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As part of the 2023 Passive House Network Conference happening in Denver, the Ice Box Challenge was held in Fort Collins, Louisville and Denver.

Thank You Ice Box Challenge Sponsors:


Two boxes are constructed, one box to the local building requirements, while the other is built to the international Passive House Standard. The two boxes are then placed in a central, high foot-traffic area for a set period of time – usually two weeks.

Both are filled with 2,000 pounds of ice. Monitoring devices and cameras inside the boxes can measure the temperatures and photograph the depleting ice.

The amount of ice left in each box at the end of the display period is then measured, and the level of remaining ice is used to demonstrate how well each ice box kept out the heat.

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Public events are planned for the placement of the ice and the reveal at the end, with remarks by public and private supporters of the effort.

During the 2-week period of the exhibition, volunteers will engage public visitors and explanatory events can be planned to engage school, camp, or other groups of kids and adults.

A free game to guess the final weights of the ice in each box will offer prizes to the closest guesses.


Thank you for the support of:

B.Public Prefab – Hammerwell – Geometry & Materials – Hord Coplan Macht – Alpen High Performance Products – Boss Architecture – Davis Partnership Architects – Greg D. Fisher Architect – BuildStrong Academy – Emu Passive

In Cooperation with:

And that’s a wrap!

Our Colorado Ice Box Tour came to an end on September 23rd in Denver. Once again, the final totals show the power of Passive House building standards!

Final weights:

  • Code Box: 817 lbs
  • Passive House Box: 1524 lbs

If you’re excited about what the Ice Box Challenge has proved—that Passive House is the way to go—then we invite you to join us for our 2023 Passive House Network Conference online on September 28th and online and in Denver on October 4th-5th. Join us in bring Passive House to the people, because we all benefit from better building standards. Learn more and register here.

Thanks to our organizers and volunteers, as well as our sponsors Xcel Energy and 475 High Performance Building Supply.

Denver is underway…

The boxes have been assembled and the ice is awaiting its fate! The Ice Box Challenge continues in Denver at Union Station, where the boxes are already causing a buzz amongst people passing by. A Happy Hour Social will be held on September 12th for those interested in checking on the ice’s progress and connecting with other Passive House enthusiasts.

Starting weights: 

  • Code Box: 2,027 lbs
  • Passive House Box: 2,149 lbs

Thanks to our sponsors Xcel Energy and 475 High Performance Building Supply.

Louisville Reveal, August 11

The results are in! After sitting for two weeks in the Louisville sun, where the average high was 86°F, the final totals speak for themselves:

  • Code Box: 813lbs. with a 60% loss
  • Passive House Box: 1508.5lbs with a 25% loss

Check in soon for news of the Denver Kickoff, happening September 9th!

Louisville Kickoff, July 28

The kickoff in Louisville Colorado went off Friday as part of the Louisville Street Faire with remarks by the City of Louisville Sustainability Specialist, Hannah Miller, local Passive House homeowner Kevin Lombardo and Passive House Rocky Mountains Chapter Leader, Tyler Whaley. Great job everyone! Thank you sponsors Xcel Energy and 475 High Performance Building Supply.

Ft Collins Reveal, July 15

The reveal took place during the city’s Building Forward climate event and included remarks by Mayor Jeni Arndt and other city officials! The final results were conclusive:

  • Code Box: 714 lbs. with a 65.9% loss
  • Passive House Box: 1336 lbs. with a 34.7% loss

And we are happy to award prizes, including free conference admission, the International Passive House Awards book and Ice Box Challenge T-shirts to the top three guess – the best coming within 5 pounds of the combined total remaining weight!

It was an exciting day with vendors, Passive House Rocky Mountain members and a whole bunch of new people learning the basics of Passive House in a visceral reach out and touch it sort of way. Great job everyone! Thank you sponsors Xcel Energy and 475 High Performance Building Supply.

Ft Collins Kickoff, July 1

Officially, the Passive House Box started with 2,047 lbs. of ice and the Code box started with 45 more pounds, at 2,093 lbs.

Ft Collins Installation, July 1

Building the Boxes