Sean Maxwell

Happy New Year! What are your resolutions? Spending more time with family and friends? Improving your fitness? How about joining an effort to improve the energy efficiency of Australia’s National Construction Code? That may be the biggest challenge, but well worth a try.

Since moving to Australia from the US last year, I’ve been pleased to meet a vibrant community of people truly committed to lessening the carbon footprint of our building stock. But I’ve also come to realise we have a long way to go before we catch up to Europe and the US with the way our buildings are being built.

Let’s look at some fresh data. The House Energy Efficiency Inspections Project final report, recently released by CSIRO, summarised results from a project whose goal was to inspect the energy efficiency features of 20 recently built houses in each capital city in Australia.

Energy efficiency measures are required by the National Construction Code but virtually never inspected. Draught sealing, a basic energy efficiency measure, was measured in 129 homes with a blower door. The average leakiness was 15.4 air changes an hour at 50 Pascals – in simple terms that’s about 25 times leakier than the Passive House standard, and three to five times leakier than the International Energy Conservation Code’s requirement for homes in climates similar to Australia’s. That’s not good.

Still, not all the homes did poorly. There were in fact houses that were really trying to achieve energy efficiency, and some did an admirable job. One home aiming for the Passive House level of 0.6 ACH@50Pa got down to 1.4. That’s pretty good, but it illustrates the difference between homes that have their energy efficiency features actually inspected through a program like Passive House and those that are built by standard Australian procedure, which involves a minimum of oversight. In short, you get what you pay for, right?

The National Energy Efficient Building Project, led by the South Australian government, just weeks ago published its Phase 2 results. The project included a pilot of on-site inspections of energy efficiency features of new homes. They found that there is often a gap between what is assumed in software energy models and what is actually built. One may wonder if this discrepancy applies to what is sold to home buyers, but according to the study, for builders “there is little risk associated with cutting corners”. In other words, you only get what you pay for if someone checks.

Clearly there is a need for verification of energy efficiency features. According to the NEEBP report, “Councils recognised the benefits of assessing ‘as built’ energy efficiency compliance for promoting quality, sustainable buildings in their regions. The importance of promoting accountable industry performance with the NCC and protecting new home consumers were key drivers for Council involvement.” Many people in Australia have been active on this issue over the years, but as someone involved in testing, inspection, and commissioning high performance homes and buildings for years, I am a believer in the power of testing buildings to prove they were built well.

You can’t manage what you don’t measure

As I visit more job sites in Australia, some things strike me as odd. A little while ago I walked onto a site and saw a drill battery charger with an inspection tag on the cord. I find it unusual that tagging of all electric devices on job sites is enforced so militarily here in Australia, when so many other things are ignored. Of course, tags are something you can see, so they’re easy to verify. Compliance with other regulations like Code requirements to reduce building air leakage and duct leakage is a lot harder to verify. How do you prove that you’ve made ductwork airtight? After all, a visual inspection of air leaks is difficult, not only because air is invisible. Testing is the only sure-fire way to ensure compliance and that you get the performance you paid for.


At that job site I snapped a picture of the tag on the battery charger and began work. The real reason we were at this building was to diagnose and fix a poorly performing smoke ventilation system in a renovated supermarket. The system uses masonry shafts connected to very large roof fans designed to exhaust 40,000 litres/second of smoke in the event of a fire. Unfortunately, the system was only managing just over half of the required flow from the space, as a great deal of capacity was being lost somewhere in the system.

The photo on the left below shows one of the problems we discovered in the shaft. No, the pipes you see in the picture are not part of the ventilation system; they are part of another tenant’s cooling system. And no, they don’t have any business in the ventilation shaft. Whoever put those pipes there busted very large holes through the masonry shaft wall and didn’t bother to properly patch them. Just a few metres away (right picture), several entire blocks were missing from another wall of the shaft. I guess they ran out of blocks? A makeshift sheet metal patch was placed over the hole but not properly sealed. No wonder the system wasn’t delivering the required airflow.


