Project DescriptionThe clients, a retired couple well into their “golden years,” wanted a modest, private, and very modern house that would embrace their deep commitment to environmental stewardship and personal health. The solution is a Net Zero Passive courtyard house that was the star of a recent Green Homes Tour throughout the Raleigh/Durham/Chapel “Triangle” region in central North Carolina.
Constructed primarily of 5500 psi concrete, this modern, 2300-square-foot (heated) house is nestled on a small hill in a clearing in a forest near Pittsboro, NC, overlooking a natural meadow. The architect was careful to disturb the meadow as little as possible.
From the approaching drive, the house – dubbed “Happy Meadows” by its owners -- presents a quiet entry on the northern elevation. Its low, modest profile respects the setting while honoring the homeowners’ modernist sensibilities. A series of concrete pavers leads to a small porch at the main entrance, which is framed by columns and a projecting roof made of naturally finished Southern yellow pine – a warm visual counterpoint to the concrete facade. (The pine reappears around a back porch.)
Inside, the living/dining/kitchen space occupies the core of the house with bedrooms and other spaces located down hallways on either side. Large window expanses across the southern elevation open the entire house to an abundance of daylight and panoramic views of the meadow and sky. Manufactured by Klearwall®, these hardwood-framed windows are triple-glazed, Passive House-certified.
The house is situated on the site to maximize passive solar gain in the winter and to provide unfettered sun for the 5.4KW rooftop photovoltaic array that is designed to produce 98 percent of the energy the house will use. (A small upgrade of panels in the future will allow the owners to power a small electric vehicle and become Net-Positive.) Since natural light fills the house’s main living spaces, electric lights -- all LED -- are rarely needed during the day.
Operable windows provide cross ventilation when weather permits, taking advantage of the strong, cool prevailing breezes that rise from the meadow in the spring and fall. Geothermal ground source heat pumps provide extra heating and cooling when necessary without wasting natural resources.
In a Southern climate that can reach 100 degrees in July and August, the house’s thick concrete exterior walls, extreme insulation, and polished concrete floors contribute to a noticeably cool interior even in the summer. A four-foot-deep roof overhang on the southern elevation also shades the interior all summer but lets the winter sun penetrate into the farthest interior walls and warm the concrete floor.
An internal courtyard – a favorite design element for this architect – off the main living space provides an immediate connection to nature from many vantage points in the house. A screened porch adjacent to the courtyard allows the homeowners to dine al fresco and enjoy views of both the courtyard and the meadow without being bothered by insects (a very real issue in this region). A covered deck beyond the screened porch provides a tranquil place outside for sitting and gazing across the meadow (when weather permits) and watching deer and other forms of wildlife that meander through the meadow regularly.
Water collection and a wildlife habitat also were key design concepts. The architect has achieved almost 100 percent rooftop rainwater capture and created a successful habitat in two parts:
(1) The majority of the rainwater from the roof flows to gutters then to rain chains that form delightful rivulets as the water flows into a 1200-gallon underground cistern, which supplies all irrigation needs. The roof is also a white EPDM Cool Roof, which delivers the cleanest capture, compared to asphalt or built-up roofing, while reflecting heat away from the house.
(2) A butterfly roof over the screened and covered porches channels some of the rooftop water to a scupper detail that directs it into a small, rectangular pond close to the house that the homeowners overlook from the master bedroom. The water then overflows down a channel to a wildlife pond at the base of the hill.
The architect paid special attention to providing an optimal habitat for frogs as their numbers have declined precipitously in the past decades. So far, the strategy is a huge success: The pond is teeming with tadpoles. And as avid gardeners, the homeowners’ practice only organic methods, ensuring an ongoing, non-toxic environment for all inhabitants of the property, human and otherwise.
The indoor air quality is excellent because the house features No-VOC finishes and Air Renew Essential sheetrock. This special sheetrock converts any VOCs that persist into an inert compound within it. A Conditioning Energy Recovery Ventilator (CERV) -- a cutting-edge green feature -- pre-dehumidifies incoming fresh air during summer and lets the homeowners set thresholds for humidity, CO2, and VOCs.
The bulk of the PVC used in the house is 100-percent recycled. This detail was very important to the homeowners who expressly wanted to avoid contributing to PVC’s toxic manufacturing process.
“Happy Meadows” has achieved a third-party-certified negative Home Energy Rating (HERS) score, the best HERS score available.
It also meets the following high standards:
• Certified to Passive House Plus
• DOE Challenge Home
• EPA Indoor AirPlus
• NAHB Green Builders Standard Emerald (highest)
A super-insulated house, it will also have a third-party-verified air leakage of .5 ACH (Air Changes per Hour) or less.
The architect was determined to minimizing construction waste and to use recycled materials wherever possible. Since the house was built with precast concrete panels assembled off-site by a local company, the amount of construction waste significantly decreased. Inside, she sourced scrap material for many of the details, including reclaimed sinker cypress for shelving and casework. She also found beautiful yet inexpensive slab remnants of rare stones that she pieced together for countertops.
Along with environmental stewardship, the homeowners wanted their house to include integral aging-in-place features because they intend to stay in this house the rest of their lives. That request informed the one-story design and includes completely level transitions from the garage and exterior entries: Thresholds are recessed into the concrete slab flooring to eliminate tripping hazards. The architect also designed a guest room that can easily become a caregiver’s suite.
Happy Meadows Courtyard House cost approximately $265/square foot to build, which includes the rooftop solar array, geothermal system, underground rain collection system, the CERV unit, the outside water features, the Klearwall windows, and all of the other high-cost elements.