LifePoint Hospitals’ new Clark Regional Medical Center (CRMC) in Winchester, Kentucky, opened in April 2012, becoming the first hospital in the state to run on a 100% geothermal heating and cooling system (For more on the project, see Healthcare Building Ideas article "Bluegrass Building").
“CMTA’s been doing this for a long time, but LifePoint called on us to present something to them that was new and innovative, and an energy-efficient design. And this is what we all, as a team, came up with,” says Kevin Sandrella, PE, LEED AP, electrical engineer with CMTA.
When first considering an appropriate type of HVAC system to use at the 79-bed CRMC, geothermal quickly rose to the top of the list, thanks largely to the geography of Kentucky, which consists greatly of underlying rock, says Chris Malicki, AIA, LEED AP BD+C, principal on the CRMC project for Stengel Hill.
Rock, Malicki adds, is a great heat sink, with consistent temperatures year-round. Rock is also easy to drill, which makes a project cheaper to undergo and the system itself more cost-effective to pursue.
However, for hospitals across the country—specifically outside of Kentucky—there are a number of additional issues to consider when undergoing a geothermal project, as well as challenges specific to healthcare that must be combated.
While the use of geothermal isn’t necessarily new to healthcare, Malicki says oftentimes systems are used in combination with normal air handling units. So when it comes to pursuing a 100% geothermal project, there are a few basic components that need to be in place.
First is having the right site.
“We’ll drill an initial test drill to determine if the soil is right. These wells are about 400 feet deep, and it really takes the right combination of layers of dirt, rock, water, and the right strata to be able to drill those wells and get the thermal transfer to and from the earth that you need,” Sandrella says.
The next consideration is whether there is enough room on the site to drill all the wells necessary. For the CRMC facility, 217 wells were drilled.
However, using geothermal in healthcare is particularly challenged by spaces like the OR, where very specific air filtering requirements must be met, such as the static pressure required for final filtration. To find a solution, the team turned to its vendors.
“One of the manufacturers put together a package, which is what we ended up with at CRMC, where they took their standard heat pump and put an extra fan module on top that was capable of achieving the extra static pressure that we needed to get through the final filtration,” says Douglas Hundley Jr., PE, LEED AP, CxA, mechanical engineer for CMTA.
Temperature itself must also be maintained in the OR, which is generally kept cooler than elsewhere in a facility at 65 to 68 degrees Fahrenheit. If cooled with a standard discharge temperature of 55 degrees, the relative humidity will go up.
“You have to maintain a minimum relative humidity in a space or you start to have issues with paper sticking together or something like that, so we had to get a lower discharge temperature off the units to be able to do that efficiently,” Hundley adds.
While there are challenges, a big reason why geothermal tends to be an efficient mode of heating and cooling is that, if applied properly, it can eliminate the constant reheating of air often found in the healthcare setting.
“You spend so much energy in reheat; you cool the air down and then you just reheat it,” Hundley says. “When you break it up individually into multiple heat pumps, we’re never reheating with our heat pumps.”