Home' Homes : Homes 2011 Contents Scoop Publishing | WA’s Best Homes & Design 2011/12 101
SUN & SHADE
Unprotected glass is the greatest source of heat
gain in a well-insulated home. In summer, it
can be a hundred times greater than through the
same area of insulated wall, and in winter, heat
loss can be 10 times greater.
Eaves, blinds and deciduous creepers and
trees can be placed and angled to shade your
windows in summer but let winter sun in.
Louvres are also becoming popular and can
be set at angles to increase solar gain in winter
and reduce it in summer. They can also direct
breezes for cross-ventilation.
Double glazing, used overseas for decades, is
now gaining popularity here to reduce winter
heat loss (surprisingly, more of a problem in
Perth than summer heat gain). It doesn’t
prevent radiant heat from entering, but slows
down conducted and convective heat losses.
With the big influx of products, it offers a way
of incorporating large windows without
sacrificing thermal efficiency.
One way of quantifying the sustainability of a home or
product is to get a carbon assessment. Local product
eTool has been identified as one of the world’s leading
tools for this by the Curtin University Sustainability
Policy Institute. eTool can compare the environmental
impacts of materials and house design. Its Life Cycle
Assessment (LCA) includes analysing the embodied
energy (the energy and carbon that goes into the
materials, their transportation to site, assembly and
maintenance) with the operational energy (energy used
to run the building) over the building’s design life.
It also includes a cost analysis to find out which
design will give the best value for the environment and
your hip pocket. Figures are now showing that with
intelligent design principles, including an eTool LCA,
designers can produce a home that costs less to build
and run and has a lower carbon footprint, lasts longer
and has greater resale value. The web-based software is
free for anyone to use, or the eTool team can conduct
the assessment for you.
Although WA is behind other states in making
rainwater tanks mandatory in new homes,
rainwater harvesting is becoming more common.
It is hoped this will continue, despite the fact
there’s no state government rebate in the city and
federal rebates are no longer available.
An average roof in Perth can collect about 50 kL
(50,000 litres) of water a year and, when plumbed,
can supply up to 20 per cent of a household’s
water needs (depending on tank size). Tanks range
in size from a few hundred litres to 50,000 litres
and styles range from slimline tanks to bladders
installed under the house.
The cost to buy, install and connect one
varies greatly but is about $3000 for a 2kL
tank and $3500 for a 5kL tank.
Most urban homes are limited to tanks of about
2kL unless they can be integrated underground or
under verandahs at design stage.
If tanks were mandatory for new homes, and
continued to be installed in existing homes at
the current rate, the annual demand on Perth’s
scheme water supplies could be cut by 2.9
gigalitres (2.9 billion litres) by 2015 – enough
to supply more than 10,000 homes with water
for a year – and 13.9GL (enough for more than
50,000 homes) by 2030.
“An average roof in Perth
can collect about 50kL of
rainwater a year, enough,
when plumbed, to supply
household’s water needs”
Building and renovating is no longer just about creating your
dream home. Clever design and planning can make a difference
to the environment – and your home’s running costs – but it’s
hard to know where to start. So we surveyed architects, builders,
designers, environmental experts and government authorities
to produce a practical guide to what you can do now to make
a real difference in the years ahead.
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