With all the news about record cold temperatures (it was -14°F the other morning sans wind chill) it’s interesting to note how much Windows can leak.
The temperature on the left is from a remote sensor placed outside away from the house so that it does not pick up any residual heat. The other is a sticky thermometer placed outside on a double pane window. The thermometers read to within a degree when placed near each other.
Nine degrees is a pretty steep temperature gradient.
Our house has modern, high-quality, double-pane windows and we’ve found that keeping the drapes closed keeps the heat in and measurably lowers our heating bills.