Harnessing and improving access to daylighting in apartment buildings is a concern of governments at national, state and local level as well as the private sector. In this they share a common goal to improve health and amenity. However, their focus can vary and the outcomes compare like chalk and cheese.
The National Construction Code of Australia (NCC) contains requirements for setbacks, light wells and windows that are seen as a minimum, necessary to maintain health and safety. Amenity is not the concern of the NCC. The state government apartment guidelines have requirements for setbacks, light wells etc generally in excess of the minimum provisions contained in the NCC. The aim is to provide ‘adequate’ daylight rather than a minimum. The local council developed tool is called BESS. It promotes deemed to satisfy (DTS) measures for daylighting that are a close match to the state government apartment guidelines (apart from room depth and orientation issues). It also provides an alternative for modelling. However, to pass the modelling BESS requires 80% of living rooms and bedrooms to meet its daylight target. In a large residential tower surrounded by similar buildings this requirement has proved difficult to achieve. Passing the BESS tool is seen as ‘best practice’ by these local councils.
The Green Star tool, a voluntary tool developed by the Green Building Council of Australia (not a state or local government authority), has had methods of benchmarking and assessing daylighting for some time. It is recognised as containing the benchmarks for national best practice, national excellence and international best practice. Interestingly, the Green Star tool ignores daylighting in bedrooms and encourages designers to place the kitchen prominently in the best daylit part of the apartment. The state guidelines and BESS on the other hand both expect bedroom daylighting to be assessed and encourage kitchens to be as far removed from the perimeter as possible.
While there are some similarities of intent above, the differences in application and resultant design outcomes can be significant. At the moment these tools co-exist but don’t mesh. The inconsistences make claims of equivalence or even comparisons of merit difficult.
A solution is required to bridge the gap between the tools, a solution that will correlate their various outputs and align them, perhaps on a scale from minimum compliance to best practice as has been flagged above.
The NCC will always define minimum compliance and Green Star will always aim for the opposite end of the spectrum. The State government apartment guidelines had a difficult gestation, arrived quite diluted and are unlikely to evolve anytime soon.
The BESS tool is the most dynamic of those discussed. Perhaps it is within the reach of BESS to find a way to calibrate the outcomes from the various assessment methods. But important questions will need a resolution such as should the daylighting requirement in bedrooms be dispensed with? Should kitchens be near or far from the perimeter?, What are the right daylight targets? What is an acceptable number of apartments that can fail the test in a large development?, and should each room be assessed individually or the development as a whole?
One idea is to have the BESS tool acknowledge the existence of the state government apartment guidelines, align their physical requirements and give a project an ‘adequate score’ for meeting these. An increased score could then be offered for going above and beyond by satisfying the BESS daylight targets. In this way a project could provide adequate daylight and not appear as a ‘fail’ in BESS. If BESS were to introduce an ‘adequate’ benchmark in its scoring mechanism then it could be used to assess (and compare) the full range of projects from minimum compliance to best practice and beyond. This may go some way to establishing an accepted correlation between tools and design outcomes.
If the design industry cannot establish some common ground or a bridge between these tools it may be left for VCAT to determine the correlations, one case at a time, with all the potential chaos and perverse interpretations that a narrowly focused decision might spawn.
Sean McArdle
Associate Director, SBE, June 2017.
sean.mcardle@sbe.com.au