Tue, 19 Dec 2023 05:55:09 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126960#Comment_126960 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126960#Comment_126960 Mon, 19 Dec 2011 13:31:05 +0000 piersadler
The article cites the deaths of 25,400 older people in the UK from cold in winter 2010/11 and asks whether whole house MVHR would have been their salvation. I think in airtight buildings the answer is probably 'yes' and in well insulated airtight buildings definitely 'yes'.

The clear failing in this article and apparently in the thinking which supports it is that it appears to be based on a prejudice against MV without addressing the reasons why it is used. Without mentioning airtightness, without mentioning Passivhaus (where it is a requirement), the article is worthless.

My request is for better informed evidence based debate in GBM. I'd like to know what other members think, particularly on the issue of Mechanical Ventilation. I am not a particular supporter of MV, although I recognise that airtightness has a part to play in energy efficient buildings and that Passivhaus has a serous role in the future.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126967#Comment_126967 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126967#Comment_126967 Mon, 19 Dec 2011 13:52:00 +0000 davidfreeborough
I can understand the desire to design houses which don't rely on "artificial" ventilation. However, any alternative needs to stack up with MVHR from an energy conservation point of view &, before any conclusions can be drawn, needs to be prototyped on real houses & monitored through at least one heating season.

There will always be a market for "Eco Homes" which feel "Green" & I think Sue Roaf's approach will appeal to those who don't ask to see the heat loss calculations. However, there is a solid scientific basis for the Passivhaus approach which cannot be just swept away with a load of "hot air" & that provides an invaluable guide to those trying to understand the real energy consumption of their proposed home.

David]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126970#Comment_126970 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126970#Comment_126970 Mon, 19 Dec 2011 13:57:05 +0000 RobinB http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126987#Comment_126987 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=126987#Comment_126987 Mon, 19 Dec 2011 15:09:08 +0000 joe90 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127075#Comment_127075 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127075#Comment_127075 Mon, 19 Dec 2011 21:24:53 +0000 djh
She refers to a 'Technical Report 14' that apparently supports her views and makes it sound independent. She completely fails to mention that she is an author of this too! It's perhaps worth noting that the report is focussed on older properties and says "Although the proposed heating strategy cannot reduce the energy consumption to the levels expected of newly built houses with modern standards of insulation, it can be used together with other technical upgrade measures". It also recommends greater ventilation.

She refers to an article that is not yet published, making it very difficult to judge. She also fails to mention that she is on the editorial board of the journal in which the article will appear. Again, hardly independent. When summarising criticisms apparently made in the article, she doesn't distinguish between those inherent in the systems, and those caused by faulty installation or operation and maintenance, which are quite different problems to my mind.

So I don't feel able to take an informed view of her article. But the points above, together with a whole sequence of non-sequitur and apparently rhetorical questions throughout the article mean that my instinctive emotional reaction to it is pretty negative.

I join piersadler in requesting a better standard of journalism in the Green Building Magazine.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127100#Comment_127100 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127100#Comment_127100 Tue, 20 Dec 2011 00:23:36 +0000 wookey
I don't like the power consumption of MVHR either, and especially if you take a low-energy aproach anyway, it's not hard to fit one badly and use more energy than you did before (although very likely with better air quality in exchange). With modern kit this problem seems greatly reduced. (I think RobL said his is running at under 5W much of the time - that really isn't a problem).

I don't see how you can make really low-energy buildings without it, but then not all buildings are passivhauses(en?), and it clearly makes sense in some circumstances: the Cambridge company Breathing Buildings is doing very good work halving the energy use of schools and offices by fitting smart natural ventilation. Yes it's nothing like as good as a passivhaus, but it's a hell of a lot better than the aircon +open-windows they had before.

So I think there is a place for her approach, although it would have been better to make the comparison without suggesting that there is 'no scientific evidence' behind the MVHR/MEV approach.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127108#Comment_127108 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127108#Comment_127108 Tue, 20 Dec 2011 07:43:24 +0000 JSHarris
What is beginning to annoy me is the way that MVHR seems to be being advocated by manufacturers as an energy saving measure for ordinary houses. I very strongly suspect that it's no such thing for the majority of houses in the UK, that are generally far from being adequately air tight.

Personally I'd like to see whether it would be possible to make a zero energy passive MVHR system, the snag being to find a way to make it work acceptably under all weather conditions. I may have to settle for just using PV to offset the power used by the fans.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127120#Comment_127120 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127120#Comment_127120 Tue, 20 Dec 2011 09:01:35 +0000 joe90 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127132#Comment_127132 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127132#Comment_127132 Tue, 20 Dec 2011 09:57:54 +0000 RobinB http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127140#Comment_127140 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127140#Comment_127140 Tue, 20 Dec 2011 10:18:02 +0000 davidfreeborough
David]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127299#Comment_127299 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8304&Focus=127299#Comment_127299 Wed, 21 Dec 2011 14:03:55 +0000 piersadler I think there is probably a lot to be achieved by replacing air conditioning with natural ventilation in many cases and I also agree with JDHarris that MVHR in buildings which are not sufficiently airtight is a very poor choice, but whatever the issues in the debate, lets have more evidence based and balanced arguments in GBM.]]>