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Case Study 1 - Apartment Building
We Conducted a level 2 energy audit and water harvesting assessment of a 15 storey apartment building situated in Woolloomooloo in inner Sydney.
Below is a summary of our key findings.
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Summary of energy audit outcomes
The energy audit identified opportunities to:
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reduce electricity usage by 84 MWhpa (15% of total electricity consumption). |
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reduce greenhouse emissions by 90 tonnes (tCO2-e) |
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save $6,634 a year off electricity bills. |
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achieve a payback of 2.6 years. |
Examples of energy saving opportunities
The following examples illustrate some of the energy saving opportunities identified during the audit.
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Replace incandescent candle lamps with CFL lamps |
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While the wattage of individual 25W candle lamps used in the main foyer is relatively small the combined energy consumption of a number of candle lamps operating 24/7 can be significant.
We estimated that replacing the incandescent candle lights with CFL candle lights could provide annual energy savings of 2,970 kWh and cost savings of $242 with a payback of 1.4 years.
In addition to energy savings CFL candle lights have a longer life span of 10,000 hours, providing additional maintenance savings.
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Replace 50W downlights with high efficiency 13W CFL downlights |
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50W halogen downlights were used in several areas of the building including the main foyer and lift lobbies. 50W halogen downlights are widely accepted to be an inefficient form of lighting. They require a high internal temperature and produce a significant amount of unwanted heat.
We identified several options to replace the lamps with more energy efficient lamps including: Infra-Red Reflecting 35W halogen downlights, 13W CFL downlights and 7W LED downlights. Of these 13W CFL downlights were determined to be the most cost effective option, providing annual energy savings of 41,115 kWh and cost savings of $3,343 with a payback of 1.4 years.
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Upgrade underground car park T8 fluorescent tubes with T8 to T5 converters |
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Standard twin 36W T8 fluorescent tubes provide lighting 24/7 in the underground car park of the apartment building. We identified a number of options to improve the efficiency of the car park lighting including: installing fixed dimming (voltage reduction), replacing the fittings with high efficiency single quad phosphor fittings and reflectors and replacing the 36W T8 fluorescent tubes with 28W T5 fluorescent tube using T8 to T5 converters.
Of these the option to install T8 to T5 converters was determined to be the most cost effective, provding annual electricity savings of 4,793kWh and cost savings of $390 with a simple payback of 3.4 years.
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Power Factor Correction (PFC) |
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Meter data for the apartment building indicated that the average power factor at peak demand was approximately 0.68. The installation of a 75 kVAr capacity PFC unit at around $6,000 is estimated to provide demand savings of 36kVA, however as the Domain Apartments is on a kW (not kVA) demand tariff it will see no cost savings through the installation of PFC. |
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Water harvesting assessment
As Sydney is currently on level 3 water restrictions the use of potable water to hose down hard surfaces is prohibited. Building management identified an opportunity to harvest rainwater from the roof of the apartment building. This water could be used to irrigate the courtyard garden and to hose down the exterior courtyard, main entrance and other areas.
We conducted an assessment of the viability to harvest rainwater. The following is a summary of the findings:
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There is an opportunity to collect 84kL of rainwater a year. |
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Our assessment indicated that installing a 10kL tank may allow for the collection and supply of 96% of annual wash down water demand (240L/day). |
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The indicative cost to install the rainwater tank was $9,800. |
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No cost savings will be generated as the rainwater will not replace the use of potable water. |
Sizing rainwater tank capacity
It is important to correctly size a rainwater tank to match the site demand for rainwater, the catchment area (m2) and local rainfall. A bigger tank costs more money and takes up more space. The following figure shows that, over a certain tank size, there is a diminishing return on the amount of rainwater that can be collected. We calculated that increasing tank size above 10kL will not significantly increase the amount of rainwater that can be collected and used.
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Contact us to discuss how we can help you improve and promote the environmental performance of your business.
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