Insulation refers to an energy savings measure, which provides resistance to heat flow. Naturally, heat flows from a warmer to a cooler space. By insulating a house, one can reduce the heat loss in buildings in cold weather or climate, and reduce the heat surplus in warmer weather or climate. Insulating a house has several benefits such as energy savings, cost savings and increased comfort. Barriers to undertake energy savings measures may be split incentives, relatively high investment costs, and the time and effort required to realise the energy savings. There are several types of insulation against heat loss in cold climates, each with its own technical characteristics and financial costs and benefits. Insulation measures are generally one of the most cost effective energy savings measures.
By insulating a house, one can reduce the heat loss in buildings in cold weather or climate, and reduce a heat surplus in warmer weather or climate. Thus, insulation limits the need for heating or cooling the house. Heat losses or heat surpluses arise because of differences between the indoor and outdoor air temperature. Naturally, heat flows from a warmer to a cooler space, and the temperatures will converge to an equilibrium temperature, a physical phenomenon based on mechanisms like transmission (the heat flow through materials) and ventilation (heat flow by air). Insulation aims at reducing the speed of this convergence of temperature in order to decrease the need for heating or cooling.
This technology description focuses on insulation against heat loss, but includes some references on insulation for cooling.
Several types of insulation measures exist. Below insulation measures for residential buildings are described:
Wall, roof and attic, floor and soil insulation
Wall, roof and floor insulation may be done by fixing insulation material to the wall, roof or floor, either on the inside of outside, e.g. by using insulation plates. Different materials for walls, roofs and floors require different types of insulation measures. Buildings may for example have cavity walls consisting of two ‘skins’ separated by a hollow space. This space already provides some insulation but can be filled up with additional insulation material, e.g. foam, to further improve the insulation effect. Roof insulation for flat roofs differs from insulation for steeper roofs.
Floors are usually made of wood or concrete, each requiring specific insulation measures. Another option to reduce heat losses to the ground is soil insulation, for example by placing insulation material on the soil in a so-called “crawl space” (a very low basement).
The age of a building is an important factor determining the type of insulation and the way in which it is installed, e.g. if insulation is put on the outside or inside of the construction.
Window and door insulation
Windows and exterior doors have a large impact on the heating and cooling requirements of a building. New materials, coatings, and designs have led to significantly improved energy efficiency of new, high-performing windows and doors. New high-quality windows may be up to six times more energy efficient than lower-quality, older windows (Pew Centre, 2009). Some of the latest developments concerning improved windows include multiple glazing, the use of two or more panes of glass or other films for insulation, and low-emissivity coatings reducing the flow of infrared energy from the building to the environment (Pew Centre, 2009). Attention needs to be paid not only to the window itself, but also to the window frame, which can significantly impact a window’s insulation level.
Another insulation measure that reduces the amount of heat loss is sealing cracks in the ‘shell’ of the building. Cracks cause infiltration of cold air from outside or leakage of warm air to the outside. Strips or other material can be used to seal cracks in moving parts, such as windows and doors, and in places where different construction parts are attached to each other.Feasibility of technology and operational necessities top:
Increasing insulation is technically feasible for almost all buildings, although it is most efficient to add insulation during the construction phase. Because of the diversity of insulation measures, a suitable option is generally available for almost every building, since most buildings have room for improvement with respect to insulation. Next to technical requirements, human preferences regarding comfort and aesthetics also play a role, e.g. for windows better insulation comes with lower insolation, i.e. less light.
In practice, the suitability of insulation measures depends largely on the current technical state of a dwelling. Specifically the insulation already in place limits additional insulation. This is due to the physical space left for insulation and the suitability of the existing construction (e.g. availability of a cavity wall or sufficient cavity width, enough frame space to install better insulated but usually thicker windows, enough crawl space under the floor), but also because the law of diminishing returns applies: Every additional layer of insulation yields less energy savings than the previous one.