What is the Difference between Convection and Drafts?
Old, drafty windows are the cause of much chagrin (and more than a little discomfort) for homeowners everywhere. Window drafts make it next to impossible to be comfortable inside the home during the cold winter months. And they also increase heat bills, because they make the furnace or home heating system work much harder just to keep the home at the desired temperature.
But sometimes we think our windows are drafty when they are not. Convection is a physical process that sometimes confuses people into thinking they have a window draft. Drafty windows can be the result of poor caulking, improper window locking or sealing, weather stripping that is either shrunk, damages, or missing altogether, or racked windows that won't seal at all. Many problems causing drafts are easy to fix, but sometimes the function of the window is impeded enough that window replacement is in order.
Convection Different from Drafts
Some homeowners get new windows precisely for that reason, only to find that their new energy efficient windows feel drafty to them. Though it can be difficult to tell if it is caused by convection or drafts, it is usually the former. Convection happens when air gives up its heat to the cooler surface of the glass and then sinks toward the floor upon being cooled. This movement in turn brings more warm air in toward the glass, which creates what appears to be a draft. What is occurring is the process of warm air forcing cold air to move owing to the density differences in the air at different temperatures. Heated air from your ductwork flows through the home and when it reach the window, it pushes cold air off the surface of that window and down toward the floor. Convection is proof that windows are working properly.
Author: Joseph Gringeri