Editor’s note: Each year, the U.S. Department of Energy (DOE)’s Office of Energy Efficiency & Renewable Energy honors the best of its Zero Energy Ready Homes (ZERHs)—which is now called DOE Efficient New Homes program. The winners are announced every fall. Here’s a preview of the coverage from the September/October issue of Green Builder, featuring a finalist from DOE’s previous roster of award honorees.
Not many builders are confident enough in the energy efficiency of their homes to post their homeowners’ utility bills on their websites, but Insight Homes of Bridgeville, Del., has made a habit of it.
Insight’s Peterman II model has landed the company’s third Housing Innovation Grand Award from the U.S. Department of Energy (DOE). The award goes to the builder that constructs the most homes in a year that are certified to DOE’s Zero Energy Ready Home (ZERH) criteria.
Insight Homes constructs about 200 homes a year and is committed to building all of its homes to the requirements of DOE’s ZERH program. It has certified more than 1,000 homes to the program so far.
Building to the requirements of the DOE program has helped Insight meet its energy efficiency goals. Every DOE Zero Energy Ready-certified home meets the requirements of ENERGY STAR Certified Homes. They must also be certified to the U.S. Environmental Protection Agency (EPA)’s Indoor AirPlus criteria and meet the hot water distribution requirements of the EPA’s WaterSense program.
DOE Zero Energy Ready homes must also meet IECC 2015 insulation requirements, be blower door tested for whole house air leakage, comply with moisture management guidelines, have ducts inside conditioned space, and use Energy Star-labeled windows, lighting, and appliances. Homes must also have solar electric panels installed or have the conduit and electrical panel space in place for future installation of solar panels.
Insight also received a Housing Innovation Award for its Peterman II home model in the Production Home category. The home is zero energy ready, with conduit in place for future installation of the solar panels. Even without the photovoltaics, homeowners who purchase Insight’s Peterman II model can expect energy cost savings of more than $4,500 per year, or more than $220,000 in the first 30 years, compared to a home just built to code.
Insight Homes utilizes an integrated design process when developing the plans for a new house model. Through this process, the designers meet with key trade partners, including the HVAC, structural, framing, and plumbing trades to get input to ensure high performance targets can be met in a functional and buildable design.
Insight Homes employs a panelized wall system consisting of 2-by-6 framing at 24-inch on-center stud spacing and other advanced framing techniques to reduce wood and increase insulation in the walls such as insulated headers, reduced framing around windows, and two- and three-stud corners with studs positioned to allow insulation into the corners.
Every panel is made in a climate-controlled indoor environment where materials are protected from the elements. They are precision cut and attached with laser-guided pneumatic nailers and self-squaring roller tables to enable every panel to be constructed with an accuracy within 1/16th of an inch. The wall panels have a 7/16-inch coated OSB exterior sheathing.
This product saves time and money by serving as the structural sheathing and the primary weather barrier when all seams between panels are taped. The wall cavities are insulated with R-23 of netted and blown fiberglass. No plumbing or HVAC is installed in the exterior walls. The walls are clad with vinyl siding.
The home also has a finished basement. The poured concrete walls are protected on the exterior with a liquid-applied water proofing and dimple board drainage membrane that extends from grade down to the footing drain. An interior perimeter drain is installed and connected to a sump pit.
The foundation slab sits on 4 inches of clean gravel for a capillary break and is covered with a polyethylene vapor barrier. In the finished areas of the basement, the walls are insulated with R-15 spray polyurethane foam applied to the inside of the foundation walls within the frame stud bays. In the unfinished areas of the basement, 2 inches (R-10) of foil-faced polyisocyanurate rigid insulation is applied to the face of the poured concrete wall. The band joists are insulated with R-19 open-cell spray polyurethane foam.
The vented attic is constructed with engineered roof trusses that include an 18-inch raised heel design to allow for full depth insulation over the top plates of the exterior walls. Insulation baffles are installed in each attic bay to prevent wind washing from the soffit vents and to provide a path for attic ventilation air to flow from the eaves up to the ridge vent.
In the mixed humid climate, this air flow helps to pull heat and humidity out of the attic in the summer and to prevent ice dams in the winter. The attic is insulated with 16.25 inches of loose blown fiberglass insulation to achieve an R-49 insulation value across the full ceiling plane. For any vaulted ceiling areas, R-38 fiberglass batts were used.
