ScienceAlert Homepage

Australia has lagged behind in regulating for building performance. California, for instance, legislated for energy efficiency in the mid 1970s. However, over the past five to 10 years, the Building Code of Australia (BCA) has steadily tightened its rules and we are now poised to benefit from the experiences of those quicker off the mark.

Even when efficiency is the topic, the throw-away mentality seems to apply, even to major structures such as office buildings. Many of us are attracted to the glamour of the new and innovative and less inclined to value what’s already there.

This modern phenomenon has been described as conspicuous conservationism or, even more harshly, as ‘ostentatious eco-design – status at the cost of real environmental good’.

But, in the words of prominent American architect Carl Elphante, “The greenest building is the one that’s already built.”

Although this will not be true in every case, overseas experience shows there is much that can be done, at a reasonable cost, to add ‘green life’ to older buildings, and there are examples of this global trend in Australia.

Arup, working with the Property Council of Australia (PCA), has compiled a handbook for building owners that outlines these options – Existing Buildings: Survival Strategies.

Older office buildings make up more than 93 per cent of the rental office space in Australian cities, most of it designed before the introduction of green rating systems. Existing stock is slowly replaced at a rate of less than three per cent per year. Once built, offices need to be refurbished every 20 to 25 years and buildings undergoing major refurbishment must comply with current regulations.

Building owners who do not respond to these new green regulatory requirements will face a compounding disadvantage: growing operating costs, decreasing rental yields and a struggle for tenants in a competitive environment of high amenity expectations.

However, this decline is far from inevitable. Not only is there scope for reducing the environmental impact and tooling up older buildings to comply with the increasingly stringent green regulations ahead, but it is a matter of urgency that this is done.

‘Reduce, reuse, recycle’ is the environmentalists’ maxim and these three Rs apply as much to office buildings as to anything else.

Reducing energy use, including from mechanical and electrical systems, can often yield the greatest benefit with the least investment of new material and energy resources. Surprisingly significant efficiencies can be made at minimal cost through a maintenance and housekeeping review. Simple changes such as labelling zone lights clearly, modifying setpoints and procuring green energy can make a real difference.

For older buildings, the second R (reusing) leads to three more: refurbish, retrofit and rejuvenate. Not just for energy efficiency, but to create working spaces full of daylight, clean air and greenery. When deciding whether to demolish and rebuild or retain and revamp it is important to start from a baseline against which targets can be set and ultimately measured.

Forgetting to calculate the costs associated with demolition and new construction is a common energy accounting omission, according to Flinders University economist Owen Covick, who chairs the Energy Consumers’ Council of South Australia. The pitfall, he says, is to start the energy stopwatch from the beginning of normal use, ignoring the relative impact of the costs before the point when monthly energy savings start to show up. The energy accounting for both options should factor in everything on both sides of the column: the costs associated with tearing down a building and starting afresh with new materials, and the energy costs of retain and revamp improvements.

A study by the UK’s BRE Trust in 2002 showed that, generally, refurbishment solutions are lower both in environmental impact and whole-life costs (over 60 years) than comparative site redevelopments. The exception was where significant low-energy features, such as natural ventilation, could not be introduced to the existing building, but could be incorporated into a new development. A new, energy-efficient office building will not actually save energy for some decades. A replacement building may never reach the energy break-even point.

Older buildings tend to fall into two categories. The first is those built before World War II, when resources were relatively scarce. When their operating systems are brought up to speed, these buildings can be remarkably energy efficient. In Sydney, a seven-level office building at 39 Hunter Street, constructed in 1916, has achieved a Six Star Green Star Office Design rating, the first heritage-listed building in Australia to do so. Its refurbishment, handled in large part by Arup’s specialists, included cutting out an atrium, adding high-efficiency lighting, putting in displacement air conditioning and using the sprinkler tank for thermal storage, helping to reduce peak-load energy consumption.

In the second category are the early modern era buildings (1950s through 1970s), built at a time when resources seemed unlimited. While they are a problem, it is not necessarily an insoluble one. Creative solutions include adding triple skins and incorporating functional adaptations as design elements.

Another recent Australian example is 500 Collins Street, Melbourne – a 30-year-old building rising to 28 levels. It was refurbished three floors at a time with tenants in situ. The owners installed chilled beams which allowed extra air-handing capacity that was used to supply fresh air. The upshot was a 50 per cent improvement in fresh air rates and a 39 per cent reduction in sick leave days, in addition to an air conditioning system that will use 30 per cent less energy than conventional systems.

As for the third R – recycling building materials after demolition will conserve some of the building’s embodied energy – the energy that is bound up in the building’s materials. Arup’s approach here is far from glamorous, but it is effective: a database of materials that are computer-tracked to their destination.

The built environment is too important for us to be paralysed by pessimism, which is counter-productive as well as unjustified by the facts. What we need do is invest in our existing office stock so that it can meet the demands of today’s tenants for energy efficiency and increased amenity.

Every existing building represents a considerable energy investment from the materials and energy that went into its construction. These buildings are a city’s heritage, its skyline and its distinct character. They should be valued for what they are truly worth and not discarded without a proper weighing-up of the realistic alternatives.

Existing Buildings: Survival Strategies – a toolbox for re-energising tired assets is available from the Property Council of Australia.

Top 10 ‘Quick Win’ initiatives

There are many ways of improving existing office buildings, with varying benefits, constraints and costs. Some initiatives are quite straightforward in terms of cost, time and disruption and produce immediate benefits – these are the ‘quick wins’. These initiatives are easy to achieve, yet yield substantial benefits.

• Replace existing lamps with T5 fluorescents.
• Modify air conditioning setpoints to provide a wider control band, within acceptable comfort boundaries.
• Provide clear light switch labelling.
• Re-balance and recommission all plant.
• Use low irritant or non-chemical cleaning products.
• Implement a comprehensive preventative maintenance program.
• Maintain up-to-date, comprehensive accessible O&M manuals and building users’ guides.
• Provide sub-metering of electricity, gas and water.
• Ensure controls are working correctly.
• Provide water-efficient appliances.

Paul Sloman is a Principal of Arup and leads the NSW Buildings Group. In a wide-ranging career as a mechanical services engineer, Paul has developed a particular interest in the built form and the use of passive engineering techniques to control the internal environment, and energy-efficient buildings. Working almost exclusively on integrated design projects, he is interested in good design through organisational efficiency, energy-conscious design and thermal comfort. Arup is the force behind many of the world’s most innovative and sustainable building, planning, infrastructure, transport and civil engineering projects. The Beijing National Aquatics Centre was designed by a consortium of Arup, PTW Architects and the China Construction Design Institute (CCDI).