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Hot water running costs

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The table below provides the approximate annual energy costs for various types of water heating systems, for different household sizes.

1 person2 people3 people4 people

1 person (60 litres per day)

Water heater type Energy star rating Annual energy cost Annual GHG emissions (kg/yr)
Gas
Natural gas – storage 5.5 star rating $230 515
4 star rating $285 635
Natural gas – instant 7 star rating $160 380
5.5 star rating $180 425
LPG – storage 5.5 star rating $370 605
4 star rating $460 745
LPG – instant 7 star rating $240 430
5.5 star rating $275 490
Electric
Peak tariff – storage N/A $555 2040
Peak tariff – instant N/A
$395 1450
Off-peak tariff – storage N/A $455 2555
Solar
Natural gas boosted High efficiency $35 95
Standard $40 110
LPG boosted High efficiency $45 100
Standard $55 120
Electric boosted – peak tariff High efficiency $110 410
Standard $185 670
Electric boosted – off-peak tariff High efficiency $85 455
Standard $135 750
Heat pump
Peak tariff High efficiency $150 545
Standard $235 860
Off-peak tariff High efficiency $100 545
Standard $155 860

2 people (90 litres per day)

Water heater type Energy star rating Annual energy cost Annual GHG emissions (kg/yr)
Gas
Natural gas – storage 5.5 star rating $290 645
4 star rating $350 775
Natural gas – instant 7 star rating $230 535
5.5 star rating $260 605
LPG – storage 5.5 star rating $465 755
4 star rating $560 910
LPG – instant 7 star rating $355 615
5.5 star rating $405 700
Electric
Peak tariff – storage N/A $740 2730
Peak tariff – instant N/A
$585 2160
Off-peak tariff – storage N/A $575 3245
Solar
Natural gas boosted High efficiency $45 125
Standard $60 160
LPG boosted High efficiency $65 140
Standard $90 175
Electric boosted – peak High efficiency   655
Standard $270 990
Electric boosted – off-peak tariff High efficiency $130 730
Standard $195 1095
Heat pump
Peak tariff High efficiency $195 720
Standard $310 1135
Off-peak tariff High efficiency $130 715
Standard $200 1130

3 people (120 litres per day)

Water heater type Energy star rating Annual energy cost Annual GHG emissions (kg/yr)
Gas
Natural gas – storage 5.5 star rating $350 775
4 star rating $415 915
Natural gas – instant 7 star rating $295 690
5.5 star rating $340 785
LPG – storage 5.5 star rating $560 910
4 star rating $665 1075
LPG – instant 7 star rating $465 795
5.5 star rating $535 905
Electric
Peak tariff – storage N/A $925 3420
Peak tariff – instant N/A
$780 2875
Off-peak tariff – storage N/A $700 3935
Solar
Natural gas boosted High efficiency $65 165
Standard $85 215
LPG boosted High efficiency $95 185
Standard $130 240
Electric boosted – peak tariff High efficiency $260 950
Standard $365 1345
Electric boosted – off-peak tariff High efficiency $185 1040
Standard $265 1475
Heat pump
Peak tariff High efficiency $245 895
Standard $385 1415
Off-peak tariff High efficiency $160 885
Standard $250 1395

4 people (150 litres per day)

Water heater type Energy star rating Annual energy cost Annual GHG emissions (kg/yr)
Gas
Natural gas – storage 5.5 star rating $410 905
4 star rating $475 1055
Natural gas – instant 7 star rating $365 845
5.5 star rating $420 965
LPG – storage 5.5 star rating $655 1060
4 star rating $765 1240
LPG – instant 7 star rating $575 975
5.5 star rating $660 1115
Electric
Peak tariff – storage N/A $1115 4110
Peak tariff – instant N/A
$970 3585
Off-peak tariff – storage N/A $820 4625
Solar
Natural gas boosted High efficiency $85 215
Standard $110 285
LPG boosted High efficiency $130 245
Standard $175 320
Electric boosted – peak tariff High efficiency $350 1285
Standard $470 1740
Electric boosted – off-peak tariff High efficiency $250 1395
Standard $335 1885
Heat pump
Peak tariff High efficiency $290 1070
Standard $460 1695
Off-peak tariff High efficiency $185 1045
Standard $295 1655
  • Annual energy costs are based on a Melbourne household with the stated average daily hot water use. For gas instantaneous and gas boosted solar water heaters the running costs take the electricity use into account. Electricity tariffs are based on a general (or peak) rate of 31.9 c/kWh, and an off-peak rate of 20.9 c/kWh. Natural gas tariffs are based on a typical declining block structure for a house with gas heating, water heating and cooking, which means that the more gas that is used during each billing period, the cheaper the unit cost. Natural gas tariffs used for gas storage and instantaneous water heaters: 2.49 c/MJ (1 and 2 person household); 2.46 c/MJ (3 and 4 person household). For solar-natural gas boost, a tariff of 2.36 c/MJ has been used. LPG tariff is based on bulk supply (210kg cylinder) in Melbourne area: $1 per litre or 4.0 c/MJ. Energy tariffs do not include any on-time payment discount, and do not include the annual supply charge or cylinder rental fee. Annual costs for your household will depend on your daily hot water use. This will depend on the frequency and length of showers, the flow rate of the shower rose and shower temperature, use of hot water in clothes washing, and use of hot water for dishwashing and bathing, etc.
  • Solar and heat pump water heaters efficiency levels are based on the following STC allocations in Zone 4 (southern Victoria): solar gas boosted – standard (29), high efficiency (33); electric boosted solar – standard (27), high efficiency (31); heat pump – standard (28), high efficiency (35).

Reduce your hot water costs

Regardless of the type of hot water system you use there are simple ways that you can reduce your hot water costs.


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