In 2005, Martha Rose Construction Inc. (MRC) upgraded the specs in their Built Green Certified homes to include high performance and healthy home features. In 2007, MRC joined the Department of Energy's Builders Challenge Program. Less than 1% of the market builders in the country work under this umbrella, which has a tag line “Research Towards Net Zero.” It charges its builders with striving to reach net zero while still being replicable and affordable. A recent name change better illustrates the goal: “DOE Zero Energy Ready Home.”
With the help of the mechanical engineers that work with DOE on this program, Martha Rose Construction began trying different space and hot water heating combinations. The projects the company undertakes are small by development standards and they are custom designed for each site, even though they are sold on the speculative marketplace after completion.
The goal was, and still is, to find the magic bullet for water and space heating that combines affordability with efficiency and practicality. When the calculated heat loads are extremely low due to super insulation, air sealing, and heat recovery ventilation (HRV), it no longer makes monetary sense to have a fancy heating system. The Building America engineers promote the KISS (keep it simple stupid) concept!
In this article, we will look at the factors that led Martha Rose Construction to try different heating types and the level of builder and buyer satisfaction with each combination. Four projects' mechanical systems will be reviewed and we will end with what is likely the best recommendation going forward for a high performance home.
The author is a builder in the Seattle marketplace, and has made a career in the construction industry for over 41 years.