Self-sufficiency: for environmental reasons or just for fun?

Presentation for the winter-workshop 'Infrastructures of Consumption & the Environment'

Wageningen, November 27, 2000, 11.50-12.10


I would like to tell you a story. A story about a dream and about the collapse of dreams. It is a personal story, but it is also the story of a housing project for which building and living in an ecological responsible way was the main starting point. The project is called The Green Roof (
It all started in 1989. Eventually, in 1993, 66 houses were built. I have been a participant of The Green Roof since its start and I have lived there until 1998.
Ever since we started thinking about the project, the use of building material and the consumption of water and energy has had our attention.
Personally I have been heavily involved in the development of ecological responsible ways of using water. We developed some extraordinary experiments, some of which are only used in parts of the project.
Our main starting point was the idea that taking care for the environment is an individual responsibility. We believed that only a change of conduct and the use of small-scale technology would finally result in a better environment.
From this starting point two experiments were developed. Both were based on the idea of independence of large-scale systems.

The experiments were:

  • Collection of rainwater and its utilisation in flush toilets (12 dwellings).

  • Composting toilets and grey water purification systems in 10 dwellings. These dwellings do not have a connection to the sewerage system.

Two measures were supposed to reduce our dependence on large-scale systems:

  • Water savings through water saving taps and water saving toilets.

  •  Disconnection of rainwater from the sewerage system through a pond with a fluctuating water level.

It is now the year 2000. We have had seven years of experience with different systems. Over the years my own views towards small-scale practises have changed considerably.
We have had serious technical problems. These problems were partly due to lack of money. So these could be remedied.
But there have also been doubts. Doubts about the environmental benefits of the systems we used. I will explain some of the experiments to you and cast some light on the doubts that were raised.

Rainwater never gets lost
We never had any technical problems with the rain water system. The savings on drinking water that can be reached with this system are around 30%. The rainwater is only used to flush the toilets. Thirty percent is rather lot, but we still have to raise the question whether the installation of rain water systems is justified by the environmental benefits.
This system uses two times more electricity than the regular system in which drinking water is used (0,4 versus 0,8 kWh/m3). The reason for this is the small scale of the rain water system. Small pumps require relatively more electricity. Besides, the system relatively takes much more material to install it than other large collective systems. At the level of an individual house there is a huge difference: in stead of one water pipe the rainwater system needs a double system of pipes, a barrel, a pump, en appendages.
Free-flow rain water systems (without a pump) use less electricity and require less technical equipment. But they are hard to install in a building. Consequently the barrel is much smaller so less drinking water can be replaced by rainwater. 
The first time I became critical about these systems was after I discovered that several drinking water companies had become interested in large-scale dual water systems. Why try to catch rainwater on a small scale when you are pumping anyway? Rainwater never gets lost. It falls down and can be collected where is goes, in surface water or in ground water, and with limited means. These large-scale systems seemed to be more efficient. 

My conclusion: Apart from the problem of desiccation (verdroging) of wetlands and natural reserves, the existing drinking water distribution system seems to have little disadvantages. Individual rainwater systems can party solve some problems, but replace them by an energy problem. This is especially problematic, because the threat to the environment when it comes to energy is much larger. When we really want to do something to the environmental impacts of  drinking water production it is probably better to start using surface water instead of ground water.

The sewerage system is not so bad after all.
One of our experiments concerned the installation of composting toilets in ten houses, using two systems. These composting toilets were important to us. We had been careful with water and electricity and managed to do quite well in our old houses, even without special equipment. But the reduction of wastewater is simply not possible without the use of technology.

We started experimenting with composting toilets, because:

  • There is no loss of drinking water

  • There is no pollution and the problem of polluting sewerage overflows is ended

  • There is no loss of organic material

When it comes to these three issues the composting toilets were indeed successful.

But still the experiment was a total failure. Next week the housing corporation will remove the whole system. The biggest problem will be how to remove the compact mixture of straw, organic waste and the faeces of the 5 habitants that lived there in the past 7 years, as this mixture never became compost. We have tried everything: different carbon addings, different aeration, digging in the heap, stabbing holes in it with sticks, leaving worm to live in it, but it was dirt that could not be handled in any way.
The system needed a lot of maintenance and this was a tough and dirty, maybe even dangerous job. After 7 years of trying and hoping for improvement people gave up and nobody wants to do it anymore.
Another disadvantage of the composting toilets is the amount of electricity that is needed to operate the ventilator. It uses at least 1 kWh a day, when put at its minimum requierement (40 Watt). When you know that the savings of drinking water with this system is about 120 litres of drinking water per day, it means that these savings cost about 7 to 8 kWh for every m3. Turning seawater into drinking water costs less energy! 
Maybe the problems with the compost toilets have technical reasons. Maybe we did something wrong. But I think that trying to compost in a low-tech manner inevitably leads to problems. 
The experiment with sewerage-free housing has failed. Ordinary toilets will be installed with a connection to the sewerage system. We may find some comfort in the idea that The Netherlands does not have a serious problem with drinking water after all. And that there is too much manure in the country anyway, and that wastewater purification plants take out phosphates more and more.
The greywater purification system seems to function really well. But since there are no composting toilets any more and the ‘black water’ flows into the sewerage system, we might as well let the grey water into the sewerage system. It will again save us some kilowatt-hours.

From water to energy
I left The Green Roof two years ago and I live now in an old apartment. I do not experiment with water anymore.
I still think individual responsibility is important. My belief that independence of large-scale systems leads to environmentally sound solutions has vanished. A year ago I have installed 6 solar panels, connected to the grid. 
In my view there is a fundamental difference between the collection water and solar energy. Water does not get lost very easy, it goes somewhere anyway. The energy from the sun does get lost when we do not catch it through solar panels or solar collectors. The same goes for wind energy.
Collecting water can be done more efficiently on a large scale. But the collection of solar energy and wind energy has to be done on a small scale and at least decentralised. This is the only way it can work.
With my 6 solar panels, the use of energy saving light bulbs, a laptop computer, a type A refrigerator and a central heating system that shuts itself off I will hopefully be self sufficient this year. Still only about 5 - 10 % of the electricity I produce is simultaneously used. 

Yes, I do fantasise about installing a rainwater system. Something that is probably impossible in my apartment. When the moment comes to make my fantasy come true, it will not be for environmental reasons, but because I still harbour my dreams about self-sufficiency.


Michèl Post