PLANNING BASIX DIY METHOD ‘FINE-TUNING’ After the BASIX targets increased areas (such as granny flats) for thermal comfort with affordable options in July 2017, HIA members raised The floor area correction factors applied using the DIY method, thus saving the concerns about how the DIY method in the CSIRO CheNath engine underlying expense of engaging an accredited assessor within the BASIX tool was working. software accredited by the Nationwide to run a simulation. Particular concern was raised that Energy Rating Scheme (NatHERS) were However, it is important to note that due granny flats and fairly simple single-storeyincluded to correct for the heating and to the options available to an assessor when slab-on-ground house designs were having cooling loads of proposed dwellings with using NatHERS software, certain projects difficulty achieving a ‘pass’ using the DIYfloor areas below 190 square metres. In will still achieve a better outcome when method. HIA raised these concerns with the other words it will now be easier for granny ‘simulated’. Department of Planning and Environment. flats to ‘pass’ BASIX using the DIY method It should be noted that these changes After HIA raised these concerns the than it was prior to the ‘fine-tuning’. are not ‘BASIX target changes’. Rather department commenced a project to 3. Improving the correlation to determine these changes are ‘tweaks’ to how the ‘fine-tune’ the BASIX tool. heating and cooling loads with the DIY tool works. What has been ‘fine-tuned’? method for light-weight constructions In short, the DIY tool now treats light-weight...PROPOSED DWELLINGS 1. Options to increase the minimum cladding in a similar way to the SimulationWITH FLOOR AREAS BELOW insulation requirements method using NatHERS-accredited 190 SQUARE METRES. IN Previously the DIY method only had software. This means that proposed OTHER WORDS IT WILL automatic defaults for insulation. Now the dwellings with framed walls user can choose to upgrade the insulation and/or suspended floors are less reliant NOW BE EASIER FOR to better reflect insulation commonly used on high-performance glazing and/or GRANNY FLATS TO ‘PASS’ onsite. This will often result in a better dark roofs to satisfy the BASIX thermal BASIX USING THE DIY outcome with less reliance on performance comfort requirements. METHOD THAN IT WAS glazing to achieve a pass. This ‘fine-tuning’ has now been 2. Incorporating floor area correction implemented, and as a result certain PRIOR TO THE ‘FINE- factors to dwellings with small floor projects may be able to achieve a ‘pass’ TUNING’ P26 BUILDING NEWS ISSUE 1/2019