[Greenbuilding] Passive Solar and HVR/ERV systems

[Corwyn]

On Feb 23, 2007, at 17:37, Ian Albinson wrote:
> I take it your basement is windowless? That's why you'll being using 
> radiant to bring the temp up?

Effectively, yes.

> With the current design, I looking at no basement, but the master 
> bedroom, spare/storage and utility rooms
> are on the first floor level, ie. on slab level. I do worry with 
> passive though, even with a wide bank of windows
> to those rooms, that the concrete will be cold underfoot without 
> radiant heat.

Even _with_ radiant heat the concrete floors underfoot will seem cold.  
A well insulated high mass house doesn't require high temperatures in 
the slab to keep it warm.  Consider two examples, one full solar with 
most of the heat being stored in the slab, the other full radiant heat 
(no solar).  Since you supply heat to make up for the losses (which are 
the same), both slabs will be exactly the same (average) temperature.

Concrete needs to be very warm to be perceived as warm to the skin 
(near 90º).   You will probably never get it that hot no matter how you 
heat it, unless your house is losing a _lot_ of heat.

> If I cover the concrete with rugs or a wood floor, I'm going to lose a 
> lot of my thermal mass though.

Well, not lose, so mush as insulate, but yes it will be less effective. 
  The trick is to insulate your feet.

> How would a storage tank system work, instead of an on-demand unit?
> The tank system will be there anyway because of the solar, so would it
> be better to have a 2nd active tank to heat the remaining temp 
> difference,
> or the instant system?

I wouldn't recommend a second tank over a tankless, unless your only 
power source is electricity.  A solar savvy tankless will only heat the 
water enough to bring it to desired temperature.   A tank will keep 
water at that temperature even if you aren't using it, and the sun is 
about to supply all the heat you need.  (Yes, that can be mitigated 
some).