The mission of the Green Building Initiative is to accelerate the adoption of building practices that result in energy-efficient, healthier and environmentally sustainable buildings by promoting credible and practical green building approaches for residential and commercial construction. To accomplish this objective buildings are scored on a seven point scoring system for Site Design, Resource Efficiency, Energy Efficiency, Water Conservation, Indoor Air Quality, Homeowner Education, and Global Impact. The design and construction of this home addresses all of these issues.Site Design
When Beth and I first walked the land as we were designing the home we located an abandoned logging road, a windrow of abandoned and rotted stumps, a truly Ancient Oak (which we immediately cordoned off with yellow caution tape), and a flat area at the top of a rise over the creek that was bordered to the north by a rock out-cropping with natural washes to the NW and NE that were populated with native ferns.
We brought the driveway in through the old logging road and stump piles, harvesting the rotted stump soil and stockpiling it for future gardening. We cut a notch in the hillside and set the home along the north side of the notch to maximize solar gain and provide a garden area to the south of the home with a retaining wall for Noreen to do her morning gardening ritual. The subsoil was carefully pitched to drain gradually to a 150' x 4' x 12" French drain / rain garden that forms a crescent through the center of the garden and receives all the rain fall from the hill side as well as the gutters allowing the water to persist in the garden and nurture the native plants we are establishing there. An 80' long drystack stone wall rises out of this French drain and divides the garden into two zones. Geneva Green from Greenstone Gardens was brought into the project as construction was just beginning and worked closely with the crew to protect the ferns and trees during construction. The landscaping was started before the roofing and siding were complete.
The home itself is a passive solar design set on a radiant heated slab with two glazed shade trellises in addition to two porches easing the transition to the gardens. Foot paths are permeable glacier jack pebbles. The home has 32" roof overhangs with 5" gutters so that the cedar shingle siding can be left un-painted to reduce both VOC's and maintenance. It is also has a solar heated radiant floor system with two panels on the roof that warm the floor and also provide domestic hot water with the assistance of a Rinnai propane fired demand water heater.
Because we are located in a hurricane prone area the home has extra steel reinforcements and 100% OSB wall and roof sheathing. In NC we say it's not the wind so much as the flying trees that you need to worry about.Durability and Resource Efficiency
We consider durability and reduction of maintenance to be critical elements of our design and construction philosophy. We use hurricane hardened "advanced energy framing" techniques, galvanized steel termite proofing, enhanced foundation water proofing, under slab radon and humidity ventilation through the roof, covered entry porches & 32" roof overhangs, obsessive Tyvek taping, aluminum clad energy star windows with steel pan flashing on the sub sills, and engineered fresh air make-up system designed to provide 7.5 cubic feet per minute of "balanced" fresh air per occupant. The variable speed 14 SEER heat pumps were double engineered in collaboration with our Energy Star certifier and our AC installer providing independent load calculations and cooperating on the system design to enhance de-humidification.
For us the key to resource efficiency is waste reduction which means getting the right materials to the job just as they are needed and clearly communicating with the crew what material is intended for what location. Our Excel based material pick lists identify the destination and use of every stick in the drop and help on-site people to identify shortages before they are dire.
Land fill fees on this job were less than $250 for construction debris. All brush and root debris was mulched off site by Carolina Resource Recovery. Trees were cut up for firewood. Cardboard and bottles were recycled by the crew and at least three loads of re-cycling were hauled by the boss. (Who can recycle and talk on the cell phone at the same time.)
Recycled content materials on this job, in addition to fly ash concrete, included three pallets of industrial scrap soapstone that we purchased for $200 per pallet and used to build all the vanity tops, the fireplace hearth, part of the kitchen countertop, and window sills and shower seats.
This home was designed in collaboration with our friends at Southern Energy Management . Once it was complete they came back to run blower door tests, duct blaster tests, and computer performance modeling. According to their calculations it will use 38.5% of the energy required by a house of the same size built to NC code standards.
It is also a home built in keeping with the Not-So-Big guidelines promoted by Sarah Susanka . So not only does it use less energy than other houses of the same size but it also is not so big to begin with. The fact that Beth Williams draws with pencil instead of a computer helps her to get right down into the house and maximize the usefulness of the space with in the walls and of the space surrounding the home that we like to call the "outdoor rooms."