The holes in the blocks allow air to travel within the shaft wall itself and end up in strange places. During the sealing process we travel around the building to check that everything is going well. When I walked into the stairwell which abuts the shaft, I noticed a hissing sound which I knew was air leakage. On the left below you’ll see the large block shaft wall outlined on the right, but this is not where the air was leaking. Peering closer, I noticed air leaking out of the door frame out of the adjacent wall, and even coming out near the call box on the far side of the door.


Air was entering the holes in the block wall on another floor, traveling through hollow cores and many joints, and passing into entirely unassociated walls elsewhere in the building. In this case a ventilation “shaft” becomes a truly a complicated structure – not the simple tube shown on the drawings. The door frame for the store next door is obviously not intended to be part of the life safety system for the supermarket. But air is a difficult thing to control, and sometimes it stubbornly refuses to follow the arrows drawn on the building plans.

I was told the building was built some 15 years ago, when standards were perhaps a bit more lax, and possibly later modifications to the duct system were never inspected. Today, the National Construction Code requires Australian Standard 4254.2, and that standard requires duct sealing and testing for large systems. Shouldn’t we be testing more ductwork now? Unfortunately, the NCC says that you need to follow AS 4254.2 but isn’t clear that you need to bother testing the ductwork. I don’t understand how you can expect a standard of performance if you don’t test it to verify.

I had taken a picture of the inspection tag on the battery charger because I thought it was silly. The very next picture on my camera was of the pipes into the ventilation shaft. Why we could be so obsessed with tagging battery chargers and so lax with something as important as a smoke exhaust system is troubling. This is part of a larger discussion about construction quality control in Australia. Don’t get me wrong – I can show you just as many examples of cringe-inducing improvisations in New York City buildings – but this just points to the universal need for testing and inspection as an integral part of construction. Other parts of the world are starting to get the picture, and we need to catch up.

Duct systems, whether they are safety-related or not, should be tested for air-tightness because visual inspection alone is inadequate and because proper performance depends largely on duct tightness. In this building, a visual inspection from the outside of the shaft would not have revealed that the pipes and the sheet metal patch were not sealed well on the inside. Energy use and airflow are physical, quantifiable things; testing quantifies them.

Using building science to inform our codes

In past articles I’ve focused on building envelope air leakage and only mentioned duct sealing in passing. They’re both important, and as president of the Air Infiltration and Ventilation Association of Australia, I’m hoping we can educate home owners, builders, designers and government officials about the benefits of testing buildings and ductwork to ensure quality. The blower door test is one of the most common and effective building quality assurance tools, yet most Australians have never heard of it.

What’s also troubling is that when I mention air sealing to Australians, I often get pushback. Some quip that the climate in Australia isn’t severe enough to warrant air sealing. Anecdotally, I have to argue with this because I have never been so chilly as I was in our draughty apartment in Bondi this winter, even coming from New York City where they have actual winter. Many people also have the misconception that sealing a building up “too tight” is dangerous. Theoretically, you could seal a building so tight that people could suffocate. Like a space station. Luckily, there is no way on earth that would happen.

The best building science encourages us to “build tight and ventilate right” to properly deal with moisture and pollutants, but when I approached a few people in the government about putting blower door testing into code, one of the first responses was a mention of condensation and the risks of sealing too tight. The recent Condensation Stakeholder Survey commissioned by the Australian Building Codes Board echoes this concern. I understand the concern, but if you look at the underlying causes of moisture problems in Australian buildings, overzealous air sealing is not usually one of them. In fact, testing for air leakage may help focus our attention on the root causes of “leaky building syndrome”, which are poor detailing and bad designs.

Water will always find a way into even the best buildings. Of course it rains, but water also comes up through concrete slabs and foundations by capillary action and leakage. Inside buildings, there are numerous sources such as cooking, bathing, and the perspiration and respiration of people, not to mention pools, hot tubs, and the like. When buildings are built, many construction materials such as concrete and timber possess large amounts of moisture that must dry out over time. Witness the truth spoken by Joe Lstiburek of the Building Science Corporation: “Buildings get wet from the outside. Buildings get wet from the inside. Buildings start out wet. Wet happens.” But dealing with this moisture effectively should not mean drying it out with lots of air leakage.

