Thermal Insulation for Buildings

About this course.

Thermal insulation is fundamental because it slows the flow of heat between the inside of a building and the outside, which keeps interiors closer to a comfortable temperature and dramatically reduces the energy needed for heating and cooling. The short answer is that heat always moves from warmer to cooler places, so in summer it flows into a building and in winter it flows out; insulation resists that flow, so a well-insulated building stays warmer in winter and cooler in summer with far less mechanical heating and cooling. It is often the single most cost-effective measure for improving both comfort and running costs over the whole life of a building.

To appreciate why insulation matters, it helps to picture a building with none. Its roof, walls and floors offer little resistance to heat flow, so on a hot day heat pours in through the roof and walls, and the interior climbs toward the outdoor temperature; on a cold night, heat drains out just as freely, and the interior falls toward the cold outside. The occupants then rely almost entirely on mechanical heating and cooling to hold a comfortable temperature against this constant flow, which is expensive and never quite succeeds, because the moment the system stops, the temperature drifts back toward outdoors. Insulation changes this by placing a layer of high thermal resistance in the path of the heat, slowing the flow so the interior holds its temperature far longer and the heating and cooling systems have much less work to do.