Guy Martin’s House Without Bills

[SimonD]

3 hours ago, Iceverge said:

What is your occupancy per m3 of internal volume.  If it's low enough the volume of internal air can buffer periods of over and under ventilation.

 We are 4 plus dog in a volume of above 900m3. But as I mentioned above, ventilation requirements change dramatically once a hydrophilic fabric is introduced into the equation. So, to quote from an earlier study I read when deciding on my design:

 

Quote

During the humid and cool weather, the hygroscopic materials
improve the indoor conditions, but during the cold weather, the
effect is minimal. An important result from the humid and cool
test periods is that the comfort and air quality in a room with
significant hygroscopic materials and a ventilation rate of 0.5
ach is nearly the same as that in a room with no hygroscopic
materials and a ventilation rate of 1 ach. 

https://web.ornl.gov/sci/buildings/conf-archive/2004 B9 papers/002_Simonson.pdf

 

Now, it does acknowledge that consideration regarding air polutants is probably separate, but other studies using MVHR show similar reductions on ventilation requirements simply because moisture drive such a significant proportion of those ventilation requirements.

 

18 hours ago, saveasteading said:

It looks as if we have a club of three at present, and some others dithering or not committing.

 

Yes, indeed. At some point when I actually find some spare time, I might draw together my collection of research into this and building physics just so there more readily available reference.

[Iceverge]

Interesting study that. 

 

Undoubtedly there's marked humidity buffering effect with the hygroscopic materials.  

 

The test was done in the presence of controlled mechanical ventilation. Had this been turned off I suspect RH would have climbed higher than desirable in both cases. 

 

Passively/manually ventilating can work with the proviso you have one of the following. 

 

1. Heat driven stack effect.

2. Very large internal volumes. 

3. Diligent occupants. 

 

Hygroscopic materials will undoubtedly help smooth out the worst RH extremes with the latter two. 

 

However for almost all owners I would think mechanical ventilation would still provide much cheaper and more consistent control over IAQ.