re: thermal mass?
30 mar 1997
graig pearen wrote:
>i too would like to learn more about thermal mass.
it absorbs heat when it warms and gives heat back when it cools... it's useful
for storing solar heat, or for cooling a building in summer by ventilating it
with cooler nighttime outside air and closing it up during the day and letting
the mass absorb the heat that leaks into the building during the day, when the
air outside is warmer. thermal mass helps a building most when it's surrounded
by insulation. superinsulation is good for heating, but for natural cooling
you need thermal mass.
>i have had my shop for 2 years now and it has lots of thermal mass.
>(concrete floor, lathe, milling machine, and other 'heavy stuff').
>even when the temperature is sirttng at -30c for a couple weeks,
>the shop never gets below -10c.
if the shop is large and the slab has no insulation underneath, it will be
partially heated by the warmer ground underneath, on a cold day. insulation
around the edge of the slab would help.
>a year ago, i had my bulldozer in the shop (about 5 tons) and had the
>shop up to room temperature on the weekend during a cold snap. a week
>later, with no heat in the shop and the outside temperature daily high
>of -35c, a pan of water still wasn't frozen!
steel has about the same thermal capacity as water by volume, altho
it's a lot heavier and more expensive...
>this past winter i only had heat in the shop one day and the coldest
>the shop ever got was -10c! there are no windows and it is only
>insulated to r20 in both the walls and ceiling.
windows are poor thermal insulators compared to walls, so a building with only
walls may be warmer than one with windows, in a cold cloudy climate. the best
of both worlds may be an attached sunspace with lots of windows that allows
sun-warmed air to flow into the building on sunny cold days, and stays cool
on cloudy days, robbing no heat from the building.