What is a blower door test, and do we need to use one?

High-performance buildings have more design and construction thought put into them than a typical New Zealand project. As discussed in one of our other articles, the designers and builders are trying to minimise the thermal losses from the project. This inherently means that the buildings become more air-tight with less or no thermal-bridging in the construction. So, the obvious questions arise, if we have spent all of this time and energy designing and constructing a high-performance home, how do we verify we are getting what we asked for?

The simple answer is to carry out a blower door test. This is an internationally recognised testing system that provides tangible results for the project team to use during the build. The blower door is fitted to a doorway or window opening in the building. It then pulls air into the building and monitors the amount of air that leaks or is lost out of the building envelope. It then provides a test result that is universal throughout the world and allows the owners to benchmark their project. There isn’t a better way to see where parts of the building may not have been built as well as others then using smoke inside the project and seeing it pour out of the home. It is a clear and simple tool for any high-performance building team.

We recommend that the blower door is used at two times during construction. The first time is before the project is lined, this is when issues can be amended and lessons learnt. The second is when the home is complete, this provides a final performance measurement for the owners to either use to assist in officially certifying their Passihaus, or knowing where their home is on the performance ladder.

TAWA has performed many blower door tests on client’s homes, and sometimes once the project has been completed to verify results. Once the home is completed there really is no way to amend the building envelope to increase its performance. So, we suggest you consider this approach early in your design phases.

We encourage you to get out there and start having conversations about blower door testing. If this is something you are interested in, give us a call or if you are not in the Waikato or the Bay of Plenty go to www.blower-door.co.nz to find a local blower door expert in your area. The test is completed within an hour, so we suggest you start the conversation with your build team for your next project and demand to know what you are paying for in terms of performance.

What is it like to live in a high-performance home?

Our first Passivhaus project was built in NZ in 2011/12. This project was a pioneer for the Waikato region, and the clients were, and still are, passionate ambassadors for this type of housing. The project was well-planned, managed and built, however were the results going to align with what our software and experience were telling us? We needed verification, and the best way we can do this is to install temperate sensors throughout the home and monitor the performance over several seasons and years. We were very lucky that the owners of the home were skilled in this area and a system was installed to monitor the temperate throughout several rooms within the home, under the ground and outside the home. This provided us with an extensive amount of data to use. It provided us with a clearer understanding of what we had designed, it provided us with learning opportunities and most importantly it provided us with the ability to understand how Passivhaus worked within the New Zealand climate, which is different to where it originated in central Europe.

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What is a high-performance home?

High-performance is part of the sustainability conversation we have with all of our clients from the outset. It is a critical component of the building design that provides the long-term efficiency of your home. It is also very important to consider and incorporate the other areas of sustainability, such as environmental products, low waste, landscaping, people, etc. It is such a large topic and there are many solutions or areas that can be used.

At TAWA, high-performance is designed into all of our building designs, whether it be in the form of a certified PassivHaus, solar-passive home or commercial project. This is where we focus intensely on the building envelope. Our extensive experience in designing high-performance homes in New Zealand over the past 10 years and our specialised Passivhaus software enable us to provide tangible performance-driven results. The key with this approach is that it uses the unique climate data from your site so that the conversations about performance can be accurate, and happen before you start your build, therefore allowing projects to be priced and conversations about building performance and cost to be held early.

The performance conversation is just one part of the equation; the project still needs to meet your architectural and design requirements. No two homes we have designed have been the same (to date), so this approach allows us to be flexible in the design of the home, but keep this conversation at the forefront. We utilise several different products and strategies to achieve the agreed performance gains, and we tailor this to each client.

What we are trying to achieve in a high-performance home is to balance the “gains” with the “losses” so that we keep the internal environment of your home as even as possible with little to no heating requirement. This therefore reduces on-going livings costs, and improves the living experience that comes with being in a high-performance home, or Passivhaus.

Gains are the sum of the heating gains for a project, such as; sun-light entering the home, occupants and heating sources. The losses are a sum of the heating lost through the walls, roof, floor, ventilation, etc. The designers skill and experience comes to the forefront in maximising the gains, and the technical understanding of constructing homes for performance is where the losses are managed. Below is a simple example of what that could look like for a home.

We encourage you to start having conversations about performance, and demand to know what you are paying for in terms of performance for your next building.

“THE PERFORMANCE OF A HOME IS ABOUT BALANCING THE ‘GAINS’ WITH THE ‘LOSSES’ TO KEEP THE INTERNAL ENVIRONMENT OF YOUR HOME AS CONSISTENT AS POSSIBLE WITH LITTLE TO NO HEATING REQUIREMENT”.