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["clanSkeen" <sgian AT planetc.com>]

> If one had a room with less glazing than needed to heat it optimally (warm 
> only at 2pm on a sunny day so supplemented by woodstove) and one put black 
> 55 gal drums of water in front of the glazing that is there. Would it make 
> the room colder? Why or why not?

It's a trick question.

After the sun has been shining on the barrels all afternoon and then the sun 
goes down, the room is going to be warmer than it would have been had the 
barrels not been there.   If the room cools off to, say, 45 degrees and you 
have a wood fire in the room the next morning, the room will be cooler than 
it would have been had the barrels not been there because the water in the 
barrels will be absorbing some of the heat that would otherwise have just 
been warming the air.  It takes much, much less heat to warm air than it 
does water.   But then again, if you let the fire go out mid morning [before 
the sun is shining through your window, say].  Then the room will be warmer 
than it would have been had you not had barrels in it.  The water will have 
absorbed some of the room heat and it is lending it back as the air in the 
room since air also cools off much faster than water does.

But the real question is:  Is the AVERAGE temperature in the room higher 
with the barrels or without them.   To see why this is a trick question 
consider this:  you have a five gallon pot on the stove and a one pint jar 
with which you are going to fill it from the sink.  If you leave the sink 
running when you fill up the jar and take turn a few steps to empty it into 
the pot, will you run more water down the sink than you put in the pot?  It 
depends of course mainly on how fast the water is coming out of the sink 
spigot.  If it is a small dribble of water, the amount you lose down the 
drain will only be a tiny fraction of what goes into the pot.  But if the 
water is on full force with the result that it only takes  three or four 
seconds to fill the pint, then you are losing more water down the drain than 
you are putting into the pot.

The key here is your insulation and how fast heat is lost through the 
window.  If the temp swings in the room are great and stays cool for  large 
part of the day, the water has so much more capacity to store COLD that you 
are actually making the room colder with it.  If the temp swings are not 
extreme and the room does not stay cool for a long part of the day, your 
barrels are making the room warmer.

James