Attic hatches in side walls or the ceiling plane are insulated with multiple layers of extruded polystyrene rigid foam board and are gasketed for air sealing. No mechanical equipment or HVAC ductwork is permitted in the attic. All top plates along interior walls are sealed with canned foam, as are any penetrations for light fixtures, exhaust fans, plumbing stacks and more through the ceiling plane.
Every home certified through the DOE ZERH program is inspected by a HERS rater and tested for air tightness. This Insight home achieved an air tightness of 1.9 air changes per hour at 50 Pascals (ACH50).
Air sealing occurred in two stages. The first stage occurred before drywall was installed and after mechanical rough-in when all penetrations through the subfloor to the crawlspace, through the top plates and chases to the attic. The exterior walls were sealed using expanding foam sealant. Rough openings around windows and door frames were sealed with low-expansion foam sealant.
The second stage occurred after drywall was installed when spray foam was used to seal the back side of the ceiling drywall, along the top plates of all interior partition walls, and any penetrations through the ceiling drywall and partition walls (for light fixtures, exhaust fans, plumbing stacks, and more).
The home is heated and cooled with a dual-fuel system, including a central air source heat pump with a variable speed compressor and a propane furnace. The heat pump has a heating efficiency of 10.0 HSPF and a cooling efficiency of 20.0 SEER. The modulating gas (propane) furnace has a heating efficiency of 97.5 AFUE.
The mechanical equipment is in a conditioned control room in the basement. The duct system trunk lines are rigid, round sheet metal ducts while branch takeoffs are insulated flex ducts with a manual balancing damper at each branch. The MERV 13 air filter is located in a central return box placed in a wall of the living space to provide easy access for replacement.
By locating the return register vertically in the wall, the accumulation of dust and debris that can occur with a floor register is avoided. All systems are equipped with a Wi-Fi-enabled thermostat. Ventilation is provided by exhaust fans in the bathrooms.
Given the longer shoulder seasons in the mixed-humid climate, space conditioning demands for sensible load may be minimal. Coupled with high-performance windows, 6-inch exterior walls, and larger overhangs, the heating and cooling load is significantly reduced for a home of this size. With the space conditioning system not calling for heating or cooling, the homes are designed to have the central air handler fan (with an ECM motor) run in manual mode at
30 percent fan capacity for a minimum of 45 minutes every hour.
Ceiling fans are installed in the central living spaces, including the living room, loft, morning room, and master bedroom. The periodic cycling of the air handler, coupled with the standard ceiling fans, can help to ensure mixing of the air throughout the home and prevent stratification from occurring when there is no demand for heating and cooling.
All of the home’s lighting fixtures use LED light sources. The home’s refrigerator, dishwasher, and tankless water heater are all Energy Star rated. The home’s plumbing system consists of a central manifold with PEX piping. The homerun distribution system supply lines are sized for each specific end use and shut-off valves are installed at each point of use. The fixtures are EPA WaterSense-labeled.
All homes certified through the DOE ZERH program must meet the requirements of EPA Indoor AirPlus. Insight Homes uses low-VOC paints, construction adhesives, carpeting, and other materials that allow the home to achieve the gold level of certification under the National Green Building Standard.
In addition to meeting the DOE ZERH designation, which includes Energy Star and Indoor AirPlus certification, Insight Homes has also committed to building all its homes to be certified to the National Green Building Standard. These performance programs require third-party inspections, as well as performance testing at several stages of construction to ensure compliance with strict guidelines. In addition, Insight Homes’ HVAC suppliers require system commissioning and air flow testing prior to occupancy.
“Insight’s entire business model evolved around home performance, efficiency, and a healthy indoor environment,” says Brozyna. “Because we made the decision to make these high-performance features standard on all the homes we build, we are able to negotiate better pricing from vendors on higher performing products.”
Savings are achieved by placing large-volume orders rather than purchasing them as individual upgrades. This allows Insight to incorporate better equipment in all of its homes more cost effectively, Brozyna adds. “Insight Homes was started with the vision to be better and do better for home buyers,” he says. “When our customers are still amazed, 5 years after moving in, at how low their energy bills are, we know we are living up to our motto: ‘It’s just a better house.’”