Unwanted energy transfers can be reduced in two main ways. The first is lubrication. When two surfaces rub together, friction transfers kinetic energy to thermal energy. A layer of oil or grease keeps the surfaces apart, so they slide past each other instead of rubbing directly. This reduces friction, so less energy is dissipated and the parts stay cooler.
The second is thermal insulation. Energy is transferred out of a hot object or building mainly by conduction through its walls. Insulating materials have a low thermal conductivity, so they transfer energy slowly. Many, such as wool or foam, trap air, and trapped air is a poor thermal conductor. A thicker layer of insulation lowers the rate of energy transfer, so the rate decreases.
In a house, loft insulation, cavity wall insulation and double glazing all reduce the rate of energy transfer to the outside. Double glazing traps a layer of air between two panes of glass. Less energy is wasted, so heating bills fall.