THERMAL PERFORMANCE
PRIMERS FOR THERMALLY EFFICIENT HOME DESIGN
Here are 12 things you’ll almost certainly need to do when designing and constructing a home for a cool temperate climate zone of Australia if it's to achieve a thermal performance of 7.5 stars or greater (rated without fear or favour under NatHERS). They are listed by order of importance, as relevant from early to later design stages.
1. Orient the home and its layout to maximise northern exposure for living areas.
2. Use thermally efficient windows and external doors (frame and glass systems).
3. Be frugal with glass area (have it not exceed 20% of floor area where possible) and/or use thermally efficient doors and windows with particularly high thermal efficiency (Uw < 2.5 and SHGC > 0.5) as listed in the Window Energy Rating Scheme (WERS) database.
4. Have a more generous expanse of glazing facing solar north (or within 15 degrees thereof) that has clear exposure to low winter sun, but only if the dwelling also has a good amount of internally accessible thermal mass.
5. Provide comprehensive and effective external sun shading of all glazing from summer sun.
6. Have a reasonably compact plan form, to reduce the building's external surface area to floor area ratio, and hence also reduce unwanted conductive summer heat gains and winter heat losses.
7. Incorporate doors, screens and flexible walls (such as large sliding panels) to separate air compartments within otherwise open living zones, thereby allowing more effective containment of mechanically heated and cooled air.
8. Ensure that location, size and detailing of door and window openings provide broad and easy pathways for cross (horizontal) and stack (vertical) ventilation through the dwelling interior.
9. Use materials with high thermal mass, heat storage capacity and surface conductance (i.e. ability to absorb and release heat) and broad surface area in direct contact with interior air.
10. Provide substantial insulation for floors, walls, roofs and ceilings.
11. Avoid recessed light fittings that require substantial gaps or cut-outs in ceiling insulation.
12. Provide airlocks to the home’s most regularly accessed entries and exits.