Making existing systems even better

The energy-savings potential in the buildings sector (both commercial and residential) is said to be massive. A 29% reduction in projected building energy consumption could be achieved globally by 2050 with the wide deployment of best available technologies and efficiency policies — according to a 2015 IEA report titled ‘Building Energy Performance Metrics’*.

While buildings currently use an estimated one-third of the world’s energy, there has been some significant progress in Australia to make buildings more energy, waste and water efficient. The establishment of the NABERS rating scheme some 15 years ago and other rating schemes has helped with this transition, particularly in the office building sector.

Energy Action Director of Projects & Advisory Services Dr Paul Bannister played a key role in the development of Australia’s NABERS Energy and Water rating systems and has published more than 80 papers on energy efficiency-related issues. He says the previously coveted NABERS 4 star rating now seems passé, with 5 star ratings being achieved with some technologically quite ordinary buildings. However, even for the seemingly efficient buildings, further savings are still possible with a minimal capital spend using the latest in efficiency technology.

“We are constantly re-examining our expectation on what can be done with efficiency technologies,” Bannister said. In his recent paper titled ‘What simulation can tell us about building tuning’ (which won the Australian Institute of Refrigeration, Airconditioning and Heating (AIRAH) W.R. Ahern award recognising the best technical paper by an AIRAH member published in the preceding year), he looks at how recent advances in building simulation models can help determine the effectiveness of HVAC energy-saving strategies.

“One of the critical things that has really driven energy efficiency in the commercial building sector has been this sort of discovery path on how to make existing technology work better rather than necessarily spending large amounts on new technology.”

Bannister says these building simulation advances have the most benefit where large HVAC systems are used, because the optimum set-up may not be absolutely clear in these larger technologically complex systems.

Over the past 5–6 years, the commercial building sector has improved its efficiency by about 30–40% — half through control optimisation and the other half through technology. “[Simulation] is the one way we can test and identify new methods of improving the performance in the commercial building sector,” Bannister said.

For example, in Australia, we tend to optimise our buildings for cooling and overestimate how much time of the year the building is actually cooling. “Australian buildings often perform very badly in heating mode and that’s because we design them for cooling.” But Bannister’s paper results indicate that in some climates within Australia, the building is spending more time in heating than cooling.

2nd-tier challenges

Even though so many commercial buildings have already been improved in Australia, Bannister says there is the ever-decreasing unimproved section of the market which has open to it all of the technological improvements that have swept through the market in the last 15 years. These range from upgrading chillers and HVAC, implementing control systems, tidying up some areas of air distribution, changing to LEDs for lighting and moving from fixed to variable air volume (VAV).

“If you halve the air volume coming out of a fan, you reduce the energy consumption anywhere from 75–85%, so even minor adjustment [in VAV] can be very profitable,” Bannister said.

Dr Bannister was also recognised as an Energy Efficiency Champion by the Energy Efficiency Council (EEC) in November 2014, and his involvement in the improvement of the 87 Marsden Street office building in Parramatta received the 2013 Best Commercial Building Energy Efficiency Project.

When it comes to 2nd-tier commercial building, “all too commonly, buildings of these type have original equipment that is inefficient with rudimentary control systems. Some have not undergone updates for energy-efficiency savings due to perceived cost constraints.”

Bannister describes the Parramatta building upgrade as an interesting project because the fundamental technology of the building was not changed. Due to budgetary and technological constraints, the upgrade didn’t focus on a capital- and new technology-intensive recipe, but rather careful design and commissioning to replace the end-of-life HVAC equipment. Even though the technology used was not the best available, it resulted in an over 50% reduction in energy consumption. Less than 12 months after completion, the building went from a 1.28 star rating to being officially certified to be performing at the 4.5 NABERS Energy (Base Building) rating.

Predictions for the year ahead

Commenting on LED, Bannister says the technology is moving so fast it is almost hard to recommend when to get in. But there are some tricks around this as there are “one or more standards for interchangeability for the LED light sources. Unlike an ordinary lamp, [with LEDs] you can replace the light source rather than the whole lamp. We haven’t yet seen upgrading the light source, but that’s probably going to happen in the next two years.”

Bannister predicts in the year ahead that we will see more and more on-site solar PV renewables as this is “definitely an advancing trend”.

“The thing that makes solar so effective on buildings is that it is very low maintenance, and to a large extent, you plug it in and it works.”

Whereas, wind power, he says, has moving parts, which involves maintenance, and the environment around most buildings is too turbulent and unpredictable for it to work effectively. He also predicts that cogeneration and trigeneration are not going to advance much, except in Victoria, largely due to gas prices.

The future

Recently engaged by the Better Buildings Partnership in the United Kingdom, Bannister is setting off for London soon to develop a scheme to guarantee the in-use energy performance of new offices, based on Australia’s NABERS rating scheme. “One of the things that has characterised the Australian industry is the use of NABERS because it is an in-use rating and very few countries around the world have anything equivalent.”

What Bannister would most like to see for the future in Australia is the lessons learnt with HVAC in the upper end of the commercial building sector make their way into the rest of the sector. We have identified it is possible to make up to 50% energy-efficiency improvements with HVAC, but that hasn’t extended outside the NABERS-based office building domain. He says we don’t see the same transformation happening in hotels, shopping centres and at the institutional level, such as hospitals.

“With the office building sector it became just as attractive to improve the efficiency of the building as it was to improve the look of the foyer. Whereas for most hotels it is still a lot more attractive to improve the ‘front of house’ rather than to improve ‘back of house’ efficiency.

“There has been a massive upskilling to the [air-conditioning] industry over the last 5–10 years, so I’d like to think that that is going to lead to [HVAC] energy efficiency in more than just the office sector, but I may be dreaming!”

*International Energy Agency report — http://www.iea.org/publications/freepublications/publication/BuildingEnergyPerformanceMetrics.pdf