Energy efficiency made easy

Not necessarily. It depends on a number of factors including house design, orientation, colour scheme, the percentage of glazing, whether it’s a single or double storey house, which State and climate zone you’re in, and what you currently use as your default glass. There’s a lot to consider, but we’re here to help!

Upgraded glass is critical to improve energy performance. Depending on your climate, you may need to choose double-glazed windows and doors. All climate zones will see an improvement by using low emissivity (Low-E) glass.

Low-E is a term used to describe glass with a special coating applied that helps to either stop heat from entering a home, or escaping from a home, dependant on which surface the coating is applied. There are a large number of different Low -E glasses available with different performance ratings, costs, availability and even different looks. Hard coat is used in single glazing because it’s robust, where soft coat has to be on the inside pane of a double-glazed unit. Our team can help you choose the right type of glass for your project.

In all climates, it’s important to have a low U-value, which reduces the amount of heat or cold that gets transferred from the outside air temperature to the inside of your home. This helps keep the inside of your home more comfortable. In heating climates like VIC and the ACT, you want a higher Solar Heat Gain Co-efficient (SHGC) which allows heat from direct sunlight to enter your home. In cooling climates like QLD, you want a very low SHGC to keep the heat from the sun out. NSW has a mix of both climates depending on the region.

Single storey houses, darker colour schemes in VIC and lighter colours in QLD, or a glazing area less than 25% of the conditioned floor area are some examples of design factors that make it easier to reach 7 stars.

Large double-storey houses, large amounts of glazing, open plan living areas with large voids and big windows, and certain colours can make it harder to reach 7 stars. Certain orientations relative to the sun also change how well a house design will rate.

In heating climates you want to draw heat into your home, so darker colours are better. Cooling climates are the opposite; you want to keep heat out, so lighter colours are better. NSW has a mix of both climates depending on the region.

Windows and doors are the ‘weakest’ point in a house when it comes to heat gain and heat loss, and once the glass is upgraded the frames become even more important. Also, your window colour is usually tied into the colour of your roof, fascia and guttering, all of which have an impact on energy efficiency, so the entire colour scheme of your home becomes critical.

In heating climates, you can see an improvement in performance by using a thermally broken frame. This is a frame with a polyamide (plastic) strip in the middle to stop heat or cold transferring from outside to inside, in much the same way as an air gap in double glazing works for the glass.

A qualified energy rater will need to prepare an energy report for each new house. This report is prepared using software that takes into account all construction materials, ventilation, glazing, overshadowing, orientation, percentage of glazing etc. The energy rater will upgrade materials from baseline specifications to higher performing materials until a 7 star rating is achieved. NSW uses a system called BASIX, which does something similar.

Generally speaking, your windows and doors will usually be the last items upgraded as these upgrades are the costliest. Changing your colour scheme to suit your climate zone is usually a free change. Upgrading wall and ceiling insulation is reasonably cheap, as is the waffle-pod in your slab, and both are quite effective in improving energy performance.

Overshadowing refers to the amount of shade your house gets from surrounding objects like trees, houses and other buildings. In a cooling climate, it’s a positive because the shade stops the heat from the sun making your house even hotter. In heating climates, it’s a negative because you don’t get the free heat from the sun heating up your house.

In QLD, you’re still able to use QDC MP4.1 which gives you an automatic 1 star boost if you have an alfresco area of 12m2 or greater that is open on at least two sides and has a ceiling fan. This effectively means you only need to reach 6 stars for the rest of the house. There is no option to use any Solar PV systems to reduce the 7 star requirements.

The 7 star requirements are for the building ‘fabric’ only, which are the walls (including windows and doors), roof and slab. All other inclusions fall under the new ‘Whole of Home’ requirement. This adds up things like Solar PV systems, heating and cooling appliances, hot water systems, pool and spa equipment, and lighting to give you a rating out of 100. New houses must reach 60/100 as a minimum. The higher your rating, the closer you are to having a Net Zero home. You cannot trade building fabric at 7 stars against the Whole of Home factors; they are dealt with separately, e.g., PV does not offset a poorly insulated house.