Aspen’s mining era aids in one-of-a-kind electrification solution
By Ken Urbanek
Sometimes our greatest ingenuity is right under our noses. Such was the case with our design of the City of Aspen’s new city hall, which included a one-of-a-kind geoexchange system that uses the site’s below-grade dewatering system to create usable energy for heating and cooling. Going into the design process, we knew that our client wanted the building to be zero-carbon-ready, so that meant we would be going down the electrification path.
Our design team initially pursued a traditional vertical bore geoexchange system to meet the city’s carbon reduction goals and the needs of the building, but the excessive cost and limited area for the wells in the mountainous site proved to be problematic. But in conversations with the owner and seeing what was really happening in the dewatering system located beneath the existing parking garage adjacent to the site, our team discovered a unique opportunity for an alternate type of a geoexchange system.
We found that Aspen’s history as a mining town presented a unique opportunity for an alternate type of geoexchange system: The town’s mines greatly impacted the underground water dynamics of the valley, which meant that each minute 1,000 to 1,500 gallons of water were gushing through an adjacent 1980s-era parking garage’s dewatering system. Since the new building would be connecting to this parking garage, our team harnessed this energy source by connecting it to a series of buffer tanks and heat exchangers to create usable energy for heating and cooling.
The temperature of the water running through the system averages below 45 degrees F, providing the city hall with a free cooling source. Running the water through high-efficiency heat pumps provides hot water for not only the building but also for snow melt on the city’s public walkways and a grand staircase on the site.
Although it was a significant opportunity, intercepting and integrating the site’s below-grade dewatering system was a difficult constructability task due to the tight below-grade interception location and the consistent flow of ground water. But the benefits outweighed the difficulties, and the system ultimately saved the owner the cost and physical space required of a more traditional system while also avoiding the need for drilling wells, which would have been a disruption to the resort town.
This one-of-a-kind mechanical infrastructure system sets a new precedent for sustainability in the mountain region and the greater Colorado market and contributed to the project’s LEED Gold and WELL Silver certifications. The project also won a 2023 ACEC Colorado Engineering Excellence Award for its innovative design. By keeping our eyes open and always looking for opportunities to try innovative solutions, we are able to push the envelope with high-performance buildings.
