New research shows that underground heat given off by buildings is growing and is a potential risk to the environment and general infrastructure. Rising underground temperatures may be compromising the safety of civil structures.

Most underground structures, such as basements, parking garages, subways, and tunnels, release heat that warms the rocks and soil they were built in. Over time, geological layers expand and contract, and potentially damage the supporting rocks and soil and risk shifts. Excess heat can deform rocks and soil, and, potentially, the construction materials embedded within it.

One major study in Chicago’s Loop involved the usage of 150 temperature sensors throughout the surface and subsurface environment in the Chicago Loop to determine trends and correlations between outdoor and subsurface temperatures throughout the seasons in building basements, parking garages, and tunnels.

Analysis of the temperature readings showed strong correlations between the temperature at the surface of the Loop and those in certain underground structures, based on how deep the structure is and the use of the area. Building basements tended to be hotter because of boilers and other processes used there. Older buildings generated more heat, presumably, because they are less energy efficient to use waste heat. However, whether heat is generated in the space or not, higher-than-expected temperatures were measured. In addition, these higher temperatures could, in time, cause millimeter-level soil deformations. The researchers believed this would not compromise structural integrity but may worsen operational efficiency.

It should be noted that these results may differ in other areas based on the density of big buildings, their uses, the soil structure (Chicago has high-clay soil which conducts heat more than rock), and the location of Lake Michigan and the Chicago River not far away (acting as a heat sink).

Therefore, if excess heat is produced and found in underground structures and tunnels, might it be part of the solution for Climate Change and energy efficiency? Might ground source heat pumps be able to use some of the underground excess heat and displace some electricity and fossil-fuel-powered heat/steam generation for comfort? Thus, excess heat may represent an opportunity. Heat maps could potentially be developed to identify the best locations to remove excess heat (reducing collateral damage) and use it for heating buildings or hot water production.

CCES has the experts to help you determine whether air- or ground source heat pumps might be a solution for you to reduce your energy usage and costs and reduce your greenhouse gas emissions, too. Contact us today at karell@CCESworld.com or at 914-584-6720.