Custom builder TC Legend Homes packed energy-efficiency features into this tidy retirement cottage in Bellingham, Washington, but left out the hefty price tag. The homeowners got the true zero energy home they always dreamed of for a move-in price of less than $144 per square foot.

Natural comfort is provided with south-facing orientation and extended overhangs that block unwanted sunlight in the summer and allow desired solar heat gain in the winter.

A roof-mounted 3.2-kW solar electric system is all it takes to power the home thanks to ultra-efficient insulation and comfort systems. These features helped the home earn the U.S. DOE Zero Energy Ready Home certification.

High-efficiency appliances and water-saving fixtures save significant energy and water.

Low-/no-VOC glues, adhesives, paints, and water-based concrete floor sealer helped the home earn an EPA Indoor airPLUS certification and contribute to a healthful indoor environment.

The open layout allows more buoyant solar heated air to flow to the second floor naturally via the stack effect.

The natural comfort orientation of the TC Legend home is exemplified by the south-facing windows and doors, which allow sunlight to heat the stained concrete slab floors. These thermal mass floors provide a natural comfort balancing system for the home, absorbing heat during the day and radiating it back into the rooms at night. The ultra-efficient windows have insulating triple-pane glass and insulated vinyl frames that keep in the heat while letting in an abundance of natural daylight.

One ultra-efficient ductless heat pump provides all the heating and cooling the small home needs with a heating efficiency (HSPF) of 12 and a cooling efficiency (SEER) of 21.5, far higher than the minimum federal standard of 7.7 HSPF and 13 SEER.

The ultra-efficient foundation insulation in the TC Legend home consists of insulated concrete form (ICF) blocks that wrap the edges of the floor slab in R-28 of high-density foam and concrete while an additional R-20 of rigid foam provides an insulating layer separating the slab from the ground.

TC Legend uses structural insulated panel (SIP) thermal blanket construction. Each panel consists of a layer of rigid foam insulation sandwiched between two layers of OSB wood sheathing.

The SIP panels come to the job site already precision-cut for quick assembly. The 10-inch-thick SIP roof panels provide ultra-efficient attic insulation at the roof line for open interior spaces. Every seam is caulked and taped to provide a whole-house draft barrier.

House wrap is installed over the entire exterior wall surface and integrated with adhesive flashing around windows and doors for a whole-house water protection system.

TC Legend installs durable fiber cement siding for a weather-resistant and pest-resistant home.