D.C.'s Ice Box Challenge

The ice box challenge at Farragut Square in Washington, D.C., on July 20, 2018. Photo Credit: Kirstin Fearnley.

Between July 7 and July 20, a park in downtown Washington, D.C., played host to a public science experiment. The Ice Box Challenge considered whether conventional building structures or passive solar building structures were more energy efficient.

Two small structures, brightly painted and approximately the size of a bus shelter or a backyard shed, were erected in the middle of Farragut Square. One adhered to standard U.S. building codes. The second was built to European Union super-insulated passive solar house standards, Passivhaus. On July 7, 1,800 pounds of ice blocks were inserted into the buildings, which were then sealed for two weeks. During that time, the high temperatures ranged from 82°F to 98°F and included six days where the temperatures were over 90°F.

The public was invited to guess how much ice would remail in each building when they were reopened after two weeks.

On July 20, a group of dignitaries gathered to announce the results, including Dirk Wouters, Ambassador of the Kingdom of Belgium to the United States of America, and Caroline Vicini, Deputy Head of the European Delegation to the United States. They shared why this was such an important experiment in the wake of the 2016 Paris Agreement, in which nations of the world agreed to combat climate change and promote a sustainable, low-carbon future. (President Trump has announced his intention to withdraw the United States from the treaty in 2020, but many municipalities across the country have signaled that they will continue to work toward the treaty goals independent of federal policy.)

So, how much ice remained in each house after two weeks of exposure to D.C.'s summer heat? The conventional building had 463 pounds, or 26%, left of the original 1,800 pounds. The passive solar structure retained 838 pounds or 47%.

the results are in: 463 pounds of ice remain of the original 1,800 pounds stored in a structure adhering to conventional U.S. building code (left), while 838 pounds remain from the structure that adheres to E.U. Passive Solar design code. The pipe indicates the size of the original block of ice. Photo Credit: Kirstin Fearnley.

What makes a structure built using passive solar design different from one built conventionally? While the use of the word solar brings to mind panels added to a building's roof, passive solar design is actually quite a bit different. Instead, it involves building an air-tight structure and uses triple-paned glass windows and thicker walls and floors constructed with materials dense in thermal mass to provide insulation. Those materials may include sandstone, cement, marble tile, concrete, and adobe. Passive solar buildings rely on a heat- and moisture-recovery ventilation system to keep interiors warm in the winter and cool in the summer. You can learn more about passive solar buildings in Science NetLinks' three-part green invention lesson series for grades 6–8: Mitigating Climate Change through Passive Solar DesignDesigning a Building Using Passive Solar Energy, and Modeling Passive Solar Homes.

While greenhouse gas emissions are often associated with forms of travel, it is actually buildings that do much of the damage. In Washington, D.C., for instance, 74% of greenhouse gas emissions come from heating and cooling buildings. Passive solar buildings reduce greenhouse gas emissions while simultaneously reducing energy consumption and cost at only a tiny increase in original building costs.

The D.C. edition of the Ice Box Challenge was presented by the European Union, together with the Embassy of Belgium, Golden Triangle Business Improvement District, Nicholson Kovalchick (NK) Architects, the Office of the Secretary of Washington, D.C., and the District Department of Energy and the Environment.


Your email is never published or shared. All comments are reviewed by Science NetLinks before they appear on the site.

Did you find this resource helpful?