If you’ve bought a new home in Victoria in the last few years the builder would have impressed you by saying its an “energy efficient” 5 star home (or maybe even 6 stars).

Unfortunately even if all existing homes were converted to 5 star homes this won’t get us to the low carbon future we need. And in fact many new 5 star homes use more energy than forty year old 2 star homes. The 5 star standard is misleading, and needs to change if we are to have truly low energy homes.

The major flaw with the 5 star standard is that its focus is solely on the theoretical heating and cooling performance of the home. A 5 star home should use less energy to heat or cool per square meter than a homes with a lower rating. However the largest contributor to greenhouse gas emissions in most Victorian homes now is not heating and cooling – its appliances! Additionally most new homes feature halogen downlights – one of the most inefficient forms of lighting on the market. Finally, there is no validation that the specified insulation and sealing of the building – key to minimising heat loss and gain - is done properly.

Homes now have more appliances in them than ever before. And I’m not talking electric can openers. In particular large screen plasma and LCD TV’s use several times more power than the modestly sized CRT screens they replaced. A large plasma TV will draw 400 watts. To put that in context, if the TV runs 12 hours a day, it will produce more than half the greenhouse gas a car produces in a year. But the Victorian home energy standard doesn’t take appliances into consideration.

Walk into any display home, and it will be filled with bright halogen downlights. For some reason these are still often linked with low power consumption because they are “low voltage”.  To the contrary, to produce a given amount of light halogen downlights use five times as much power as an energy efficient fluorescent light. I’ve heard of new homes that have over 50 halogen downlights in them. If all these lights were on you would require a $40,000 solar PV system to keep them illuminated . But the Victorian home energy standard doesn’t take lighting into consideration.

The Victorian home energy standard does take heating and cooling into consideration. But only on a theoretical basis. Two fundamentals of high performance passive solar design are high levels of insulation and good sealing. The home energy rating specifies the level of insulation and sealing that a building must install in a given home. But unfortunately there is no inspection in place to verify that this level of insulation and sealing is actually installed. I recently undertook a major home extension, which required that the entire house, including the original part of the home and the extension, was a 5 star standard. I spent a lot of effort and time getting the insulation and sealing right. However, had I been lazy and not bothered to spend dozens of hours with a caulking gun and gap sealant, my house would still be classified as 5 stars because the design was certified as a 5 star design. The problem is that there is no mandated inspection to verify the quality of sealing and insulation. There are inspections for the footings and the framing, but not for the insulation and sealing. My building inspector didn’t even notice the effort I had gone to properly seal the sisalation around the windows. The home is certified as 5 star as designed but not as built. In effect its up to the builder as to whether they do the job properly or not. And considering that making sure that batts are not compressed and there are no gaps, and that all penetrations to outside must be well sealed is time consuming and costs money, why would a builder bother if there is no inspection to validate the quality of the work?

On the other hand the Australian Building Greenhouse Rating Scheme (ABGR) for commercial buildings is actually effective in reducing building energy use. The reason for this is that it is based on the actual performance of the building, based on one year’s worth of billing data. It cuts straight to the bottom line – the actual amount of greenhouse gas produced when operating the building. So the type of appliance (eg computers), the lighting, and the actual heating and cooling performance are all important to achieve a 5 star whole of building ABGR rating. These building genuinely use less energy, and produce less greenhouse gas emissions, than lower star buildings.

The bottom line when it comes to averting dangerous climate change is reducing greenhouse gas emissions. The residential 5 star standard isn’t achieving this, because it doesn’t focus on the bottom line – the actual energy use and greenhouse gas emissions of the home when occupied and in use.