After years of telling friends, "When we remodel our house to Passive House standards we will use 80% less energy than similar homes in the area," and crossing our fingers that the data proved out, we are delighted to share with you our first year's energy data for living in Midori Haus.
What is Midori Haus? The name simply means "green house" since Midori is the Japanese word for green and Haus is the German spelling for house. The house was originally built in 1922, a California Bungalow on the westside of Santa Cruz, California. Soon after we bought the 89-year-old house in 2010 we discovered Passive House and was convinced that it was the right approach for the remodel. Graham Irwin of Essential Habitat did both the architectural design and passive house consulting. Taylor Darling of Santa Cruz Green Builders took on challenging and interesting work and boy did he deliver! Patrick Splitt of App-Tech designed the solar thermal system and Duane Wilson from Wilson Hydronics installed the system. The house we bought had good bones and showed signs of deferred maintenance. So we kept the foundation, most of the framing, floor and roof. Everything else was replaced. Deconstruction began in December 2011 and we moved in March 2013. The house was comfortable.
Our total energy data for the first year of occupancy (March 2013 - February 2014) was only 4,334 kWh. This includes both electricity and natural gas. We use solar thermal for hot water but we don't have PV (yet) to offset electricity usage. When I compared our first year energy usage with the prior occupant's usage I felt validated. We did indeed use 80% less energy than the prior occupant!
When we did the baseline blower door test on the original house it came in at 22 ACH. When George Nesbitt of Environmental Design/Build performed the final blower door test it came in at 0.59 ACH. Taylor and his crew did a meticulous job of air sealing. Terry Nordbye of Practical House provided advice to the crew on air sealing techniques.
By the way, if you've watched Faith Morgan's Passive House Revolution Film you'll see some mid-construction photos of Midori Haus.
For future reading about Midori Haus I invite you to visit the Midori Haus blog.