8-Star Homes: a "cost-optimal" solution
Further to my recent work on "pushing the rating envelope" I've found recently-completed research which shows that a home with a building envelope rated to an 8-star standard, along with an appropriately-sized solar hot water heater and solar photo-voltaic array for electricity generation will provide the most 'cost-optimal' housing solution for Australian housing. This is consistent with the recommendations of the accompanying report to my 10-star challenge design submission, which noted that while a 10-star rating is achievable, the cost of the specification required to do so would be cost prohibitive for many households.
Achieving 8 star efficiency is primarily a matter of applying passive solar design principles - which I've written about previously - and settling for a more compact dwelling (no mega-'McMansions' here, thankyou). These fundamentals under-pin the Studio G design philosophy, rather than being an 'optional extra'.
From an article originally published in "Architecture & Design":
Analysis carried out for Lifetime Affordable Housing in Australia (LAH) provides new insights into lifetime costs and energy savings for volume housing design options and identifies sensitivity factors.
Lifetime Affordable Housing in Australia is a study at RMIT providing essential research to inform policy, enabling Australia to provide high performance urban housing within current and future economic and environmental limits.
Dr John Morrissey, from RMIT, said: “We are now entering into the concluding stages of this project, and are in the process of disseminating our research findings, which have significant policy implications.”
The research indicates that the cost-optimal approach amongst the options considered is enhancement of the energy efficiency requirements under the building code to the optimal cost-benefit target of 8 stars equivalent performance.
They also indicate that an 8 stars building envelope performance standard, in conjunction with on-site solar PV and solar hot water, is cost optimal and in line with international policy directions for on-site RE.
Morissey adds: “Design based interventions represent the most cost-effective means of improving residential thermal performance. In this regard, the research indicates passive solar energy efficiency design can provide an important and low cost step towards reducing environmental impacts”.
“More compact designs with passive solar features are more adaptable and can potentially be provided at lower cost than bespoke alternatives;
“House size is a critical factor in performance, and furthermore, better performing designs require less adjustment across different orientations; and
Building standards regulation could be used to further drive energy efficiency standards without undermining affordability.”
Visit http://www.rmit.edu.au/cfd/laha for further findings and policy recommendations