Monday, January 4, 2010

Home Heating - notes about Insulation and FiberGlas

Any pursuit of winter heating economies should have insulation first on the list.

Fuel you burn once but insulation will last your life time and that of your children's life times.

If you spend on insulation only what you want your savings on heat to give you back you will miss the problem of the heat your house will lose when your electricity goes out and the inconvenience you will have chopping wood to make up for it.

For your or your contractor's planning for a new heating system one should always require first a plan for the amount of insulation to be used. This is so you can size a new heating system realistically. The more insulation installed the smaller the heating unit needed.

Insulation needed in new home construction is always easier added to before construction than after construction.

At one time an amount of insulation thought to be a "super" amount was one with an R value of 18 or 19. Now, in 2009, that is the minimum required by law for any new construction. The reasons it was changed are largely due to rising costs of fuel.

Now, a super amount of insulation is more likely to be an R value of 30 to 36. (In Europe it is higher still.) To obtain a value of30 to 36 would require 6" of rigid Styrofoam or 6" of polyisocyanurate (aluminum on both sides). This would supply a 3.5” wall and 3" added outside or it would fill a 5 1/2" wall and 1" added outside it.

The insulation about a basement should always be considered, too. Treat it the same as any outer wall.

Attics normally are insulated with FiberGlas to avoid moisture problems between the rafters. That would use about 5.5” of FiberGlas to give an R value of approximately 20. To achieve the same insulating value as the walls 30-36" would call for an additional 2" of rigid insulation, laid across 2"x6" rafters.

Other kinds of insulation may be used and other configurations of framing may be used
but the R values should be kept.

Windows are major sources of heat gain and loss. There is no simple way to limit it. The most modem windows with all their multipanes and tints can hardly be said to be well insulated.

To learn the R value of them simply take the reciprocal of their conductivity.

I know of no commonly used good method of insulating windows. Years ago I custom

fit 2" thick pieces of polyisocyanurate insulation in all our windows that could be put in and taken out easily. It made a significant difference. We have since seen it only once in any other house.

We put the insulation in during cold weather to keep the heat in and again in hot, sunny

days to keep the sun and heat out. It is one of the major reasons for our heating and cooling successes.

Outside or inside swinging insulated blinds are never practical.

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