Student Worksheet

Energy Audit Workbook - School

NAMES:

CLASS NAME:

START DATE:

END DATE:

Starting your audit

Why do an energy audit?

By doing an energy audit you will be able to:

• Look at the energy uses in your school;
• Record the details of the energy used;
• Make some evaluations or judgments about the school/business' energy use; and
• Make some recommendations to the school about how to save energy and money.

Doing your audit

Step 1.

Start your audit by finding out the total amount of energy used at your school over one year. You can do this by examining the school’s energy bill. And using the school energy bill you can also work out the financial cost of this energy for the year (you can always just use a bill for a three-month period and then multiply it by four to get a yearly average).

Mark down your findings on the tables provided (Tables 1 and 2).

Looking at your Schools Energy

Table 1. Electricity

Table 2. Gas

Go to your room!

Step 2.

Work out where the energy is being used at your school.

Each group will have been assigned a classroom that they audit. One in the classroom, have a look at the appliances that are in the room. How often they think these sources or appliances are used: Everyday? Once a week? Once a month? Rarely? Never? Only in summer or only in winter? And where is the energy being wasted? For example, are lights being left on in unoccupied rooms?

Record your answers on the table on the following page, Table 3.

What types of energy are used in your room?

Table 3.

What types of energy are used in your selected room?

Step 3. Before moving onto the next step, please answer the following questions:

1. Did you find any examples of energy inefficiency at your room? Where and what were they?

2. What other information would you like to add? Did any of the users of the appliances that you studied share any information about how they tried to be more energy efficient with their appliances?

What is the amount of energy used?

Step 4.

Work out how many hours a year your appliances are used.

Using the table below (Table 4) calculate the total number of hours per year that the appliances in your room are on and used. Some appliances will only be used during school terms or business hours while others may be left on all year round. How can these be calculated differently? (Tip: you can work out the amount of school days per year for those that are only used during school/office times.)

Table 4.

Working out the electricity emissions in your room

Step 5.

Now it's time calculate the amount of carbon dioxide in kilograms that are produced as a result of the number of kilowatt hours of electricity used in your room over one year.

To calculate emissions (kg CO2) for electricity you first need to calculate kilowatt hours.
To do this follow this equation:

Hours per day appliance is on (hrs) x days per year appliance is on (days) x watts ÷ 1000 = kilowatt hours

(You will already have calculated the hours per day x days per year in Table 4 for the appliances in your room.)

You then multiply the kilowatt hours by the electricity emissions intensity figure (EEI) for your state. The electricity emissions intensity figures (EEI) for each state are as follows :

EEI-VIC = 1.31
EEI-WA = 0.98
EEI-QLD = 1.04
EEI-ACT = 1.06
EEI-SA = 0.98
EEI-NSW = 1.06
EEI-TAS = 0.13
EEI-NT = (unfortunately there is no available data for the
Northern Territory so in this case we’ll use South Australia’s; 0.98).

The complete equation for calculating the greenhouse gas emissions each appliance for your state:

hrs x days x watts ÷ 1000 x EEI

Below you will find an example of a simple calculation involving electricity from a light globe to help you understand how this might work in practice.

Working out the electricity emissions in your room

Equation using a 60 watt light globe
Take a common light that has a typical power rating of 60 watts per hour. If the light globe runs for 24 hours per day, 365 days a year, it will run for a total of 8760 hours. In this example we use the EEI for the ACT to demonstrate the equation.

The calculation for this is: 24 hours per day (hrs) x 365 days per year (days) = 8760 hours a year

This means that the light will use 525,600 watt hours of electricity in the year.
The calculation for this is: 8760 hours x 60 watts = 525,600 watt hours (Wh) per year

To convert watt hours to kilowatt hours (kWh), divide by 1000.
The calculation for this is: 525,600 Wh ÷ 1000 = 525.60 kilowatt hours per year

A light globe using 525.6 kWh a year uses 688.54 kg of CO2 gases per year.
The calculation for this is: 526.6 kWh x 1.06kg/kWh (EEI-ACT) = 515.08 kg CO2

The complete equation here is: 8760 x 60 ÷ 1000 x 1.06 (EEI-ACT) = 515.08 kg CO2

Try it for yourself!
Have a practice with this equation using the example of evaporative air-conditioning that has a typical power rating of 400 watts.
If the air-conditioner runs for 6 hours a day for 80 days, it will run for a total of
.............................. hours.
The calculation for this is: 6 hrs x 80 days = ........................hours per year

This means that the air-con will use ............................ watt hours of electricity in the year
The calculation for this is: ................... hours x 400 watts = ................... watt hours (Wh) per year

To convert Wh to kWh, divide by 1000.
The calculation for this is: ...........................wh ÷ 1000 = ........................... kWh

An air-con using ............................. kWh a year uses ............................ kg of CO2 gases per year.
The calculation for this is: .......................... kWh x EEI kg/kWh = .................kg CO2

The complete equation here is:
.................... x 400 ÷ 1000 x EEI = ...................... kg CO2

Calculate the greenhouse gas emissions for the electrical appliances in your room. Use Table 5 to record your answers. If you're not sure of the watts for your appliance, have a look at the Typical Power Ratings table at the end of this worksheet.

