RDI’s Home Ownership Program builds new homes or renovates existing ones in Franklin County in western Massachusetts. Its building process utilizes both proven & emerging green technologies to construct homes that are attractive & environmentally efficient. RDI’s current project, the Wisdom Way Solar Village comprising twenty near zero net energy homes in Greenfield, Massachusetts, puts the organization at the forefront of green building technology. These homes produce almost all the energy they require to operate. Beginning in 2006 with construction of its first near zero net energy home all of RDI’s homes reach this new standard. More info.
All RDI homes are ENERGY STAR certified. All of the current homes also meet the standards of LEED® for Homes.
HISTORY
The first of the Wisdom Way Solar Village homes is the one hundredth affordable home built in the Rural Development, Inc. Home Ownership Program. The over sixty homes built since 2000 have all been ENERGY STAR certified. The ENERGY STAR Home Energy Rating System (HERS) ratings in the old system ranged from 87 in the early years to 91.9 by 2006, as the houses steadily become more energy efficient. Since the indices changed in 2007, RDI homes have rated from 65 down to 21, with 100 being a standard code built home and 0 being a zero net energy home that uses no energy other than what it produces.
The two homes already rated by ENERGY STAR at the Wisdom Way Solar Village received ratings of 18 and 8, meaning they use 82% and 92% less energy than a standard code built home.
After building some twenty ENERGY STAR homes, RDI began its relationship with the Massachusetts Technology Collaborative (MTC) in 2002 with an award for a Feasibility Study of $20,000. At that time RDI put a design team together that included Bill Austin, architect and principle of Austin Design. His firm designed a “photovoltaic” house and has continued with RDI, designing first the Colrain near zero net energy home and now the Wisdom Way Solar Village homes. Since 2004 RDI has installed over 26 kW of photovoltaics (PV) on eleven different affordable homes with the help of various MTC programs.
RDI has also been involved with the U.S. Green Building Council and its LEED® for Homes program, serving on the pilot’s Affordable Housing Working Group and constructing the first affordable single-family home to earn a LEED® certification in New England, the first affordable single-family home in the United States to achieve ‘Silver Certification’, and two additional Silver homes. In May 2007 RDI’s near zero net energy home in Colrain, MA received ‘Gold Certification.’ This home is the prototype for the Wisdom Way Solar Village homes currently under construction.
In 2006 RDI began to work with Steven Winter Associates as part of the U.S. Department of Energy’s Building America program. Engineers from this program designed the mechanical systems for the Colrain house as well as the Solar Village homes. In 2008 RDI received an award for the Colrain house as a Pioneering Builder through Building America’s Builders Challenge Program .
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GREEN BUILDING FEATURES
• Advisory team of green building experts
• Sustainable site selection and development
• Small building footprint
• Orienting homes for maximum solar gain
• Material efficient framing
• Tight air sealing and 24 hour ventilation
• Durability and moisture prevention measures
• Highly efficient insulation
• Highly efficient low-e argon windows
• Water conserving plumbing fixtures and dishwashers
• Environmentally preferable materials
- - Sustainably grown wood flooring
- - Environmentally friendly resilient flooring
- - Low VOC interior paint
- - Cement based siding
• Recycled and locally made building components when feasible.
• Recycled or minimized construction waste
More Detail:
Energy efficient domestic hot water: RDI’s near zero net energy homes produce domestic hot water using solar collectors on the roofs. The collectors deliver solar heated water directly to a super insulated storage tank. When there is household demand for hot water it is drawn from the storage tank through an on-demand gas powered hot water heater. The on-demand heater will turn on and heat the water as needed if the solar heated water does not leave the storage tank at a high enough temperature.
In all RDI homes, built prior to the near zero net energy homes, water used by the household is heated in the boiler and then flows to a super insulated storage tank, known as an indirect hot water tank. In a typical hot water tank the water is heated by coils in the tank and then is re-heated each time it cools down. With an indirect hot water tank the water is heated one time by the boiler itself. Combined with a high efficiency boiler this is one of the least expensive ways to heat water.
Increased insulation: RDI uses dense pack blown-in dry cellulose insulation in its houses. Cellulose is manufactured locally from recycled newspapers. The dense pack cellulose in the walls and ceilings reduces air flow and sound transference. R values measure resistance to heat flow. The higher the R-value, the more insulating performance. RDI’s near zero net energy homes have double stud wall construction with twelve inches of insulation for an R-value of 42 in the walls. Cellulose is blown into the attic to a depth of 15 inches for an R-value of 50+ in the ceilings. RDI’s standard ENERGY STAR homes, built prior to the near zero net energy homes, had R-19 insulation in the walls and R- 38 in the ceilings.
Mechanical ventilation: RDI’s carpenters give a great deal of attention to air sealing the homes. (ENERGY STAR has excellent information on air sealing.) A house that is built tight requires ventilation to keep the indoor air quality healthy and reduce moisture levels. A continuous quiet exhaust fan mounted in the bathroom draws outdoor air into the house and exhausts stale air in a controlled manner.
Controlling air flow in the unconditioned basement by: sealing the sill plate, piping air to the boiler (not applicable in Wisdom Way Solar Village homes which have no central heating), weather stripping the basement door, and insulating interior bulk head doors.
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NEAR ZERO NET ENERGY FEATURES
Near zero net energy is a term that refers to buildings that produce almost as much energy as they use. The primary techniques used in RDI homes are those that start by reducing the heating, cooling, and electrical loads. In the Wisdom Way Solar Village a three-bedroom home is modeled to have a design heat load of 12,600 Btu/h when the temperature is 2° F outside. Typical heating systems are designed for a heat load of 40,000 – 100,000 Btu/h at 2° F . The Solar Village homes have no central heating at all, relying on passive solar with a gas-fired sealed combustion room heater in the main living space as backup. These homes also have no air conditioning. They were designed so that as many rooms as possible would have windows on different walls, allowing for cross-ventilation to cool the home in the warmer months.
