been combined with heat recovery from the ventilation system to give a package which has
reduced heating bills in high-rise flats by 90-95%.
Another good way to catch solar energy is to add a conservatory to the south side of the
house. If that is not possible, it can be added to the side which catches the most sunlight,
or even on the roof. Not only does this provide a highly productive growing area and extra
space for the house, but the energy relationships are similar to those between the chicken
house and its glasshouse. In winter, warm air from the conservatory can be vented into the
main body of the house, and in summer the rising current of hot air in the conservatory can
be used to draw cool air from the north side of the house and thus cool it down. Meanwhile,
the conservatory converts some of the waste heat from the house into food.
Plants can be used to increase the energy efficiency of buildings. For instance, ivy grown
up the north wall of a house can reduce winter heating needs. This is also beneficial to wild-
life, and, if the brickwork is sound, will preserve it rather than cause deterioration. Using
living plants as part of the actual structure of a building in this way is known as 'biotecture'
and it is another way of using biological resources instead of non-renewables.
When using more conventional materials, it is necessary to be aware of where they come
from and choose materials that respect both Earth and people. This means avoiding such
materials as aluminium, with its very high energy cost, some forms of mineral fibre insula-
tion, which may cause cancer in the workers who make them, and paints containing titani-
um dioxide, which is harmless in itself but very polluting in its manufacture. Alternatives
to all these exist. For example, many natural insulating materials, such as wool or cork, can
be preserved from rot, fire and rodents with a harmless dressing of borax.
Water supply and sewage disposal are under great strain both in cities and elsewhere,
and much can be done to ease the problem by making better use of the available resources.
At present, we fill the sewers with a mixture of rainwater off the roofs, 'grey' water from
sinks and baths and 'black' water from toilets. The rainwater can be used for drinking, as it
is probably purer than what comes out of a tap, while the grey water can be used for flush-
ing the toilet and supplementary plant watering. By separating the three and using each
quality for its highest use, mains water consumption in the city can be reduced by half for
the cost of a little plumbing. In the country, rainwater could provide for all our domestic
needs, as it does on many Australian farms, in a far drier climate than ours.
The real sewage can be purified by passing it through a series of carefully designed beds
of reeds. Reeds and other water plants have the ability to remove organic matter, disease or-
ganisms and even chemical pollutants such as heavy metals. Reedbeds have been installed
to cope with both domestic and industrial effluent. They take up less land than convention-
al systems, and can even be installed vertically in a series of plastic tanks.
Rather than seeing sewage as nothing but a problem we need to see it as a resource, full
of valuable organic matter and plant nutrients. As long as we treat it as only something to
be got rid of we will be dependent on a continuing input of fossil fuels to produce artifi-