The home is built on a radiant heated slab that is linked to the two solar panels on the roof. We have noticed in our homes that feature solar water heating that the tanks are often up to 170 degrees by the middle of the day. Since it is hard to heat water that is already hot the panels decrease in efficiency as the temperature of the storage tank rises. Since we have an energy efficient Rinnai instantaneous water heater we can afford to push all the solar heat the slab can use out of the storage tank and cool that tank to 76 degrees at which point it's ability to absorb solar heat is optimized. For days when the sun doesn't shine or when it shines too brightly there are two variable speed heat pumps for back-up heat and for AC.
The best way to save energy is not through super efficient heating and cooling systems but through simple energy conservation. The home is insulated with 5 inches of spray foam (Demelak ) in the walls and 8" in the roof. The windows and appliances (except the stove) are energy star rated. Wide roof overhangs provide shade in the summer while large amounts of south glazing let the sun warm the home in the winter. There's nothing new about this, just common sense and careful craftsmanship. Because the house needs so little energy to begin with we don't have to work so hard to supply the energy it needs.
While this home is on a large lot with a good well we still felt it was part of our goal to minimize water usage. We used water conserving shower heads, toilets, and faucets (except on the luscious bath tub.) We minimized water usage on the landscape by using native plants and planting no lawn. We created an eighty-five foot by four foot on-site storm water retention system in the guise of a rain garden that holds a huge amount of water under and behind the dry stack stone retaining wall and releases it slowly into the soil rather than letting it rush down the hill to the creek.
Indoor air quality was of moderate concern in this home but we built it in an attempt to meet NAHB Green Building Initiative Gold Level so we put a number of indoor air quality features into the design. There is no carpet all interior finishes both the paints and the clear wood finishes are Low VOC (Volatile Organic Compounds.) The OSB plywood in the framing and the particle board in the cabinetry both meet Low VOC standards. We used plasticizer free grouts and tile adhesives (would not have known this was an issue if not for the GBI.) The gas fireplace in the den, the wood stove in the living room, and the Rinnai water heater are all sealed combustion devices that draw their combustion air from outside the house. The area under the slab is ventilated to allow radon and other nasty gases to escape through the roof.
The GBI and Energy Star both encourage builders to "provide 7.5 cubic feet per minute per occupant of balanced air exchange." When we first read this we were pretty baffled as to what they were requiring here but it turns out not to be so complicated as they make it sound. Basically it means running a 100 CFM Panasonic bath fan for one hour for every 12 hours that the home is occupied by one person. We accomplished this by putting timers on the bath fans. The "balanced" part means that you have to dedicate a vent to allow filtered outside air into the home to balance the air that is removed by the bath fans, range hood, or clothes dryer. Since the clothes dryer can remove 300 CFM of air from the house when it is running we locate this intake damper in the laundry.
|10 x 14 garden shed with extended eves|
We use a paper/digital "welcome letter." This is a simple letter welcoming the homeowners to their new home and sharing the phone numbers of key trades who helped to create it along with a narrative describing maintenance, green building systems, emergency shutoff locations, local recycling programs, and the phone numbers of painters and a handyman service for minor repairs. This letter is presented along with a CD ROM containing a digital copy of the letter along with key documents such as the termite certificate the certificate of occupancy, product PDF's, draw requests, specifications, selection worksheet, change orders, projected construction schedules, and digital photo's of the construction of the house and a digital copy of the blueprints.A Lot of Green for the Green
The key "green" elements of this house that cost extra were the solar collectors ($5,900) and the spray foam insulation ($4,400 extra over fiberglass) The benefits of the solar include $1,400 of state and $1,170 of federal tax credits in the first year along with reduced environmental foot print and energy costs and guilt free soaks in that giant bath tub. The benefits of the spray foam insulation include reduced noise and dust and improved comfort esp. in the summer when the ductwork is inside the conditioned envelope. We don't provide "Payback Calculations" on the grounds that we would not provide such a calculation on a granite counter top so why should we provide one on reducing global warming. But these increased costs should prove to be a good investment for as long as these owners stay in their home and can only increase in re-sale value as the cost of energy increases.Aging in place design
This home also features accessibility features designed to keep its owners living there for a long, long time. All doors are 2'8" wide; access from the street is step free. Access to the shower is handicap friendly. All door knobs and faucet handles are levers to accommodate a person with stiff hands. Framing for grab bars in built in and documented by digital photographs which are part of the CD ROM homeowner's manual.