You might blame the people who dilly-dally as they walk through the door, bringing gusts of hot air along with them.

You can doubt the veracity of your air conditioner, which, if it's at least 10 years old, may not be cooling your home as efficiently as it once did. You can even curse the sun – the origin of your discomfort.

But if you're truly bewildered by why your home feels warmer than usual this year, don't overlook the possibility your home may need an infusion of wall insulation.

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