[Strawbale] Sub Floor Radiant Heating

[Ilan Ungar]

So heating earth is complicated. In that case, I don't think I should have a
problem insulating the bottom of the slab since we use pile (or is it
Caisson?) foundations and the slab does not transfer loads to the soil.

I was asking about slab thickness because I imagine I would want the heat to
be smooth with little low and high peaks. This means larger heat storage,
correct? With a typical 20 cm slab and 10 cm flooring and filling (???), one
would remain with a cold floor after a single cloudy day. So, what would the
parameters for arriving at a correct
floor-thickness/heatsink-volume be?

A larger heatsink will require more heat which I think I could easilly
provide, in my climate, through solar panels, to water tank, to in-slab PEX
piping, especially when charging of a large heatsink should begin ahead of
the heating season.

I have printed the long article provided by Shody for bedtime reading. So
far, it looks supportive:

"The relatively low temperature required for circulation water in a
radiant-floor heating system provides an opportunity to utilize solar hot
water. This approach works best with concrete-slab systems;
higher-temperature water is generally required when the tubing is attached
to the underside of wooden floors. While such systems are fairly complex and
expensive, radiant slabs offer one of the best ways to make use of solar
energy for heating portions of a building without direct access to sunlight.
Most practical are systems in which solar energy heats water in a storage
tank that can then be circulated through the slab"

The article also mentions the high cost of this system, around $14,000.
Solar panels and tanks are not that expensive here, is it the PEX that makes
this system so expensive?

Derek Roff wrote: "But a well-built, well-designed home in your climate may
not need a
radiant floor heating system.  With a good passive solar design, you
will need little backup heat."

Thanks Derek. Wouldn't that require lots of tripple glazing at the South
with heatsinks absorbing sunlight etc? In that case, wouldn't that require
backup heating after a single cloudy day?

In the climate we have here, I am imagining an insulated floor slab, with
solar heating. Seems to me I can even have the house ventilated in winter
with open windows during the daytime. Once the windows are shut, within an
hour or so, I'd get a nice cozy temperature throughout the house…?

Thanks a lot. Ilan.



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-- 
Ilan Ungar, Architect.
Lehavot Habashan 12125
Israel
972 4 6953429
972 52 2431398