Passive House and Off Site. The value of collaboration
In June I presented at Colab 24, the Offsite annual 2-day conference in Auckland on the Passive House Standard. I first got curious about the offsite space in 2020, having time and capacity during lock down to see if there were better ways to help create good Architecture that was good for people and planet.
Like our conventional construction industry, I found the offsite space very much focusing on doing status quo but just in a factory.Fast forward 4 years, armed with my Passive House Certification and Homestar Qualifications,I felt it time to nudge this space towards building better.
The offsite space, together with Passive House, has the potential to address both building for climate change requirements and affordability issues we are currently and will continue to face. Here is why I think that.
“Offsite Construction is efficiency of process, not product” Gerry McCaughey.
Foresight.
Offsite Construction relies on great planning. While it is faster on site and has the ability to fast track the construction, that speeds lost if issues haven’t been foreseen and rectified before manufacture begins. Passive House requires a large amount of planning in the design stage,to ensure that energy efficiency is created in the design. It cannot be achieved retrospectively.
Repetition
The economy of offsite construction relies on repetition on various levels. This is created for optimization of the process. Bespoke projects using offsite practices lose this economy. Passive House relies on repetition of good construction techniques. Reducing thermal bridging and good practices around airtightness can become part of the process, rather than a change to status quo, which means it happens efficiently and effectively. That improves quality and can create economy as it becomes standard practice.
Design Investment
Often the faster something is designed, the less considered it is. Successful offsite projects are designed for an efficient process.Passive House requires an intense design stage, far more than minimum building code practice requires. Coupling the two considerations in the same design phase means one can inform the other in the stages it needs it most.
Quality
Passive House requirements are where our 2030 targets are sitting. MBIE (Ministry of Business and Innovation) has collaborated with Passive House Designers to define our operating targets for energy efficiency in buildings. The construction of our future buildings is going to need to bebetter quality than what we are currently producing on mass. An indoorcontrolled environment in an Offsite space means that quality of airtightness,window installation, jointing of junctions and reducing thermal bridges can bedone right first time, irrespective of weather conditions or physical site restraints.
But its not all smooth sailing…. there are challenges.
Challenge
The challenge that the offsite space is facing in its building for climate change requirements is that often offsite methodologies greatly affect and determine the design. While the opposite can be true for conventional construction. Designing to any form of energy modelling standard,like Passive House, building orientation and location are key. Design influences results, window sizes and orientation matter. Shading is important and actual site climate data is critical to designing for accurate performance, not assumed values.
If the offsite space is truly to emerge as a Hero in the building for climate crises, there needs to be enough structure for efficiency and economy and the right amount of flexibility for location specific performance.
I remember saying to Scott Fisher, CEO of Offsite NZ, this space has the great potential to solve problems, but also the very real danger of accelerating the poor performance of our current housing stock.
The challenge is huge, but the potential is too. The optimist in me still believes this is a space of solutions.
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