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Energy Managers Association
Water Efficiency
“Its all about control”
Introduction
Water efficiency can take many forms
Changing staff behaviour towards water use
Monitoring and targeting
Buying more water efficient appliances
Potentially the biggest impact and the most
sustainable is to review the controls for water use
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Control of water using systems
Control of water using systems can be simple
A tap is a basic control mechanism
Level control (e.g. in water storage tanks)
Pressure control e.g. varying pump speed to
match supply to demand
© EMA
Control of water using systems
Toilets
– half flush/full flush cisterns or consider water
saving devices which displace volume
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Control of water using systems
Men’s urinals
– many systems flush continually on a ball valve
– consider motion sensors or timers to restrict flushing
to occupancy hours
Cistermiser IRC valve
– Check regularly for constantly flushing urinals
© EMA
Control of water using systems
Showers
– standard shower head can discharge at 15
litres per minute
– low flow heads, volume discharged should be
less than 10 litres
– 1 shower used for 5 minutes per day would save 9,125 litres a year
– For a 100 bed hotel,
that could be 912,500
litres per year
© EMA
Water pumping systems
Pumping systems
– water is commonly pumped
within buildings for potable,
heating, cooling or process use
– how are they controlled?
– are pumping systems over
pressurised, potentially causing
leaks?
– do pumping systems just pump
water around buildings when
there is no requirement, losing
or dumping water?
© EMA
Pumped tank level control system
If the high level switch off probe stops working, the
pump will run continuously, overflowing the tank. As
water is still available within the building, would anyone
know?
High level Switch off
Low level switch on
Overflow
Waste
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Water pumping systems
Pumping systems
– how are pumps controlled?
– do they switch off when there is no
production, operation or demand?
– are pumps fixed or variable speed?
– even if they are variable, do they
respond to changes in building
demand or is their speed just
reduced and fixed?
– for potable systems, is pressure
too high or set for the top floor?
– if fixed speed, is excess water
pressure dumped?
© EMA
Control of water using systems
Heating and cooling use
– ensure boiler blowdown systems are not continuously
operational or valves “cracked”
– in evaporative cooling systems and cooling towers, avoid
continuous bleed or timed dumping
– in steam systems, use good steam traps to avoid
constant leakage.
Can condensate
be returned to the
head of the system?
© EMA
Control of water using systems
Summary
Understand where and how water is used
Identify whether any controls are in place
Understand what those controls are and how
they work
Are the existing controls effective?
If not what can be done to improve them?
© EMA
Questions?
