Case Study 1 Chad Pty Ltd (CPL) is preparing to design and implement sustainabil
ID: 2339065 • Letter: C
Question
Case Study 1
Chad Pty Ltd (CPL) is preparing to design and implement sustainability systems and processes. You find (as the environmental director) that energy is a key resource for business operations; first for heating water and second for operational and security lighting. Management of these key resources for business operations can save the company money. Therefore the first step is to measure the water flow at the premises and the second step is to calculate the cost of heating water for 250 days each year. The second key resource for business operations is energy for operational and security lighting for 365 days each year. You report directly to William South, the CFO.
The daily rinsing process for fruit and vegetables requires the tap to run for 40 minutes per day and use 11 liters of water flow per minute. The water is heated to 60oC. The table below provides the number of kWh required to heat one kilolitre of water to various temperatures
Hot Water Temperature
kWh required to make one kilolitre of hot water
45oC
56 kWh
50oC
62 kWh
60oC
77 kWh
70oC
98 kWh
CPL electricity usage for lighting for operational and security purposes is set out below.
Number of lights:
12 lights
Light Wattage per light: (Fluorescent lights)
40 watts or 0.040 kWh Light Wattage:
Electricity cost per kW Light Wattage:
$0.25 /kWh:
Hours of lighting use per day:
18 hours
Required: Please note: all your answers should be to two decimal points (cents)
a. If the business uses water heated to 60oC, assuming the electricity cost per kilolitre is $0.25 per kWh, calculate the annual electricity cost to the business associated with the heating of water used to 60o
b. If the business uses water heated to 50oC (assuming the electricity cost per kilolitre is $0.25 per kWh), calculate the dollar saving if this lower temperature is used.
c. You are considering fitting the tap with a flow restrictor that will reduce water flow to 5 litres of water flow per minute. You expect run the tap still for 40 minutes per day. Calculate the electricity cost if the reduced water flow was heated to (i) 60 degrees and (ii) to 50 degrees.
d. Using your working to answer (a), (b), and (c), calculate the energy cost savings from (i) reducing the water flow without reducing the water temperature and (ii) reducing the temperature without reducing the water flow.
e. Calculate the annual lighting cost for the Arrow Pty Ltd using the following formula
__ lights x ____ kW x _____ $/kWh x ____ hrs x _____ days = $______/yr
f. How much can a business save on electricity costs by using energy-efficient lights if the business replaces the 40-watt fluorescent tubes with 5 watts LED bulbs that could be inserted into 20 light fittings? Each light fitting costs $5 to supply and install.
g. Provide your recommendation(s) to the managing director about what energy reduction activities to implement. Use your answers in a) to f) to support your recommendation to make the greatest combined energy costs savings. Include capital costs (mentioned in (f) above) of installing new light fittings if your calculations show that is the best option.
Hot Water Temperature
kWh required to make one kilolitre of hot water
45oC
56 kWh
50oC
62 kWh
60oC
77 kWh
70oC
98 kWh
Explanation / Answer
Formula Sheet
A B C D E F G 2 3 Hot Water Temperature kWh required to make one kilolitre of hot water 4 45oC 56 kWh 5 50oC 62 kWh 6 60oC 77 kWh 7 70oC 98 kWh 8 9 a) 10 11 Number of days a year 250 12 13 Time for which tap is run 40 min per day 14 Water flow rate 11 litres per min 15 16 Water Used per day (Litre) 440 =D13*D14 17 Water used per year (Litre) 110000 =D16*D11 18 19 kWh required to make 1000 litre of hot water at 60 deg 77 20 21 kWh required to make 110,000 litre of hot water at 60 deg 8470 =D19*(D17/1000) 22 23 Thus KWh required to heat water annually is 8470 24 Cost per KWh $0.25 per KWh 25 26 Total annual electricity cost if water is heated at 60 deg $2,117.50 27 28 b) 29 30 Number of days a year 250 31 32 Time for which tap is run 40 min per day 33 Water flow rate 11 litres per min 34 35 Water Used per day (Litre) 440 =D32*D33 36 Water used per year (Litre) 110000 =D35*D30 37 38 kWh required to make 1000 litre of hot water at 50 deg 62 39 40 kWh required to make 110,000 litre of hot water at 50 deg 6820 =D38*(D36/1000) 41 42 Thus KWh required to heat water annually is 6820 43 Cost per KWh $0.25 per KWh 44 45 Total annual electricity cost if water is heated at 50 deg $1,705.00 46 47 Cost Saved =Cost of heating to 60 deg - Cost of heating to 60 deg 48 $412.50 =D26-D45 49 50 Hence by reducing the temperature from 60deg to 50 deg cost saved is $412.50 51 52 53 c) 54 Number of days a year 250 55 56 Time for which tap is run 40 min per day 57 Water flow rate 5 litres per min 58 59 Water Used per day (Litre) 200 =D13*D14 60 Water used per year (Litre) 50000 =D16*D11 61 i) 62 kWh required to make 1000 litre of hot water at 60 deg 77 63 64 kWh required to make 50,000 litre of hot water at 60 deg 3850 =D62*(D60/1000) 65 66 Thus KWh required to heat water at 60 deg annually is 3850 67 Cost per KWh $0.25 per KWh 68 69 Total annual electricity cost if water is heated at 60 deg $962.50 70 ii) 71 kWh required to make 1000 litre of hot water at 50 deg 62 72 73 kWh required to make 50,000 litre of hot water at 50 deg 3100 =D71*(D60/1000) 74 75 Thus KWh required to heat water annually is 3100 76 Cost per KWh $0.25 per KWh 77 78 Total annual electricity cost if water is heated at 50 deg $775.00 79 80 d) 81 82 i) 83 Cost saved by reducing the water flow without reducing the temperature =Annual cost of Heating water at 60 deg without reducing water flow -Annual cost of Heating water at 60 deg with reduced water flow 84 $1,155.00 =D26-D69 85 86 Hence Cost saved by reducing the water flow without reducing the temperature $1,155.00 87 88 i) 89 Cost saved by reducing by reducing temperature without reducing the water flow =Annual cost of Heating water at 60 deg without reducing water flow -Annual cost of Heating water at 50 deg without reducing water flow 90 $412.50 =D26-D45 91 92 Hence Cost saved by reducing by reducing temperature without reducing the water flow $412.50 93