Contemporary Home Enjoys Durability, Energy-Efficiency
Thoughtful design combines with present-day craftsmanship to form a “sanctuary.”
Green marketing may attract home buyers, but quality construction is what makes happy homeowners. The occupants of this award-winning, Charis Custom Homes-built house in North Canton, Ohio are so happy with the result, they refer to it as their Sanctuary.
In this case, a sanctuary’s No. 1 criteria is durability. Charis Homes builds with insulated concrete forms (ICFs). The resulting walls are storm, moisture, fire and bug resistant. Thanks to a grid of steel rebar that runs vertically and horizontally, walls are rated to withstand winds up to 180 miles per hour.
Clean air, energy-efficient appliances, and a weather-resistant exterior are only a few reasons this home’s owners consider it to be their sanctuary. Photo courtesy Charis Homes
Charis used 11-inch-thick, R-22 ICFs to form the full wall height from footing to roofline for the one-story plus full basement home. The ICF basement walls insulate the sides of the basement slab.
Footers were poured into a stay-in-place form product that has built-in channels to provide interior and exterior drainage of the foundation. The 9-foot-tall basement exterior walls were covered with a dimpled plastic polyethylene membrane that relieves hydrostatic pressure against the wall by providing a pathway for liquid water to flow down to the footing drains.
The first-floor ceiling drywall forms the air barrier between the house and the vented attic. To prevent air leakage, all drywall-to-top plate seams and joints were sealed with three inches of closed-cell spray foam. Crews carefully sealed around wiring, lighting fixtures, and bath exhaust fan ducts before installing 16 inches of R-50 blown cellulose. For the garage attic, R-20 blown cellulose was installed.
The hip-designed truss roof was sheathed with 7⁄16-inch Oriented Strand Board (OSB) that was fastened with steel plywood clips. A 50-millimeter-thick ice-and-water shield was installed at all valleys and from the eaves up 36 inches past the wall line, then 1.5-inch aluminum drip edge was installed before laying the synthetic water-resistant underlayment, which was topped with 30-year architectural shingles. Soffit vents and a 4-inch continuous ridge vent ventilate the attic.
The Sanctuary’s base is comprised of insulated concrete form (ICF) blocks stacked like bricks, reinforced with rebar, and filled with concrete to form a sturdy, nature-resistant structure. Photo courtesy Charis Homes
A gas tankless boiler with an Annual Fuel Utilization Efficiency (AFUE) rating of 95 provides domestic hot water and space heating. The space heating is provided via radiant floor loops beneath the subfloor in the basement and via a coil in the central air handler for the rest of the home.
The specially designed indoor fan-coil unit is matched to an outdoor condensing unit for a SEER 16.3 heat pump so the air handler can provide heat from the boiler or cooling from the heat pump. This conditioned air is distributed throughout the home via a system of small-diameter ducts. These ducts discharge higher velocity jets of air into each room through multiple small, round supply vents.
The main duct, or plenum, is one-fourth the size of a conventional duct, and the branch ducts use flexible ducting with an inside diameter of only 2 or 2.5 inches, so they easily fit within interior walls and floor joists. This allows more options for keeping the ducts within the conditioned envelope of the home.
The branch ducts are factory-insulated and have gasket connections to minimize air and thermal losses. The system provides quiet operation and thorough mixing of air in the rooms for even temperatures.
Efficient Daylighting, Energy Savings
The builder chose to install triple-pane windows that are argon-filled and vinyl framed, with a U factor of 0.17 (R-5.9) and a solar heat gain coefficient of 0.21. These windows are easy-to-operate double-hung styles, where both sashes in the frame can be moved up and down, helping to facilitate cross ventilation of the home.
A cove molded sash replicates the look of classic wood windows. The engineered, sloped sills form a negative pressure pocket that keeps sashes securely in place and water flowing away from the home, even during the most adverse weather conditions.
In addition to the double-hung exterior windows, transom windows were installed above interior doorways on the main floor and in the basement, to bring daylight into the interior of the home, reducing the need for artificial lighting during the day. When lighting is needed, all of the fixtures in the home use LED light sources.
