Deep energy reduction in an un-renovated c 1880 farmhouse at Raven Rocks
by John Morgan
I was inspired to strive for a specific deep reduction in home energy use in 2009 when I learned about the "Thousand Home Challenge" (THC). See the box for a short explanation.
The old farmhouse I live in was originally heated by wood with a three flue central brick chimney, then a coal furnace, followed by heating oil. Raven Rocks had rock wool insulation blown into the 5" rough-cut stud walls soon after purchasing the place in 1979. To make room for the Raven Rocks Press print shop in the basement, we replaced the furnace with a used cast iron boiler with baseboard hot water heat in the early '80s. I added two extra panes of glass to the old single pane windows.
When I first tried to meet the THC Option B, I dropped the winter heat to 50 degrees, from the previous low 60s, and made all the other energy reductions I could think of. (In case you are wondering, I live alone.) I was shocked (challenged) to discover I wasn't even close to meeting the THC, which forced me to face the decision about how to upgrade the heating system. I had considered a new efficient boiler or thermal solar with radiant heat.
My ultimate goal is to renovate the house toward the Passive House standard (see box), which will eliminate the need for a conventional heating system. I was learning that a small super efficient, ductless mini-split heat pump (DHP) may represent the optimal heating system for a house built to the Passive House standard, though one unit would be considerably too small to heat a whole conventional house. I decided to experiment and installed the smallest and most efficient Fujitsu DHP available at the time, December 2010.
The unit, rated at 9000 Btu, runs efficiently over its capacity range of 3,000 to 22,000 Btu. I expect it to be an appropriate heating solution after the house is renovated toward the Passive House standard, but it is too small to heat the entire unmodified house to normal comfort levels. However, three winter days after the installation, I decided I could live with the DHP as my only heat source and tore out the old boiler.
The first year after installing the DHP I met the THC with room to spare. In 2012, my second year with all electric DHP heat, I had the lowest total electric use in my 32 years in the house. The DHP is located in my office, where I need the heat the most in winter. It is a modern version of having a stove in the living room. The minimum heat setting is 60 degrees, so my winter comfort level has increased, except on the coldest days. I plan to add PV panels to generate electricity.
For more information on this and other THC cases see: www.thousandhomechallenge.com/case-studies
The compressor for the heat pump is on the outside wall next to the window.
Interior component of the ductless heat pump.
Pre & post annual energy use compared with THC Option B
Energy use over time (converted to kWh)
Energy consumption by end use (in kWh)
John M. Morgan, 53650 Belmont Ridge Rd., Beallsville, OH 43716 • 740-926-1481 • email@example.com