After more than a decade scrutinising and writing about environmentally sustainable design and building products for the magazine, Warren McLaren bravely turns the microscope on his own retrofit project.
My printed copies of The Last Straw, an international
journal of straw bale and natural building, commence with Volume 1, 1993. I
participated in one of the earliest practical workshops on strawbale
construction in Australia. I worked for five years in Australia’s first
commercial strawbale building. So, where do I live? In a cosy, earth-rendered home
of straw? Alas, no. Instead, I reside in the proverbial triple-fronted, brick
veneer house, complete with a black tile roof! It rankles.
But sometimes, real life trumps daydreams. When my wife and I
moved out of Sydney to a country village, my choice of rural location won out.
In balancing the ledger, she got the type of house she wanted. Having
previously built two homes from scratch, she pined for something she could just
walk into, without needing to lift a finger. And who is going to argue with a
With my long-held vision of building a strawbale home left
unrequited, I needed to embrace a new challenge. Was it possible to green the
basic, stock-standard Aussie house? Without a mortgage, or a loan?
Well, we’ve given our best shot. In fact, the only
renovations we’ve made in the past six years have been solely about making our
home more comfortable for humans, whilst being less of a burden on the broader
Our new home was the epitome of Australian house vernacular,
especially for the end of the last century, when it was built. However we did
inherit a few saving graces, such as blown cellulose insulation in the ceiling,
a slow combustion wood heater, ceiling fans in the bedrooms, a north facing aspect
and eaves sized correctly to block summer sun from entering windows.
What then have we done to up the ante on these few scant
eco-credentials, and improve the liveability of our abode?
Firstly we replaced
the original carpet (a rapidly wearing polypropylene) with a more durable all wool
berber. We had also tried to go with a natural jute underlay, such as Tontine’s Wunderlay,
but our carpet company was rather recalcitrant and wouldn’t come to the party,
saying they didn’t have any experience with such products. In the end, a
recycled foam underlay was used beneath.
Nearly all of the north and south facing windows are
floor-to-ceiling panes of ordinary 3mm glass. The Your Home Technical Manual reckons
up to 40 per cent of a home’s heating energy can be lost, and up to 87 per cent
of its heat gained through windows. Obviously the fenestration in our abode was
completely unsuited for the Southern Highlands of NSW, where it snows briefly
every few years, with temps easily dropping to −8°C during the winter, and
summer highs nudging 40°C.
Home Technical Manual gives advice on glazing in such regions: “… double
glazing is recommended in this climate because on each winter’s day there are
19–20 hours of heat loss through glass with a maximum of 4–5 hours of heat
gain.” We would’ve loved to have replaced all the windows in the house with
funky new double-glazed windows, but there were three reasons why we didn’t: embodied
energy, inconvenience and cost.
New double glazed windows aren’t cheap, especially when we
planned to upgrade every window in the house—bar the wet rooms.
Our compromise was retrofitted double glazing: Magnetite.
Optical-grade acrylic panes are fitted with magnetic strips that seal with a
resounding ‘thunk’ onto a mini-frame of quad-like plastic that has been mounted
into the window reveal.
Using data from the Australian Window
Association’s Window Energy Rating Scheme (WERS) Magnetite suggests that a retrofit
such as ours improves the U value of windows by 40.3 per cent. Visitors to our
home reckon, anecdotally, that it has added about 8°C to the inside warmth
To further mitigate any night-time loss of heat, we installed
curtain rails and fully enclosed curtain pelmets around the top of window
architraves. Of course, windows are but one element of the building shell.
There is next-to-nothing that’s thermally efficient about brick veneer walls and
they are rather awkward to insulate once construction is finished. We briefly
considered the notion of taking off the plasterboard and lining all the walls
with batts. Those three nemesis of embodied energy, inconvenience, and cost
again quickly quashed the idea.
I did toy with the idea of covering the external brick walls
with sheets of corkboard insulation by Portugal’s Amorim Isolamentos. But with
Australian suppliers very thin on the ground, we decided our fledgling family couldn’t
afford the expense and risk of experimenting with something so left-field.
In the end we settled on Insulabloc.
This is expanded polystyrene foam sliced into little 1cm cubes. The product has
a high recycled content and is made in Australia. Insulbloc Australia provided
test results from the Australian Wool Testing Authority (AWTA) showing
Insulbloc garnering a thermal insulation rating of R4.0 per 100mm thickness. It
was installed by removing tiles above the cavity wall and blowing the tiny blocks
into the wall void with a big reverse vacuum style hose. Insulbloc suggest such
a finished insulated wall is equal to about R6.
The wall between lounge and garage was an uninsulated stud
wall with plasterboard on both sides. Here a hole saw cut openings for the
Insulbloc to be inserted while a thin sheet of insulating batt was positioned
to keep the cubes in place until I got around to plastering the cutouts back
in, and repainting.
In the roof we already had the blown cellulose that was
in-situ when we moved in. To supplement that, we self-installed two layers of
R2 Tontine Thermal
Batts. These batts are made of soft, non-itchy thermally bonded polyester fibre
with 83 per cent recycled content.
These efforts on the building envelope have greatly improved
the comfort of our home. We reconfigured the open plan nature of the house by
adding three timber-framed glass doors to the lounge room. These allow us to
control heat flow and noise.
Alas, that ghastly black tile roof remains, and is, I
believe, the greatest contributor to heat ingress into the house during summer.
Having said that, after Aussie
Solar installed a 2kW solar array of 12 photovoltaic panels we shaded a
significant portion of the north facing tiles. Thirty evacuated tubes from the
gas boosted Hills Esteem solar hot water system shade another part of the roof.
Rain Harvesting’s Advanced
Leaf Eaters filter out gutter debris as precipitation is diverted to our
27,000 litre rainwater tank, and a Davey
RainBank pumps rainwater from the tank to our Bosch front-load
washing machine, laundry, toilet and yard taps irrigating our nine veggie
beds and 30 fruit and nut trees
We have also picked the usual array of low hanging fruit for
a green retrofit. Lighting is now either
compact fluorescents or LED strips and globes. External doors and yard gates
are lit with motion-sensor, solar-powered LEDs. Our east-facing windows have
removable shadecloth screens to reduce the heat gain of the summer sun. A large
shade sail is erected each summer over the north facing wall, to similarly keep
old Sol from throwing his heat onto the bricks there. We replaced the energy guzzler of electric stove
with an Omega induction cooktop. Being highly energy efficient, it has the
instant heat of gas, without the attendant dangers of naked flames and
non-combusted, unflued gas.
What is still to be done? A massive amount. I’d love to
cover those black roof tiles with a light coloured reflective paint, or at the very least
install a sun-powered, hot air extraction fan, like the SolarWhiz.
If the grape and passionfruit vines turn out not to be successful summer wall
screens, then we may need to bag or render the external brick walls, also with
a light coloured reflective paint. Very average vinyl flooring in the kitchen
and dining area is scheduled to be replaced, probably with cork. Some dark
spaces would benefit from a solar powered ‘skylight’, such as the Solaro
Day or Kimberley Illume, which both avoid issues of heat gain usually
associated with skylights.
However, the piece de resistance may well be a renovation of
the double garage into a guest bedroom and extra living space. This will require
the current work bench and tool storage, currently domicile in the garage, to
relocate to new premises, resulting in a new workshop being erected in the
backyard. Maybe strawbales will get a look in, after all. One can but dream.