Fears about mold may also lead to misplaced blame on air sealing, and some people confuse insulation with air sealing. It is true, insulation inhibits heat transfer, effectively making some building elements colder. Sometimes the surfaces become enough to cause condensation and mold in the presence of moisture-laden air. One reaction is to install vapour barriers – often heavy plastic – that prevent moisture diffusion into the walls through the building materials. Yet the wise among us realise that the bigger threat is almost always air leakage.

Far more moisture is carried into walls through air leaks than through vapour diffusion. The graphic below is adapted from the Building Science Corporation, showing the difference in moisture transport by vapour diffusion and air leakage. Given equal environmental conditions on the inside and equal environmental conditions on the outside, in a climate similar to Sydney’s, air leaking through a 6.5 cm2 hole will introduce nine times more moisture than diffusion will introduce through the wall material itself.


I review these topics because I firmly believe the way forward for Australia is to embrace better inspections and testing as an integral part of construction. There is a lot of room for improvement. The majority of Australian buildings are so leaky that there is no real threat to indoor air quality until serious reductions in air leakage are made. When buildings do get tight enough to warrant mechanical ventilation, many ENERGY STAR home builders in the US upgrade their code-required toilet exhaust fans to extremely quiet, efficient and affordable continuously-operated ENERGY STAR fans. Certainly, it is true that you can’t simply tighten up buildings without also dealing with moisture and indoor air quality, but it doesn’t have to be that hard, and we have to start somewhere.

Not too long ago I met a Sydney-area developer that was building hundreds of homes that were claiming to be some of the greenest and most energy-efficient homes in Australia. I wondered whether any of these homes had been tested for air-tightness. Out of a desire to help this developer gauge how well their homes were being built, I offered to do a free blower door test of one of the homes, and the results would be for their eyes only. I never heard back, and it’s probably because they were too busy to respond. But part of me can’t help but wonder if they would rather not know how they were actually doing. Isn’t it easier to make bold claims if there is no evidence to the contrary? Or, more cynically, if they promised energy efficiency but failed to deliver, would a test showing leaky homes be a liability? It’s almost better to have it remain a mystery.

Changing the Code

Jan Brandjes, who has been building verifiably energy-efficient homes in Australia for decades, is a big believer in blower door testing, which he learned back in the 1980s working with houses in the R2000 program in Canada. Blower door testing is second nature to him, “a sure-fire honest way to check the quality of the workmanship.”

I couldn’t agree more. I also agree with his thought that the NCC itself needs a major upgrade. When it comes to sustainability, Brandies says, “I wouldn’t light a fire with the building code. It’s that bad.”

So how could the building code be used to improve Australian building air tightness? Using the performance-based code approach, the code could be modified to include testing and inspection as one method of compliance with a performance requirement for an airtight building. For example, a basic performance requirement should be that a building contains an air barrier that retards air leakage, and that the air barrier is continuous and not compromised by penetrations for services.

One method of achieving this performance requirement is to inspect the air barrier and verify that it is indeed continuous and that all penetrations have been sealed.

An alternative method to inspection for compliance is a blower door test. Compliance can be relatively quickly demonstrated by conducting a blower door test on the house or apartment. Some US states have made alternate methods for single-family and multi-unit residential buildings, specifying easy and inexpensive apartment-only tests for multi-unit buildings and allowing sampling in larger buildings.

It may be an easy choice for some builders to go the “inspection” route rather than face a test. After all, a visual inspection is subjective, while a blower door test is a verifiable quantitative test. Compliance with current code-required inspections is already a problem in Australia, and the blatant conflict of interest created by the person inspecting the work also being paid by the worker raises eyebrows in other parts of the world.

