In 2010, we retrofitted our 4773 square foot (including 75% finished basement) home in suburban Denver. The home was built in 2000 with conventional construction, nothing over the top as far as insulation, windows, and efficiency go.
Shortly after moving in we had a blower door test done and learned about where we had insulation inefficiencies throughout the home. We added more insulation to the attic taking it from an R-30 to R-60. The basement was unfinished at the time so we made sure it was adequately insulated as well and increased the minimal R-13 insulation to a R-21. We also had all ductwork sealed which reduced air leakage from 20% to less than 3%.
For the geothermal residential retrofit we drilled eight 300-foot loops on the North side of the home. We planned ahead and added additional loops for a future 1990 square foot metal shop we were going to build in the next few years. All eight loops were manifolded into a common header and connected to the 5-ton geothermal water to air heat pump in the home as well as a 5-ton geothermal water to water heat pump for the shop. The pumping system utilizes high efficiency ECM pumps that save approximately 70% of the energy typically used with a common pumping system.
The shop was built with radiant tubing in 5 inches of concrete all spaced 6 inches apart and batt insulation in the walls and ceiling at R-25. There is a total of just under 4000 feet of 1/2 inch pex tubing for the radiant floor heating system. Sixteen loops approximately 250 feet long each made up the radiant floor which allowed the geothermal system to operate at a lower temperature for heating and reduces heating costs in the worst months of the winter. The shop averages about $20-30 per month while the house averages about $60 a month for heating and cooling. The only natural gas used in the home is for 2 gas fireplaces, used for aesthetics only.
The comfort level and overall aesthetics of the geothermal system are what we as homeowners love the most. The three level home can easily be warmed up or cooled down very quickly, is quiet and extremely comfortable. And with lots of outdoor family time, the loud, outside air conditioning condenser is not missed! Installing the most energy efficient heating and cooling system can be done in all types construction. Retrofits are very successful and will save the homeowners money when designed and installed appropriately.
Kari Rau is co-owner and VP at Colorado Geothermal Drilling and CEO and owner at HGB Home Co. LLC. She holds the title of World’s Okayest Mom, is a serial chips and queso addict, and loves to gossip about geothermal to anyone who will listen.