The Powerhouse on Union Street – Green Tour Site # 1

A Creative Path To Zero Energy for Two Small Homes

The accessory dwelling unit (ADU) on this property is a powerhouse. Literally. The solar panels on the roof of this small one bed, one bath ADU, produce a “net positive” amount of energy. This means that it at the end of the year, this home nets a positive amount of energy and even nets enough energy to power the main house.

Insulation levels: before and after. If you look closely at the measuring stick, you can see that 22 inches of insulation was added to the attic.

This project is remarkable in that it preserved the original home on the property that was built in 1926, transforming it into a model of energy efficiency in its own right. The owners worked with Green Savers, a local home performance contractor to complete an energy assessment to see where the home was losing energy and created an action plan to make the home as energy efficient as possible. They air sealed the building envelope to get rid of drafts, added insulation to the ceiling and crawl space, blew insulation into the walls, installed an efficient ductless heat pump to heat and cool the home, and upgraded the water heater. Then, they built the new ADU and added solar.

The new ADU was designed to match the style of the original home and is open and bright. Getting to zero energy with the right design is simple: airtight envelope, lots of insulation, and super-efficient appliances. One of the biggest energy-saving features is the Mitsubishi ductless heat pump that heats and cools the home using 50% less energy than a typical electric heating system.

Ductless heat pump outdoor unit.

Ductless heat pump indoor head.

Make sure to ask about: How to design a zero energy home and how to create an energy savings plan for your existing home