Comments on: no Code 6 without MVHR

By: o

Fri, 22 May 2009 12:38:39 +0000

Or just use passive heat recovery ventilation – not as thermally efficient heat recovery, but no electrical load either.

Walls, roof and floor u-values of 0.1 are far from impossible. Windows and doors can get a fair bit lower too. But only worth upgrading windows and doors on fully detached houses.

What is bad about heat recovery ventilation? Letting hot air flow out of buildings in cold weather is a complete waste.

By: zero carbon consultation II: summary « carbon limited

zero carbon consultation II: summary « carbon limited — Tue, 30 Dec 2008 14:05:20 +0000

[...] standard, based on Passiv Haus. This is a big point of contention as it will almost certainly force all new homes to have MVHR. This would be very bad on several levels and I’ll come back to this point in a future [...]

By: Casey

Casey — Fri, 08 Aug 2008 14:14:21 +0000

@Robert:

I think detached houses by their nature are less energy (and materials) efficient than semis or terraced housing.

Regarding the floor area, you’re probably right that a typical detached house is bigger than I’ve allowed for here. However, I think the comparison is still valid and it’s unlikely that the slight change in surface area to floor area ratio will make much difference. In fact, I’ve assumed a box here, without any architectural features apart from windows, so this is a best case in terms of surface area to floor ratio.

Yes, wall area takes account of windows. That’s the net and gross figures in the table. I didn’t allow for a sloping roof, but you could argue that most houses are insulated between joists anyway rather than warm roof construction.

By: Robert Meeks

Robert Meeks — Thu, 07 Aug 2008 09:50:31 +0000

Surely detatched houses will be likely to be larger than this area with proportionally less external wall area? This makes quite a difference in the calculations. Otherwise yes why are we building detatched houses which are energy in-efficient?

Also Im hoping you are reducing the wall area to take account of the window area and any sloping roof?

By: Tom lelyveld

Tom lelyveld — Wed, 18 Jun 2008 08:40:35 +0000

Useful round up. This was the understanding we’d come to but hadn’t set it all down with the unit type permutations.

I was wondering if you’d had a look at the new EST guides with recommended routes to achieving zero carbon. Its not clear if they have noticed that they have run out of roof space for PV/SHW pretty rapidly. Pretty strong support for the offsite argument.

Regards
Tom

http://www.energysavingtrust.org.uk/uploa ds/documents/housingbuildings/CE292%20Ene rgy%20efficiency%20and%20the%20cfsh%20Lev els%205&6_May%202008.pdf

By: nick devlin

nick devlin — Mon, 09 Jun 2008 14:31:07 +0000

Great Round up there my son.

I also think it is a dead end. Particularly where one might be looking at biomass for the main heating source. Why recover heat at 0.422KgCO2 when the fuel source is 0.025Kg.

I appreciate the idea of Passiv-Haus, and the notion of tunnelling through the cost barrier to remove for example a central heating source. But I dont believe in reality that the tunnel goes anywhere. Meeting these standards just requires more money and is not in my opinion money well spent.

There is of course a much more detailed debate to be had about this, but given that I am about to go and get a cold beer in Sevilla and further my understanding of the subjuntive in Spanish, it can wait. It is possible too, that the above may not be compatible in 34 degree heat. hasta luego….

By: on zero carbon and routes to get there … « isite

on zero carbon and routes to get there … « isite — Fri, 06 Jun 2008 11:58:08 +0000

[...] Mels post .. and Phils post for excellent round ups and for good technical comment take a look at CarbonLimimited from [...]

By: Mark Brinkley

Mark Brinkley — Fri, 06 Jun 2008 11:49:57 +0000

Thanks for doing the maths. It’s what I expected. Interesting that the detached house doesn’t get there even with MVHR. Just how are they going to get built? Or is this part of a wider agenda to keep building nothing but flats?

Mark