25 October 2013

How can we build houses that better withstand bushfires?

| johnboy
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fire

By Douglas Brown

As we are currently witnessing, transferring the suburban house into a setting susceptible to bushfires causes a lot of problems.

Put simply: if you are going to live in a bushfire area you should expect to live in a home that is designed and built differently. Our challenge is to create a new, better architectural form for bushfire-prone areas, and to develop a way to upgrade existing homes.

Building to a standard

Regulators have sought to improve the bushfire protection of the standard Australian house by implementing measures from the Australian Standard 3959.

This standard improves the fire performance of each building component but as yet does not describe how these components could be assembled into a building. This design process is particularly complex; there is no one perfect solution but rather a variety of options that can be selected for any individual building site.

Many organisations have been working in this area: CSIRO, the Australasian Fire and Emergency Services Authorities Council (AFAC), the Bushfire CRC, a number of the state and territory fire agencies and Australian tertiary institutions. I have been researching this area for my PhD, and hope my findings can push the process ahead a little.

I asked residents in bushfire-prone areas which parts of their home they would take shelter in during a bushfire and which parts they would avoid. What was surprising was the large range of responses for both these questions.

While the bathroom was the most popular choice for taking shelter, with a focus on the ground floor to facilitate escape, there were up to 16 other places where residents plan to take shelter during a bushfire.

There were up to ten different places residents would avoid during a bushfire. They fall into four main categories: spaces with large amounts of glass facing the fire threat; lounge or living rooms; upstairs (because of limited escape) and the parts of the house closest to the direction of the anticipated bushfire threat.

Houses could be built into the side of a hill. Les Stockton

Architects could use this knowledge when designing future homes in bushfire-prone areas. Bathrooms for example could be located at the junction of two outside walls and include an external door. Large expanses of glass facing the direction of the fire threat could be replaced with low walls with windows above.

The same residents were asked how their house could be improved to withstand a bushfire. They suggested bushfire shutters, roof sprinkler systems, non-combustible decking and verandas, mesh flyscreens, an underground area and increasing the cleared area around the house. If incorporated, each of these would have to be validated, tested and improved by industry experts. An example being rooftop sprinklers systems which require both a water supply and a generator to function. If the connections for either of these are inadequate the system will fail. Further research may produce ways to improve the reliability of these components.

There will need to be more work done on the materials we can use for future buildings. Researchers should also look at alternative options, such as having part of the house constructed underground or bermed into the side of a sloping block.

Not all is lost

Somewhere among the heartbreak of losing a home is the future opportunity to rebuild better than before.

This is a chance to not only improve the fire protection of the house but make it energy efficient by trapping, storing and reusing energy and water. This is particularly relevant when the supply of grid power and mains water are interrupted, restricted or cease altogether during a bushfire.

Thought should also be given to making the home a pleasant place to live; one that nurtures family life and individual reflection.

All of these things are achievable. But building such a house requires residents to change some of their perceptions about how their home will look and function.

Future homes are likely to be smaller, with fewer windows and no external timber. They will also require regular maintenance, keeping energy efficiency devices in good condition, and maintaining the carefully planted and cleared area around the house.

Making bushfire responsive houses affordable to the majority of residents is a challenge that the architecture profession may wish to contribute to in a number of ways. Architects could elect to volunteer their services and help individual families to rebuild. This however is a large and time consuming task.

An architectural competition could be set up to find the best cost-effective home designs which mitigate or remove the ways flying embers and direct flame contact from a bushfire gain entry into a house.

Having a resource of pre-prepared designs would be good: the painful dilemma of research in this field is that it takes time, and residents who have recently lost their homes have very real needs right now. For me it’s personal, as many of the 252 residents who generously completed my questionnaire live in Springwood and other adversely affected areas of the Blue Mountains.

Douglas Brown received a PhD scholarship from Bushfire CRC.

The Conversation

This article was originally published at The Conversation.
Read the original article.

[Photo by thinboyfatter CC BY 2.0]

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Henry82 said :

Generally, not building your house in the bush helps.

Or near large inflammable objects in general such as trees. Good advice.

Build it under the sea.

Ok, firstly an open plan house has no influence whatsoever on what happens in a bushfire. The official advice is to seek shelter in a part of the house with multiple escape routes and a supply of water. An open plan house would probably make this easier if anything.

