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This is sort of a physics question: Could you pump cold water through radiators to cool your house? The obvious flaw is something like "cold doesn't radiate," but, then, don't we have the general principle that a good antenna for transmission is usually a good receiving antenna too, and hence the cold "radiator" should absorb thermal radiation from other objects? (In addition to cooling by convection.)
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insulation?
We have a huge attic and are interested in insulating it. The last picture on this page is of the attic:
http://www.pas.rochester.edu/~tobin/co-op/prospective_houses/960_south_plymouth/
We live in Rochester, NY. How would we go about finding out how much insulation we would have to add? The landlord says it will only be worthwhile if we extend those beams to make room for a greater thickness of insulation.
Re: insulation?
Doing the math, heat loss is linearly related to the U value, and the U-value is the inverse of the R-value. Roughly, give or take maybe 10% depending on your exact roof construction, the benifits of adding batt insulation in terms of the total assembly R value are:
R-0, current, 4.5R => 0.22 U-value
R-13, 3.5" batts => 16.7R => 0.06
R-19, 6" batts => 22R => 0.045
R-30, 9.5" batts => 31.5R => 0.0317
Heat loss is proportional to the U value (other factors such as the difference in temperature between the sides and the area are assumed equal in this comparison), so even a little insulation gets you the big savings jump. You can think of your current roof as loosing 22% of your heat, while throwing in R-13 batts means you only lose 6% of your heat (assuming you don't turn up the temperature now that its insulated!), and R-30 would cut that 6% in half to 3%. So any insulation helps you out quite a bit.
However, installation labor is probably 2/3rds to 3/4ths of the cost. And hanging R-30 batts is about the same effort as R-13 batts (unless you have to extend the rafters...). That's probably where the 'worth it' is coming in. As long as you are paying the high, pretty fixed labor install cost, you may as well pay the small incremental cost to install to the recommended value.
The textbook answer to how much insulation is needed looks to the much-chewed-over society standard, set with due assumptions of construction cost versus life-cycle savings. The ASHRAE guidelines for Rochester call out minimum insulation (not final assembly) R values of:
R-15 for above deck insulation (usually hard foam that is a continuous sheet under the roofing, without air gaps or thermal bridges)
R-19 for metal buildings
R-38 for attic and other installations
Note that one option may be to throw batts between the rafters and then cover that with hard foam insulation for additional r-value (although this may be an obscenely expensive way to go). Also, remember to vent between the insulation and the roof deck properly. I have an attic full of insulation that I have to tear down and reinstall with the proper air gap (http://www.cor-a-vent.com/PDF/S4002P.pdf) the winter :(.