In order to encourage more builders to take the testing route, some help from government would be advisable. A voluntary label for a new home, touting the fact that it has been tested and inspected by an independent third party, would help differentiate it from typical practice. Also, incentives from state and local governments to do more blower door tests would help builders understand what they’re doing wrong and improve over time. The graphics below show what such an approach could look like for the 2019 Code and the 2022 Code. At first, blower door testing is optional but could be encouraged through government or private industry labels or incentives.


This strategy gives the building industry three years starting in 2019 to adapt and learn from mistakes. Mandatory testing would not be required until more than five years from today. In addition, the threshold of 10 air changes an hour is not challenging. By comparison, the International Energy Conservation Code requires a maximum of five air changes an hour in the mildest of climates – twice the proposed level.

For now, it seems that tighter homes are definitely possible in Australia. Of the CSIRO data mentioned above, one third of the 129 homes tested already passed the threshold of 10 air changes an hour. This may lead some to concern that the level may be too lenient, but the immediate goal at this point is to get people used to inspecting and testing their buildings. Then we can concentrate on tightening the standard in subsequent years.

Government and private industry intervention

Of course, these ideas depend on several things. First, there must be an industry that is ready to implement the requirements for air sealing inspection and testing should a code requirement come into effect. Efforts have begun by forming an industry association called the Air Infiltration and Ventilation Association of Australia, whose members include testing professionals. Second, there is a need for government intervention to aid the industry in its transition to verified construction quality.

In the US, the ENERGY STAR for Homes program is an example of a successful government intervention. Over the past 20 years, successive versions of the program have raised the bar on what is considered energy-efficient construction, influencing code to the point that many provisions of the IECC resemble earlier elements of the voluntary program. Resources such as the Thermal Bypass Checklist guide aided builders in understanding the underlying building science and achieving compliance.

Similar resources can be used in Australia to help differentiate tested and inspected homes as a value over the status quo. Looking at the marketing language, ENERGY STAR doesn’t lead with energy efficiency; they promote comfort and quality first: “The blue ENERGY STAR label on a new home means: Peace of Mind; Enduring Quality; Wall-to-Wall comfort; Proven Value.”

These are all quality-related buzzwords, not energy efficiency language. The Australian market may respond similarly to the US.

The AIVAA is working on a Proposal for Change for the National Construction Code to catch up to the rest of the world when it comes to building and duct tightness testing. Stops along the path include adding additional definitions to the code for relevant building science terms, defining basic requirements for an air barrier, calling out specific air sealing details, adding optional blower door testing as a path to compliance and, finally, some years from now requiring mandatory testing of new buildings.

The property industry may help by demanding more verification of build quality. Green Star, the Green Building Council of Australia’s building certification program, offers an Innovation Challenge point for doing a blower door test on a building and another for achieving a stringent level of air tightness. You don’t even have to pass the test to get a point! But in the first two years since Innovation Challenges were introduced, 211 points were awarded but only one was for a building air tightness test.

I’m guessing there are a lot of reasons for the low uptake. One is possibly a lack of awareness of what a blower door test even is. There is also probably uncertainty about how much it would cost, what it entails, or how it would benefit a project. Lastly, many projects simply don’t know who to ask about testing because it’s still fairly new in Australia. These are all issues AIVAA hopes to alleviate by becoming a resource for projects seeking advice about building and ductwork air tightness. Representing AIVAA, I will be conducting a webinar on 8 March for the GBCA on building air tightness testing. The GBCA has taken the right approach by encouraging projects to test even if they don’t expect to pass, because they can still expect to learn from the experience.


Ensuring build quality is a concern worldwide, of course. Take the example of fire-stopping. Passive fire protection includes stopping the passage of smoke and hot gases between compartments in a building. Manufacturers often colour their products red to make it easier to breeze through a code-required visual inspection of fire-stopping measures. Most inspectors see the red, and check a box. Look at the picture. Does it look fire-stopped to you? It passed inspection in New York, but when we tested it, these low-rise multi-unit residential homes were very leaky. If it were my home, I would like to make sure that my fire-stopping actually stops fire. A blower door test can verify what a visual inspection cannot, because a passing grade is a number, not an opinion.

