‘Passive’ home more expensive to build but cheaper to run, achieves highest bushfire risk rating

Australia’s first passive house built to the highest bushfire rating has been unveiled in the midst of an early start to the bushfire season, as experts gather to advise residents on fire safety.

Key points:
– Home builders have designed and built an eco-friendly passive home that meets the development requirements for the highest bushfire risk rating
– The energy-efficient home costs $3.80 a day to power, but construction costs were 22 per cent higher than a standard build
– A bushfire architecture consultant said building bush homes partially underground could be the future for fire protection

When Joe and Merylese Mercieca began building solar passive homes 15 years ago, architects, suppliers, and contractors told them it would not work.

Without the available solar technology, the Merciecas were able to achieve a solar passive rating by thinking creatively and adapting commercial products for residential builds.

“So we proved everybody wrong 15 years ago … [and] we’re doing it again today,” Mr Mercieca said.

Their latest creation is Australia’s first passive house to meet the development requirements for the highest bushfire risk rating — Bushfire Attack Level Flame Zone (BAL-FZ).

The display home in New South Wales’ Blue Mountains region has a complex system of remotely controlled electric shutters, fire resistant external cladding and fluid ventilation, balancing energy efficiency with strict fire safety standards.

Certification for a passive house required strict energy efficiency measures, while BAL-FZ certification required protection from wandering embers and extreme heat.

Mr Mercieca said the calculated daily cost of powering the house was equivalent to a cup of coffee a day, due to the home’s sophisticated ventilation system which maintained a steady internal temperature year round.

What is a passive home?
– A passive home design takes advantage the sun, body heat and cooling breezes to maintain a comfortable temperature range
– This can eliminate the need for auxiliary heating or cooling
– Good passive design considers a home’s climate, orientation and shading
– Proper sealing, insulation, and mechanical ventilation keep passive homes warm in winter and cool in summer
– Passive design also uses building materials with a high thermal mass and the right window and door glazing systems for a home’s climate and orientation
Source: Department of Environment and Energy, Your Home

“So [it costs] $3.80 to run this house a day without solar. We’ve actually put solar on this house so that we can achieve carbon-zero,” he said.

Mr Mercieca said achieving air tightness in the home was vital for supporting the robust ventilation system, and most homes were likely to experience 15 air changes a day.

“We had to be 0.6 [air changes an hour] as a maximum to meet certification — we actually got it down to 0.39,” he said.

In the entire external envelope of the house, we have a combined 11-millimetre diameter hole, so it’s smaller than the pinky finger.”

Triple-glazed windows and climate-specific insulation round out the home’s laundry list of features.

Mr Mercieca said the experimental nature of the build raised its cost to 22 per cent dearer than a standard build, but he hoped to be able to lower the figure to 15 per cent in future.

How fireproof cladding saved the Mercieca family home

As an early bushfire season rages across regional Australia, the Merciecas know first hand the importance of building bushfire-ready homes.

When devastating fires swept through the Blue Mountains in 2013, the Merciecas were encircled by fires and trapped on their property in the mid-mountain town of Winmalee.

“We were stuck at our office and at our home in 2013, we didn’t have a chance to get out,” Mr Mercieca said.

Caught up in a blaze that would go on to destroy over 200 homes, the Merciecas watched as one of their cars caught fire and rolled into their nearby office building.

Once the smoke had cleared, the office block along with four vehicles were left charred and destroyed.

Their nearby house, however, survived the inferno because of fire retardant external cladding which resisted nearby floating embers.

“What that reinforced was that what we were doing was the right thing,” Mr Mercieca said.

He said their latest home’s blend of environmental and safety features should provide peace of mind for prospective residents in times of unpredictable bushfires.

“It is a safer place to be, and that’s what they’re designed for,” Mr Mercieca said.

“If you need to retreat, then you can retreat to the house and you’ve got more of a chance.”

‘Deal with your grief’

In response to the disastrous 2013 fires, an Australian-first community conference was formed to educate Blue Mountains residents on building and renovating their homes with the latest fire safety techniques and technology.

Now in its fifth year, the Australian Bushfire Building Conference has been attracting industry leaders from around the country for a small trade show alongside expert talks.

Bushfire architecture consultant Dr Douglas Brown attended the first year of the conference in 2014, and said residents appeared visibly traumatised one year on.

“Some people came and you could tell they’d lost their home, because they just looked stunned, they just looked overwhelmed by everything,” he said.

Dr Brown encouraged families rebuilding after bushfires to take their time, given the complex nature of fire safety products and ever-increasing safety regulations.

“I say ‘you need to deal with your grief’, so lease a place for a year, get your kids back into school, you get back into work,” he said.

“Don’t think about your house for a year until you push through the grief and you’ve had a year of getting your life back into some sort of order.

“The regulations are very well-meaning, a lot of thought and conscious decisions have gone into it. But it is quite overwhelming and it does tend to change.”

Dr Brown said he has currently been co-authoring a book on bushfire architecture which planned to rethink how homes were built in fire prone areas.

“The issue is this: we take a suburban home, we put it into a bushland setting, and we say ‘we’re going to improve the level of fire protection of various components’,” he said.

“But that’s not enough, we need to do more, we need to say ‘we actually need to design differently’.

“We might need to have homes in bushland settings which are partly underground or have earth coming halfway up the wall as a protection.

“How a building will look in the future in bushfire prone areas is likely to be different.”

Article By Donal Sheil & Luke Wong – ABC NEWS – Source Link