Just before Christmas, the report for Phase 2 of the National Energy Efficient Buildings Project (NEEBP) was published. The project, led by the South Australian Government but co-funded by all the Australian states and territories, is aiming to provide solutions to enable a more efficient building stock.
Phase 1 was carried out in 2013 and involved a wide consultation with a variety of stakeholders: industry, policy makers and regulators, with the aim to identify the main issues faced in the application of the National Construction Code Section J (i.e. energy efficiency).
Although Phase 1 wasn’t specifically focussed on residential buildings, this is certainly the direction the project seems to have gone in; evidently the main responses from stakeholders were associated with the domestic stock (or at least those respondents were shouting the loudest). A key finding of the Phase 1 review was that there is a big disconnect between the design and the construction of a building; maybe inspections could be a way of bridging this gap. And so welcome to Phase 2 Project One.
Unfortunately only 59 homes were inspected as part of the study. I’m unsure whether this was the due to time constraints, budget constraints or simply limitations in suitable buildings and willing Councils. Either way, 59 homes is not really enough to develop solid results and determine trends. To be fair, the report admits its own shortfall and I guess that’s part of the reason why this was detailed as a ‘pilot’ and not a ‘trial.’ Of the 59 assessed, only 27 were inspected twice, once post-frame and once near completion, so statistically the findings are pretty much irrelevant.
The inspections were carried out by the building surveyor and included checking the roof, wall, windows, shading and building services against design documentation and deemed-to-satisfy performance. There is clearly a large degree of uncertainty in the results, with a number of ‘inconclusive’ or ‘no inspection opportunity’ responses. As shown in Figure 1, fewer than 30 houses provided conclusive results for the majority of the topics covered.
There are many difficulties in on-site assessment of building fabric energy efficiency, to which some people suggest that thermal imaging may be the answer. In my opinion though, there are far too many variables due to climate conditions, and what would the images then be compared with? Thermal imaging is great for existing constructions to see where your weak spots are, but testing on construction sites as a confirmation of quality, I’m not so sure.
Inspections clearly aren’t without their limitations. I’ve heard stories about builders putting in double the thickness of insulation in an accessible panel that they’re going to show the building surveyor, but throughout the rest of the building they’ll halve the thickness to save on materials and labour - more money in the bank for them. This is pretty shocking, but unfortunately more common than we might think. One thing I wasn’t sure about when reading the report was whether the builders were made aware they were taking part in the pilot study on energy efficiency. Is it possible to have unplanned audits, and catch builders with the element of surprise?
Interestingly draught-proofing was on the list for the surveyors to assess. Now I’m not sure how many of you have been present at an air pressure test - I’d strongly recommend it if you haven’t - but it’s actually extremely difficult to see where the gaps are in the construction. I really wouldn’t be surprised if some of the houses deemed as having sufficient draught-proofing in the pilot had infiltration rates of greater than 15ach, which means they're leaking like a sieve. This certainly isn’t the fault of the surveyor, but simply an additional supporting call for making air pressure testing all our buildings an NCC requirement.
The requirement for documentation from builders is absolutely paramount - think As Built Green Star (also relevant that the Design rating has a self-destruct timeline), with proof through purchase orders. I’m surprised that Green Star AB doesn’t require a site inspection to complement the paperwork. It’s a knowledge gap that many ESD consultants don’t ever go to site.
I’m certainly far more comfortable with assessing the individual building elements rather than comparing hypothetical modelling results with actual built performance. The performance gap is a minefield anyway due to user variation and climate conditions, let alone when conjoined with NatHERS (the black box of mystery). This concept is definitely something to be developed in the future, but I don’t think now is the time.
There’s not a lot of point having Building Code if its criteria are not being met. We certainly need to turn our focus away from design- based standards to construction standards, if only temporarily. The NEEBP Project One has been a good start, but has highlighted fairly significantly that there is a long way to go.