Rebuilding after the bush-fire holocaust

As you can imagine, as a building designer, even a retired one, I've been thinking about this a lot. All the talk of rebuilding at any cost, a kneejerk reaction I believe to make things look like we are all right behind those poor buggers who've lost everything (and we are, don't get me wrong) is not a good idea.

An opportunity not to be lost

This disaster is, in my opinion, an opportunity not to be lost. I would be extremely surprised if 99% of all the homes lost in the Victorian Bush were not totally inappropriate for the conditions. What I see on TV tells me those places were built for life STYLE, not life REALITY.

Take all those fireplaces left standing, ghostly reminders of what used to be. Notwithstanding the fact that it probably gets very cold there in winter, those fireplaces were built for LOOKS. They are probably viewed as 'pre-requisites' by tree changers building their 'dream home', when in fact they are appallingly inefficient in both heating a house in winter (most of the heat goes straight up the chimney) and keeping a house cool in summer when cool internal air is drawn up the chimney by convection, sucking in hot air from outside. The solution to that of course is to turn on the aircon. When energy rating a home, introducing a chimney immediately removes a whole star (sometimes more) from that rating.

In fact, I am fast starting to think that all the things that make a house energy inefficient also make it more prone to bush fire destruction.

How well insulated were all those homes? How large were all their windows? Were they built out of bricks? How many were built off the ground?

Chimneys would, I think, cause a draft from the outside into the house, possibly even bringing embers into the house, particularly through gaps in eaves etc. If a possum can get into your roof, just imagine how many embers could get in!

Now also imagine how hot bricks and tiles would get in a fire ball. Well over 200 degrees I would guess. That heat, radiated inwards, could easily set the frame on fire unless incredibly well insulated
(well beyond what is required to control regular heat flows on a day to day basis).

I'm also wondering how many of these houses might have been built with steel frames to avoid termite problems. Steel frames conduct heat from the outside of the envelope to the inside very effectively. I have experienced this first hand when a friend built a house I designed out of steel, and then complained, when I expressly told him this would happen, that the studs could easily be identified through the walls as bars of heat... That was the western sun, making maybe 30 degree heat. Now convert that to 200 degree radiant heat.....

It is also a long lasting fad to have huge glazing in modern houses to bring the inside to the outside, especially in places with views such as the Victorian forests would offer. Glass has virtually zero insulation rating, and allows radiant heat unobstructed entry. It's not outside the realms of possibility that when the fires struck, inside temperatures could have reached the dizzy heights required for some things to combust instantaneously, burning the rest of the building in the process.

And finally, quite a few of these homes were built on posts, allowing heat and flames even, to gain entry under floors. No prizes for guessing the result of this surmising.

Solutions

Solutions? Well there are in fact quite a few. Like building within the earth itself, or with thick rammed earth, limiting glazing to no more than 10% of the floor area, heating with combustion heaters instead of
open chimneys, heavy insulation, and I think heavily insulated metal barriers for windows in emergencies. These could even be used in extreme weather like when it snows, or temperatures reaching nearly 50 degrees, something likely to happen more and more as Climate Change starts to bite.

These solutions would not only save homes, they would also save lives.

Mike

Mike Stasse is a retired Energy Efficiency and Sustainability Consultant, and is a qualified Building Energy Rating Assessor. www.greenhousedesign.green.net.au damnthematrix.wordpress.com

See also: "Fire bunkers could have helped in the Victorian fires" of 10 Feb 09