Heating and cooling solutions
● East and west windows are challenging to shade externally; the lower sun aspect makes overhangs and awnings largely ineffective. Light-coloured 90 per cent shade cloth is the most effective.
● Ideally, there should be no direct sunlight on internal floor or wall surfaces between 10am and 6pm in summer, to avoid overheating.
● Quality well-fitting curtains and blinds are only as good as the operator: close them as soon as daylight/views are not needed in winter, and when direct sunlight hits the window in summer.
● Thermal mass such as concrete or ceramic tiles absorbs the sun’s heat during the day, even if not directly sunlit, and releases it slowly as the temperature falls. If shaded in summer, it absorbs surplus heat and keep the house cool. Laying another flooring material on top reduces this effectiveness.
● In modern houses, air leakage can account for 20 per cent of the space heating energy loss. A well designed house is ‘built tight and ventilated right’. Locate doors or windows to capture prevailing summer breezes and allow for secure cross-flow ventilation.
● Overheating in New Zealand homes is usually room-specific. At-risk rooms receive much direct afternoon sun, have limited external shading and are enclosed during the day with minimal ventilation. To mitigate, stop sun from entering at the wrong time of the day in summer; paint the exterior in light colours or with heatrejecting darker paints; include small, high windows that can be left open; shade the ground around the building; plant larger trees and shrubs to create a cooler microclimate.
● Even well-designed homes may need a little active cooling in summer. Modern ceiling fans require as little as 18 watts of power at their highest setting (about 1/100th of the energy used by heatpumps). Specifications, placement and operation are key. Fan airflow energy efficiency is measured in cubic metres/hour/Watt – the higher the etter; at least 200m3/hr/W. Fans should be located immediately above each activity area, as they cool people not the air.