By Belinda Strickland

23 June 2011 – The City of Melbourne, Owners Corporation Victoria and others are embarking on a project that could transform Victoria’s existing multi-unit residential buildings to become more sustainable. Here is how it came about.

Multi-unit housing represents a significant and growing proportion of Australian residential property, currently comprising 20 per cent of our housing stock. However, a substantial portion of multi-unit housing stock has been built under minimal or no energy and environmental performance standards, including buildings built during the recent period of sharp growth in this sector.

In its 2008 national study on residential energy use, Energy Efficient Strategies suggested that these buildings present an “energy liability” which unaddressed, will remain so over their lifespan.  The need to provide energy efficient solutions for this poor energy performing stock is critical in addressing the sustainability of the city’s built environment.

Energy Australia’s 2005 report into the stationary energy use and

On average, a person living in a high rise apartment accounts for twice the energy-related emissions of a person living in a house’ (GWA, 2007). Also taken from the 2005 EA study, total dwelling greenhouse gas emissions for each dwelling type was featured in a previous article by The Fifth Estate, “Apartment blocks the missing link in sustainability”

The reports by EA and GWA point to a need for mitigation action in the energy use attributed to common and shared services in multi-unit housing, particularly in its mid to high-rise stock (four to eight storeys high and nine or more storeys respectively).

As identified in GWA’s report, common services may include common area lighting and airconditioning, lifts, car park ventilation and pool services.  Shared services may include centralised heating and cooling and centralised hot water.

As the governing body for this common property, owners corporations (formerly body corporates in Victoria) have a potential role to play in reducing energy consumption in the common and shared services pertaining to their properties.

The City of Melbourne found this to be the case in its 2007 to 2008 “Sustainable Living in the City” pilot project, or SLIC

The pilot project involved low cost retrofits together with behaviour change workshops in four high-rise Melbourne apartment buildings targeting reductions in the areas of water, waste and energy.

Areas targeted for energy use reduction included common area lighting, individual apartment lighting, pool heating, hot water systems, showerheads and standby power.

Low cost was an important factor in the transferability of the initiatives undertaken.  All four participating buildings, comprising over 600 dwellings, were able to achieve significant greenhouse gas abatement and water savings.

One of the most cost-effective strategies for reducing emissions trialled in the SLIC  was the replacement and reduction of common area lights.

The CoM’s 2008 final report into the project found that savings were high due to the large quantity of these lights, many of them on 24 hours a day.  In addition, halogen lights, which are very inefficient, were consistently prevalent in the common areas across all four properties.

In the CoM’s case study sheet on Spring St Towers, the replacement and reduction of hallway and foyer lighting at this property was shown to achieve a saving of $13,056 per year allowing a payback period of 13.7 months.

The City’s final report noted that of the three buildings with car parks, lighting energy use reductions of 25 percent, 28 percent, and 31 percent were recorded following the installation of voltage reduction units.  These reductions resulted in a payback period of one and a half to three years. See here

Figure 2: Spring St Towers car park lighting energy usage(Source: CoM, 2008, “Case Study – Spring St Towers”

Figure 2  demonstrates the car park light energy savings achieved at one of the properties.

A voltage reduction unit is “a microprocessor that provides the normal mains power for start up and then reduces power flow for ongoing operation.”

Water heating comprises a significant energy end use in residential buildings. Of the three apartment blocks trialled in the SLIC that had a centralised gas hot water service, all were found to have very high levels of wasted water as noted in the CoM’s “Ring Main Balancing Fact Sheet

This inefficiency resulted in some residents waiting up to 10 minutes for hot water. By balancing the ring mains and in some cases replacing insufficient insulation, substantial water and gas savings were achieved for these buildings, as well as improving amenity for their residents.

Figure 3: Gas hot water service consumption before ring main balancing, Spring Street Towers Source: CoM, 2008, Case Study – Spring St Towers

The CoM’s case study note on Spring Street towers revealed that ‘almost half of the gas used by the system was ‘lost’ through the system rather than being used to heat water,’ as shown in Figure 3 opposite.

Building upon the learnings from SLIC, the CoM has recently received funding from Sustainability Victoria’s Sustainability Fund to undertake a project which aims to develop and test solutions to help transform Victoria’s existing multi-unit residential buildings to become more sustainable.

The project is being run in partnership with Owners Corporation Victoria, Moreland Energy Foundation and the Cities of Port Phillip and Yarra. This is particularly pertinent to the CoM for which apartments, units and flats comprise over 70 per cent of its housing stock.

The CoM’s final report on SLIC found that owners corporations “are eager for specific, reliable information that they can use to build business cases for retrofits and building management solutions”.

Julie McLean of Owners Corporation Victoria supports this finding, observing that “owners are marching”, but managers are currently at a loss for resources to know how to respond.

The participating owners corporation managers from SLIC are reportedly using the model and data from this project as a basis for business case presentations to owners corporations in other buildings under their management.

As two of the participating owners corporation managers manage almost 60 buildings in the city, this proposition represents significant market dissemination of sustainable initiatives for this sector.

The case study example of SLIC demonstrates some of the sustainable improvement measures available to multi-unit buildings, particularly in the areas of common area lighting and hot water.  Improvement measures for these areas utilised current proven technologies, often with low implementation costs and/or viable payback periods.

The means to put these measures into effect can be provided by the owners corporation, by virtue of its existing institutional framework.

Findings from the SLIC project’s final report suggested that “the most effective way for councils and other government agencies to make improvements in high-rise buildings is to engage with [owners corporations] to improve common areas and to liaise with residents”.

With the dedication of strategic support and resources, this is an area of opportunity that has the potential to dramatically improve energy efficiency in the multi-unit housing sector, in turn, contributing to the long-term sustainability of the city environment.

Belinda Strickland is an architect currently based in Kakadu National Park. Her primary area of interest is sustainability in the built environment. This article is an edited extract from a minor thesis completed for a Master of Social Science (Environment and Planning) at RMIT University in November 2008.

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