Heating case study


Project Reference021 C 1
Industry or SectorCommercial Office Building
Energy UseHeating
Date AddedJanuary 2006
AbstractThe use of high efficiency boilers and dedicated domestic water heaters instead of a calorifier results in gas savings of 50% for this Melbourne office building.


Southern view of building

The two heating water “boilers” in this 1960s office building needed replacing because of excessive maintenance costs and falling reliability. The client had received quotes for boiler replacement, the lowest quote was $68,000. The boilers supplied hot water for building heating, and domestic hot water via a calorifier.

Genesis Now recommended evaluating a range of energy saving opportunities, including high efficiency condensing boilers and a dedicated domestic water heater.


Genesis Now investigated water heaters on the Australian market, but could not find any which achieved the energy efficiency of some of the condensing water heaters available in Europe. However, working with potential suppliers, we were able to arrange for the importation and installation two high efficiency boilers.

We also redesigned the hot water system to include a dedicated domestic water heater and to dispense with the calorifier, this enabled:

  • The heating system to be switched off in mild and warm weather
  • The heating water temperature to be lowered in all but the coldest weather, thus reducing heat losses from the hot water reticulation system and improving heater energy conversion efficiency.

Our calculations showed that this solution would have a lower total cost of ownership than the original concept. The Client accepted this solution, despite the higher initial cost of $97,500 ( $29,500 higher than the cost of replacing “like with like”).


The boiler replacement was carried out during the week of 1 May to 5 May, 2005

Average daily gas consumption before and after heating system replacement:

    May to Nov 2004 22.2 GJ/day May to Nov 2005 11.2 GJ/day (50% saving)

Investment Performance

Investment (additional)$29,500 
Electrical SavingsTBAkWh/year
 TBA$ / year
Gas savings ($5 / GJ)$20,100Per Annum
Investment return14%Per Annum
Maintenance Savings$10,000 
Total Savings$13,361 
Investment return (marginal cost)68%Per Annum
Investment return (project cost)21%Per Annum

Notes: Electricity savings accrue from switching off the heating water pump and boiler ancillaries, and from reduced cooling to combat heat leaking into the building.
Even though this project was initiated by a maintenance requirement, the total project is financially justified by the energy savings alone.
Despite the gas savings of 50% from this action, Genesis Now and the Client are working together to achieve further gas savings in this building, and are achieving additional large savings;  these will be documented in a further case study when more gas consumption data is available.

We will be happy to discuss the opportunities to reduce gas consumption in your building.

For other success stories, please see our Case Study page