The IECC already requires blower door testing of low-rise residential buildings, but when New York State was considering adopting the latest IECC, I recommended that builders have the option to test a sample of individual units in multi-unit buildings instead of the whole building. I reasoned that the goals of energy efficiency would be met, but by testing the compartmentalisation of individual units, we would get many other benefits as well. Compartmentalised units reduce the transfer between units of secondhand smoke and other pollutants, smells, noise, pests and vermin. They also perform better in a fire. Again, testing is the best method of verification. The Codes Committee agreed and the recommendations were adapted to their draft code updates. Following on this success I recently submitted a proposal for change to the IECC to mirror the language in the New York code.

Codes are powerful tools for change, but there are other ways that Australians can take leadership by demanding better verification of construction quality. For example, states or councils can require that public refuges in bushfire-prone areas are tested for air tightness. In fact, there is a good case to be made for many government buildings to require testing, because the government (taxes) will bear the cost of operating the buildings for years to come. This is the reasoning behind the Australian military’s standards for construction that include air tightness testing. Educational institutions, hospitals, and private industry can also lead by example to change the industry for the better. 

Realistically it may take 10 years to get compulsory blower door testing into the code. Though you could change the code overnight, you probably shouldn’t. It takes a great deal of time to change the way that any industry does things. And the language must be clear, unambiguous, and useful. As a model, the language in the International Energy Conservation Code is a good start. It is descriptive enough that if you follow the minimum requirements for sealing spelled out in it, you should probably not have a hard time passing a blower door test. Sure it’s true, most tradies will never read the code, but they probably don’t need to. What they need is training, accountability and incentive.

Most builders want to do the right thing. They want to take pride in their work. But they are tired of rules changing and resistant to increases in construction and compliance costs. I can’t blame them. New rules can indeed be onerous and costly. But think back to my example of the battery charger with the inspection tag on it. Just for information, I got a quote from a test-and-tag outfit to see how much it costs to comply with Australian Standard 3012. For a jobsite with 20 extension leads and small tools, the cost may be something $125-150.

Compare this with the cost of a blower door test in a mature market 10 years from now, where every new home is tested. $350 a home may not be unreasonable, especially in a development. Isn’t this worth it to ensure one major aspect of building quality?

The AIVAA will be posting useful information regarding testing, the National Construction Code and initiatives to improve Australian buildings’ energy efficiency.

Sean Maxwell is president of the Air Infiltration and Ventilation Association of Australia, an industry group pushing for better building performance through improved air tightness of buildings and ductwork. AIVAA is preparing an upcoming webinar for the Green Building Council of Australia on blower door testing for Green Star projects to be held on 8 March 2016.

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  1. Thanks for putting up the cost of building a new house by $5000, for what?
    Faulty electrical appliances can kill people, there is no comparison……
    Anyway, the way the economy is going, many people will end up living under sheets of twisted corrugated iron.

  2. Yes the NCC is in bad shape on all aspects related to energy efficiency – not just airtightness, the insulation and windows standards are irrational accross jurisdictions/climate zones. It’s time for a blank sheet of paper and building science to prevail over politics and business vested interests.

  3. Hi Sean/ Richard,

    I agree plenty of opportunities.
    Another excellent report for the Government (DEEWR) that assessed Passiv Haus airtightness and insulation, Pro Clima membranes etc for adoption into the Australian construction industry was Airtight and Superinsulated construction by prof Shane West in 2010. The report contains recommendations for R6 walls, vacuum double glazing, CO2 heat pumps and natural ventilation systems with examples that were built and tested back then.

  4. Great article! At Umow Lai we wrote the Green Star Innovation credit.

    I agree air tightness testing is a huge opportunity for Australia to improve their minimum design standards with something that can be actually tested and get us closer to our COP21 commitments.

    There are also huge opportunities to improve both NCC Section J1 Fabric and J2 Glazing too…