The Urban Permaculture Farm Magazine

Design Objective:

This home was designed to meet the constraints of a lot with 20’ frontage and fit on an infill lot “grandfathered” by zoning regulations as well as blend in with the neighborhood’s many smaller homes, especially shot-gun style homes.  The home was designed to produce more electricity than it consumes, take advantage of the sun through both passive design and active systems to provide heat in the winter, and harvest rainwater for non-potable use.  Further, the home is designed to minimize energy usage using reasonably available technology at a cost no more than 25% beyond the cost of a similar home and that extra investment having a payback of 10 years.  Simply, I wanted to show that it is possible to build an efficient home at a reasonable size for a reasonable price in an urban area.

Design Features:

The home is 16’ wide at the front and 82’ long including the front porch and rear-load garage with alley access, taking advantage of the New-Bern Edenton Neighborhood Conservation Overlay District zoning rules allowing zero lot-line building and the “grandfather” clause allowing a single-family home to be built on a lot that was existing and unimproved when zoning laws were put in place.  The kindness of a long-time resident allowed for the removal of a fence (to be upgraded and replaced) and temporary use of some of her land (to be landscaped upon completion) for construction access.

The home is a shot-gun style design.  From the outside, it will have a traditional appearance with Hardiplank lap siding combined with board and batten siding created from Hardiplank and genuine Cedar shakes in the 4 gables.  This gives the home a fire-resistance and some insulating value.  The rear-load single-car garage will be accessed off the former Selwyn Alley.  Landscaping will be based on primarily indigenous plants needing very little or no water.  Landscaping on the rear adjoining lot (to be combined with the existing lot post-construction) will consist of a firepit with a boulder seat wall, a paver driveway to use as a combination patio and parking area, and a vegetable garden designed to provide a significant portion of the homeowner’s vegetable supply.

Inside the home, a more modern style is apparent on the first floor.  There is a 2 story livingroom, open to a dining area and galley-style kitchen.  The floors are sealed concrete, part of the construction slab.  They contain tubes for radiant floor heating and provide thermal mass for passive solar heat storage.  The south-facing windows were designed to allow sun to enter during the winter months and shade the home using overhangs and shutters during the summer months.

The first floor also contains a full bathroom and a bedroom, as well as a rear entry area to the screened porch and garage.

The second floor of the home contains a home office for the owner overlooking the livingroom, but partitioned off using antique stained-glass windows from a pub in England.  This provides both sound and air-flow control.  At the top of the stairs is a functioning skylight which will provide a natural chimney effect for cooling when opened.

The next room is a master suite, with a cathedral ceiling covered in wood.  This allows for heat to rise during the summer, minimizing the use of air-conditioning.  The Master bedroom is open above an 8’ wall to the master bath, which features a glass-mosaic shower and a large walk in closet.

Clever location of windows and glass doors has allowed for a Downtown Raleigh skyline view from both rooms upstairs.

Structural Systems:

The home was designed to take advantage of multiples of 4’ sections – the standard size that materials come in.  This minimized the waste from the construction.  Further, all waste was segregated and anything that could possibly be recycled was recycled.  Materials were sourced locally wherever possible to minimize transportation costs.  The framing was completed using Advanced Framing Technique – 2x6 studs 24” on center rather than 2x4 studs 16” on center as well as using one sill plate and one top plate rather than two.  This method uses about 15% less lumber and allows for more insulation and fewer thermal bridges.  The home is insulated using Icynene Sprayfoam.  This method seals every gap and crack in the home and provides extremely high R-Values.  The roof is standing seam metal – designed to last indefinitely and eventually can be recycled.  All windows and doors with the exception of the antique door to be used at the front of the home are Energy Star Certified.  The antique door will be installed to modern standards.

Mechanical Systems:

The home is heated by radiant floor heating – tubes of water heated by the energy of the sun and stored in a super-insulated tank in the garage attic will circulated warm water through the concrete slab on the first floor and in between the floor joists on the second floor to provide a continuous, gentle heat.  The absence of air blowing improves indoor air quality as well as comfort in the winter.  If there is at least 5 hours of sun during a day, even on the coldest winter days, there will be no energy consumed for 24 hours heating the home.  On totally cloudy days, a gas demand water heater will provide a backup heat source.  In addition, there will be 3 direct-vent gas fireplaces in the home which will use exterior air for combustion.  The solar portion of this system is eligible for a 30% Federal Tax credit and 35% NC tax credit.

Cooling will be provided by a Quad zone Ductless Mini-split system (36,000 btu).  This system is highly efficient with a SEER rating of 18.5 and no loss in efficiency in ductwork.  Typical ductwork experiences losses of about 30% of efficiency.  The house is divided into 4 zones and each zone is individually controlled, allowing for minimal cooling of unused areas.  This system is technically a heat pump, so it provides a 3rd backup for the radiant floor system, or a way to take the chill off if the morning or evening is cool but the owner does not want to heat the slab for the entire day.  Energy Star ceiling fans in the living room, study and each bedroom will provide air circulation to minimize air conditioning needs as well.

In a home built and sealed as tightly as this one, fresh air exchange can be a problem.  This home will use a Broan Smart-Sense system to allow a controlled amount of exterior air to enter the home when needed to exhaust stale air from cooking or bathing.

Electrical Systems:

The home will generate about twice the electricity it uses from the 4.7K Photovoltaic system on the roof.  This electricity will be sold to Progress Energy and provide a financial return to the owner.  In addition to the return from the combined 65% tax credits in the first year, annual payments from the utility and SREC credits will be received.  This means the sale of electricity will cause the upgrades in this home to have a payback of approximately 10 years.  The systems will last approximately 40-50 years – continuing to provide a financial return and help the community by generating clean energy.  Light fixtures and appliances are Energy Star rated wherever possible, and compact fluorescent bulbs will be used.

Plumbing Systems:

Although the cost of water is not extremely high in Raleigh, the City has experienced some droughts and a reasonable person could easily project an increase in water costs as development and growth in the City continues as projected.  This house will use City supplied water for drinking and bathing, but it will store and use up to 1200 gallons from each inch of rainfall.  This water will be filtered and used for watering the garden, flushing the toilets (even though they are dual-flush toilets) and eventually the cold-water side of washing clothing.  There is a 1200 gallon tank buried in the small front yard for storage, and rainwater is piped to the tank from the downspouts.  That water is then pumped into the house for use.

Domestic hot water is provided 85% by the Solar Thermal system as well, with a small electric backup for cloudy days.

Summary:

This home will be lived in by its designer and owner, Scott Shackleton.  It will be an example to the community that energy efficiency and care for God’s creation does not need to be overpriced, nor is it only available for high-end large homes or homes on large lots.  It is anticipated that this home will receive “Gold” level certification as a green-built home by the National Home Builders Green Building Council.