdotal, despite the neat looking graphs. For instance he states the rapid cooling time having let the house reach 40 degrees on an August day. Firstly, it's worrying that a highly insulated house could reach that temperature in a day, so I hope he was giving the temperature of the conservatory. Secondly, if that's heat due to solar input the air temperature could have been uncharacteristically low, so opening windows is bound to have a rapid effect. There are also confusions between measured performance and expected performance - in some places he states figures for previous seasons, and in others he mixes figures that he expects to see in future. One is a fact, the other is a guess.

The biggest problem I have with the article is that it is presented in the first person and effectively is an opinion piece. However, it's trying to present itself as factual, which it most definately isn't. Some of his conclusions are quite sound - builders do tend to have a rather more pragmatic approach to eco-friendly building than green theoreticians. However, some of them appear to be based on personal predjudices and guesswork. The whole piece would come off better as being either an independent assesment of what he's done (with suitable explanations and detail) or as an opinion piece of what he believes works - but not as both.

I did like the bit where he described his home automation set up as "powerfull looking". :D

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