icebox 2026

By Jay Fox

Passive House Accelerator published a story about the Ice Box Challenge Montreal a few weeks ago. As we noted then, a conventional Ice Box Challenge involves two small buildings. The dimensions of the two are buildings are identical; the major difference is that one is built to the local code, and one is built to Passive House standards. Placed inside each one is a large block of ice. There are no active cooling systems, so the building enclosure does all the work to keep the ice from melting. The two buildings are then placed in a public square during a warm month for several weeks, after which the two blocks of ice are weighed. The winner is the building with the most ice left unmelted.

The HABiTEK team in 2025. You can read our previous coverage of the Ice Box Challenge Montréal by clicking on the link below.
The HABiTEK team in 2025. You can read our previous coverage of the Ice Box Challenge Montréal by clicking on the link below.
Read Article

The biggest distinction between what’s happening in Montreal and previous challenges is that the students are taking the lead. The 2027 Ice Box Challenge will include multiple student teams from Quebec and possibly beyond. Moreover, the students will be competing against one another and against a code-built structure. The team with the largest amount of ice remaining, will be crowned the winner.

In anticipation of next year’s event, HABiTEK, a student-led club team from École de technologie supérieure (ÉTS), performed an old-fashioned Ice Box Challenge on their campus. The challenge ran September 1-30. According to HABiTEK Design Team Leader David Lamothe, the ice in the code-built building melted after 20 days, while the Passive House building lasted for the entire duration of the event. What’s more impressive is how consistent conditions within the Passive House building remained throughout the month.

“The average indoor temperature in the Passivhaus was around 5°C (41°F), compared to 11°C (52°F) in the building built to code, which also experienced much larger temperature fluctuations between day and night,” Lamothe said in an email exchange with Passive House Accelerator. “Humidity levels also rose much more slowly in the Passivhaus, possibly due to the hemp insulation’s ability to absorb moisture.”

We’ll be checking in with the ÉTS again to talk about their design. In the meantime, readers can access the data from the September challenge on HABiTEK’s site: https://stats.habitek.ca/  

The top image shows the two buildings on the ÉTS campus during the September challenge. Photo courtesy of HABiTEK

Published: October 19, 2026
Contributor: Jay Fox
Categories: Article, Educational Campaign, News