Most of the talk (and action) of green design and eco architecture is premised on having a clean slate, a blank canvas, on which to conjure up more award winning, high star rating, icons of sustainable creativity. Yet the vast bulk of our buildings are already with us. Seven out of eight million Australian households live in existing separate houses and/or terrace/town houses. This is where the biggest bang for buck resides, if we really want to affect environmentally positive change. We need to swivel our focus onto our rather copious stock of energy inefficient brick veneer (and similar) homes. And eco retrofit them. Warren McLaren lists some "bolt-on" that require little or no renovation to an established dwelling, but will appreciably reduce the building's environmental impact and save on running costs.
Insulation
To their credit the federal government understood the immense climate change leverage potential of retrofitting already built Australian houses. However their much beleaguered Home Insulation Program (HIP), although technically astute, was poorly administered, allowing for a few opportunistic operators to rort the system and put lives at danger. Not to mention stigmatising an otherwise very legitimate and important industry. Even without generous government benevolence, installing insulation in existing homes remains one of the most cost-effective ways to improve energy efficiency, whilst reducing both utility costs and carbon emissions. Ceiling insulation is most effective, as our roofs can allow for the passage of up to 35 per cent of a dwelling's heat loss and gain. But how can established houses insulate their walls where up to 20 per cent of heat escapes and cold penetrates? Products like Insulbloc (pictured left) can now be easily pumped into existing brick veneer cavity walls to offer an insulation rating of about R4.0 per 100mm, higher even than most pre-installed wall batts.
Fenestration
Windows can contribute to about a fifth of a building's ingress and egress of warmth. Glass, although providing wonderful visual amenity is a highly conductive material. With the aluminium frames common to most Australian homes touting a similarly high conductivity, dwelling heat loss and gain is amplified. Professionally applied high grade windows can minimise some of this heat transfer. Solargard claim their window films can help reduce air conditioning energy expenditures by up to 30 per cent. However films don't counter the issue of conductive metal frames. Here retrofittable double glazing systems, like Magnetite, are more effective. A thin plastic (unfortunately of PVC) subframe is fixed inside an existing window frame, and covered with metal strapping. Optical grade acrylic windows snap onto this subframe, via corresponding magnetic strips. The acrylic is said to have six times better thermal conductivity than glass, while the plastic subframe effectively negates any "thermal bridge" created by the original metal window frame. Magnetite suggest their system improves a windows' summer heat gain by 56 per cent and winter warmth loss by 81 per cent. Better results than some off-the-shelf double glazed windows.
Shading
Originally conceived in Australia, the modern shade sail has become ubiquitous, especially around schools and daycare centres. Blocking up to 90 per cent of ultra-violet rays, shade sails not only protect young Aussies from melanoma, but can also safeguard a house from one of a home's most significant sources of uncomfortable heat gain - direct sunlight. With the demise of appropriate eaves for shading, retrofitted shade sails can effectively block most of this radiant heat, in order to limit unnecessary air conditioning loads. Intelligently designed installations can be subsequently demounted during winter to allow the ingress of sunlight for passive solar heating. Whilst there are said to be over 1,200 companies nationwide dealing in shade sails, the pioneer of the shade sail is arguably Gale Pacific and their Coolaroo product. They also offer a range of modern external window shades and awnings for homeowners not enamoured by the usual shade sail configurations. A higher tech retrofit is something like Vergola's adjustable louvre roofing.
Reflective Paint
If external shading is an effective way to reduce heat gain through windows, then reflective paints are the equivalent for roofs. It is unfathomable why a sun-soaked country persists in erecting dark coloured roofing. Even high quality ceiling insulation is hard pressed to combat the heat absorbed into roof cavities underneath these dark hues. Painting roofs white, or a similar high reflective shade, is the best solution, as it can lower internal room temperatures by up 12 degrees Celsius. However white roofs are not an aesthetic sweetspot. Nutech Paints NXT Cool Zone paint allow homeowners to retain their dark roofs yet substantially reduce heat gain. Their charcoal has a Total Solar Reflectance (TSR) above 35 per cent and reflects 500 per cent more heat than conventional roof paint, or new tiles, which are said to have a TSR of less than seven per cent. Reflective paints is a growing market, with others like Solarcoat, Thermoshield, Insuladd, et al, offering similar thermal paints.
Renewable Energy
The Australian Photovoltaic Association found that in 2010 Australia experienced 480 per cent growth in solar panel installations with 99 per cent of them being grid-connected systems. The Clean Energy Council has indicated that as of August 2011, "1031 MW of solar power was installed in Australia - representing more than 500,000 household systems," with over 45 per cent of these installed between January and August of 2011. Last year Australia was also touted as being one of the first countries to reach "grid parity," whereby solar electricity is competitive to that supplied by coal fired power stations, even without government rebates. Companies, like Selectronic have taken grid-connected household solar systems a step further, with their grid back-up inverters. During power outages, unlike most grid-connect system, Selectronic's SP PRO inverter switches automatically to a built-in back-up pre-charged battery to continue uninterrupted electricity supply, providing power for the likes of lighting, and/or fridges and freezers.
Water Saving
The bulk of Australian housing estate dwellings have been typically erected on a concrete slab, limiting more sustainable water management options. But not negating them entirely. One obvious option is harvesting rainwater for quenching the thirst of a vegie patch, lawn and garden. However for mains-like pressure, and integration into a house, a pump may be required. The Davey RainBank, Bianco Rainsaver and Onga WaterSwitch all allow rainwater to be deployed to fill washing machines and laundry tubs, as well as flushing toilets. When tank rainwater availability drops below a certain threshold, (or during a power failure) these pump add-ons seamlessly switch back to providing mains water. Davey reckon their RainBank can save up to 40 per cent of household's drinking water supply. Products like the Redwater, or the Jontol water diverters recirculate back in the household water supply the first 9-10 litres of otherwise wasted cold water that so often results from turning on a hot water tap. Redwater believe such diverters can save about nine per cent (or 16,000 litres) of a home's annual potable water.
Weather Seals
The California Energy Commission suggest: "Improperly sealed homes can squander 10 to 15 per cent of the homeowner's heating dollars and reduce the effectiveness of air-conditioning in the summer." They reckon a 6mm gap under an external door leaks the same amount of air as having a 230 mm square hole punched in your wall. The Australian firm, Raven, who have been making a burgeoning collection of weather seals for the past 60 years, have their take on the above statistic: "The gap around an average door equates to a hole ... the size of a house brick." Weather seals, particularly for doors and windows, may provide the most value for money spent in eco-retrofits. They are inexpensive to purchase and easily installed by even the most novice of home handypersons.
