After a light snowfall, take a look at your roof in the morning as the sun rises to see how energy efficient your home is. If the snow is already melting, that means heat is rising to the attic's roofline and melting the snow. This means one thing: a poorly insulated attic. If the roof still has an even coating of snow all the way around, it means your home is efficient and your attic floor is airtight and well-insulated. Sometimes you can even see clear patterns where heat is escaping and warming parts of the roofline, which will give you a clear guideline where leaks are and where you need to add insulation.