Slashing power in the Snowy Mountains

Dig underneath the Snowy Region Visitor Centre and you will find the secret to its energy efficiency: a geothermal heating, ventilation and cooling (HVAC) unit. The unit was installed in the late 1990s by the National Parks and Wildlife Service (NPWS) when the Jindabyne regional headquarters and Snowy Region Visitor Centre was built. Although the geothermal unit is very energy efficient even by today’s standards, the results of an Energy Saver audit are helping NPWS to run the system and the buildings even more efficiently.

NPWS Jindabyne Manager Environmental Services Megan Bennett explains that the geothermal unit in Jindabyne transfers heat from and to the building via pipework circulating water below the ground, where the temperature is a constant 15°C. This increases the efficiency of the air-conditioning units by up to 30% more than their conventional counterparts. In heating mode, it’s easier to source heat from the ground at 15°C than surrounding air at low to subzero temperatures. In cooling mode, it’s easier to reject heat into the ground at a temperature of 15°C than the surrounding air at temperatures of 35°C.

So it came as a surprise to Bennett when an Office of Environment and Heritage (OEH) Energy Saver audit revealed the building’s air-conditioning system could be improved.

Bennett says that while she was aware before the audit that the building lacked some fairly standard things, like insulation in the ceiling, she had no idea of the efficiencies that could be gained by automating parts of the building’s HVAC systems.

“Some of the HVAC issues that we discovered through the audit included the temperature setpoints were too high in winter and too low in summer, resulting in substantial energy waste, and the system didn’t take into account how many people were in the building at any time,” said Bennett.

“The HVAC system also didn’t take advantage of the ambient external air temperatures in spring and autumn, which could be used to reduce the load on the compressors.”

The audit’s HVAC recommendations included the design and installation of a building management system (BMS) to automate and optimise the cooling and heating temperature setpoints for the building’s air handling units (AHUs); introducing an optimum start/stop function for AHUs to take into account ambient outside air temperatures; using CO₂ sensors to control outside air for the visitor centre and theatre; and adding an economy cycle on AHUs to take advantage of spring/autumn conditions.

The audit also recommended HVAC system training for managers, to ensure they understood optimal operating requirements and could effectively supervise the HVAC maintenance contractor.

Other recommendations included:

• sealing the roof void and adding insulation and a new exhaust fan;
• installing air curtains and wind shields at entrances to reduce heat losses and gains;
• adding a timer switch on the circulating domestic hot water (so it was turned off when the building wasn’t being used);
• replacing halogen downlights with LEDs;
• reintroducing motion sensors to control lights in enclosed offices.

Bennett says NPWS Jindabyne has funding approval to install the BMS, which together with some initiatives already completed will go a long way to achieving the audit’s projections of effectively halving the building’s electricity consumption for a capital cost of $175,000 and a payback period of four years.

“The audit provided us with a level of energy expertise that we simply didn’t have in-house,” said Bennett. “It not only made complicated things - like our HVAC system - seem simple, but inspired us to do something by making us aware of the potential savings. The itemised business cases also helped us to prioritise the work.

“We’re really happy with the audit results and especially the fantastic savings it will enable us to achieve.”

To find out how your business can access a subsidised energy audit, visit www.savepower.nsw.gov.au/energysaver.