DESIGNING AN ENERGY EFFICIENT HOME
Believe it or not, the small actions you take to be more energy efficient when designing your home can have a very significant impact on improving the environment and saving you money in the long run.
Today the average home consumes almost 40% more electricity than it did in 1990.
While the Building Regulations require that new buildings achieve minimum standards of energy efficiency, higher levels are in many cases worthwhile. Since a house being built today can be expected to be occupied for 60 years or more,an energy-efficient design can yield considerable savings over its lifetime.
Although some energy-saving measures can be implemented at a later stage, retrofitting is often more expensive and less effective than incorporation when the house is being built. Apart from reducing fuel and electricity bills, an energy-efficient home design can provide improved comfort for occupants while helping to protect the environment. It can also provide insurance against future increases in fuel costs.
Transmission of sunshine through windows passive solar heating) can reduce heating costs.The selection of a site which is exposed to the low-altitude winter sun can allow for passive solar heating.
Energy assessment
Many decisions affecting the energy performance of a house are taken early in the design process. A method of calculating annual heating energy consumption should be used to compare alternatives at the preliminary design stage.
Levels of insulation higher than those required in the Building Regulations are in many cases economically justified. Insulation should be well distributed around the building shell. It is better to have a good overall level of insulation than, for example, a highly insulated floor with no roof insulation.
Adequate ventilation is essential to provide fresh air and to remove moisture, odours and pollutants. However, excessive ventilation during the heating season results in energy wastage and can also cause discomfort due to draughts. Controlled vents should be installed in every room; trickle or slot vents incorporated in window frames can ensure a reasonable amount of continuous fresh air and can be opened up or closed down to a minimum as required.
If the house is exposed to the low-altitude winter sun, glazing should be concentrated on the south facade. Window area on the north facade should be minimised to limit heat loss. Thermal mass within south-facing rooms, e.g. masonry walls or concrete floors, can absorb and store solar energy during the day and release it gradually during the evening. The heating system should have a fast response time and good controls to maximise the usefulness of solar gains. Overheating protection in south-facing rooms in summer can be provided by
overhanging eaves, blinds, natural ventilation, thermal mass or other means.
Windows should have a high resistance to heat loss. ‘Low emissivity’ double glazing, which has a special coating to reduce heat loss, is required.
