Geothermal as part of the high performance home system
In a high performance home, the tight building envelope and the geothermal HVAC function as part of a system.
According to Mark Sullivan, Bosch Thermotechnology national account manager, "What ever you do with the building envelope will enhance your geothermal performance and your geothermal performance will help you get the most bang for your buck out of the building envelope enhancements."
Sullivan cited the example of a 2,000 sq. ft. house built with standard wood framing and brick cladding. Typically that common type of house would require HVAC with five to six tons of heating and cooling capacity.
"But, if the home is built with attention to detail and building science enhancements, such as upgraded windows, doors and insulation, then there's a concomitant reduction in HVAC requirements.
"You will need three to four tons of HVAC capacity, so consequently you can reduce the cost of your HVAC system by building a better house.
"The smaller HVAC system will do the job at a lower cost, because it's cheaper to purchase and uses less electricity. And, the homeowner will have a greater level of comfort because you've done the things with the envelopes that will keep the home from having hot and cold spots and those kinds of things. And then, you can talk about hot water such as solar or high-efficiency water heaters, in many cases you can still use your geothermal unit as a hot water assist provider with those systems."