Thinking Green:Layout 1 11/09/2009 14:29 Page 61
thinking green
Saving and reusing
rainwater
Over the past few years, in a drive to reduce consumption of mains water, recycling
rainwater has changed from being thought of as ‘nice-to-have’ technology, to being
specified and installed on many commercial-type buildings.
T
ODAY’S rainwater harvesting The water can be used with or without contracts, because often the developer
technology comes with filters, the addition of a header tank, for a will be looking after the school-building
underground storage, and the variety of non-potable uses such as once it has been built, leasing it back to
opportunity to recycle the water flushing loos, urinals and irrigation. the local authority.”
captured safely within a building for a As an educational resource, suppliers
variety of non-drinking uses including Cost vs benefit such as Kingspan can provide a display
flushing loos and washing vehicles. According to Andy Thompson, the cost of monitor for the reception area, linked in
But lowering individual water installing a rainwater harvesting system to the building’s BMS to provide instant
consumption means more than simply varies according to the size of the roof area, access to the system’s status and the
investing in the latest equipment. It the annual rainfall, and the expected water water consumption records for both
means changing mindsets and behaviours, requirements, which is usually based on a mains and the rainwater for staff,
educating the adults-of-tomorrow to school or college’s annual use for toilets, students and visitors.
value a resource that earlier generations urinals and sometimes irrigation. “Typically,
have too often wasted, says Andy the initial cost of a system ranges from
www.kingspanwater.com
Thompson, divisional development £4,000 to £18,000, with payback periods
manager for Kingspan Water, which in terms of a reduction on water bills
produces a range of systems for against the equipment cost running at
rainwater harvesting and greywater around five years on average.
recycling. “Thanks to global warming,” he “This is good news for
explains, “water is becoming an local authorities but it
increasingly scarce resource and today’s is also beneficial
student will need to manage in a world in for PPP and
which water consumption rates are less PFI
than half those currently.”
Environmental rating
It is clear that very few schools will
now be built without a high BREEAM
rating: funding on all BSF projects is
conditional on a school achieving a ‘very
good’ or ‘excellent’ rating, says
Thompson, and rainwater harvesting
has proved a reasonably inexpensive
way to gain a high rating. “It also greatly
reduces schools’ annual water costs,
allowing the savings to be spent on the
things that schools really need.”
All rainwater harvesting systems
operate using typical roof drainage
layouts. This means rainwater runs
down the roof and into the
guttering and down pipes in
the normal way before
passing through a filter, which
removes the leaves and
debris. The rainwater is then
stored in an underground tank
How Kingspan's Envireau rainwater harvesting
containing a pump and filter. system is used in a commercial property.
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