Actual, evidenced performance

The Passive House Standard is a 'building standard' rather than a rating system, and is the most proven method for delivering actual levels of health, and energy efficiency, in the world.

Since it's inception in Germany in 1991, thousands of buildings have been designed and built to this standard, all around the world. Often incorrectly thought of as a 'cold climate' approach, the standard is completely site specific, and there are certified buildings in climates as diverse as the heat in Dubai and Australia to the cold in Scandinavia.

The certification requirements are set to ensure the building achieves minimum levels of performance and comfort, and you either achieve it or you don't. The standard can be used for new buildings and retrofitting old buildings, and there are PH schools, libraries, hospitals, even swimming pools!

The Passive House Institute New Zealand have a range of information and publications.

All about the outcomes

At it's most basic level, the Passive House Standard begins with the principles of passive solar design.
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  • Good orientation
  • Utilising solar gain
  • Considerate shading design
  • Use of airflow in summer

However passive solar design is designed to rely on a lot of things that can't be relied on - namely people, and the weather. A cloudy week and you don't get enough solar gain, or if someone forgets to open the windows in summer you'll overheat. 

The Passive House Certification process uses predictive energy modelling to remove these unreliable elements, and show you how the building will perform as you're designing it, rather than just hoping it will work out in the end. 

5 principles of building performance

For any building to perform well, there are 5 main principles that need to be balanced:
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  • Adequate insulation for the site and climate - not too much, not too little!
  • Minimum levels of continuous ventilation with heat recovery - to ensure CO2, moisture, VOCs etc are all removed, and replaced with sufficient fresh air
  • Thermal bridge free construction - to reduce heat loss, but more to avoid cold spots, condensation and discomfort inside
  • Excellent windows & glass - windows are the weakest point of your whole building, they're worth investing in
  • Airtight construction - to prevent heat loss and interstitial condensation risk (moisture getting into your walls, roof, etc)
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However these all need considering together - if one is missed it can create even worse issues. The Passive House Process ensures these are all balanced, to deliver the best outcome; and the stringent on-site quality assessment requirements ensure it's built to achieve these, as well as designed.
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Homes where people thrive - an excellent resource on the Passive House process

Fabric First

Passive House Design is often referred to as 'fabric first' - ie it is primarily concerned with the parts of the building that make up the thermal envelope and interior environment, however it doesn't dictate what this fabric is - just what the required performance and comfort outcomes are.
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​There are Passive House projects built from straw bales, concrete blocks, timber frames, the list goes on! The only requirements are they meet the required metrics for:
  • Heating energy demand
  • Heating load (the size of the heating system)
  • Frequency of overheating - any time over 25 degrees
  • Air leakage
  • Overall energy demand
How these are met, is up to you!

Passive House - done WEL

Every project at WEL is modelled using the Passive House Planning Package, a predictive energy model software. This provides a roadmap for how the building is performing, and where the weak points are in the design. 

The certification process is akin to getting a Building Consent - an additional level of Quality Assessment undertaken independently from the project team, and signed off by the Passive House Institute in Germany. While going through the certification process is the ideal outcome, we also recognise not every client will have achieving Certification on their list and would prefer to put those funds elsewhere -  we can work with you through this process.

Director Joe is a Certified Passive House Designer with a number of projects under his belt, including his own home Lower Saddle Passive House. He is also the Passive House Institute New Zealand Auckland Chapter Lead, and organises hands-on events to educate industry in the benefits of, and how to achieve Passive House design.