Household energy ratings
in Greener Homes on 25 April 2010
Home buyers benefit from reading the eco-scorecard.
Household energy efficiency ratings (or star ratings) tell you how comfy the temperature of your home will be throughout the year.
“Most people wouldn’t know the star rating of their house,” says Matt Fisher, from the Association of Building Sustainability Assessors. “But the stars have a dollar value in terms of the price and running cost of the home – that will become better understood as a lot more houses advertise with their star rating.”
So how are the ratings figured out?
Energy assessors plug the details of your plans (or existing building) into a nationally accredited software program, such as FirstRate5 or AccuRate. The program analyses the home’s layout and orientation, and the construction of the roof, floor, walls and windows.
This information is matched with the local climate to calculate how much heating and cooling you’ll need. “It’s a very sophisticated model,” Mr Fisher says. “Using climate data collected over many years, it calculates [the home’s temperature] for every hour of every day of the year. It works out the amount of heat or cooling energy necessary to keep the house comfortable.”
Homes can score between zero and 10 stars. At zero stars, the building does next to nothing to protect against temperature outside; at 10, it will be comfortable all year round without artificial heating or cooling. A five-star home is good, but far from outstanding.
Last year, state and federal governments agreed to lift the residential standard from five to six stars. The states must bring the rules into effect by May 2011, at the latest.
“It’s a step in the right direction, but we need to go further,” says Liz Minchin, Age journalist and author of new eco-book Screw Light Bulbs. She argues the regulations should have been more ambitious, by adding a timetable for even higher standards and factoring house sizes into the ratings.
“The five-star regulations helped slow down the increase in emissions from Victorian homes, but those emissions are still growing – largely because houses are getting so much bigger,” she says.
“Bigger homes typically take more energy to keep cool or warm – and that costs everyone money in rising energy bills, because we need to build more expensive power generation to cope with spikes in electricity use.”
The good news is that the governments have agreed to another change that should push household energy efficiency higher. Homeowners and landlords will soon be required to declare the energy, water and greenhouse performance of a house when they put it up for sale or lease.
It means that buyers and renters will be able to compare the environmental impacts and ongoing costs of different homes. Even though the full details and start date aren’t set (it will be phased in from May next year) the plan is relevant immediately – especially for people considering renovations.
Ms Minchin says a similar mandatory disclosure scheme in the ACT has shown that energy-efficient homes attract higher prices. A study for the federal government found that in 2005, lifting the energy rating of a median-priced house in the ACT by just half a star added about $4,500 to its value.
“Buyers are becoming more conscious of climate change and energy prices,” Ms Minchin says. “Real estate agents say people are asking about energy ratings more and more.”