/ 9 January 2007

Kevin’s ark: How to build an eco-house

For the longest time I lived in a modest mansion in Parkview, Johannesburg, which we bought just before the 1994 election. Built in 1913, it oozed charm and character, but I couldn’t help thinking that it did not use space efficiently.

When we heard that an old Coca-Cola factory in Milpark was being converted into lofts we rushed to try to bag one, but even though the place was just rubble and disorder, the waiting list was already over 200 strong.

Other lofts began to spring up nearby and for some time I thought that I would be able to buy one of the shells, and then bring in steel and concrete to shape it into something special. At one stage I thought I had the choice of five such spaces, but not too long after had to come to terms with the fact that I wasn’t on the list at all. Shell allocation, I came to realise, works in mysterious ways.

In nearby Richmond, though, was the shell of a house just waiting for a makeover. A neighbour said that it had been abandoned between two and three years previously. An ambitious renovation had begun, and then stopped. Blackjacks and vagrants had moved in. Much of what was not nailed down was stolen.

I had two goals for the project. The one was to maximise its space potential. Too many of Jo’burg’s older houses that have been renovated are rabbit-warren-like, with rooms added on willy-nilly with little feel for the original flow, not to mention the soul, of the house.

I also wanted to see to what extent the house could be designed on green principles. It had no plumbing, geysers, electricity, and only half a roof, so there would be no cost of getting rid of legacy systems.

Being green

But what does it mean to be green? Not too many months ago I visited a village in the Western Cape that has an eco-friendly home under construction. It also had no geysers, no electricity, hardly any plumbing and less than half a roof. Made of cob, it was all very interesting, but I came away thinking there would be no cold beer at the end of the day.

The truly green house is not connected to any grid. It collects its own water and generates its own energy. It also disposes of its own waste. It may even be carbon neutral or positive, selling excess clean energy into the central grid.

But it would be exceedingly costly and difficult — stupid even — to attempt such a house at present in the South African urban environment.

City homes can aim to be sustainable, though, if they are designed to minimise both inputs and outputs. They can aim to maximise efficiencies so that running costs are low, as is waste output.

Sustainable homes aim to limit negative effects on the environment by using local and natural materials, recycled items and local products and services. They aim to be low maintenance and maximise energy efficiency by good orientation to the sun and using effective insulation.

My own goals include using imports only in exceptional circumstances and requiring that any green technology employed has to pay for itself in less than three years.

Some websites offer online checklists where you can score your home in terms of how sustainable it is. But these are usually of limited value as what makes sense in Europe, for instance, is unlikely to be suitable for Johannesburg. In the north heating is the main thing, in the south cooling may be as, or more, important.

My project, though, from the checklists I have seen, would get one immediate tick: since the whole project is a renovation, this scores big in its favour.

I visited Joubert Park in downtown Johannesburg where a potting shed was converted into offices for the Greenhouse project, a city-funded project that aims to promote sustainable living.

You can view no-flush compositing toilets, rainwater harvesting, solar panels to provide hot water and electricity, solar cookers, grey water recycling and the recycling of building materials and get advice such as where to source eco-friendly paint and materials.

The staff are happy to admit failures, such as that the compositing toilets did not work too well at first. They also sell a useful booklet which details, with drawings, how the various technologies work.


The first principle of sustainable building is the most important: the house has to be correctly orientated to the sun. In Johannesburg it should be located east-west so that it can get the full benefit of the northern sun all day. While architecture may in the past have tried to create uniformity, today north-facing windows are likely to be large, those south-facing will be smaller, or absent.

One of search giant Google’s numerous acquisitions is Sketchup, available for free download at sketchup.google.com. With a basic tutorial in no time at all you can create drawings in three dimensions. You can even rotate it to check out all the angles.

Visit Google Earth, fly to the Johannesburg street address of your project and then pull down the coordinates. Bring up Sketchup and check out how the sun will shine on your building, complete with shadows, by time of day and month of year.

I had no idea what overall goals I should attempt, so, plucking figures from the sky, decided to aim to reduce my electricity bill by 80% and waste outputs also by 80%, although I have read that at 50% reductions you can pat yourself on the back for building an environmentally friendly home.

Hah, the cynics say, what is the point of pursuing an eco agenda when you drive a gas-guzzling car instead of using public transport or a bicycle? This is true, but using public transport or a bicycle is not going to change patterns of demand. It will take an entire new tax policy to ally energy usage more closely with the true costs, which include environmental damage, to achieve this.

