The owner of this condo, in Lyons, Colo., came to Dusel Custom Builders to remodel her kitchen and to address energy-efficiency issues revealed by an energy audit. The goal: an energy-efficient home on a $25,000 budget.

Company owner Clay Dusel says the team used the original audit’s infrared images to identify leaks in the thermal envelope but worked with another consultant, Mark Bloomfield of Sustainably Built, to make decisions about upgrades. Bloomfield is working with the maker of a new testing software called OptiMiser designed to help users calculate the return on investment for different upgrades.

The condo, part of a four-unit building, offers energy-efficiency advantages, Dusel points out, because there’s less exterior wall to insulate. And, he adds, as energy prices climb, an insulation package is an easy sell to homeowners.

For the interior walls where Dusel removed drywall, he filled the stud bays with Icynene open-cell spray foam and added ½-inch rigid foam to form a thermal break under the new drywall. In areas where the existing walls remained intact, he removed the exterior T1-11 siding, installed 2-inch rigid foam, then replaced the siding. He had the exterior insulation cover the rim joist, a “notoriously leaky part of all homes — and one that can be difficult to repair.” Dusel didn’t install rigid foam on all the walls because the exterior faces were complicated and replacing the siding was cost-prohibitive.

Condensation resulting from the 35-year-old condo’s poorly vented fiberglass-insulated ceiling had caused the roof sheathing to rot. The roof had already been replaced; Dusel sprayed Icynene foam between the rafters. He also pulled up sections of the subfloor and sprayed foam on the rim joists.

Once the remodel was complete, the homeowner hired a solar contractor to install photovoltaic panels. Due to the other energy upgrades, the solar system was 40% smaller than originally designed.

Dusel believes that with all the improvements and the solar system, the condo will soon be close to a net-zero house. He doesn’t have proof yet because it will take a full year to track the home’s solar use, and the solar panels have only been in place for six months. He wrote a blog about the project with the aim of educating homeowners about the various cost-effective energy-efficiency options they have when remodeling.

This is a longer version of an article that appeared in the June 2011 issue of REMODELING.