Solar Experience in Montezuma County

This posting describes my success with simple passive solar principles. Some of these had been learned at an earth shelter house seminar at the University of Minnesota. I made a cardboard model of the house I wanted to build and handed it to a Montezuma County contractor. He built it. That was in 1980.

Standard materials and construction techniques were used. The house was economical to build. PV panels added in 2013 raise its efficiency. Empire Electric buys the surplus power. Here are the details:

• The rectangular 44’ x 24’ house faces directly south
• 4’ X 6’ windows and 6’ double pane patio doors admit the sunshine.
• The doors and windows have clear glass. If building code demands Low-E glass, try to get a variance.
• The objective is to admit all the sunshine that we can.
• Drapes close off and insulate the glass on winter nights and summer days.
• Concrete walls and floor for the lower portion are insulated with 2” rigid foam on the exterior and under the floor to serve as thermal mass. This mass absorbs the heat which has penetrated through the windows.
• It is critical to balance the mass with the amount of glazing. Imbalance will cause either overheating or a cold house.
• The upper floor is insulated with 1” rigid foam outside the studs and 3 1/2” fiberglass between them.
• The 2’ overhang is a permanent awning which restricts sun entry in summer when the solar angle increases.
• A small stove on the lower floor supplements heating. No butane or propane is used.
• A 20 gallon, 120 volt water heater is good for a family size of 3, even 7 when visitors come.
• Countertop oven, microwave, electric stove are used to prepare food in that order.
• A photo voltaic array was put on the south side of the barn in 2013. The installed cost was $15,500 for 14 panels. Rated capacity is 3220 watts.

The best performance centers on the several weeks of mid-winter. The sun angle is then low in our Colorado, and the cold, clear nights change to bright sunny days. The house then takes in enough warmth that temperature in the living space is above 70 degrees until bed-time at 10:00 pm. Although it can’t exactly be felt, heat goes into the concrete walls. But in the floor its warmth can be felt when in stocking feet even near the patio doors.

As I got older (I am now 88) I found myself wanting a wood fire at night even when the house temperature was 70⁰. But now, I can rationalize that it is OK to use a portable electric heater because of the photo-voltaic panels. On a cloudy winter day there will be enough warming radiance coming through the glass to keep me warm when I am engaged in regular household activity. The house is freeze proof. It can be left with the drapes half-closed and the temperature will not fall below 55 degrees. With the drapes are operated every day and night, the air temperature will not fall below 64 degrees.

For summer, there is a 500 BTU wall air conditioner. It gets limited use. The construction keeps the house cool. All appliances and water heating are electric. Monthly usage centers around 250 Kilowatt hours with one person living in the home. Electricity usage may reach 500 kWh if five persons occupy it. A clothes line is used for drying clothes.

Critical to lower hot water use is that the water heater, showers and all sinks are grouped on one wall so that pipe runs were kept to a minimum. A low flow atomizing shower head (Delta 52650-PK) works quite well with a full curtain that confines the water spray and maximize its heating effect.

There is an advantage of wood for the stove being available from the piñon juniper forest.   A hundred years of mismanagement caused the stand to be far too dense and most of the pines were killed in the beetle epidemic of 2003. Before the photo-voltaic panels made electric heat a responsible choice; about one cord was burned in the stove each year.

Ceramic tile was used for the lower floor. It goes without saying that there should be no insulation, no carpeting of this thermal mass.

About the Author

The electric meter spinning backwards
from William's solar

William Hendrickson lived through the depression and served as an engineering officer on merchant ad navy ships during WWII and Korea. He had a career with the National Park Service as manager and ecologist. He married into Montezuma County after meeting a waitress when they both had summer jobs at Mesa Verde. He is working to reduce the immense quantities of energy we all use.