House 14
Click here to enlarge photos
House #
House Style
Size Ft2
Year Built
Cost/Ft2
14
Earth-bermed, stick-built (advanced framing), super insulated, high mass
1966
1989-96
$75*
Architect/Designer
General Contractor
Sub-contractors (significant) & Type
Howard Cherrington Howard Cherrington Owner
Primary E-Design Factors
Significant E-Products Used
Results—Positive/Negative
Passive solar
Earth-bermed with stepped insulation
Super insulated SPF and XPS(R-30 walls, R-60 ceiling)
PV system 1600W
Dual pane Low-e windows
Steel roof, with snow breaks
Masonry heating stove
Footings insulated with XPS 2’ down and 4’ out from house for [PAHS]
1600W, grid-tied, battery backup, photovoltaic system.

Trace Inverter
Earth berming with differential insulation of bermed wall.
House has been very comfortable.

Owner wished he had installed a solar hot water system (will be installing one this year)

* This cost/ft2 is based on the owner being the builder, if one had it built today (2008), it would be ca. $175–200/ft2
Howard Cherrington designed his first passive solar, earth sheltered house in 1978, and since that time has designed and built a large number houses in the Methow Valley. His interest in the unsustainable, and inefficient way we use energy began in 1974 during the '73–74 OPEC oil embargo . Howard combines the skills of a designer/artist and engineer. His studies in architecture lead him to consider methods for increasing the efficiency of energy usage in housing design. Research lead him to passive solar methods for heating and cooling, which along with earth-berming are simple, time tested, and elegant methods. In addition to energy efficiency, Howard believes that design should minimally impact the site, both visually and ecologically, and reflect other sustainable principles: a house should, to the extent possible, blend into the site, have a quality of workmanship that will allow the house to last for centuries, and use local, renewable materials which have low embodied energy. He retired from construction in 1992, to do house design only.

This house is worked naturally into the hillside, and protected from the prevailing winter winds. It is earth-bermed, and stick built using advanced framing. In addition to the bermed earth for insulation*, the house uses a combination of spray polyisocyanurate, and extruded polystyrene (XPS). The 8" thick bermed concrete walls were given a waterproof coating, and then coated with spray foam insulation which decreases in thickness with depth below the surface (resulting in R-30-–R-10 for the walls). The house is super insulated. The ceiling is R-60, and the walls R-30. Howard has attached XPS sheeting 2' deep on the exterior side of the footings, and then 4' out from the footings around the house; this creates a dry, insulated earth mass below the concrete slab floor of the upper level and is in direct contact, not insulated from, the earth below it—after three years of occupancy the earth beneath the slab stabilized to 62˚F (a concept similar to PAHS).

For heating, the house uses the solar heated masses of the floor slab, and a 16" south facing rock faced concrete wall; to supplement the heating needs there is a masonry fireplace (which requires only a 20–40 minute fire per day in the heating season), and electric baseboard heaters set to 68 degrees to provide a steady state of heating . The masonry heater is a high mass, baffled construction unit designed to burn wood at 1200 to 1500 degrees. He has found that the masonry heater works best if it is fired at the same time each evening (5 o'clock) and releases its heat over the next 6 to 24 hours. It has a ceramic glass front that heats the room immediately. The stove slowly floods the high mass heater with warmth, peaking at about 8 hours, and diminishing over the next 24 hours.The floor around the heater slowly heats up within a month of regular firings. The burn time is dependent on how sunny it is, and how cold the next day is predicted to be. The lower level studio (and small green house/room) is heated with a combination of electric baseboard heaters, the solar heat gain from the green house, and the heat from the earth mass below the concrete slab of the upper main living area (the east wall of the studio abuts the earth mass). Solar heating accounts for 20–40% of the heating needs.

Construction waste was minimized by planning cuts carefully, and reusing the plywood from the concrete forms for sheathing.The bathroom fixtures use low water flow. The kitchen appliances are energy star rated from 1996.The house has a 1600W, grid-tied, battery backup, photovoltaic system, which provides 1/4–1/3 of the electrical needs of the house. The roof is standing-seam steel. The windows are dual pane, low-e, and there are insulated shades for cold nights.

The approach to the front door follows a gentle curve on a hillside with an earth-berm tapered from small side to larger side with beautiful native plants along the pathway (see enlarged 2nd photo). Some of the native plants growing on the earth-berm were taken from seeds around the property and some naturalized. The entry is an air lock space with room to shed jackets, and is an extra way to add more energy efficiency for cold or hot weather. The home interior continues the form of the pathway, with spaces that flow together seamlessly. This flowing aesthetic shows the strength of a Cherrington design.

Builders Advice: Do your research, and find out what has been done in the Valley. Make sure that any architect/designer you hire knows how to efficiently deal with the Methow's extreme climate. Use passive systems as much as possible. Active systems require maintenance and energy. If you can use an earth-berm, it will save a lot of energy.

*
Earth-berming is especially good in dry climate like the Methow because of the higher insulating value of dry earth.