Practicing what you preach is always harder than it seems. We took the opportunity, when fitting out our new office in Sydney, Australia, to utilise our expertise and knowledge in integrating sustainable design and construction practice and initiatives.
NABERS, is the National Australian Built Environment Rating System (NABERS) which measures existing building’s energy, water, waste and indoor environment efficiencies and assigns a rating. The first rating tool was developed for office buildings. Tools are also currently available for residential, hotels and retail buildings.
The system, assigns a rating to the whole building, a tenancy or just the base building component from 0 to 6 Stars. A 3-Star rating is categorised as industry average, and a 6-Star is considered an aspirational target (in energy terms to get a 6 Star rating you must use 50% less energy than you would to get a 5-Star rating!).
Greenstar utilises the NABERS Energy rating tool as one of the ways to demonstrate compliance with the compulsory energy component. Greenstar is broken down into nine categories, Management, Indoor Environment Quality, Energy, Transport, Water, Materials, Land Use & Ecology, Emissions and Innovation. The points for each category have been assigned a weighting factor, which varies according to the type and location of the building.
Greenstar’s rating system, awards 4 Stars to buildings that signify ‘Best Practice’, 5 Star to building which signify ‘Australian Excellence’ and 6 stars to buildings which signify ‘World Leadership’.
As Energy Efficiency is core to our business, we set our goals on achieving a 6-Star NABERS Energy rating and a 5-Star Greenstar Tenancy rating. To put the NABERS Energy target into perspective, we need to use 78% less energy than an average office tenancy.
In order to achieve this target, we initially focussed on the large energy users within tenancies, such as supplementary air conditioning, lighting & office equipment.
Supplementary air conditioning is normally installed to deal with cooling loads that exceed the ‘norm’ such as in computer rooms and high occupancy meeting rooms. We avoided the use of a supplementary air conditioning system for our meeting area, by integrating it into the open plan office (the base building air conditioning system was commissioned and balanced to suit our tenancy layout). We avoided the use of a supplementary air conditioning system for our computer room, by not having one (the communications equipment is located in a special rack located within the open office space, and it was chosen to be low powered and temperature tolerant).
In terms of lighting, the building owners were intending on replacing the existing lighting in the tenancy with Envirolite e1 fittings. For our tenancy a baseline Illumination power density (IPD) of 5.85W/m² was achieved (when BCA Section J adjustment factors are taken into consideration this equates to 3.48W/m²- well below the BCA Section J requirements of 9W/m2).
The e1 luminaires are fitted with a 37W T8 tube or where necessary a single 18W T8 tube. All lights were fitted with dimmable electronic control gear, which was utilised during commissioning to set a lighting level of 320 Lux on the working plane.
The increased level of lighting control was negotiated with the light fitting suppliers, and as a result occupancy sensors were used to control lighting in zones of 30 m² or less.
The lights dim to 50% if no occupancy is sensed after 5 minutes. If, after a further 5 minutes, no occupancy is sensed, the lights turn off. The sensing times are quicker for areas which are infrequently occupied, such as the tea area and photocopier area.
In addition the office layout was designed such that low height partitions and glazed office partitions were used. 86% of our work settings have access to daylight based on Greenstar calculations (all lights, not just those along the perimeter, are controlled by Photoelectric cells such that they turn off when there is adequate daylight).
Controlling ‘small power’ loads can also be challenging. In our next newsletter we shall include an article on the dual circuiting used to control the operation of office equipment.
In the meantime we will continue to monitor our energy consumption (initial results suggest we are well on track to achieve a 6 star NABERS target).