Relieving peak electricity demand

by FM Media
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New research has shown that cutting greenhouse gas emissions from Sydney office buildings can also help reduce the pressure on electricity supply infrastructure citywide.

The growing demand for electricity at peak times has led to plans for significant spending on network infrastructure, the largest component driving up Sydney’s electricity prices.
Peak demand is important because electricity networks require spare capacity to accommodate extremely high power usage, which typically occurs only for a few hours, a few times a year, usually on hot summer days. The research shows there is potential to reduce some of this large spending through energy efficiency and demand management.
Calculations (1) based on 25 Sydney office buildings for 2008 have revealed some important results:

  • As the yearly electricity performance of buildings improves, as tracked by the NABERS energy rating scheme, maximum electricity consumption on the hottest days also falls.
  • If a single building boosts its rating from the Sydney average of 2.5 to 5 Stars, then it could halve its yearly electricity consumption (56 percent reduction) and use nearly a third less in times of peak demand (26 percent reduction).
  • New research shows that if all buildings in the Sydney CBD boosted their average NABERS rating from 2.5 to 3 Stars, then it would be like ‘turning off’ 13 large towers (2) in the height of summer when networks are straining to supply power (peak savings of 18.4MVA).
  • A typical large office tower in Sydney’s CBD uses nearly as much power in one work day as a typical Sydney home uses in one year, and that’s just to keep the base building services such as air-conditioning, lifts and common area lighting running. When you include tenant energy consumption, such as office equipment and office lighting, one work day’s energy consumption of a large office tower is nearly double the yearly energy consumption of a typical Sydney house.

The NABERS rating is one of the best ways to tell if office buildings are power-hungry. The rating became compulsory in 2010 for most office buildings selling or leasing space over 2000 square metres, and the current Sydney average is just 2.5 of the available 5 Stars. This study implies that for every 10 percent reduction in buildings’ yearly electricity consumption, there is a 4.5 percent reduction in peak demand.
In eastern Australia, electricity usage during summer afternoon peak periods has increased dramatically. More than $46 billion in spending for electricity network infrastructure is planned across Australia in the next five years (3), and as much as $7.6 billion of this is new capital expenditure on networks in New South Wales to manage growing peak demand (4). These costs are being passed to consumers via their energy bills, which, in the case of New South Wales, last year increased by up to 13 percent and are planned to increase significantly in the next few years.
The findings come from a paper by Jesse Steinfeld, engineer, Sustainability and Environment at Investa, and were published in the journal Energy and Buildings. Steinfeld’s study was undertaken with building data from GPT, Investa Property Group, Stockland and Colonial First State.
On release of the research, Craig Roussac, general manager of Sustainability, Safety and Environment of the Investa Property Group, said, “Accommodating growing peak demand is one of the major drivers in Sydney’s electricity network expansion. If energy efficiency and smart demand management can reduce electricity demand at these key times, the costs and scale of network expansion can be reduced.
“A half-Star improvement is actually not so hard – there are plenty of buildings that have achieved much more. The research highlights that there are huge opportunities for tuning up our buildings to cut peak demand.”
The analysis also found that large electricity customers pay about 13 percent of their bills to cover peak capacity charges each year, and a further 32 percent to cover network energy charges – equating to approximately $150,000 per year in peak demand charges and $350,000 in network energy charges for the largest CBD buildings. Clearly, reductions in peak demand mean lower energy expenditures for big business.

The Investa Sustainability Institute launched Green Buildings Alive to encourage a holistic approach to energy supply and energy management in buildings. By using the portal, professionals from different disciplines like building, energy management and electricity networks can share information and learn from real experience.
There is huge potential for technological solutions involving air-conditioning and lighting, as well as behavioural changes relating to occupant thermal comfort.
Actions to improve existing buildings’ greenhouse and energy performance may include: raising building and equipment standards, rewarding energy and peak demand performance more generously in Green Star ratings, increasing financial incentives for energy efficiency and peak management, promoting (renewable) distributed generation, and introducing innovative schemes such as mandatory power factor correction.

1. J Steinfeld, A Bruce, M Watt (2011). ‘Peak load characteristics of Sydney office buildings and policy recommendations for peak load reduction’, Energy and Buildings, doi:10.1016/j.enbuild.2011.04.022.
2. A large office building has a floor space of approximately 25,000 square metres.
3. E Langham, C Dunstan, G Walgenwitz, P Denvir, A Lederwasch, J Landler (2010). ‘Reduced Infrastructure Costs from Improving Building Energy Efficiency’, prepared for the Department of Climate Change and Energy Efficiency by the Institute for Sustainable Futures, University of Technology Sydney and Energetics.
4. C Dunstan, E Langham (2010). ‘Close to Home: Potential Benefits of Decentralised Energy for NSW Electricity Consumers’, prepared by the Institute for Sustainable Futures, University of Technology, Sydney for the City of Sydney.

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