Achieving and maintaining high NABERS ratings in existing buildings

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 of achieving and maintaining high NABERS ratings in existing buildings.

Odd’s presentation centred around three key points:

• The financial value of achieving a high NABERS rating for an existing building.
• The importance of aligning expectation and reality.
• The process of effective maintenance.

Drawing analogies between completing a building retrofit and his experience running the Sydney Half Marathon, Odd explained, “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.”

For Odd, the first year a building operates post-NABERS rating attainment is similar to the race itself. “It’s a hard slog, 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,” Odd said.

“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

To engage conference attendees, Odd spoke about the impact a high NABERS rating can have on the total return of a building financially.

“Recent IPD data for Sydney shows there is a clear difference in annual returns for buildings above and below the 4 star NABERS mark,” Odd explained. “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.”

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,” Odd said.

“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.

“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,” said Odd.

“To help our customers, at AE Smith we’ve developed a new approach in order 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 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 added.

BMS and energy alarming

Speaking next about BMS and energy alarming, Odd explained how 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,” said Odd. “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 - a revolution in building management

The presentation 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. 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.

Well-measured equals well-managed

“The old adage ‘what you can measure, you can manage’ is really valid when retrofitting buildings,” 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. Meaning we can optimise the NABERS rating, which in turn ensures ongoing returns for the building owner.”