Moving to six stars
WORDS
Michael Green
Building code regulations for energy ratings are on the rise from five to six stars, and mandatory disclosure of a home’s star rating at sale time is coming soon. Studies show it is the unglamorous and often low-cost fundamentals that work best to lift a home’s energy performance towards a 6-star rating.
techniques such as good orientation and cross-
the insulation and comprehensive draught
ventilation. “You need to involve someone who
proofing,” he says, “but that constituted just 20
understands thermal comfort right from the
per cent of the total upgrade cost.” In contrast,
beginning,” she says. If you wait until you have
double-glazing proved highly expensive for more
settled on the design, moving to a higher rating
limited benefit.
can become expensive. “By then, there’s usually
Although these findings vary according to
been so much blood, sweat and tears put into
the dwelling and the modeling undertaken,
the plan that you’re loath to change anything,”
Maksay says householders can learn
Carmichael says. “To get it up to six stars, the
important lessons from the study: focus on the
building sustainability assessor is left with little
fundamentals before going for trendy upgrades
option but to recommend expensive inclusions
– seal gaps and insulate walls and ceilings. “To
such as double glazing.”
really improve your star rating you have to tackle wall insulation, whether that’s with blow-in
RETROFITTING EXISTING HOMES
granulated mineral wool or polystyrene, or by
Although the timing and details are still
removing the weatherboards or plasterboard and
unclear, the federal and state governments
inserting batts.
HOUSE ENERGY RATINGS ARE ON THE RISE
have agreed that a dwelling’s energy efficiency
“Insulating your ceiling and ignoring
again. The regulations in the national building
should be disclosed when it is put up for sale or
your walls is like trying to stay warm wearing
code have been lifted from five to six stars.
lease. That’s sure to provide a big incentive for
a beanie, but no clothes,” he says. “The other
Within a year, the new rules will be in place
homeowners to lift their green game. But is it
message is that there’s a difference between
throughout the country (except in NSW, which
possible for every home to hit six stars?
wimpy and comprehensive draught sealing. You
uses the BASIX rating system instead). The star rating system is based on predicted
The Moreland Energy Foundation (MEFL) and Sustainability Victoria have analysed
need more than just door snakes.” Maksay adds another important caveat:
heating and cooling requirements for your
the efficiency potential of dozens of existing
all-out blitzing your home’s star rating probably
home. Depending on your location, a 6-star
houses. The researchers surveyed each dwelling
isn’t the smartest way to spend your money, or
rating means you’ll need up to a quarter less
and calculated its energy rating. Then they
save energy, because it only takes into account
energy to stay comfortable than you would
modelled a series of upgrades: ceiling, wall and
the building fabric. “You can reduce your energy
under the old 5-star rules. With utility prices on
floor insulation, draught proofing, drapes and
costs cheaply in other ways, with efficient
the march, that equates to a hefty saving on your
pelmets, external shading and double-glazed
lighting, appliances and hot water systems, and
bills.
windows.
by reducing standby power,” he says.
So how much does it cost to convert 5-star plans to six stars?
Govind Maksay of MEFL says that without
“Also, if you’re renovating, think about
major renovations, six stars will be very difficult
how you can heat and cool your house more
to achieve in most homes.
effectively – for example, you could put a super-
The average upfront rating of the houses
efficient reverse-cycle air conditioner into your
Timothy O’Leary and Dr Martin Belusko of the
they examined was just 1.7 stars. With a full suite
living room and limit the total area you need to
University of South Australia analysed a dozen
of retrofitting measures in place, the average
keep at the right temperature.”
house designs offered by volume builders. Using
jumped to five stars. But out of the 45 dwellings
standard materials and without any major
studied, only half a dozen were able to reach or
LINKS
redesigns, they found it would cost an average
exceed six stars.
www.unisa.edu.au/nbe
NEW HOMES
$3900 to lift the plans to the new level.
In Maksay’s initial study, the full retrofitting
www.absa.net.au
package came in at an average cost of over
www.mefl.com.au
Association of Building Sustainability Assessors,
$22,000. However, the changes weren’t all equal,
www.sustainability.vic.gov.au/2904
says it’s possible to build to six stars at no extra
in either impact or cost. “On average, over 80
cost, so long as you include passive solar design
per cent of the rating improvement came from
But Alison Carmichael, CEO of the
88 — SANCTUARY
DESIGN MATTERS
Depending on your location, a 6-star rating means you’ll need up to a quarter less energy to stay comfortable than you would under the old 5-star rules.
6-STAR HOUSES
J In Victoria, the new 6-star rating is mandatory only for new homes and major renovations, but getting the star rating as high as possible on existing houses like this Melbourne brick veneer home is still desirable and would significantly reduce the energy required for heating and cooling. Initially rated at 2.4 stars, MEFL and Sustainability Victoria’s study found that this house could be upgraded to perform at 5.6 stars by retrofitting a range of sustainability technologies: draught proofing, underfloor and wall insulation, drapes with pelmets and external shading, as well as upgrading the existing ceiling insulation (right). The cost of the retrofits was estimated at $9,947.
Retrofitting stars – Case studies From Moreland Energy Foundation (MEFL) and Sustainability Victoria’s On-Ground Assessment of the Energy Efficiency Potential of Victorian Homes (see link at left) VERMONT HOUSE
COBURG HOUSE
Construction type: 1970s single-storey, detached brick veneer, 175sqm.
Construction type: 1930s single-storey, detached weatherboard, 108sqm.
Suspended timber flooring.
Combination of suspended timber and concrete slab flooring.
Rating before upgrade: 1.5 stars
Rating before upgrade: 1.2 stars
Rating after full upgrade: 5.3 stars
Rating after full upgrade: 3.7 stars
Cost for full upgrade: $45,724 (including double glazing worth $26,288,
Cost for full upgrade: $18,376 (including double glazing worth $11,455
which added 0.4 stars to the rating, after drapes and pelmets)
which added 0.2 stars to the rating, after drapes and pelmets)
“This home is orientated well,” Maksay says. “The long axis of the block
“This house is not oriented very well,” Maksay says. “It only has a couple
is east-west, so it has a long northerly aspect and the living areas are
of windows to the north and one of them is in a bedroom. Wall insulation
situated to the north. All the utility areas are on the southern side, with a
made a significant impact here – more than doubling the star rating of
small amount of glazing. It has very good sub-floor access so it would be
the house – but there wasn’t sufficient access to install floor insulation.
possible to insulate the ceiling, walls and floor to a high level.”
However, the house is ideally suited to using an efficient gas heater in the kitchen and living space only, because that area is thermally isolated. The Vermont house is centrally heated, so even though it reached a higher star rating, it would have a much larger overall annual heating and cooling bill.”
SANCTUARY — 89