Most of the energy used in homes is for heating and cooling. Turning down your thermostat, installing good insulation and getting a more efficient boiler can help cut your fuel bills and your carbon emissions. Financial support is also available to make your home more energy efficient.
The amount of energy you conserve will depend on several factors including the size, shape, and construction of your house; the living habits of your family; the type and efficiency of the heating and cooling systems; and the type of fuel you use to cool or heat your home. Once the energy savings have paid for the installation cost, energy conserved is money saved - and saving energy will be even more important as utility rates go up.
Heat flows naturally from a warmer to a cooler space. In winter, the heat moves directly from all heated living spaces to the outdoors and to adjacent unheated attics, garages, and basements - wherever there is a difference in temperature. During the summer, heat moves from outdoors to the house interior. To maintain comfort, the heat lost in winter must be replaced by your heating system and the heat gained in summer must be removed by your air conditioner. Insulating ceilings, walls, and floors decreases the heating or cooling needed by providing an effective resistance to the flow of heat.
Batts, blankets, loose fill, and low-density foams all work by limiting air movement. (These products may be more familiarly called fiberglass, cellulose, polyicynene, and expanded polystyrene.) The still air is an effective insulator because it eliminates convection and has low conduction. Some foams, such as polyisocyanurate, polyurethane, and extruded polystyrene, are filled with special gases that provide additional resistance to heat flow.
Reflective insulation works by reducing the amount of energy that travels in the form of radiation. Some forms of reflective insulation also divide a space up into small regions to reduce air movement, or convection, but not to the same extent as batts, blankets, loose-fill, and foam.
One of the most popular questions homeowners ask before buying insulation is which type of insulation is the best. That really depends on:
The R-value of a substance is its direct measure of its resistance to transferring energy or heat; R Values are expressed using the metric units (m2.K/W). Basically the higher the figure the better it is at resisting energy transfer, so the easier it is to maintain a difference in temperatures across it for a longer time.
In the metric system, the R value measures per meter squared the amount of degrees kelvin temperature difference required to transfer one watt of energy. So an R value of 1 means per meter squared a single degree difference will transfer one watt of energy. So an R value of 2 will transfer half a watt of energy for a degree of difference.
Usually the R value is given for a certain type and thickness of material as installed (often known as the 'added R value'); i.e. a low density glasswool batt would need to be 130mm installed to achieve an R of 2.5, but only 100mm thick of medium density. Note: We say 'as installed', taking a low density batt that is designed to work in 130mm as installed and squashing it to fit in 100mm will not be the same as using a medium density batt in the first place.