There is, in my
opinion, little doubt that Australian houses since around the 1930s, when brick
veneer started replacing the more expensive double brick construction in
southern Australia, are poorly designed with regard to climate (e.g., see here).
The old “Queenslander”,
set up high to give a shaded ground floor and with wide verandahs, was well
suited to making the most of climate conditions in northern Australia, but the
cheapness of brick veneer and other constructions, and the allure of flashier
pseudo-palaces has led to houses that are designed to be impressive socially,
and are thoroughly impractical in terms of adaptation to Australian conditions.
(Architects bleating about using air
conditioning – and I’ve been arguing with them on that point since the 1980s –
are completely missing the point; at least concerns over climate change have
started bringing them around on that point.)
The diagram below
gives a simplified idea of the Queenslander approach – and yes, we did allow
for floods coming up to a certain height when I was a kid (e.g., if there wasn’t much rain, the lawn mower just got put up on
blocks, but if there was heavy rain, everything would get shifted up as high as
possible, some of it onto the upper storey).
Typically, this
construction was weatherboard: there was negligible heat mass, and insulation
was unheard of, but it was possible to sleep in the cooler night air on the
verandah (well, it was cooler if you
didn’t need a mosquito net … ). It didn’t fare so well in winter, but it
was possible to sit in the sunlit edge of the northern verandah to warm up. (It does, incidentally, get quite cool in
inland and some northern areas - below freezing, at times, even in the Red
Centre. [Our lowest temperatures, in the Australian Alps, are below -20°C.] Frost
killing grass is still a problem for many cattle stations in winter. When I
worked in Mongolia, where the temperature can get down to -50°C, an English
expat complained to me that the coldest he had ever felt was in an inland NSW house in in the
80s.)
Sadly, many of these
houses lost significant advantages when verandahs started to be enclosed to
provide more indoor living area (i.e.,
bigger, and thus flashier housing). Some of the enclosed areas had louvres
in an attempt to retain some advantages, but the reduced open area of the
louvres didn’t compare with having a truly open verandah.
In my view, passive
solar housing could be considered as having developed as a “least effort” way
to adapt the existing approach to building houses into something that is more
suited to living in a way that is better adapted to the climate. As an example,
consider the issue of eaves.
Rather
than have a verandah, which shelters walls entirely from the sun - an excellent
idea in summer, but less attractive in the cooler winters of the southern half (and some inland areas) of Australia –
the concept is to have a partial eave which allows the lower sun of winter to
reach windows, and shades those windows against the higher sun of summer, as
shown in the diagram below (note the
relatively lower ceilings).
Isn’t that a lovely
looking diagram? Seems logical, too.
However,
let’s look at the situation face on, not just sideways. As shown in the diagram
below, viewed that way, all summer sun positions that are below that of the
winter peak – and that means, during, for instance, one of Melbourne’s
notorious heat waves, with temperatures of 30°C at night and high 40s during
the day (and how long before those peaks
are 50°C?), the hot morning and afternoon sun will shine directly onto the
windows.
Hopefully, the house
will have incorporated some of the other passive design features (such as reflective surfaces internally to
“bounce” winter heat across to the shaded side of the house, and, relevant to
the example being considered, insulated curtains with pelmets – or, even
better, external shades over window), but, even then, the walls will heat
up – I’ve spent some such days hosing (in
pre-drought days!) walls in a vain attempt to manage that.
This is the beginning
of the problems I have with passive solar design.
My
next issue concerns the mismatch between the design and the required functions
of the house: as an example, consider the commuter enjoying the features of a
passive solar house on a winter’s morning …
For many months of
the year in Melbourne, I leave for work before the sun rises. I’m aware that it
is possible to turn on electrical or (if
it has been checked for and cleared of carbon monoxide problems) gas
heating, but having to do so makes a mockery of trying to have a house that is
better suited to the climate – and especially given that there is are several
environmentally friendly alternatives.
There is one more
problem I want to touch on, and that is: suburbia.
Residential
allotments are getting smaller, houses are getting bigger, and, as a result, we
can have the situation shown below – which, with apologies to Godot (and Beckett), I call “Waiting for the
Winter’s Sun” …
That
is actually a useful diagram, as it illustrates a key point: even in suburbia,
roofs will often be exposed to a considerable amount of sunlight, and thus
heat. So … why don’t we use that? I don’t know, maybe put in a little solar
powered fan and a heat mass under the floor?
The diagram shows the
principles, and a possibly more efficient adaptation.
