Building energy consultant Sean Maxwell recently moved to Australia and immediately identified holes in how Australia’s buildings are being constructed – literally. If Australia wants to lead or even catch up on green buildings it seriously needs to address building air tightness, he argues in the first of a two-part series.
Australia is behind the US and Europe in an essential aspect of green building: reducing air leakage. Unsealed building envelope and duct leaks are often some of the largest and most rectifiable flaws in new and existing buildings. Current building practice is arguably 20 years behind the rest of the world, and Australians continue to miss out on one of the most cost-effective, durable and comfort-enhancing measures that can be taken in a new building.
The Australian government’s guide to sustainable home building estimates that air leakage in Australian homes accounts for 15-25 per cent of winter heat loss and also has cooling penalties. South Australia consulting firm Sustainability House points out that new homes in this country may be as much as three times as leaky as commonly assumed, leading to unexpectedly poor performance and high energy bills. Similarly, leakage from ductwork is another problem that hurts energy efficiency by letting heated or cooled air escape unused.
One way to tackle these problems is verification through testing. The vast majority of homes and commercial buildings in Australia are built without any quantitative verification of building envelope or ductwork airtightness. This is a shame because these are relatively easy and inexpensive tests to do, enough that parts of the US and the UK require them explicitly in their building codes. The lack of testing in Australia means what is promised is not always delivered. It amounts to a hole in Australia’s green building, so to speak.
Change of course will not come immediately. Realistically speaking this will take years, and will require much more than strengthening building codes. To begin with, cooperation is needed between many sectors of the Australian building industry – academia, consultants, designers, builders, manufacturers and suppliers.
Since moving to Australia recently, I was disappointed to learn I missed the most recent opportunity for big change: the 2016 National Construction Code, which was quietly released and contained pitifully weak language relating to air sealing. The period for comments has already closed. In addition, the codes are now going to a three-year cycle, which means the next opportunity for change is 2019.
While disappointing, this development actually gives a good target for change: the 2019 code. What is needed over the next three years is a collaborative, cooperative, and I think exciting effort to create change in a market that sorely needs it.
Before I left New York City for Australia, I had the opportunity to help guide New York State’s Codes Committee as they considered adopting the 2015 International Energy Conservation Code and its requirements for airtightness testing of the building envelope and ductwork of residential buildings. While the process was very slow – my first presentation to them was back in 2012, and they still haven’t officially adopted the new residential code – it gave me the realisation that change is possible. I’m excited to work with people here to change things for the better.
Taking a look at some options for making big changes, here are some of the “carrots” and “sticks” to push and pull the industry in the right direction. Over this segment of the article, and the next, we’ll discuss all of these.
Major change in Australian building practice will ultimately come from major changes to building codes. Let’s compare Australia’s to those of other countries. In the UK, Section L of the Building Regulations calls for mandatory air leakage testing of many buildings. In the US, many states have adopted recent versions of the International Energy Conservation Code, which calls for mandatory testing of both building envelope and ductwork tightness of many residential buildings. Of course, mandatory testing in both countries was not introduced to an industry unprepared. It came at the end of a long transformation of the market over decades.
My own experience in the buildings industry began under the US’s ENERGY STAR for Homes program, a voluntary and often utility-subsidised program for new low-rise residential construction. This program began in 1995, and over the past 20 years the requirements for compliance have steadily increased. The transformation of the residential market in the US is an example that Australia should follow. The graphic below charts some of the parallel progress between the voluntary ENERGY STAR program and aggressive energy codes that states have adopted.
From 1995-2005, under early versions of the ENERGY STAR program, building airtightness tests were required but in some states there was no mandatory threshold that had to be met. The goal was to get builders used to sealing leaks, and to develop the expertise of the home energy rating industry.
In 2006, Version 2.0 of the program required homes to be sealed to a maximum threshold. I remember the pain and embarrassment of flunking builders who just hadn’t done enough sealing to pass the test. But major outreach and training efforts helped them get the hang of it. Within a few years, hundreds of thousands of ENERGY STAR homes were being built every year, all of them tested to verify compliance.