Key features of RDI’s near zero net energy Wisdom Way Solar Village homes, many of which are similar to RDI’s standard green building features, are:
- A small footprint with an open floor plan (1392 square feet of conditioned space in a three bedroom home above an unconditioned full basement);
- A southern orientation with photovoltaic and solar hot water systems;
- A very tight building envelope;
- Recycled blown-in dry cellulose encircling the building envelope:
- 12 inches in the offset double 2x4 walls for R-42;
- 14 inches in the ceilings for R-52;
- 11 inches in the basement ceilings for R-38.
- Very high efficiency windows on the north, east, and west sides of the homes with a U-value of 0.18, a Solar Heat Gain Coefficient (SHGC) of .26, and a Visible Light Transmission (VLT) of 0.42.
- High efficiency windows on the south sides of the homes with a U-value of 0.26, a Solar Heat Gain Coefficient (SHGC) of .36, and a Visible Light Transmission (VLT) of 0.53.
- Continuous 50 CFM exhaust ventilation;
- ENERGY STAR refrigerator, dishwasher, and clothes washer (plus natural gas cook stove and dryer);
- Compact fluorescent light bulbs throughout;
- On-demand natural gas water heater as back up to solar hot water system;
- A sealed combustion Monitor room heater located in the central living area on the first floor (no fossil fuel based central heating system is necessary);
- No air conditioning;
- A unique air distribution system designed to move air and heat from the first floor to the second floor bedrooms; the ducts for this system as well as all of the vent fans will be sealed with mastic.
Preliminary REM/Rate modeling for the Solar Village predicts annual gas use of 205 therms for back up space heating, 89 therms for cooking and laundry, and 20 therms for back up water heating.
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SOLAR ELECTRIC SYSTEMS
In 2005 RDI began installing photovoltaic (solar electric) systems on houses with
appropriate southern exposure using grants from the Massachusetts Technology
Collaborative in cooperation with ICF International.
SOLAR HOT WATER SYSTEMS
In 2007 RDI began installing solar hot water collectors on its near zero net energy homes for domestic hot water production. On-demand gas water heaters are installed for backup.
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MASSACHUSETTS NEW HOMES WITH ENERGY STAR PROGRAM
All houses built by RDI’s Home Ownership Program since the year 2000 have earned ENERGY STAR certification. The Massachusetts New Homes with ENERGY STAR program is s a new construction program based on an energy efficiency standard developed by the Environmental Protection Agency (EPA). ENERGY STAR qualified homes are at least 15 percent more energy efficient than homes built to the 2004 International Residential Code (IRC). These homes are five-star rated and nationally recognized for greater value, lower operating costs, and increased durability, comfort, and safety.
ENERGY STAR certification requires pre-construction planning and post-construction inspections from an independent ENERGY STAR rater. The final inspection results in a Home Energy Rating System (HERS) rating. The scale for the HERS changed in 2007. In order to be ENERGY STAR certified the HERS (Home Energy Rating System) index must be no higher than 85, with 100 being the standard code built home and 0 being a zero net energy home that uses no energy other than what it produces.
Typical features in an ENERGY STAR home include:
- An Efficient Home Envelope, with effective levels of wall, floor and attic insulation properly installed, comprehensive air barrier details, and high-performance windows;
- Efficient Air Distribution, where ducts are installed with minimum air leakage and are effectively insulated;
- Efficient Equipment for heating, cooling, and water heating;
- Efficient Lighting, including fixtures that earn the ENERGY STAR; and
- Efficient Appliances, including ENERGY STAR qualified dishwashers, refrigerators, and clothes washers.
Homebuilders, such as RDI, can apply for incentives through the Massachusetts ENERGY STAR for Homes program. The EPA’s initiative is supported in RDI’s region by National Grid and the Western Massachusetts Electric Company. RDI works with ICF, an administrator of the ENERGY STAR for Homes program in the Northeast.
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BUILDING AMERICA PROGRAM
Building America is an industry-driven research program, sponsored by the U.S. Department of Energy, designed to accelerate the development and adoption of advanced building energy technologies in new and existing homes. Building America forms research partnerships with all facets of the residential building industry to improve the quality and energy efficiency of homes. The goal is to develop cost effective solutions that reduce the average energy use of housing by 40% to 100%. Ultimately, Building America research will lead to net zero energy homes, which produce as much energy as they use.
Building America has been a key partner in the development of the Colrain and Wisdom Way Solar Village near zero net energy homes.
LEED® FOR HOMES
The RDI Home Ownership Program builds its homes to LEED® for Homes standards. However, because there is a cost involved not all of RDI’s homes are certified by LEED®. The LEED® (Leadership in Energy and Environmental Design) Green Building Rating System is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings. Members of the U.S. Green Building Council representing all segments of the building industry developed LEED® and continue to contribute to its evolution. The U.S. Green Building Council is the nation’s foremost coalition of leaders from across the building industry working to promote buildings that are environmentally responsible, profitable, and healthy places to live and work. To see specific features incorporated into the Wisdom Way Solar Village, click here.
Homes earn LEED® for Homes at one of four levels– Certified, Silver, Gold, or Platinum. Homes are rated by a LEED® for Homes provider who also advises throughout the planning and construction process. RDI currently uses Steven Winter Associates as its LEED® for Homes provider.
LEED® for Homes rates homes in eight categories:
- Innovation & Design Process
- Location & Linkages
- Sustainable Sites
- Water Efficiency
- Energy & Atmosphere
- Materials & Resources
- Indoor Environmental Quality
- Awareness & Education
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