Ridge-Top Passive Solar New Home
Site characteristics or focus during construction:
Main goal was to build an environmentally responsible house. House was designed to take advantage of unobstructed passive solar gain to the south, spectacular views to the east. Provided earth berm on western lower level, garage buffer and minimal windows to the north. Southern and eastern exposure on driveway for snow melt. Intent was to build a “100 year house” by using quality materials and construction techniques.
Insulated concrete forms (TF system) used for stemwalls and retaining walls for energy efficiency and ease of construction. Conventional framing utilizing Forest Stewardship Council (FSC) certified sustainably harvested framing and finish lumber, siding and pre-fabricated trusses. Engineered to minimize the amount of wood required and to use composite products. Features salvaged flooring and interior trim, Trex decking and Hardipanel fiber cement sheet siding.
Passive Solar System:
South facing windows with floor mass to absorb and store solar gain. Lower level is slab-on-grade, upper level has 4” thick layer of gypcrete in living/dining and slab-on-grade at kitchen/dining.
Main Heating System:
Auxiliary Heating System: Hydronic radiant floor system with natural gas fired boiler (also provides domestic hot water). Freestanding natural gas stove in great room provides quick response heat.
Super-insulated roof (R-60 assembly) and walls (R-26 assembly) with blown-in cellulose insulation, additional 1” rigid insulation at exterior walls and raised heel height on trusses for greater insulation thickness at eaves. Tight construction with air-to-air heat exchanger. High performance fiberglass windows with low e high solar transmittance glass and cellular blinds. Fluorescent and compact fluorescent lights throughout and energy efficient light/fan at great room. Kitchen features Counter Production recycled glass solid surface countertops, recycling center, and energy efficient appliances. Clothes drying rack in laundry room and outdoor clothesline (no dryer necessary). Water conservation features include a waterless urinal, pressure assist low flush toilets and Grohe faucets. FSC certified mahogany entry door. Specified concrete with fly ash for foundation and slabs.
Subjective Evaluation/ Design Considerations:
If we could do it over again we would: reduce the overall square footage; eliminate the hydronic radiant floor heating system and install a wood burning masonry heater as backup heat; install solar domestic hot water with a supplemental tankless hot water heater; use environmentally friendly plasters, paints and wood sealers.
Blower door test results: 2046 cfm @ 50 pa pressure = .34 air changes per hour. Recommendations: install electrical cover plate gaskets at exterior and interior switches and receptacles, seal washer hook-up and unused dryer vent, caulk direct vent at gas stove, and provide gasket at attic door. Observed air leakage at “airtight” kitchen recessed cans and air exchanger exhaust vents.
12 month energy usage (8/03 – 8/04) for 2 full time residents: 4712 kwh electricity ($638), 543 therms natural gas ($709), $112/mo. average ($69/mo. low, $202/mo. high). No wood burning stove.