Saturday, 30 December 2017

Post No. 1,113 - Toward's better Australian housing

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:
  1. 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]);
  2. be built with proper, effective insulation;
  3. 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);
  4. 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
  5. 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
For convenience, key links provided in the text of this article are re-presented below:


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