Energy Efficiency in Housing

There have been recent suggestions that energy efficiency ratings for new housing be increased from 5-star to 6-star.

This is fine, but in determining ratings little or no consideration is given to orientation or layout of the building, apart from areas of glazing in the various compass sectors, or the application of passive solar principles. Most of the emphasis seems to be on preventing artificially created heat from escaping from the building.

There is no denying that over the past three to four years there has been a home-building boom, with many new subdivisions spreading cities out ever further. If we were to make a critical study of these new houses, I am sure that we would find that very few have been designed to take advantage of that great renewable source of energy, the sun.

Most have been designed to be attractive from the street, so that we can drive straight into a multi-car garage, irrespective of which way the site faces or how it might best benefit from the sun.

The very first action of the designer should be to visit the site and determine all its pros and cons – above all, how best to use the sun for energy needs. Spaces like garages, bathrooms and laundries should, where possible, be placed on the southern or cold side of the building. This gives some protection from the southerly cold and does not waste the northern sector where the warmth of the sun can be best utilised.

Of course, there is an added challenge when the desired view is to the south, but there are such things as double glazing, north-facing skylights and the like to track the sun. Most people are aware of solid mass, such as concrete floors with dark tiles, solid brick ‘trombe’ walls etc, to store heat or to modify temperature. But for those with a modest budget there are now many lightweight materials on the market which provide both structural strength and excellent insulation qualities: no real need for a brick or concrete to be in it! Take for example, dare I say, plywood: excellent bracing strength and insulation qualities it comes from a renewal resource and remains a carbon store. The weather surface is still a problem, but we are working on it. Wool batts are also good and environmentally friendly but still a little dearer than some alternatives.

Back to the sun. Coordinating the widths of the eaves and the heights of the windows above the floor is the most simple of passive solar principles to control the temperature within the building. Shade can be provided at the peak of summer, thus lessening the need for air conditioning, and the sun’s rays can penetrate well into a room when most needed. The overhang also to some extent protects the glass from cold. Double glazing in PVC. frames is excellent, but there are ‘smart’ glasses available as cost compromises. Heavy drapes and pelmets also add to efficiency. And for old buildings with existing windows, stick-on plastics are now available to achieve a double-glazing effect.

Neville Gray
Home Builder