Pooled
resources
Does
pool and spa owning have to consume a lot of
energy? Hal Norman investigates.
Owning a swimming pool or spa gives us an
opportunity to relax in some luxury in the
privacy of our own homes. For many of us,
chilling out in some warm water is the ideal way
to forget the stresses of the working week and
problems at home. However, global warming and
climate change have made water and fossil fuels
increasingly valuable resources so is it possible
to soak in the pool without a nagging doubt at
the back of your mind that your ostensibly
harmless pleasure is somehow contributing to the
destruction of the planet?
The answer, according to Brian Andrews, Managing
Director of Heritage Pools Ltd, can be yes. He
explains: “You can make many green choices
in the design of an ordinary swimming pool or spa
that can help reduce the resulting carbon
footprint from the pool.” Most pools are
heated by oil or gas but this can be supplemented
by solar power.
There are a number of companies offering a
solarpowered solution to the problem of heating
the pool. For outdoor pools you can buy solar
panels which absorb solar energy through a large
surface area made of black high molecular
polyethylene. Water passing through the panel is
heated and pumped back into the pool. So, how
many panels will you need? Technical Manager Andy
Clark of Powertech Solar Ltd explains: “The
number of panels you need depends on the square
metreage of the pool. Fifty per cent of the pool
square area is used to calculate the quantity of
panel absorber area needed. For example a 10 x 5m
pool requires twenty-four panels.” The
panels can be easily mounted on a roof, a fence
or even on the lawn.
When linked to an existing pool pump the
reduction in water pressure is minimal. There are
also few worries about maintenance as the panels
are resistant to swimming pool water and
temperature-resistant from -50
ƒC
to 115
ƒC.
The company also offers the more expensive option
of solar vacuum tube collectors which are
suitable for heating both indoor and outdoor
pools via a heat exchanger. Another attraction of
this option is that it can be incorporated into
the domestic heating system, thus defraying the
total cost.
Another company working in this area is Riomay,
who reckon on supplying six 3 x 1 m solar panels
for a 10 x 5 m pool holding 75 m3 of water. This
should supply 10800 kW of heat annually, enabling
the pool to be used for about eight months in
every year. At a relatively small extra cost the
solar panels can be rigged up to supply hot water
to the house, although the tank will probably
have to be replaced by a solar thermal dual heat
exchanger tank. The system will automatically
switch to conventional power if there is not
enough solar power. Riomay also offer to make
your solar panels an attractive garden feature by
hiding them within the confines of a pergola.
While changes can be made to an existing pool, if
you are having a new pool constructed there are a
number of things you can do. A darker tile will
draw more heat into the pool and a transparent
cover will allow sunlight to heat the pool when
not in use. A thermal bubble cover will raise a
pool’s temperature a few degrees.
Installing insulation in the pool walls and floor
will also conserve heat and reduce bills. Another
option is to install ground source heat pumps,
where a 60m hole is bored into the ground to tap
into the natural thermal currents that exist at
that depth. For hot tubs a company called Eco
Spas recovers the heat lost from the spa pump to
heat the tub. Unlike many hot tubs which are made
of a single acrylic shell mounted in a wooden or
metal cabinet, the Eco Spas are moulded in
onepiece constructions. The shell of the tub is
fully insulated with foam to reduce the heat loss
and also to reduce the amount of electricity
required.