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Chicago
The warming caused by underground car parks and public transport puts a strain on buildings.
The earth beneath our cities is warming — and that warming is threatening the buildings, transportation systems and bridges we use every day, according to a new study published in Communications Engineering.
In cities, concrete and steel buildings can conduct heat absorbed from sunlight through their foundations to the ground. This, combined with the heat given off by underground parking lots, electric cables and public transport, can result in temperatures below cities much higher than at the surface.
The research analyzed an area of Chicago and used a 3D computer model that simulated how rising temperatures would affect the subsurface environment. The simulations spanned a century, from 1951 to 2051, and revealed a “silent but”. possibly problematic Effects of underground urban heat islands on the performance of civil structures and infrastructure”.
Soils with finegrained clay sediments, as is the case in Chicago, are particularly prone to shrinking or swelling with heat and water. Buildings are unlikely to collapse due to slow heatinduced deformation, but even these small changes can stress or mobilize foundations affect the durability of buildings over time.
Ground temperatures in Chicago are currently warming at about 0.14°C per year. The study found larger variations in ground temperature in the northern, more densely builtup portion of Chicago’s Loop borough compared to its sparser southern end, Science Alert explains.
The temperatures in the various soil layers varied on average in the district between 1°C and 5°C. Depending on the soil type, the higher temperatures led to displacements of 8 to 12 millimeters under different buildings.
There are already a few cities to try reuse waste heat From transportation systems like the Paris Metro to home heating and hot water systems.
This heat recycling is a viable idea that may become more necessary as the world warms.