Mark Nussbaum is an MEP (mechanical, electrical and plumbing) consultant and owner of Architectural Consulting Engineers. He specializes in preservation, restoration, and adaptive re-use of historic buildings.  He served as the mechanical engineer for the Unity Temple restoration and has been working with the building for many years prior. During the restoration, he led the project to update the heating, cooling, and water systems, including the main core of that project – the migration to a geothermal heating and cooling system.

A geothermal system uses the deep earth temperature to circulate hot and cool air, as well as produce hot and cool water. According to Nussbaum, the system heats water to 120 degrees and chills it to 44 degrees. Another goal of the new system is minimizing and managing humidity on interior walls. If exterior walls are kept warm, that warmth drives moisture to the outside.

“Interior moisture definitely played a role in some of the external damage that we saw here [at Unity Temple],” Nussbaum explained.

The geothermal system had been in the works for a number of years; Nussbaum was part of a 2004 feasibility study to see whether such a system could be implemented. It took years of investigating, planning and researching, and figuring out how all the pieces fit together. “The mechanical parts [coming together] is a big component of our work,” he said.

Nussbaum and his team are also worked on other mechanical elements. “We provided a new electric service to the building, and rewired everything,” he said. “All the historic fixtures were rewired, [and] brought up to UL code (a standard for electric safety).”

The lighting throughout Unity Temple is now connected to a central lighting control, with the capability to adjust and dim lights in different spaces. have been fitted with LED bulbs.

Plumbing was another key element, with additional storm drainage and some modern piping added to the building for bathrooms and the kitchen. Nussbaum explained that opening Unity Temple to tours was a big impetus for looking at safety elements like exit signs, to ensure that people unfamiliar with our space will be able to safely find an exit.

In addition to Unity Temple, Nussbaum’s company also worked on the Robie House (Chicago), Glessner House (Chicago), Dawes House (Evanston), Dana Thomas House (Springfield) and most recently, Pleasant Home (Oak Park).


Adapted from a 2015 interview with Mark Nussbaum.