First off, the
principle is that one collects the heat during the day, and stores it in a high
heat mass (I am thinking of 0.5 – 1 m
depth of gravel), which then radiates heat as it cools, thereby keeping the
house warmer at night and – if done properly – into the next morning. (Incidentally, I’ve written about this
before – see, for instance, here.)
On that “if done
properly”, I have heard of one house in London which, by having features such
as proper insulation including triple glazing (insulation also refers to windows, as far as I am concerned!) was
able to go through a London winter without any heating (I think this is similar, but isn’t the home I was thinking of – see also here). To get the heat still radiating the next morning, one either
needs a very high heat mass (which may
make the house uncomfortably warm at the end of the day), or a modest
amount of heat and proper insulation.
It all comes down to
good design.
And good insulation.
On that, and idea I
came across in the late 80s was someone who had built an earth-covered dome.
They had done that is response to the devastating “Ash
Wednesday” fires in the early 80s in Victoria, but it inspired
me, and others have also used this approach – this
example from the US mid-west is a notable example, this home
constructed from buried shipping containers (an
approach used successfully for the wastewater treatment plants I was working on
in Mongolia) was another example that struck me for its temperature
management, and this
post gives a reasonable overview of this approach. There are even
businesses providing homes like this now – see, for instance, here (Australian
companies manufacture domes [e.g., here and here] and design earth covered homes [e.g., here and here], but I’m unaware of
an that do earth covered domes – “earthships” have arrived here, but they’re a – very advanced - form of passive solar design).
Of course, although
earth-covered homes are very temperature efficient, and small ones
can be relatively economic, that won’t suit everyone (even if skylights are included). Also, it would be impossible to
retrofit that approach to an existing house.
Fortunately, there is
an approach where the temperature variation, rather than the house, can be
taken to the earth: geostabilisation.
The
diagram below shows how I visualise (apply)
the principle.
Its
typical application in Australia - which
is growing in popularity, I understand - is dependent on a heat pump and
applying this as a form of air conditioning, but I’m aware of a house in Europe
(I think I saw it on “Grand
Designs Abroad”) which uses
shallow pipework in a nearby field to passively recover daytime heat to warm a
house in the evening, and the decision whether or not to use a heat pump is a
trade-off between compactness and expense.
The
other aspect I have contemplated
here is boosting the efficiency of using air to transfer heat by using
expansion/contraction of air, which alters temperature in accordance with the Combined
Gas Law, although that then becomes a trade-off between cost of the air
pump (which starts to move away from a
simple fan) and the cost of the heat exchange unit.
My
current thinking on these ideas can be summarised as shown below (although I would have verandahs, skylights,
and take the heating/cooling for each wall [separately] to the opposite side of
the house [i.e., north wall cooled/heated by a system buried on the south side,
etc]; the louvres in the roof space can be closed to help insulate against
cold, or opened to allow air movement to resist heat transfer):
Summary
So, what are my suggestions?
Well, I consider Australian houses should:
- be designed to
cope with BOTH heat and
cold, no matter where they are (I
understand that the heat is a bigger killer in southern Australian than the
cold [e.g., see here and here, but this argues that the cold is worse – although that article is wrong to say Australian houses are built to keep people cool – Melbourne’s
and Hobart’s definitely aren’t!], but I’m also mindful of the cold I’ve
felt during winter in the north [the coldest I have ever felt is in Brisbane,
not my overseas work trips to cold climes]);
- be built with
proper, effective insulation;
- have a high heat
mass (concrete has a lot of advantages –
and is widely accepted as a building material in, for instance, South America,
but see also this award winning design from Queensland);
- incorporate older
features (such as verandahs – possibly
with skylights to cope with winter conditions - and high ceilings) as well
as relevant passive solar design features (which
does depend on situation, as well as location – and I’m writing that in a house
which has a massive picture window that cannot be prevented from letting heat
in during heatwaves [and we have virtually no insulation], and has absolutely
NO privacy from the neighbours, but does do some good for a few hours each day
in winter [not my design, clearly] – see also this article, on combining features); and
- include ACTIVE SOLAR, and
environmentally friendly heating/cooling approaches such as geostabilisation (or construction below ground, or with an
earth cover/berm).
If you can’t afford
to include these in your proposed house, perhaps you should be rethinking how
big your house is, and build something that is both environmentally and financially (see also here and here) more sustainable - i.e., smaller ...
Of course, there are
some challenges to implementing this – especially the lack of familiarity and
comfort of builders and building inspectors/local council approvers with such “non-commonplace:
approaches, but, above all else, the limited thinking of those who are having a
home built.
Hopefully this
article will widen at least some people’s conceptual planning.
Convenience copies of links
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