Sitting on a couch, you realize this convective motion as a cold draft and increase the thermostat. Instead, increase the temperature of the glass. Choose a number of glazings with low-conductance gas fittings, warm-edge spacers and thermally-resistant frames. They increase inboard glass temperatures, slow convection and enhance comfort.
A fantastic absorber is a fantastic emitter. Most wood stoves are black for a very good reason. You may feel a cooker’s radiant heat in your face across a space. Subsequently, your face feels cool as it radiates (emits) its warmth to a cold sheet of window glass. This uncomfortable sensation, like convection, persuades one to increase the thermostat. Low-“E” coatings emit less long-wave heating energy. In cold climates, more warmth stays in the home. In warm climates, the heat stays outside. Low-E coatings improve the insulating value of window about the same as adding another pane of glass into a unit. Therefore a double-glazed low-E window functions like a triple-glazed clear window.
Air leakage siphons about half of a typical home’s heating and cooling energy to the outside. Air leakage through and around windows is responsible for much of the loss. Well-designed windows have durable weatherstripping and high quality closing devices that efficiently block air leakage. Hinged windows such as casements and awnings clamp a lot more closely against weatherstripping than do sliding and double-hung windows. But well-made double-hungs are okay. Air leakage is also influenced by how well the individual parts of the window unit are joined together. Lowest values are greatest.
Letting Energy In
Well-designed windows block the flow of energy out of our conditioned indoor environment. But we don’t wish to block our whole supply of free solar power. In a cold climate we welcome the sun’s warmth and light the majority of the time. And once we catch the heat we do not need to give this up. In a warm climate we do not need the heat, but we do need the light.