GUIDE TO
SCHOOL COOLING & VENTILATION
AUDIT
FOR TEACHERS & STUDENTS
By Clare Pries
April 2008
© Coolmob trading as Environment Centre Northern Territory, April 2008
COOLING & VENTILATION AUDIT
As cooling and ventilation account for the greatest percentage of energy used in top-end
schools efficiency improvements in this area have the greatest potential for energy savings. The
key factors that influence the amount of energy consumed by cooling and ventilation systems
are:
the type, size and model of air-conditioners,
the heat load on the systems,
temperature set points,
the maintenance of system components, and,
the amount of time the systems are operating.
Energy efficiency actions based on some of these key factors can require detailed investigation
by engineers, however there are many simple operational and behavioural changes that can be
identified with a cooling and ventilation audit undertaken by students.
REDUCE OPERATING TIMES OF AIRAIR-CONDITIONERS
Many of a schools air-conditioning systems are automatically programmed to turn on and off at
set times of the day and on specific days of the year. Programmed times should exclude airconditioning systems from turning on automatically during weekends and school and public
holidays, if needed on these days they should be manually activated only. The start and stop
times used during school days will depend on when a building/room will be occupied and the
amount of time needed to get the building/room to desired comfort conditions. Though the time
a room will be occupied is generally known, the time it takes an air-conditioner to cool a room
will vary according to the seasons. It is common for air-conditioning systems to be programmed
to start based on worst case conditions experienced in the build-up and wet season.
Two of the quickest, cheapest ways to save energy at a school are:
Keep automatic start times as late as possible. If the costs of labour to make
adjustments to programmed times is high have timers reprogrammed twice a year only
(e.g. a later start time at the start of the dry season and earlier time at start of wet
season/build-up, if necessary). $
Programme stop times to when students leave class for the day. The
reduced load once students have left and the thermal properties of the
building should minimize the need to have air-conditioners running when
there are only one or two people in the room. The use of personal pedestal
or floor fans may be all that is required during the warmer months of the
year. If needed remote after hour’s timer switches can be used to activate
air-conditioners after classes have finished, however attention to how often
these are used and for how long is important so as not result in an increase
in air-conditioner energy use. $ - $$
•
•
The charts below represent the school day load profile of a top-end school. The first shows that
adjustments made to the stop times of the air-conditioning actually result in an increase in
energy use (B > A). This primarily occurs because air-conditioners are allowed to run for the
full after hours time setting (usually two hours), rather than being manually turned off as staff
leave.
200
180
Load profile prior to change in airconditioners stop times
160
L
o
ad(kW
)
140
Load profile after adjusting airconditioners stop times
A
120
100
80
B
60
40
20
0
06
am
6a
m
-7
am
7a
m
-1
2p
m
12
pm
-2
p
m
2p
m
-3
pm
3p
m
-3
.3
0
p
m
3.
30
pm
-4
p
m
Time
4p
m
-4
.3
0
p
m
4.
30
pm
-5
p
m
5p
m
-5
.3
0
p
m
5.
30
pm
-6
p
m
6p
m
-7
pm
7p
m
-9
pm
9p
m
-1
2p
m
The chart below shows the average load profile after adjustments to the air conditioning stop
times, and good shut down practices of after hours use switches were implemented.
300
250
Load profile prior to change in airconditioners stop times
Load profile after adjusting airconditioners stop times
Load(kW
)
200
150
A
100
B
50
0
06a
m
•
•
•
•
•
6a
m
-7
am
7a
m
-1
2p
m
12
pm
-2
pm
2p
m
-3
pm
3p
m
-3
.3
0p
m
3.
30
pm
-4
pm
Time
4p
m
-4
.3
0p
m
4.
30
pm
-5
pm
5p
m
-5
.3
0p
m
5.
30
pm
-6
pm
6p
m
-7
pm
7p
m
-9
pm
9p
m
-1
2p
m
Put in place measures to ensure classroom air-conditioners are turned off when classes
will be away on excursions, sports events, etc. $
Identify rooms that are frequently used after hours, and stop main plant being used at
these times by installing small air-conditioners in those rooms. $$
Centralized cooling plants consume considerable amounts of energy, the use of these
systems to cool the building on weekends for only a few staff is an extremely inefficient
use of energy. Restricting their after hours use is a priority in achieving energy savings
at a school. $
Inspect programmed times of all air-conditioning units. During the ‘School Energy Blitz’
project, many of the air-conditioning units had different start times and holiday periods
to that expected by staff. This most likely occurs when maintenance is carried out on
units throughout the year. $
Produce and display a yearly timetable for a/c maintenance personnel to minimize future
errors in programming units. $
INCREASE THE TEMPERATURE SETTINGS
SETTINGS OF AIRAIR-CONDITIONING SYSTEMS.
SYSTEMS $ - $$
Each degree lower than necessary consumes up to 10% more energy1, room temperatures
should not be lower than 24 degrees (25+ recommended). Fans could be used to provide an
additional cooling mechanism for:
• areas of the classroom that have higher loads or are not adequately serviced by air
diffusers
• times of the day when loads increase for short periods, for example after recess and
lunch
• for staff or students yet to acclimatize to tropical conditions
Types of fans available
PEDESTAL
FLOOR
DESK
TOWER
WALL
CEILING
1
Building Sustainability Services, 2007, ‘Introduction to Energy Savings Opportunities in NT Schools’, School Blitz Workshop Presentation, NT
Government – Department of Planning and Infrastructure.
Consider purchasing one or two fans as a trial. Things to consider when deciding on what type
of fan would best suit your needs:
• Can the fan be positioned so as not to result in any safety issues? For example
preventing trip hazards from electrical cables.
