[Strawbale] window construction

[Dave Howorth]

On Sun, 2008-04-20 at 16:29 -0500, David Neeley wrote:
> Isn't it more a function of priorities and return on investment? If
> your other details are sufficient that having a thermal break in your
> window bucks makes a noticeable difference, you are highly unlikely to
> need it.

That could be the case. But I noticed that window frame manufacturers
have gone to the trouble of producing designs with thermal breaks in the
frames, and others suggest adding further extra insulation to the frame,
so I was surprised to find plain timber used for the mount (either
lumber or ply), or rather I was surprised not to have found any similar
thermal detailing for the surround.

Since I haven't yet found any designs, I have no idea of the cost so
can't judge whether the investment would be worthwhile!

> One strategy that can work quite well is to use very insulated and
> sealed vents--or, perhaps, an energy recovery ventilator--for your air
> exchange needs combined with fixed glass windows. This eliminates the
> problems of air leakage around operable windows, so long as the buck
> and the window panel itself is well and truly sealed. A non-glass vent
> can be much more easily sealed and insulated than any window,
> too...and the optimal locations for ventilation are often not at
> window locations anyway.

I absolutely agree about the need for airtightness. Pressure testing is
necessary and so - almost certainly - is central heat recovery
ventilation.

I do believe some manufacturers in Sweden, Canada and elsewhere are able
to make well-sealing opening windows. Opening windows are still an
important psychological factor in good weather :)

Cheers, Dave