GUIDE TO A
HOT & COLD WATER
AUDIT
FOR TEACHERS & STUDENTS
By Clare Pries
April 2008
© Coolmob trading as Environment Centre Northern Territory, April 2008
HOT & COLD WATER AUDIT
There are a number of factors which determine the amount of energy used by your school to
supply hot and cold water.
The
The
The
The
The
amount of hot and cold water consumed
type of the systems used to supply the water
temperature at which the water is heated or cooled to
number of systems installed
energy efficiency (heat losses and gains) of the system components
REDUCE THE AMOUNT OF HOT AND COLD WATER CONSUMED AT YOUR SCHOOL
Leaking hot and cold water supply taps not only increase the amount of energy needed to heat
or cool the water but they also increase your schools water costs and the energy requirements
of suppliers needed to pump the water from storage facilities through mains supply lines. Have
leaking taps fixed as soon as possible. $
Install inexpensive screw on aerators to wash basin taps,
taps these will reduce the amount of water
wasted. Though your schools electrical energy will only be saved when these are used on taps
serviced by hot water systems, they should be considered for most basin water tap outlets. $
Install lowlow-flow shower heads.
heads Standard shower heads deliver 20 to 30 litres per minute, well
designed low-flow shower heads provide a quality shower at under 9 litres per minute. $
Try this quick test to determine the flow-rate of the showerheads installed at your school:
• Place a bucket of known volume under shower head
• Turn on the shower
• Time how many seconds it takes to fill the bucket
Flow rate = (60 seconds ÷ seconds taken to fill container) x container volume in litres
CHANGE THE TYPE OF HOT WATER SYSTEM USED $$$
When an existing hot water system needs to be replaced and hot water use from system is
greater than 150Ltrs per day, install solar hot water system. Apart from hot water services
which provide for shower outlets and clothes washing, many of a schools installed hot water
units are only used to provide small amounts of hot water throughout the day (fill cleaners
buckets, wash hands & dishes, etc.). The capital cost of installing solar hot water systems
where the daily volume of hot water used is low can have long pay-back periods (at current
prices). The installation of an instantaneous hot water system (or possibly a solar electric heat
pump) which do not require substantial additional pipe installation would be more economical in
these instances. Details about all these systems can be found on the government website
www.greenhouse.gov.au/yourhome/technical/fs42.htm
ADJUST TEMPERATURE SETTINGS ON HOT WATER SYSTEMS $$
Check the temperature setting of electric hot water systems. Most hot water services only need
to be at 60 degrees (this is usually the minimum set point for a hws), this should provide
adequate hot water at point of use and is over the temperature required to kill legionella
bacteria (55 degrees). Many electric hot water systems have a visible control (often under small
plastic cap) on the tank which can be adjusted by your school maintenance staff, if these are
not present it is unsafe to do and will require an electrician or plumber.
REDUCE THE AMOUNT OF TIME SYSTEMS
SYSTEMS ARE TURNED ON $
Changes to practices, infrastructure, and staff may have rendered an installed hot water or cold
water service unnecessary. An audit of your hot & cold water services should identify
opportunities to turn these off. Note, hot water services are required by health regulations to
clean food preparation areas and to wash hands prior to food preparation. The NT Department
of Health and Community Services Environmental Health section advises that soap, not warm
water, is considered necessary for bathroom wash basins.
Identify hot water systems that are not used over school holidays and establish end of term
shut-down practices for these units. A small electric kettle instead of a large urn should be used
over school holidays if there are only a small number of staff present.
INCREASE THE EFFICIENCY OF THE SYSTEM
The rate at which heat is transferred into or out of a system depends on the systems structure
and the internal and external temperatures. The efficiency of a water system can be increased
by reducing internal and external temperature differences and increasing the insulation of the
system.
• Isolate cold water storage units from heat sources $ - $$
• Insulate water outlet pipes on cold and hot water systems $
• Add insulation to hot water storage tanks if external tank lining is warm/hot.
(Degradation of internal tank insulation over time can substantially increase heat
transfer rates, most older hot water systems will lose twice as much heat as a new
efficient model). $$
NOTE!!! The pipe work and tanks with very poor insulation can cause scalding take appropriate
precautions when assessing these systems.
Cold water storage near
heat source
Insulated hot water tank
Insulated outlet pipes
STUDENT ACTIVITIES
1. Undertake hot and cold water audit of school. (Example shown below)
AREA
AREA
AREA
AREA
CLEANERS
STORE
PRESCHOOL
GYM
SHOWERS
TEACHERS
OFFICE
SYSTEM
SYSTEM
SYSTEM
SYSTEM
50Ltr Electric
HWS
80Ltr Electric
HWS
cleaners fill
their buckets
for washing
floors, etc
no
washing
hands and
dishes
no
no
yes
not applicable
HOT WATER AUDIT
250Ltr
Electric
HWS
student
showers
10Ltr
Hot water
Urn
tea & coffee
2 showers
dripping
constantly
not
applicable
no
not applicable
22 l/s
not applicable
75
Medium
75
not applicable
applicable
never
never
never
school
holidays
Is tank warm/hot?
no
yes
no
yes
Are hot water outlet pipes insulated?
yes
yes
no
no
SURVEY QUESTIONS
What is hot water used for?
Are there any leaking taps serviced by system?
Are aerators used on taps?
Shower flow rate?
not applicable
Flow rate = (60 seconds ÷ seconds taken to fill
container) x container volume in litres
Temperature setting?
When is system turned off?
COLD WATER AUDIT
AREA
AREA
AREA
AREA
SYSTEM
SYSTEM
SYSTEM
SYSTEM
SURVEY QUESTIONS
Are there any leaks in pipes or are taps
running?
Is system near any heat sources?
When is system used?
Are cold water outlet pipes insulated?
2. Discuss opportunities at school and home to reduce energy used by hot and cold water
systems.
3. Use the information in the section on ‘Estimating Energy Consumption & Potential
Savings’ to calculate the savings potentials.