Extreme weather and the growing need for sustainability have resulted in a major and ongoing shake-up of building regulations, writes Harvey Grennan.

Whether you're a believer or sceptic when it comes to climate change, there is no disputing the fact that we have witnessed extreme conditions across Australia in the past few years that have - quite literally, in several cases - shaken us to our core.

Policy-makers in every state are certainly not taking any chances. Recently there have been many changes to the Building Code of Australia (BCA), Australian Standards and other federal, state and local rules and regulations in response to these threats to life and lifestyle, and there are more changes on the way.

All houses, units and commercial buildings must now be built to be more resilient to bushfire, flooding and high winds. Construction has been banned altogether in many locations threatened by rising sea levels. And legislation now demands that greenhouse gases emitted by building and living in our homes be curbed to slow the rate of climate change.

In 2008, the Council of Australian Governments (COAG) agreed to develop a ‘whole of life' National Strategy for Energy Efficiency that mandates a six-star energy rating for new residential and commercial buildings, creating a 19 per cent saving in energy consumption over the previously mandated five-star rating. The nuts and bolts of this strategy began to appear in the BCA last year.

Other changes in building codes are coming from a COAG decision to put all on-site building requirements into a single National Construction Code. At present there are many conflicting requirements between the BCA, Australian Standards and codes for plumbing, gas, electrical work and telecommunications, not to mention state and territory variations to the regulations. Designers and builders scratch their heads and wonder which ones the local council building inspector will deign to enforce. A uniform plumbing code has been added to the BCA as the first step in delivering a national code for all trades.

As well as reflecting the growing importance accorded to sustainability issues, recent changes to the BCA are a response to the devastating Victorian bushfires of February 2009. The Australian Standard for new homes in bushfire-prone areas (AS 3959) has been completely revised and is based on six Bushfire Attack Levels, starting at low and running up to flame zone. The higher the bushfire risk of a particular locality, the more heat- and flame-resistant the construction must be. In practice, this means that weatherboard is OK in a low bushfire risk zone but building in a flame zone calls for masonry construction, metal windows and fascias, and no exterior timber.

A world-first building standard for bushfire bunkers, which must be separate from the house, has been developed with the proviso that it is a last resort. Getting out early in the event of a bushfire is still preferable to staying, even in an approved fireproof bunker.

In a region prone to cyclones, a different style of house construction is required. Typically such a house will have a steel frame strongly secured to a slab or footings, a well-secured pitched roof and cyclone-rated glass. The structure must be strong enough so that even if the windows and doors are blown out, the walls will remain in place. Aluminium shutters are a good idea.

Major changes to BCA 2010, which have already been adopted in some states, require new houses and apartments to achieve the aforesaid six-star energy-efficiency rating and standardise a pot-pourri of state energy regulations. To determine the rating, a software program calculates the energy efficiency of a dwelling by taking into account factors such as building materials, glazing, orientation, overshadowing, ventilation and the climate zone. New efficiency standards also apply to hot-water systems and lighting.

The layperson would be hard-pressed to notice many of the changes in the code. There are new standards for low-rise masonry homes in earthquake-prone areas, corrosion protection for metal structures and components near the surf, ceiling heights in attics, the location of rainwater tanks, glazing, fire safety, termite protection and balustrades.

A new test procedure has been applied to toughened glass, as the presence of nickel sulphide can cause spontaneous fracture of the glass. Tougher standards apply to swimming pool fences and windows; restrictions have been placed on skylights to conserve energy; power-operated exit doors must have a manual over-ride; and swimming pool and associated spa heaters must be solar, gas or heat-pump models, with a time switch for the last two.

New access standards apply for people with a disability in new and renovated buildings with public access. In Queensland, building covenants that set minimum floor areas for houses have been banned as unsustainable.

Even trees have come under notice. For many years there have been standards to protect the safety of workers on building sites and now a new Australian Standard (AS 4970) also protects trees on development sites, hopefully avoiding many a court battle between councils and developers.

The BCA is under constant revision and more changes can be expected with each annual amendment. Current building standards are being tested by more frequent extreme weather events. A 25-per-cent increase in peak wind gusts can cause a 650-per-cent increase in building damage. The Cyclone Testing Station at James Cook University in Townsville is working on new standards for roller doors, which are the first thing to go in a big wind.

Greenhouse gases can even attack concrete and work is under way to maximise the effective life of reinforced concrete structures. Researchers are adding fibre-reinforced polymers to concrete to make buildings more shock-proof in an earthquake.

Material matters

Here's an overview of some of the latest eco products to consider for your home:
Hemp is the latest eco building product. It is mixed onsite with a lime-based binder to form hempcrete, which is poured into timber or steel building frames as insulation and a base for interior or exterior render. Why hemp? It's very absorbent and a great insulator. Hempcrete stabilises humidity in a house, is carbon-negative and resistant to moulds, termites and other pests.

Solar hot-water systems have become more efficient with the newer evacuated-tube systems offering an alternative to traditional flat panels. Evacuated-tube technology provides hot water on more days of the year and is suited to cooler climates. Solar hot water is 60 to 90 per cent cheaper to run than electric systems. With power costs rising sharply, solar hot water makes even more sense says David Johnson, Business Development Manager of Hills Solar. “It takes four or five years for the savings in electricity to pay for your initial investment in the system and then most of your hot water is free,” says Johnson.

Save water and energy by taking shorter showers. The Waitek shower monitor measures waterflow and sounds an alarm when you are using too much water. The only way to turn the beeper off is to turn the shower off. And there's no cheating: turn it on again too soon and the beeper resumes.

Common plasterboard now comes with green credentials. Boral's Enviro, a range of wall and ceiling linings for normal and acoustic application, has a minimum of 10 per cent recycled content.

Ever considered a fence made out of old milk bottles? Futurewood makes composite fencing and decking out of plastic milk bottles, rice husks and recycled timber. This timber-look material doesn't rot and doesn't need painting.

Fancy a triumphal Roman or Greek archway that's recyclable? DecoTrim from RMAX might be just the ticket. Made from lightweight, moisture-resistant expanded polystyrene, the range extends from decorative mouldings to columns and capitals.