NABERS: the biggest change in building management since the Industrial Revolution

At the recent Retrofit & Refurb Conference & Expo held in Sydney, AE Smith’s National Sustainability Engineer and accredited NABERS assessor David Odd was invited to share his experience on achieving and maintaining high NABERS ratings in existing buildings.

Comparing the completion of a building retrofit and his experience running the Sydney Half Marathon, Odd said, “Retrofits are very similar to the process of getting physically fit. In a building retrofit, you have to upgrade the systems and get the building in shape first.”

The first year a building operates post NABERS rating attainment is similar to the race itself. “It’s a hard slog,” said Odd, “[but] you push through by remaining focused and eventually getting the ratings you’re after. But once you get to the end of the race, that’s not enough. If I stopped exercising after the marathon, it wouldn’t be long before I was unfit again, back on the couch like Homer Simpson. Maintaining your building’s hard-earned NABERS rating post ‘race’ is just the same. It takes continual exercise, continual training, and that means ongoing maintenance to stay fit and maintain a building’s NABERS rating.”

Understanding the value of NABERS

Odd spoke about the impact a high NABERS rating can have on the total return of a building financially, noting, “Recent IPD data for Sydney shows there is a clear difference in annual returns for buildings above and below the 4 star NABERS mark.

“With heating, ventilation and air conditioning (HVAC) typically accounting for 60-70% of base building (house services) energy consumption, if you want to maintain your NABERS rating, it’s critical to maintain your HVAC at optimal efficiency levels,” he said.

Odd drew attention to a common misconception about NABERS: “It’s not like the Green Star Rating, where you can pay a premium to achieve an outcome, end of story. NABERS is a performance-based rating scheme based on carbon emissions, so performance can change over time, across the entire life of the building.

“If your energy usage goes up significantly in a month, it could affect your cumulative consumption across a year. This could result in your NABERS rating going down. You may then have to wait up to 12 months to get it back up again - so it can’t be set and forget because 12 months is too long to wait before you know you’ve got an energy consumption problem which can impact on the value of your asset.”

Aligning expectation with reality

To guarantee NABERS ratings, it is important to model expectation as closely as possible to how a system will perform in the real world. Odd explained, “What you expect is informed by your understanding of how the building operates: energy consumption modelling, historical data and assumptions such as future vacancy rates. But reality is driven by the behaviour of occupants, the weather, the efficiency of equipment and many other factors - even where the thermostat is placed by the building contractor.”

He said AE Smith has developed a system to identify the risks that exist where there are differences between expectation and reality. These include modern risk assessment methodologies, automated BMS, automated energy alarming, alternative maintenance practices and leveraging online technologies for ongoing system monitoring and optimisation.

Modern risk assessment

Illustrating the benefits of accurate risk assessment, Odd touched on AE Smith’s use of the latest building information modelling (BIM) software such as dynamic thermal modelling to create accurate simulations of energy use.

By incorporating past energy bills and weather data, Odd explained how the models could be “calibrated to very closely match actual consumption, including any inefficiencies in an existing system”. Through this process, the accurate baseline that is obtained allows AE Smith to confidently simulate virtually any upgrade imaginable.

“To my knowledge, AE Smith was the first mechanical services contractor in Australia to use dynamic thermal modelling to determine the most viable retrofit options for an existing building,” Odd said.

BMS and energy alarming

Odd said AE Smith is coupling building management and energy reporting systems so that data obtained through building sensors can be used in real time to optimise BMS operations.

“Adding weather data and forecasts to this information/feedback loop can further finetune building operations and minimise energy consumption,” he said. “As an example, we can use adaptive temperature control algorithms, based on seasonal ambient temperatures, to gradually change building temperature set points over the course of the year, saving energy while improving comfort levels.”

Automated alarms can be integrated into the system to alert the facility manager and off-site service teams of any unusual variations in building, equipment or energy supply behaviours.

Condition-based maintenance

Odd concluded with a look at how AE Smith is changing maintenance practices in response to greater amounts of data and more powerful reporting and management tools now available and demanded by customers.

“Planned preventative maintenance has been around since the beginning of the Industrial Revolution,” said Odd. “But technology has enabled a better way. At AE Smith, we call it condition-based maintenance. Instead of only doing things based on a plan, we’re utilising the building information itself to bring to bear all of our resources when and where required, to make the right adjustment, at the right time, to the right system.”

This includes remote monitoring of system performance and even rectification of some issues remotely off-site.

“The accurate and immediate identification of mechanical faults informs an immediate dispatch of the right technician, with the right information, carrying the right spare parts. Monitored correctly, chances are we’ll know about the issue before the facility manager does,” said Odd.

“With all this data-informing modelling, as well as alarms and the integration of BMS and energy systems, we’re able to stay on top of a building’s performance in real time … [and] optimise the NABERS rating which, in turn, ensures ongoing returns for the building owner.”