• Can the fan be positioned so as not to impact on light quality? A strobe affect will result
if ceiling fans are positioned close to light sources.
• Can the output of the fan be easily controlled? The amount of air movement achievable
will be determined by the impact on tasks being undertaken. Too high an air flow will
result in papers flying about. Cooling can be achieved with low to medium rates of airflow when combined with air-conditioning. Make sure the fan you purchase has a
number of fan speeds so that the best speed can be selected for your circumstances.
• Is there enough floor space to accommodate a floor fan? These fans are an excellent fan
for teachers personnel use as they circulate the cooler air near the floor and do not take
up limited desk space.
REDUCE THE HEAT LOAD ON AIRAIR-CONDITIONING SYSTEMS
The load on air-conditioning systems is the result of the heat and moisture in the air entering
the building through fresh air fans, and building elements (walls, roof, doors, windows), and
radiated from appliances, lights, and people. You can reduce the load on air conditioning
systems by:
•
•
•
•
•
•
•
Providing shade (vegetation, awnings, verandas) to walls and windows. $$
Using light reflective paints on roofs and walls which can not be shaded from direct sunlight. $$$
Using treatments on windows which can not be shaded from direct sun-light. $$
Keeping doors and windows closed when air-conditioning system is on. $ (See notes
below)
Sealing holes and cracks in walls $ - $$
Undertaking an appliance and light audit to identify opportunities to reduce the energy
and therefore heat produced by these items. $
Turning off exhaust fans when not required. $
It has become common practice for doors to be left open because a room is too cold at certain
times of the day. This is generally the result of air-conditioning systems being set-up to
accommodate higher load conditions (i.e. warmest time of year, highest attendance and activity
from students) or when one system is used to cool a number of rooms. If the temperature of
rooms can not be increased, with the use of fans, in those areas that are dominating
temperature settings, or, through reducing the load on the system, then, occupants of the room
should keep an item of clothing available when required. Leaving doors open when airconditioning systems are running is very inefficient. The use of door-way air curtains similar to
those used in shopping complexes may be justified in some situations.
ENSURE MAINTENANCE ON AIRAIR-CONDITIONING SYSTEMS IS CARRIED
CARRIED OUT REGULARLY.
REGULARLY $-$$
Lack of maintenance on air-conditioning systems can increase energy consumption
substantially. Investigating maintenance issues on larger chiller plants and packaged airconditioner units should be undertaken by a professional assessor, however students could look
at the smaller room air-conditioners as these are regularly used at home. The main
maintenance issue with small room air conditioners is the condition of filters. Keeping filters
clean lets the a/c get the room to temp faster and with less energy. Check the condition of
filters in small room a/c, if very dirty check with maintenance staff as to how often these are
cleaned.
Example of poorly maintained a/c filter
STUDENT ACTIVITIES
1. Use the information on building design for tropical climates in the technical manual
available at http://www.yourhome.gov.au/technical/index.htm to discuss how a building
could be designed to minimize the use of air-conditioning. Students could design their
own homes using the information discussed.
2. Undertake cooling audit of your classroom.
ROOM
SURVEY QUESTIONS
WHAT TYPE OF COOLING SYSTEMS ARE USED TO COOL CLASSROOM:
•
ON SCHOOL DAYS?
•
ON WEEKENDS & SCHOOL HOLIDAYS?
WHAT TIME OF THE DAY ARE THE SYSTEMS TURNED ON DURING SCHOOL TERMS?
WHAT TIME OF THE DAY ARE THE SYSTEMS TURNED OFF DURING SCHOOL TERMS?
IS THERE AN AFTER HOURS SWITCH AND HOW LONG DOES IT RUN FOR?
CAN THE AFTER HOURS SWITCH BE TURNED OFF MANUALLY?
ARE THERE ANY DAYS DURING THE SCHOOL TERM WHEN THE AIR-CONDITIONER
IS ON AND NO-ONE IS IN THE ROOM?
(Field trips/excursions, sports events, etc.)
CAN THE SYSTEM BE TURNED OFF DURING THESE TIMES?
COULD DOORS AND WINDOWS BE OPENED TO NATURALLY VENTILATE ROOM
AND FANS BE USED TO CIRCULATE AIR DURING THE COOLER MONTHS OF THE YEAR?
ARE DOORS AND/OR WINDOWS EVER LEFT OPEN WHILE COOLING SYSTEM IS ON?
IF SO WHY?
ARE THERE ANY NOTICEABLE CRACKS OR HOLES IN WALLS WHICH COULD ALLOW COOL
AIR TO ESCAPE CLASSROOM?
WHAT IS THE TEMPERATURE OF THE ROOM?
COULD THE TEMPERATURE OF THE ROOM BE TURNED UP BY ONE OR TWO DEGREES?
IF ONLY A FEW PEOPLE THINK THAT TEMPERATURE COULD NOT BE TURNED UP OR
THINK IT NEEDS TO BE TURNED DOWN ARE THESE PEOPLE IN THE SAME AREA OF
THE CLASSROOM OR WEARING WARMER CLOTHING THAN EVERYONE ELSE?
IS THE ROOF OF THE CLASSROOM A LIGHT REFLECTIVE COLOUR & CLEAN?
ARE ANY OF THE WALLS OR WINDOWS NOT SHADED FROM DIRECT SUN LIGHT DURING
THE DAY?
IF A SMALL ROOM AIR CONDITIONER IS USED IN THE CLASSROOM ARE THE FILTERS CLEAN?
3. Discuss the opportunities to reduce the energy consumed by the cooling systems for
your classroom and if these could be applied to the rest of the school.
4. Use the information in the section on ‘Estimating Energy Consumption & Potential
Savings’ to calculate the estimated savings your school could achieve by applying the
energy efficiency improvements the students have identified.