What is expected to be one of the most energy-efficient homes in Boston began as the workshop for an 1850's gunsmith. Abandoned since 1980, the building was initially destined to be renovated into a passive-energy-use house, but due to structural issues, it is now being rebuilt to the original dimensions.

Led by design and build firm Placetailor, the house began with careful planning. Below are some of the photos from the construction process taken by Martin LaMonica for Cnet.com.

A cutaway view of the wall construction consisting of 12" thick structural insulating panels (SIP). Joints are filled with foam, and taped, to achieve an insulation value of R45, creating a very thermally efficient wall.

Wood strips are placed on the one-inch foam sheathing to provide a drainage plane for any water that gets in behind the siding.

Spray foam insulation was used in the basement to fill leaks and provide an insulated floor.

A Stiebel Eltron electric tankless water heater was used and installed to reduce consumption - each appliance that uses hot water has a dedicated feed, which reduces the amount of hot water that's piped around.

An air tight building was further ensured by creating an insulated hatch between the conditioned upstairs and the unconditioned basement.

(Images: Martin LaMonica via cnet)

Via: cnet / Martin LaMonica