Thermal Insulation
Heating accounts for anything up to 70% of the energy bills in buildings and yet without adequate insulation, much of that energy is being unnecessarily wasted. Insulation saves money and our nation's limited energy resources; it can also make your working and living environments more comfortable by helping to maintain a uniform temperature throughout the building. Walls, ceilings, and floors will all be warmer. Insulation can also act as a sound absorber or barrier, keeping noise levels down.
The amount of energy you conserve will depend on several factors: the local climate; the size, shape, and construction of the building; the occupancy patterns of the building; the type and efficiency of the heating; and the fuel used for heating. Once the energy savings have paid for the installation cost, energy conserved is money saved-and the annual savings will increase if energy prices go up.
HOW DOES INSULATION WORK?
Heat flows naturally from a warmer to a cooler space. In the winter, this heat flow moves directly from all heated living spaces to adjacent unheated spaces, or to the outdoors; or indirectly through interior ceilings, walls, and floors - wherever there is a difference in temperature. To maintain comfort, the heat lost in winter must be replaced by your heating system. Insulating ceilings, walls, and floors decreases this heat flow by providing an effective resistance to the flow of heat.
The effectiveness of an insulated wall or ceiling also depends on how and where the insulation is installed. For example, insulation which is compressed will have reduced effectiveness. Similarly the effectiveness of insulation in wall or ceilings can be diminished because some heat flows around the insulation through the studs and joists. With careful design, this short-circuiting can be reduced.
WHAT IS A U-VALUE?
To put it simply, U-Value is the measure of the rate at which heat is lost through a material. As it is a measure of heat loss, the lower the U-Value the better. So for example, one square meter of a standard double glazed window will transmit about 2.5 watts of energy for each degree difference either side of the window (denoted by the unit W/m2K) whereas a low-emissivity window will do better at about 1.8 W/m2K.
To download further information on U-Value click here.
CONSERVATION OF ENERGY AND THE BUILDING REGULATIONS 1997
The Building Regulations 1997, Part L Conservation of Fuel and Energy require that all new buildings achieve minimum standards of energy efficiency. Levels of insulation higher than those required in the Building Regulations are in many cases worthwhile, since today's buildings can be expected to be occupied for 60 years or more, and an energy-efficient design can yield considerable savings over its lifetime.
Part L gives maximum values for each type which should be met to comply with the Building Regulations standards of energy conservation.
Maximum Average Elemental U-Values (W/m2K)
Exposed roofs 0.25
Exposed walls 0.45
Exposed floors 0.45
Ground floors 0.45
Semi-exposed roofs 0.35
Semi-exposed walls 0.60
Semi-exposed floors 0.60
Exposed windows, personnel doors and rooflights* 3.30
Vehicle access doors 0.70
Maximum Average Elemental U-Values New buildings and Extensions to Existing Buildings
Refer to Building Regulations Technical Guidance Document Part L (Energy Conservation) for complete details .
INSULATION OF THE BUILDING FABRIC
Insulation evenly distributed over all elements generally produces better results than additional insulation applied to only one or two elements. It is better to have a good overall level of insulation than, for example, a highly insulated roof with no wall insulation.
Since increasing insulation thickness does not produce a pro-rata reduction in U-value, there comes a point where the economic return on additional insulation for any one element will be virtually nil.
Good workmanship and attention to detailing are most important when insulating a building, to avoid thermal bridging and other related problems, and could have greater impact on overall heat loss than simply increasing the thickness of insulation.
