Here's another important crosswalk, between Passivhaus and the International Living Future Institute

August 12, 2019


Crosswalks are all over the news these days; the most famous one in the world was photographed 50 years ago last week. Not nearly enough attention has been paid to another crosswalk, the recent partnership between the Passivhaus Institut and the International Living Future Institute (ILFI), the organization behind the living building challenge.

In the ILFI’s journal Trim Tab, Patsy Heasly explains how the two systems differ but can complement each other.

PHI’s certification (PH) emphasizes super high energy efficiency based on detailed energy modeling. ILFI’s Zero Energy (ZE) certification, on the other hand, has no efficiency criteria but requires documentation that all energy use is offset by renewables over a year-long performance period. For projects that achieved certification under both programs, the low energy consumption of PH facilitates achievement of ZE and the performance data generated by ZE can validate the PH modeling.

This writer always found that lack of efficiency criteria a real problem with Zero Energy certification, because you could build just about anything, as long as you had enough solar panels to balance it out. As Elrond Burrell has written, (back in the days when we used Zero Carbon and Zero Energy almost interchangeably)

In the dark freezing depths of winter, with a gale howling outside, everyone has their heating turned up high and all the lights switched on … and since the sun isn’t shining the photovoltaic systems on the ‘Zero-Carbon Buildings’ aren’t generating electricity.…So all the ‘Zero-Carbon Buildings’ are back to drawing electricity from the national grid, like every other building. And if the ‘Zero-Carbon Buildings’ are only mildly above-average energy efficient, they present quite a demand for electricity!

A certain Passivhaus expert who asked to remain anonymous wrote in an article titled “Going beyond ‘net zero’ to passive house” noted that Net Zero might not even be a sensible goal, because “the current accounting of ‘net zero’ assumes the grid acts as ‘bank’ for local energy production.

Understanding that the grid is not a bank is key to recognizing that current net zero’ accounting could lead to suboptimal building design outcomes. Buildings are being incentivized to include on-site renewable generation, but their arrays are not being sized according to their winter peak load, but rather as if the grid was functioning as a credit system that stores energy for later use.

That’s why Elrond Burrell is a fan of Passivhaus over Net Zero concepts.

The building fabric, which will last the lifetime of the building, will be highly energy efficient and ensure a comfortable building by design, regardless of how and where the required energy is generated.

I believe that the ILFI can learn a lot from Passivhaus, most notably that it’s much easier to achieve Net Zero when you start with real tough limits on energy consumption.

But every crosswalk connects the two sides of the road, and as John Lennon wrote in Abbey Road, we have to “come together, right now.” There is so much to learn from the ILFI. Their Net Zero concept ensures that the building actually performs the way it was promised to perform. They do not allow the use of fossil fuels, so it is truly Net Zero Energy, not just electricity.

But most importantly, this crosswalk also might lead down other roads, perhaps deeper into the Living Building Challenge, which looks at every aspect of a building. They “generate all of their own energy with renewable resources, capture and treat all water onsite without the use of chemicals, promote health and address inequity, operate efficiently, invoke beauty, and are toxin-free. “

These are concepts that should be in every healthy and sustainable building. In a perfect world, every building would be certified Passivhaus for energy and Living Building Challenge for everything else; there is so much they can learn from each other. This crosswalk is a great start.


Lloyd Alter
Lloyd Alter
Lloyd Alter is design editor of TreeHugger. He has been an architect, developer, inventor and prefab promoter. He contributes to,…