Mother Nature's Insulation Test
Use a blanket of snow to measure how much heat your house is losing.
For those of you who live in snow country, here's a quick field test for checking attic insulation levels: Look up! If snow is melting from your roof while neighbors' roofs with the same exposure have an undisturbed blanket of snow, your house is losing too much heat from your living space.
To get a handle on adequate insulation levels in your area, check out "How Much Insulation Should Be Installed" on the North American Insulation Manufacturers Association's website. The site is a good resource for all kinds of insulation questions.