[GSBN] Airtightness and ventilation

[Graeme North]

Oh dear

I seem to have stirred up a wee storm of hornets.

Thanks everyone for a facsinating discussion.

And my apologies to John, in particular, to rouse him from the end of his comfortable winter hibernation.  
(How are you going John, apart from having an annoying antipodean burr under your pelt?)
  
I am a child of the 60's and 70's and yes I can really remember some of that time, (truly) and yes, I am aware of a lot of the research and innovation that has gone on around the issues relating to making houses much more comfortable over the last few decades. For a lot of this work, I'm very grateful to experts like John for such valuable research and insights into building science that they provide, and it is indeed John's own and very valuable work that I often refer to, and often quote, when I need expert back up.  So thanks for that. 
  
In general I am gobsmacked by the extraordinary advances that have been made in human knowledge and technology, particularly over the last decade or two. I have recently read some mind bending research on cosmology and quantum physics that show the amazing capability of human thought. String theory, the Higgs bosun particle, and 11 dimensional universes anyone?  However this mind-bending  stuff is so far removed from day to day existence that it is hard to reconcile one with the other - indeed it does not seem even a remote possibility in some areas.   And I do  know that occasionally some high level research feeds into our world almost unseen.  Satnav for example, requires a high level of understanding of quantum mechanics to make it work and I, for one, am particularly grateful for the huge advances that have been made recently in some areas of technology  - especially in medical science. 
 Its a pity that this level of intelligence is not applied to politics.  
And some building research also seems to me to be far removed from day to day reality, as research should be.  
What I do appreciate as an architect is getting good results, and my general approach is that the simpler something is, the better, as long as it performs OK.  
That's why I won't install on-site effluent-disposal system that use pumps unless absolutely necessary because we all know that those pumps are cunningly programmed to fail on Xmas eve.  Similarly with at least a partially gravity-fed water supply rather than total reliance on pressure pumps. And I personally feel the same about air supply.  I don't want to be totally reliant on mechanical systems.  Sure if the fridge fails its a drag, but I can get by. Or if the electricity goes off I can still cook, or heat water. Maybe not so easily, but I am not stuck.  

I seek robustness and resilience and that is where the uneasiness I expressed in my initial outburst that has provoked so much comment  came from.    
 
John, and others, we do need to do a lot better in NZ as much as anywhere. There are some ghastly uncomfortable houses here, as we both know. 
I am extraordinarily aware of the need for us to provide much better houses that those that often exist, ones that are well suited to their place. 
I am not, and certainly will not deliberately, advocate for unhealthy, or unsafe, or uncomfortable houses. 
My concern relates around how to provide these without resource gobbling, environmentally polluting, inadvertent side-effects, and I fully appreciate the difference between living in an environment where -40°C and polar bears lurk outside,  or where the sun doesn't rise much for weeks or months, and the tropics.  I also fully appreciate that dealing with more extreme environments will take much more careful action than more benign places. Where I live, my house could be likened to a woolly singlet, rather than a fat-sealed double-fur skin coat.  And there is no doubt in my mind what I would rather be wearing if I was living near the Arctic regions. In those areas my house would then be a well designed strawbale house that incorporated airtightness to a large degree.  Yes please.  And with mechanical help to ventilate it too if that is what it takes to increase comfort at little cost in every sense of the word.  

I do know that a simple earth plaster over plasterboard will not suck up all the excessive humidity in some climates. But I do know that were I live, a temperate climate and with very high average humidities - i.e. 70-80%  such a strategy did transform an old house of mine that was running condensed water on the inside of single glazed windows in winter, and leaks air like mad, into a dry house that does not get condensation, even when there are several degrees of frost outside, even though it is still a relatively cold house without the fire going.  My new house does much better - its loaded with thermal mass from earthen materials, with lots of straw and wool as well.  It is dry and maintains fairly even temperatures. And I have a  sq.m. or two of humidity-inducing gardens internally that still do not generate enough humidity to cause condensation on single glazed windows. The only time my building was overwhelmed with moisture was when it was first built and drying out, and then once again, after I earth plastered my hessian supported will insulation ceilings  - to help make them more airtight as it happens. 
Horses for courses.
As we all know, its matter of location and then being appropriate.

