In 2003, Australia saw the introduction of a set of important national energy efficiency regulations for new homes. These regulations raised the quality of design and materials used in domestic buildings.
When it comes to energy usage, homes built between 1975 and 2000 fared better than older buildings as they were more likely to have insulation installed in the roof, walls and floor, (although older homes often had no floor insulation). Unfortunately they still faced significant draft proofing problems. If there are gaps anywhere in the insulation or sisalation, its benefits are significantly reduced.
The design trends during this period are the major influencer when it comes to homes leaking conditioned air. Architects from an aesthetic point of view favoured features like down lights, but there was little regard for how they were sealed. Having a multitude of lights that leak air throughout the house causes your heating and cooling system work harder, increasing your energy bill.
Other features like fixed open vents in the laundry or toilet provide the path of least resistance for air to exit. It’s also where unconditioned air can infiltrate the home. Houses on stumps will also face issues of air leaking through the floorboards.