In 2011, Version 3.0 was launched, dramatically expanding the scope and stringency of the program. Building leakage and duct tightness tests are still required, but at much tougher levels. In 2011, 26 per cent of new homes were built to ENERGY STAR standards, a startling achievement. Fast forward 20 years after the inception of the ENERGY STAR program to 2015, when many states have put into law the 2012 or 2015 International Energy Conservation Code, which call for sealing homes and ductwork to levels that just 10 years before were a stretch for many builders.
Now, look at where Australia is with airtightness requirements in its energy codes. The National Construction Code Section J calls for draught sealing, but the language is nowhere close to the stringency or specificity of either Part L of the UK regulations or the International Energy Conservation Code. It also has no mention at all of performance testing or even inspection. Let us now pause to remind ourselves that a code-built building is the worst building you can build under the law. It’s a mandatory minimum of effort, not best practice.
As for best practice in Australia, the federal government has published a guide to building a seven star NatHERS single-family home (10 being close to net zero in some climates), including climate-specific advice about levels of insulation, glazing, etc. Though the guide calls out “sealing your home,” nowhere does it mention actual testing of the house or its ductwork to ensure performance. This is a major omission. You can’t improve what you don’t measure.
Contrast this with Passivhaus design, which calls for verification of the building’s airtightness at a level more than 20 times tighter than many typical new Australian homes. Australia is never going to get anywhere near zero-energy homes if it does not embrace performance testing.
In Australia, in the absence of code requirements to conduct air tightness testing, some projects have taken it upon themselves to specify it, often referring to UK standards. But the language in contracts and the performance targets chosen are sometimes plucked from foreign standards without a solid understanding of the difficulty of meeting them in real buildings. The result can mean confusion and sometimes failure. Much of the Australian construction industry is unprepared for mandatory testing, let alone tough targets.
There have been some efforts to strengthen codes. The Building Code of Australia calls for mandatory testing and maximum air leakage of some large ductwork systems under AS 4254.2. There is a great deal of construction going on right now that should be tested under this standard, yet it is unclear how much is actually being held to the limits, or even tested at all.
The reason is that some project teams aren’t aware of or don’t understand the requirements, or they know that no one is checking their work. More startling, a few at the Australian Building Codes Board have given mixed messages about whether the language even calls for mandatory leakage limits. This inconsistency and lack of will is a big problem, but it goes to show what can happen if a standard is introduced without clear language, adequate industry preparation and insufficient support from code enforcement authorities.
Illustrating the lengthy co-evolution of the residential home industry and government regulations in the US shows that that this change will not happen overnight. It requires cooperation and partnership from many sectors of the Australian building industry, from public to private to institutional. We need to foster partnerships across industries to forward the mutual interests of a wide range of groups, some not traditionally related, including:
- partnerships with manufacturers of sealants, insulation and fire-stopping materials
- utility companies and grid operators; electricity demand management companies
- state and local governments
- economic development organisations
- property management associations and companies
- testing equipment manufacturers
- other building-performance organisations: the Australian Institute of Refrigeration, Air Conditioning and Heating; the Australian Institute of Architects; the Green Building Council of Australia
- builders’ industry groups such as the Master Builders Association and the Housing Industry Association
- the Australian Building Codes Board
These organisations and groups share a common interest in the following outcomes:
- increasing the effectiveness of Australian building codes by increasing emphasis on verification of airtightness of the building envelope and ductwork
- providing government agencies, utilities, and code officials with reliable, unbiased data and providing reasonable recommendations for policy and programs
- serving as a gathering place for building scientists, performance testing specialists, and green building advocates to support and coordinate each other’s efforts
- supporting training and education of Australian professionals
In the second part of this article, we will go into more depth regarding how these aims can be accomplished.
Sean Maxwell is an ASHRAE-certified commissioning process management professional living in Sydney. He has 10 years of experience in building performance testing, commissioning and research.