John, and others, the notion that airtight buildings may in themselves be unsafe actually comes, to me at least, from some of the very people who promote airtight fully mechanically ventilated buildings.  My eye brows were raised only last year (they were drooping a lot before that) when a USA-based expert was over talking about these sort of issues at a recent seminar, and the question was asked (not by me) about the issue of unhealthy levels of CO2 being found in airtight bedrooms. That this occurred was acknowledged as a real problem and the solution offered was,  of course, that you must mechanically ventilate. The clear impression was given that it is positively dangerous to live at all unless you mechanically ventilate.  Even worse if you open a window, or dare to venture outside where the dust  and mites and pollen and microbes will get you.  The best hope offered for well-being, or even survival, was to huddle inside a hermetically sealed room that provides mechanically filtered and heated air delivered at exactly the correct RH.  The outdoor air is painted as being as being far too dangerous to allow inside and breathed, unless is is conditioned. 
I am now reassured that this notion is not correct - silly even.  Phew! 
But I have been to Bejing, and yes, there the air IS dangerous outside, but surely the high level solution to aim for is to address the issues around fixing the pollution.

If I could find 30W fans for a few dollars here I would consider installing them in parts of well-crafted designs for colder regions here.  Mostly, the systems that I have seen here so far are more like thousands of dollars, use fairly large wattages, and require hundreds of dollars a year spent on replacing filters.  I will now be on the look out for much more efficient systems. However, if I did suggest using them I would also like to be absolutely certain that when the fans are not needed when the weather was suitable, or if the fans break down, then I could still open the windows.   

Perhaps I am getting old, but I am increasingly amazed at the level of complication, as opposed to simple cleverness, that seems to be creeping into so much of what we do.

It did seem to me I must admit, that if termites can regulate their internal air conditions so well naturally, then why the hell can't we?  
As Chris says, this ability would be an ass kicker.  
But if people like John can't solve this, then I doubt if I will, so in the meantime, I agree that the evidence-backed advice by John and others sure does make total sense for most people to adopt until we develop that level of building intelligence showed by termites! 

Or maybe we don't want to live in termite mounds.

I'm off for a break.

Cheers

   
Graeme


 



On 22/03/2013, at 12:07 AM, Feile Butler <feile at mudandwood.com> wrote:

> Has anyone tried living walls? Allegedly 1m2 of living wall per 100m2 of floor space will do the trick for creating fresh air within a building. I'm not sure if this is only for office space and whether the occupation patterns of a home would require different treatment.
>  
> It's not maintenance free, but it's a different kind of maintenance - dare I say, enjoyable and theraputic. And if designed into a project properly at the beginning - it could be a stunning focal point in a home/building, rather than kit to be hidden out the back.
>  
> Low-tech, natural and beautiful - is it too good to be true?
>  
> Cheers
>  
> Feile
>  
> By the way, despite my previous vent (excuse the pun), I do not believe that air-tightness is bad and leaky buildings are good. I agree that we need to manage air movement in and out of buildings. But I sometimes wonder are we so focused on mechanical ventilation systems, could there be other elegant solutions that we are missing?
>  
>  
>  
> Féile Butler
> MRIAI B.Arch Dip. Arch Conservation Grade III
> Mud and Wood
> Grange Beg, Skreen, Co. Sligo, Ireland
>  
> T:  +353 (0) 71 930 0488
> M: +353 (0) 86 806 8382
> E : feile at mudandwood.com
> W: www.mudandwood.com
> _______________________________________________
> GSBN mailing list
> GSBN at sustainablesources.com
> http://sustainablesources.com/mailman/listinfo.cgi/GSBN

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sustainablesources.com/pipermail/gsbn/attachments/20130324/bdad9796/attachment.htm>