Table 5.

Working out the gas emissions in your room

You may have some gas appliances in your room.

You need to do similar equations to work out the greenhouse gas emissions for those appliances, using figures for joules, gigajoules and megajoules instead of watts and kilowatts.

Typical power ratings for gas appliances are displayed as megajoules (MJ) instead of
Watts. So you may have an oven with a rating of 12 MJ. This means that this oven uses 12 MJ per hour of baking.

(You will already have calculated the hours per day x days per year in Table 4 for the appliances in your room.)
To calculate emissions (kg CO2) for gas you will first need to calculate gigajoules (GJ).

To do this follow this equation:

Hours per day appliance is on (hrs) x days per year appliance is on (days) x MJ ÷ 1000 = gigajoules (GJ)

You then mulitply the GJ by the gas emissions intensity figure (GEI) for your state. The gas emissions intensity figures (GEI) for each state are as follows :

GEI-VIC = 57.3            GEI-WA = 60.4           GEI-QLD = 57.3
GEI-ACT = 66.1            GEI-SA = 70.7            GEI-NSW = 66.1
GEI-TAS = 57.8            GEI-NT = 57.8

The complete equation for calculating the emissions for gas appliances for your state:

hrs x days x MJ ÷ 1000 x GEI

Working out the gas emissions in your room

Try it for yourself!

Using the example of the oven with a rating of 12MJ:

If the oven runs for 2 hours a day for 150 days, it will run for a total of ........................ hours. The calculation for this is: 2 hrs x 150 days = ........................hours per year

This means that the oven will produce ............................ MJ hours (MJh) of gas in the year. The calculation for this is: ................... hours x MJ = ................... MJh per year

To convert MJh to GJ, divide by 1000.
The calculation for this is: ...........................MJh ÷ 1000 = ........................... GJ

An oven using ............................. GJ a year uses ............................ kg of CO2 gases per year. The calculation for this is: .......................... GJ x GEI = ...................kg CO2

The complete equation here is:
......................... x .....................Mjh ÷ 1000 x GEI = ...................... kg CO2

Working out the emissions for the whole school/business

Step 6. Compiling the Class Data!

It's time to work out the emissions for the whole school.

Using the table below (Table 7) and the information your class has collected, add up the emissions from each room to work out the grand total of emissions for your school. If you don't have information for every room, just use the information from a similar sizes room with a similar number of appliances.

Table 6.

Any thoughts?

Step 7.

Congratulations! You've completed your energy audit! Well, almost....

Now that you’ve done an energy audit of your school can you make any recommendations as to how your school could reduce their energy use and cut back on greenhouse gas emissions.

Do you think the emissions for your school are high or low?

What do you think the school should do to cut back on energy use and the emissions it makes:

Extra Information: Typical Power Ratings

If it is difficult to find the power rating written on the appliance, use this table as a guide. However be aware that this rating is only a guide and power ratings may vary greatly from one appliance to another.

Appliance	Typical Power Rating
Ceiling fan	65-75W
Computer (PC and monitor)	190 W
Cordless phone (average standby)	30 W
Dishwasher (2 star rating, 1hr/cycle, 12 Places) 1 star	1335 W
Dishwasher (2 star rating, 1hr/cycle, 12 Places) 2 star	950 W
Dishwasher (2 star rating, 1hr/cycle, 12 Places) 3 star	712 W
Electric air conditioning (evaporative)	400 W
Electric air conditioning (split cycle, 2 star rating)	1400 W
Electric air conditioning (wall unit, 2 star rating)	1410 W
Electric central heating	4000 W
Electric oven (fan assisted)	1500 W
Electric stove top cooking (large hotplate)	1100 W
Electric stove top cooking (small hotplate)	700 W
Electric strip heater (no thermostat)	1000 W
Energy efficient light globe	15 W
Fax machine	20 W
Fish tank	50-1210 W
Fluorescent light tube	13/20/40 W
Fridge (1 door) 350-400 L (2 star rating)	1060 W
Fridge (2 door) 350-420 L (3 star rating)	1671 W
Gas central heating	19440 MJ
Gas heater (large wall unit)	35 MJ
Gas heater (small wall unit)	12 MJ

Typical Power Ratings

Appliance	Typical Power Rating
Gas oven	12 MJ
Gas stove top cooking (large stove size)	16 MJ
Gas stove top cooking (small stove size)	10 MJ
Kettle	2400 W
Microwave	1600 W
Photocopier (active)	75 W
Photocopier (standby)	180 W
Printer	10-40 W
Scanner	12 W
Small appliances (radio, portable fan)	12 W
Standard light globe	40/60/100 W
Television (LCD)	270 W
Television (Plasma)	311 W
Toaster	2400 W
DVD / VCR	25 W
Washing dishes - electric hot water system (10L/sink/wash)	330 W
Washing dishes - gas hot water system (10L/sink/wash)	1.89 MJ

Undertake an Energy Audit

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