Geothermal is the new Steam Punk
There are a few things we are doing in the building that are foundational to hitting carbon positivity. A big element is adding geothermal. For those new to this heating and cooling system, and really I never get bored thinking about it, this system takes advantage of the consistent 55 degree ground temperature, below the 3 foot freeze zone. On the side lot next to Narrow Bridge, we dug 7 geothermal wells, each 470 feet straight down. The wells are about 4 inches in diameter. Each well has a hose that loops down and then comes back up, all connected into the building.
It was a beautiful moment to see how the “circulatory system" of the geothermal loops work. The Arts Club on the ground floor will be heated and cooled with radiant floors. The coils (who knew they would be such a beautiful red) loop back and forth over the entire floor. Now that the concrete slab is poured, the 55 degree water running throughout will keep the entire space cool by the reflected temperature of the floor. There will be no “air conditioning” rather “floor conditioning”. There are no hot and cold air ducts, rather a subtle and wonderful even temperature across the entire place.
It works similarly in the winter. The water that loops through the hoses in the floor, down into the wells, and back up through the floor, and across a heat pump that heats the coils. The way this system works it is a closed loop that efficiently heats off the 55 degrees ground temperature and only needs to get to 70 degrees. That is a lot less than the air temperature in Chicago, which in the winter get below zero.
In the end, all the gorgeous drawing with red hoses and the looping water system is invisible. The concrete wa poured and is curing. While it is beautiful to begin to see the space get a more finished look, I don’t know if I have even been more delighted in this process than looking at those looping tubes and seeing how we can efficiently heat and cool such a big space.
However, the choices in how to attempt rigor with regard to carbon are NOT clear. The materials going into this part of the project, in particular the rigid foam and the concrete, are some of the highest “pluses” we are adding to our ongoing carbon “accounting”. I am so lucky to be working with Charlie Vinz, architect and friend. We are looking at the carbon birth, life, and death of this building. So much of the carbon “cost” in construction is not considered and does not include the carbon used in the creation of a building, or even worse, the death of buildings. Construction waste is a huge carbon burden. When buildings are rated, it takes into account how the building will “live”, its heating, cooling, lighting etc. Narrow Bridge is an experiment with more truthful accountability.
As such, we have given ourselves a “carbon credit” for the building, all the brick, all the steel, all the wood, already in the building. These are items which, had this been sold to the other bidders, would have ended up in landfill. If I had my druthers, we would not add concrete to this building, as it is a big carbon “cost”. However, it is the most efficient heat and cooling sink. We graded the floor to pour as little concrete as possible. We will look at the carbon calculation at the end, but likely, almost certainly, we know we will go over the “credit” we have for the existing materials in this retrofit. It is better than tearing the whole thing down and starting over, for sure, but it is still a humbling experience to really look at materials in a project and not ignore the hard choices, even when they are towards a better system for the “life/use” of the building.