This home, with its standard features, achieved a Home Energy Rating System (HERS) index of 44, which is far better than the typical HERS score of 80 to 100 for new homes built to code across the country. Calculated energy cost savings for this home are $1,875 a year. The homeowners report a low $35 per month average electric bill, and describe the home as “quiet, comfortable and dust-free.”
Radiant floor heating in the basement supplements the heating supplied by the high-velocity, small-diameter ducting system. Photo courtesy Charis Homes
And, if homeowners wish to save more money, a smart thermostat includes mobile phone-accessed budget control features that maximize system efficiency and real-time energy tracking. Also, as a requirement for the Department of Energy (DOE)’s Zero Energy Ready Home (ZERH) certification, roof trusses were engineered to support future photovoltaic panels, and an electrical conduit for solar power was run from the attic to the electrical panel.
Indoor Air Quality Highlights
Indoor air quality is a signature feature for Charis Homes. In 2019, Charis earned its second Leader Award from the U.S. Environmental Protection Agency (EPA)’s Indoor airPLUS program (whose specifications are required to be met to earn a DOE ZERH certification). The builder incorporates several features in the home to support clean indoor air, including installation of an energy recovery ventilator (ERV) that brings filtered fresh air into the home and exhausts stale air while, efficiently recovering heating and cooling energy.
Other features include drywall that absorbs formaldehyde and volatile organic compounds (VOCs), ductwork that is self-cleaning and does not allow condensation to build up within the tubing, zero-VOC paint, formaldehyde-free hardwood and plywood, and water-based wood finishes.
Charis Homes’ Marketing Director Emily Meadows says the company uses DOE’s ZERH designation as a tool to educate customers as to why building such a home is worth the additional cost.
“[In our education center], we visually have a money display showing customers the amount of money a ZERH home saves over the course of a 30-year mortgage,” Meadows says. “Showing them the data helps to prove the investment is worth it. But our biggest reward is comments from homeowners about how comfortable their home, is and how low their utility bills are.”
Walls: ICF, 11-inch R-22 total: 2.5-inch EPS, 6 inch steel-reinforced concrete, 2.5-inch EPS, 1/2-inch drywall.
Roof: Hip roof; engineered 24-inch on-center, 7⁄16-inch OSB sheathing, synthetic felt rain-and-ice guard in valleys and eaves, 4-inch ridge vent, 30-year shingles, 1.5-inch aluminum drip edge, 1-foot overhangs.
Attic: Vented attic; 16-inch R-50 blown cellulose, 3-inch R-20 closed-cell spray foam on top plates; R-20 blown cellulose in garage attic.
Foundation: Insulated basement, R-20 total: 11-inch ICFs, waterproof membrane, concrete footers with integral interior and exterior drainage system.
Windows: Triple-pane, argon-filled, vinyl double-hung frames, U=0.17, SHGC=0.21.
Air Sealing: 1.41 ACH 50.
Ventilation: ERV, MERV 11 filter.
HVAC: Combined heat and hot water with 0.95 EF gas tankless boiler, hydrocoil and small-diameter high-velocity ducts, and radiant floor heat in basement; 16.3 SEER heat pump AC.
Hot Water: Combi boiler, 0.95 EF; central manifold with PEX; smart recirculating pump.
Lighting: 100 percent LED, motion sensors, transom windows, daylighting.
Appliances: ENERGY STAR refrigerator, dishwasher, microwave drawer.
Solar: Solar ready.
Water Conservation: EPA WaterSense fixtures.
Energy Management System: Wi-Fi enabled smart thermostat.
Other: Electric vehicle charging; zero clearance shower and thresholds; no VOC paints, low-VOC sealants and glues; formaldehyde-free hardwood, plywood, adhesives.
Alan Naditz is the managing editor of Green Builder magazine. This article is content compiled from the U.S. Department of Energy. He has covered numerous industries in his extensive career, including residential and commercial construction, small and corporate business, real estate, and sustainability.