Second, multi-glazed glass is not only great for insulating a home, but is far more robust against physical intrusion and fire than regular glass. There are number of consumer grade glass products available now that are specifically certified for use in bushfire risk areas, such as Viridian PyroGuard. So if specifiers choose the appropriate materials, you can still enjoy having large areas of glass as is the trend now and ensure a good level of bushfire resistance.

In areas likely to go beyond the BAL40 rating or existing structures, it’s relatively easy to specify/retrofit measures to guard against ember attack (e.g. gutter guard) and radiant and direct impact (window shutters). There’s also custom systems that are increasingly common such as roof and perimeter sprinklers (which if I were building in a danger area, I’d probably had designed with a foam mixing system).

How many fireproof designs are also energy efficient? People like to have big double glazed windows and stone slabs, I can see the stone and concrete being useful but big windows can’t help much in a fire. People also like to use natural timbers instead of bricks and concrete and are even encouraged to do so.

Open plan designs provide lots of light but don’t lend themselves to finding a small room to shelter. Some houses might have an internal bathroom but architects hardly plan for such contingencies. I also wonder if skylights would be a problem with fireproofing.

In some areas planning requirements even encourage planting lots of trees near the hpuse so that it doesn’t stand out from the landscape conspicuously. What chance do people have?

You need parts of the space shuttle to avoid the heat.

Even if the house isn’t burnt chances are its totally destroyed by everything drying out and expanding.

Live underground

HiddenDragon5:36 pm 25 Oct 13

This was interesting:

http://www.abc.net.au/lateline/content/2013/s3873911.htm

particularly, near the end:

“But the old rusted-on approaches of thinking that a bushfire disaster is all about response and recovery, that’s completely over. We now have to embrace change on a massive scale. We’re on a massive retro-fitting of our lifestyles and our relationships with fire.”

Generally, not building your house in the bush helps.

Mike Oehler has some awesome design ideas (the $50 / $500 house, ignore the ridge house) that we would be well served to adopt.

Primal said :

I hear good things about asbestos.

Tell that to the people in Winmalee. Unfortunately, with the fire this week having destroyed 200+
houses, insurance will probably rise & combined with that is the fact that
~90% of them were fibro, the whole area is now cordoned off as an asbestos
health hazard. Even if the area is stabilized – they’re thinking of spraying
it with some plastic polymer – remediation will involve removing all the
rubble & topsoil under Hazmat conditions before people are allowed back to
re-build or have their properties condemned.

gazket said :

fire bunker, problem solved and not a phd in sight

Are you suggesting people live in fire bunkers?

I hear good things about asbestos.

gazket said :

fire bunker, problem solved and not a phd in sight

I’m pretty sure there was an ABC program about this, and how some of the poorly designed bunkers are death traps in the making. Sometimes PhDs can save lives.

HiddenDragon10:41 am 25 Oct 13

For most of the year, we – or those who are paid to run the town and protect us – live in a state of blissful denial (or something close to it), and then, when the weather turns hot and windy, it’s basically full-blown panic mode, with much of the town (supposedly) being ready to evacuate (to God knows where) at a moment’s notice. This is ridiculous. The experience of the past week has shown that even the best household preparations can be quite insufficient, and that fires can move so quickly that many would not have a hope of evacuating – even if the road system could cope with the ensuing chaos, and even if there were suitable places for sufficient numbers to go to.

If we really care about this, we need to think very hard about the myth, folklore and ideology of “The Bush Capital” – surrounding ourselves, and interlacing our suburbs, with heavy fuel loads is just asking for trouble.

fire bunker, problem solved and not a phd in sight

watto – There are a number of systems including this stuff called Barricade Gel (http://firegel.com/).
Basically a water absorbing gel that sticks to the house, fence or whatever. We tested it out and it does help deflect radiant heat. But only whilst it holds water, under sustained heat it will fail. And like most things its not a total solution. It wont stop your house burning down if embers can get in.

I think a lot of houses do get built better now, but many houses were built 20-30yrs ago, even longer when things like fire retardant treated materials were not common. I’m surprised though no one hasn’t invented a system to spray the house in some fire retardant foam in the threat of a bushfire. Maybe its just too expensive or a pain to clean up….

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