Although low-energy and zero-energy housing are internationally best practices, they are still expensive. One problem with housing standards is that they are often based on cost-benefit analysis, which can lead to incorrect conclusions about whether sustainable housing is affordable.
New research has shown that such analyses can overlook some financial benefits, such as lower energy bills or lower mobility costs. These analyses overlook the effects of factors like improved thermal comfort on householders’ quality and health. As the report shows, sustainable housing can have significant benefits for the most vulnerable members in our community.
With changes to minimum building regulations and creation of subsidies like solar rebates, the environmental performance of Australian housing has been slowing improving. Despite the many benefits of sustainable housing, such as lower utility bills, greenhouse gas emissions, better comfort, and better health, this is still a significant problem.
These benefits are not include in cost-benefit analyses. This leaves large gaps that could use for investment in sustainable housing.
What Was The Outcome Of The Study?
The study consisted of a three-year mixed-method evaluation for a small, sustainable housing development in Horsham (Victoria). The Victorian Department of Health and Human Services (DHHS) commissioned the study. It used both qualitative and quantitative methods to evaluate housing policy and environmental performance.
To maximize passive solar principles, four houses with two bedrooms were built, each one having nine stars (under the National House Energy Rating Scheme. NatHERS). Design elements and technologies included partial reverse brick-veneer construction and double-glazed windows. There was also a 1.5-kilowatt solar PV system. The rainwater tank shared with the other houses is 5,000 litres. These houses were constructed without air conditioning. The living areas have gas heating and ceiling fans.
These nine-star houses were compared to seven houses built to DHHS standards and with a six star NatHERS rating. The results were also compared to a DHHS technical guideline of industry practice. We performed a cost-benefit analysis and technical performance analysis (utility usage, internal temperature), three rounds interviewing householders in different seasons, as well as a personalized household sustainability assessment.
Using a cost-benefit analysis, nine-star housing was unfeasible for DHHS. Even if DHHS could capture the savings for the householders, the payback period was only 40 years for one of four dwellings in a high energy-price future. This was due in part to the higher than expected capital costs associated with sustainability initiatives.
The resale price per unit could be as high as A$40,000, however. A technical performance analysis revealed significant benefits for nine-star households. These benefits included lower utility consumption and bills. One resident shared the following. Look, I haven’t paid my power bill for six months. I’m still in credit.
These Households Were Found Expensive
A decrease in utility consumption, including solar feed-in tariff, made them A$1,000 more financially secure over the past year. The average household purchased 45% less electricity than the control (and 73% less that the industry standard).
Consumed 22% less water (30% lower than the industry standard. 40% lower CO2 environmental impact due to power consumption 63% less than industry standard. They were more comfortable with the indoor temperature in their home for 10% longer even with no air conditioning.
Extreme weather conditions magnified comfort benefits. The nine-star houses, which were above 41 degrees for the second consecutive day, were 16.6 degrees cooler than the six-star standard house.
This allowed householders to stay at home in heatwaves, rather than having to search for alternative accommodation as was the case with control households. One resident said. In summer, I would sit at the supermarket because it was cool. I can stay at home and eat out.
Residents Confirm Well-Being Benefits Expensive
Interviews with residents revealed positive social outcomes of living in sustainable housing. This supported the technical data. They cited improved health and better financial management as some of the benefits.
These householders claimed that they had more spending money because of low or no utility bills. They could purchase Christmas gifts for their children, pay off personal debt, lay-by, and go on holiday.
Instead of thinking Oh God, I must go and lay-by this, I now go clothes shopping expensive occasionally. This led to better mental health and stress reduction for many householders.
Research shows that housing sector may have over-relied on cost-benefit analyses, which could lead to overlooking the benefits and detriments of different housing arrangements. Combining quantitative and qualitative evaluation methods can provide a better understanding of how housing impacts people’s lives.
Our research also shows how sustainable housing benefits go beyond the environment. These positive effects can lead to improved living conditions for some of society’s most vulnerable. This can lead to a reduction in pressure on the health system and other support sectors.