Now that we have the upstairs built out, we’re on to the next portion of the build-out: HVAC. We’re hoping to build a ground source heat pump (widely called a geothermal system) as part of our personal low-carbon approach.

Since we’re on a lake and a pretty robust aquifer, we’re hoping to leverage that with an open-loop system.  We’re exploring using our existing well for the source water and then sending the water on into the lake.

Of course we’ll need permitting, etc. to ensure that we’re working appropriately, but a couple of engineers we’ve consulted have suggested that this is probably the most economical approach.

With the water providing a constant-temperature heat source, we’ll install a heat pump to provide both heating and cooling. Heat pumps can be very energy efficient, but those that use air as their primary source lose efficiency in extremely cold weather. This problem is solved by using the water as the heat source. (see more details here)

While the system will cost more up front, our preliminary estimate is that we will hit the break-even point in 8-10 years. After that, we’re ahead of the game. And offsetting the high up front cost is a 30% tax credit for systems installed prior to 12/31/2016.

We have a couple of hurdles to overcome in the process including flow-testing our current well and getting the permitting lined up for the open-loop approach. But we’ve got it kicked off and hope to have it completed later this fall.

Check back for an update next month.