CA09 - Passive Problem

The viral post that got a lot of attention.

THE TOPIC

Last week I wrote a post on LinkedIn that got a lot of attention. In fact, it caught the attention of almost 200,000 people. The interesting thing wasn’t so much the number of reactions, but rather the two different sides that began to develop.

The post was titled the Passive Problem, and you will see the graphic below. It explained that the Passive House Standard, despite its rigorous energy standard, only addresses part of the problem with buildings. The operational carbon. If you design a high-performing building but maintain high-carbon materials you are missing a significant source of emissions on your project. To be perfectly clear - Passive House is part of the solution and has created a lot of buzz around sustainable building design.

The post got attention for 2 reasons.

1. The Passive House community is very strong, and vocal. Some people took offense, and some added important caveats. The reality here is that most PH designers are passionate about more than just energy and many PH buildings also focus on lowering embodied carbon. BUT that’s not the point. The point is that energy is part of the issue, we can’t lose the importance of materials.

2. Long has the AEC industry been trying to regulate energy use. Mostly through thermal performance limits and R-Values, codes have for a long-time expected a minimum baseline. However, embodied carbon remains unregulated and a huge contributor to climate problems. We need a form of regulation, and we need it fast.

This post also highlighted a few key things we need to do better:

• We need to work together. It’s NOT Passive House vs the world.

• Passive House is part of the solution but isn’t the answer to everything.

• The important factor should be whole-life carbon, not just energy use.

THE GRAPHIC

Passive House is not a problem but can have problems.

WHY IT MATTERS

The PH Problem matters for three primary reasons:

1. We need to work together - PH is a solution

2. The amount of materials should be a factor

3. Operational carbon is only part of the problem

Let’s dig a little deeper:

1 - We need to work together - PH is a solution

Passive House has a following unlike many other groups in the AEC industry. It feels like more of a lifestyle choice than a design standard TBH. And although I applaud the intention behind these people, the manner is often a problem. PH is not THE solution to the building industry and every new building in the world cannot be designed that way. It is a solution for some problems, but it’s not the solution to many of our problems.

2 - The amount of materials should be a factor

One of the issues with a passive house model is the sheer amount of materials required to meet the intense 15 kWh/m2 energy requirements. Depending on the location, adding layer after layer of insulation just to reduce energy use isn’t a wise strategy. Whole-life carbon needs to be considered as well as simple material use. If a building uses twice the materials but uses a quarter of the energy, is it worth it? Depends on how that energy was generated. It is local specific and material relative. Do it all out of strawbale and you have a very different impact than if it was spray foam.

3 - Operational carbon is only part of the problem

Embodied carbon matters too. Chris Magwood, a legend in the low-carbon AEC industry, completed a thesis on the topic in 2019. One of the things he looks at is the embodied vs operational carbon of high performance vs code buildings with natural gas or electric heating. Surprisingly, in a climate like Toronto you are better off building a typical code building over 30 years if you have a multi-unit building running on heat pumps. (Red represents embodied carbon, yellow operational carbon)

Chris Magwood Thesis - Opportunities for carbon dioxide removal and storage in building materials.

Chris Magwood Thesis - Opportunities for carbon dioxide removal and storage in building materials.

1 TIP- HOW TO REDUCE

Today's tip isn’t a tip at all, but rather a material. Have you heard of hemp insulation? Well, now you have. Hemp is natural and sequesters carbon as it grows. It is a great example of a material that should be used more in construction to lower our embodied carbon while reducing our energy loads. Lots of Passive House designers are already using it. Check out one example from Hempitecture.

1 PERSON - TO FOLLOW

Chris Magwood - is obsessed with helping reverse climate change by making carbon-storing buildings that are also healthy, beautiful, efficient and inspiring.

1 RESOURCE - TO HELP YOU ACT

Chris Magwood recently published a book called Beyond Net Zero. I have a list of books I recommend on my website.