Lighting the way through the ‘green’ building rating maze

Energy management and environmental performance are becoming increasingly significant across today’s commercial building sector. Building owners, developers and occupiers face a complex mix of design, application and classification requirements to meet Australia’s two key ‘green’ rating tools for office buildings - Green Star and NABERS Energy. Brett Annesley, Dynalite Segment Manager - Energy Management, sheds light on the issues from a lighting control and automation perspective.

There is an increased requirement for ‘green’ functionality in commercial buildings, from the design phase through to construction, installation and operation. Assisting industry with energy-efficient and environmentally friendly office building design and performance are Australia’s two key ‘green’ building rating tools - the Green Building Council of Australia (GBCA) Green Star and National Australian Built Environment Rating System (NABERS) Energy.

Know your NABERS

The NABERS Energy system is primarily concerned with evaluating the actual energy consumption and greenhouse gas emission performance of an existing building.

Originally known as the Australian Building Greenhouse Rating (ABGR) until it was renamed in May 2008, NABERS Energy ratings for existing office buildings are derived from the actual amount of energy (electrical, gas, coal and oil) a building or tenancy consumes over 12 months. Buildings are benchmarked on a scale of one to five stars, with five stars being the least polluting. NABERS Energy ratings reflect both the quality of the building design and the management of its utilities.

While often used to rate existing office buildings, the NABERS Energy rating process can also begin during the design phase of a building. This requires the relevant stakeholders to enter into a NABERS Energy performance rating commitment agreement using an approved estimation model - this is mandatory for all projects seeking a NABERS Energy rating of four stars and above. After the building is completed and operating for 12 months with a minimum of 50% occupancy, an assessment is carried out by an accredited assessor and a NABERS Energy rating is awarded. Importantly, a NABERS Energy rating of 4.5 stars is a mandatory prerequisite for obtaining a Green Star rating.

Going Green Star

Green Star is an all-encompassing environmental rating scheme which evaluates the environmental design and potential performance of a building. Developed by the GBCA, the Green Star rating system focus is on sustainability with an objective to promote environmental design, while recognising the environmental performance of commercial buildings.

Green Star is made up of a series of self-assessment rating tools that address the overall environmental performance of office buildings. At present, these rating tools comprise Office Design v3 (assessed at the end of the design phase), Office As Built v3 (assessed at the end of the construction period), and Office Interiors v1.1 (can be assessed during design phase and post-fit-out). A number of additional pilot rating tools are awaiting ratification by the GBCA. Moreover, a design, project or building cannot claim a Green Star rating unless it has been certified by the GBCA.

Each Green Star rating tool addresses eight environmental impact categories - management, indoor environmental quality, energy, transport, water, materials, innovation, and land use and ecology.

Credits/points are awarded across these categories. The eight category scores are then multiplied by a weighting factor for each category (where weighting factor values are region-specific and take into account the issues affecting the local environment) to give a total points score. The innovation category is not weighted. A sum of the weighted category scores plus the innovation points corresponds to a Green Star rating.

Both Green Star and NABERS Energy rating tools have been developed to empower commercial building owners and occupiers to realise truly effective energy management strategies and sustained demand reduction. Here, lighting control and automation solutions play a significant role.

Intelligent lighting

By their very nature, lighting control and automation providers are in the business of energy management. With Green Star and NABERS Energy assuming greater importance to tenants and building owners, a key element of the role of lighting solutions providers is to advise and assist clients with obtaining star-rating credits for the lighting control systems they deploy.

From design through to installation, commissioning and operation, intelligent lighting systems can yield significant energy savings and earn building stakeholders credit points across both Green Star and NABERS Energy rating systems.

Significant savings can be realised and specific credit points earned, simply by ensuring lighting is only activated when and where it is required within the office. Here, automated lighting control systems with presence sensing and zoning capabilities make a huge difference. Modern energy-efficient practices demand more vigilance in avoiding illuminating unoccupied areas. Smart lighting systems incorporating sensors can be configured to establish which work areas are in use, and keep these - and routes to these areas - illuminated, while shutting off lighting in unused areas.

Other energy-saving strategies rewarded under Green Star and NABERS Energy include ‘daylight harvesting’ and luminaire dimming functionality. Daylight harvesting involves maximising the use of natural light through clever building design, which in turn minimises the use of artificial light. Often, natural light levels need only be enhanced with small amounts of artificial light. Automated lighting control systems with luminaire dimming functionality allow building owners to vary the amount of artificial light delivered to different areas of the building or floor. This kind of control flexibility means energy and money can be saved, while maintaining lux levels in accordance with Australian Standards and, most importantly, ensuring occupant comfort.

An important and often underestimated consideration in maintaining the NABERS Energy rating is accommodating changes within the building once constructed. Over its lifetime, a typical office building will experience ‘building churn’, where tenancies change, staff numbers fluctuate and office activities vary. By ensuring lighting and energy-management systems can accommodate this reconfiguration of the office space and adopting a scalable, distributed approach to lighting control, building owners can avoid wasteful and intrusive lighting refurbishments and extend the lifetime of their lighting system. Such scalable systems can also adapt to the construction of neighbouring buildings that block the sun, as well as climatic changes.

Measure and manage

Further environmental benefits can be realised, and Green Star credits and enhanced NABERS Energy outcomes gained, by looking beyond the lighting control itself. Employing integrated lighting control systems that can incorporate third-party control elements, such as audiovisual, curtains, blinds and temperature control systems, makes practical and economic sense. They allow building owners to avoid duplicating infrastructure for individual control systems, which is wasteful and costly. This is especially so for new construction projects, where installers and building owners prefer to avoid installing, managing and operating a plethora of control systems.

From a NABERS Energy perspective, much can be done with existing office building lighting systems as well. Simply retrofitting luminaires can produce significant savings. By replacing T8 38 W luminaires (common in many pre-2000 office buildings) with more advanced T5 28 W ones, building owners can improve their lumen output and increase light output ratios from approximately 0.6 to 0.8 and above, with less current draw.

It’s a proven fact that performance dictates behaviour. If you can’t measure it you can’t manage it. Equipping new and existing lighting control solutions with metering and sub-metering functionality provides building owners with valuable insight into the performance of the system by monitoring the current draw of individual floors, departments or office sections. This helps building owners compare actual performance against NABERS Energy requirements and benchmarks. Metering is especially helpful during the commissioning stage, where lighting systems are tuned to operate within the Green Star and NABERS Energy guidelines. It allows operators to establish if the lighting system is performing as intended or malfunctioning in some way, and make the appropriate adjustments.

Commissioning office building lighting control systems is as important as design and installation. Anyone can supply the system components, but installing it, integrating it with other systems and commissioning it to ensure it operates as per the energy-efficient design requires expertise. It is essential that the lighting control system professionals responsible for commissioning adhere to industry benchmark guidelines, such as those prescribed by the Chartered Institute of Building Services Engineers (CIBSE). Doing so maximises the likelihood of achieving the required Green Star and NABERS Energy rating.