When I buy food I try and ensure it is healthy both in a nutritious and economic sense. It should not contain unhealthy substances nor contribute negatively to the balance of payments. I likewise want my home ideally to be as non-toxic as possible, both in an environmental and an economic sense.


A very high proportion of building materials available on the site would be recycled. This includes steel girders, railway tracks and timber, Oregon floors, beams and windows, pressed steel ceilings, rocks, bricks and pavers.

Rubble was put into the foundations to add thermal mass, but any building site generates astonishing amounts of rubble, much of which had to be trucked away.

We have thrown very little away besides, if you exclude 50 bags of blackjacks and a few cartloads of scrap metal that was put on the pavement and which has probably already been smelted down in China.

The design of the house was half-inherited, with half a pitched timber roof in place. This soars quite attractively and will be great for helping snow slide off the roof, but is also relatively time-consuming to construct.

The design aims both to maximise the use of outside spaces and blur the distinction between inside and outside.

The new portion of the roof has been done in steel to maximise the sense of internal space, much of which is double volume and open plan.

This means that heating is potentially a problem. Solar is an obvious solution, but our experience in Parkview with solar was not particularly salutary. We paid R20 000 for a unit and were more than a bit surprised when our electricity bill remained unchanged. The vendor said it was because we were using much more water.

The consensus view is that solar power used to heat water is a cost effective technology and one that should be in widespread use in our sun-baked country. Solar PV, where solar power is used to generate electricity, is another matter.


For a short time I thought I would generate my own electricity and sell my surplus to Jo’burg Power. People do this, for instance, in Germany, but their electricity costs are about five times ours and Solar PV is better at supplying low-wattage power, such as for lights. Fridges and washing machines typically require large amounts of energy, which is better supplied by conventional electric power.

When you research eco-friendly building on the South Africa web, the suppliers and sources are invariably in Cape Town.

Boron, an environmentally free wood preservative, is a case in point. I have asked at least 10 hardware and timber merchants for a boron-based timber preservative. They invariably pick up a tin of preservative which, with virtually no exceptions, does not tell you what its active ingredient is.

It could contain polonium-210 for all you know. One shop assistant said these tins do not say what is in them because competitors could then easily copy the product.

Another store produced a well-known brand with, yet again, no clue to what it contains.

Do you think it might be polonium-210, I asked. The assistant was horrified. ”What did you say?”

”Polonium-210, the stuff which killed the former Russian spy.” ”Oh,” she replied, ”I thought you said polony.”

A timber merchant with four or five preservative options said he knew of boron and that it was environmentally friendly, but so was linseed oil, which he stocked. The difference, though, is that you cannot paint or stain wood which is treated with linseed and with boron you can. This assumes you can find an environmentally friendly paint in Johannesburg, which might not be that easy.

The Greenhouse booklet includes such a product, made by Breathecoat, a Cape-based firm. Its product passes the eco test, has several advantages over conventional paints and is competitively priced. Breathecoat has a Johannesburg-based representative and is in the process of opening a shop here.

A visit to a splendid tile and granite vendor on the East Rand displayed a similar lack of sensitivity to eco building. It has a stunning choice, but the otherwise knowledgeable assistant was unable to say what was local and what was imported.

I would like to use granite from Parys because I have a particular interest in the massive meteorite which slammed into the Earth there a few billion years ago.

”It goes under another name,” he told me confidently, and then spent the next 20 minutes trying to find any staff member who knew which of the 30-some granites they sell comes from Parys. None did.


The house has used a lot of cement, a natural product with almost magical building properties, but one that takes vast amounts of electricity to produce. Along the way I found out that by-products of industrial processes, such as fly ash or slag, can be used as extenders, reducing the cement content in each bag by up to 34%.

All cement bags are labelled to reflect this, you just have to know how to decode the label.

There is also a lot of embodied energy in the steel used to make windows, doors and stairs and to support three slabs.

The house is nearing completion. It will harvest rainwater, recycle grey water (from the washing machine and showers, but not from the dishwasher), it will use natural gas for space heating and hot water, lighting will be low-wattage and where there are large sections of glass, safety glass will be used which has better insulation properties. It will have a closed firebox linked to water-based under floor heating. An outbuilding will have a sod roof.

In the United Kingdom the market for ethical goods and services, at £29-billion, now exceeds that for cigarettes and alcohol, according to a recent report.

In Cape Town there appears to be an active market in green building products and services. In Gauteng there is none.

I have learned from this project that if there is an eco-consciousness in this country it is in Cape Town. As far as Gauteng is concerned, Noah’s flood could be coming, we don’t know it and we don’t care.