Bushfire Shelter and Earth Covered Homes: Earth Integration of buildings protects from Bushfire storms
The events of Black Saturday in February 2009 are tragic, almost
mind numbing in their repercussions and human tragedy. They
remind us once more with graphic images and untold human and animal
cost of the power of fire. To the writer, they are also extremely
sad and frustrating. Following is an extract of an article written
by the author in 1987 a few years after the Ash Wednesday fires, at
a time my family and neighbours were experiencing the feelings and
indeed the panic of impending bushfire.
Figure 1: D. Baggs' family home Castle Hill in
2000: Street Frontage
It was raining charred leaves, bark, and
ash. Strong winds were bringing the smell of fires kilometres away
right to our front door. The radio told us that another fire had
started. This one however is at the bottom of the valley.
Seventy homes were being
evacuated. For the moment, the winds were blowing down the valley
and away from us. Our neighbours sat on their third floor balcony
with binoculars, looking for the tell-tale smoke plume that would
tell them the fires had 'spotted' into the valley below us.
Fortunately, none forms that day, and a change in the weather
provided a welcome reprieve, for the time being, for our valley at
least. Many others had not been so lucky.
Backing onto beautiful remnant
Sydney Hills District Forest in the Excelsior Reserve and Darling
Mills State Forest was a wonderful environment to live and raise a
family. However, for the third time in seven years, the home had
just avoided being in a bushfire. This time was by far the worst
prospect, as the rest of the world knows, with the worst fires in
the history of New South Wales, several of the closest raging
within four to ten kilometres of our home.
Having spent the afternoon
cleaning the leaves out of the gutters of the home of one of my
neighbours, and watering the roof and garden of one of the other
neighbours who was on holidays, I did spend a little time trimming
the garden and overhanging branches. But for the most part I was
confident, that if a fire came, the house would survive intact, our
children were also calm and relaxed.
Figure 2: Excelsior
Reserve bush frontage
But it was not always so. On the
first occasion some years earlier, when the house had been
unexpectedly enveloped with smoke quickly filling the street to the
point the sun became a dull glow in the west. We had no idea where
the smoke was coming from, it seemed a fire-front was imminent and
the children became very distressed. My wife of the time was in a
real panic as she had just driven home through the almost
impenetrable smoke that filled the street.
I hurried them all inside and in
calming them down, there was great deal of comfort and satisfaction
in my being able to say to them, 'there's no need to be
afraid. You're inside now, you're safe - you live in one of the
safest houses in the world.'
Figure 3: Interior of Lounge Room
overlooking Excelsior Reserve
It had a remarkable effect on
them to hear that, and it had a great effect on me, to be able to
say it. This sense of security was also shared by my sister and her
family when they came to shelter from the fires near her house on
the northern peninsula of Sydney.
So, why the supreme confidence?
Well, it comes from the strategies employed in the design,
specification and construction of the earth covered home, and from
the experience of others in the 1983 Ash Wednesday Fires in South
The facts were, the home was an earth covered, concrete home
backed into a sloping site and backfilled with earth behind and
over the roof, with radiation shutters on every window, a separate
underground air supply and no exposed combustible materials.
Would such a home have survived in the incredible conditions of
Black Saturday or future, similar conflagration?
Based on historical precedent, yes it would have. The concrete
structure elimination of combustible materials from the outside of
the home, protection of all glazed areas from radiation and solid,
protected, windowless underground spaces in some of the rear, earth
contact areas of the home would have increased dramatically the
safety of occupants and likelihood of survival. There is no
question the home would have survived. The certainty is as a result
of historical facts.
Such a home did survive the worst of the Ash Wednesday fires at
"Eagle-on-the-Hill" in the Adelaide Hills. Everything around the
home, including the neighbours' houses, had been burnt to the
ground - yet the earth-covered home survived with nothing but a
cracked window. The windows had not been protected in any way, yet
because of the "mass" nature of the home, and the enveloping soil,
Yet when the bushfire code was rewritten thereafter, the best
possible housing typology they could imagine and managed to give
credit for was a double brick home- so where is the incentive to
try to do better???
The authorities need to look more deeply at the options and
consider better solutions - be creative and allow for innovation
and recognition that there are better, safer options in earth
integration and reflective radiation protection. It may well be
that additional supplies of bottled air might be required. But one
thing is for sure - it is hard to imagine living in bushland in
anything but an earth covered, fire-protected building and from
personal experience - the feeling of safety and the reality of the
security this provides - is priceless.
Figure 4: Wildfire Safety Bunkers - over 40,000
installations throughout Australia. Source: http://www.wildfiresafetybunkers.com.au/
During the Black Saturday fires, a number of people were saved
in underground bunkers and some were killed due to the inadequacy
of the bunker and their preparation. Earth covering can save lives,
but adequate research, careful design, detailing, construction and
preparation are required to ensure protection is successful. A
number of specialist companies manufacture prefabricated bunkers
with one, claiming to have installed over 40,000.
Figure 5: Wildfire Safety Bunkers -. Source:
As at January 2011, the Australian Building Codes board has
developed both a draft Standard for Private Bunkers and a
Regulatory Impact Statement to support an imminent decision
relating to possible inclusion in the Building Code of Australia as
the Board considers a range of options to include a code for
bunkers in the BCA. (see www.abcb.gov.au).
An extract from the foreword of the Standard by the ABCB
The obvious question is - why bother building both a house (that
will burn down) and a 'shelter'? Why not consider an alternative…
build your house as a shelter using earth to shelter from
the fire storm. To achieve this one would incorporate a fully
sealed shelter section within the home, with compressed air supply
combined with carbon scrubbing cartridge air filters (ref BCA
Standard) at the rear wall of the house where radiation is
minimized. It would require its own lighting and emergency power
source and numerous other safety items and features, but it is
entirely feasible. A storeroom or utility room that does not
normally require daylight could easily be adapted at design
This way, any family could live daily with the comfortable
modified temperatures, quiet ambient environment and solid, stable
investment., but more importantly, the security and peace of mind
about the family's safety and security.
Download the full Draft Standard.
David Baggs CEO of ecospecifier is a multi
award winning architect who now consults to designers and
architects on the design and construction of earth covered
buildings having designed and built over 40 such structures
including a school, museum and many homes. He is also co-author of
the book Australian Earth Covered Buildings first published in
1985, republished in 1992 and fully updated and upgraded in 2009 to
include Green roofs. Australian Earth Covered and Green Roof
Buildings is now a searchable pdf book in DVD format.
Download your order form here.