The following excerpts include a majority of the text from the completed Affordable Passive Solar Planbook for North Carolina. The complete APS Planbook includes all illustrations, details, floor plans, and elevations and is available in pdf format here.
Please scroll through the text as you wish or choose a section to review here:
Key Features of Passive Solar Design
Increased south-facing glass area – allows sunlight to help warm the home in winter months. South-facing windows receive close to three times as much sunlight as east and west windows in the winter and a third less sunlight in the summer. In passive solar homes the area of the south facing glazing should be 7-12% of the floor area. This amount of glazing requires the use of thermal mass to temper the incoming solar heat gain. A home with increased southern glazing up to 7% is considered sun-tempered and can be effective without the use of thermal mass.
Lower east and west glass areas – reduce summer cooling needs because it prevents unwanted sun from entering the home in the morning and afternoon. Eliminating the windows also lowers construction costs.
Orientation and site selection – are critical in passive solar design. The passive solar windows must face within 15 degrees of due south to maximize solar gain in winter and minimize overheating in summer. Be aware that magnetic south is different than true south. To find how many degrees they vary at your site visit the National Geophysical Data Center. The house should be designed on an east-west axis so the long side faces south. Trees on the site reduce summer cooling bills, but should not shade south-facing windows in winter. Effective passive solar design is not possible on all sites because the site must receive as much direct sunlight as possible during the winter between 9 am and 3 pm. Privacy is also a factor, so if the south side is exposed to the street or neighboring houses, it may not be conducive to large expanses of glass area.
Energy efficient design – the first step in a successful passive solar home includes proper installation of recommended levels of insulation, air-tight design, and efficient heating and cooling systems.
Thermal storage mass – materials such as concrete floors, interior brick walls, brick pavers, and tile store heat and regulate interior temperatures both in winter and summer.
Effective window shading – reduces summer cooling needs and glare. Window shades lowered at night can also be used to help trap the heat absorbed by the thermal mass.
Moisture control systems – increase the home’s durability, improve indoor air quality, and provide comfort in both summer and winter.
Plan the room layout – should take advantage of the sun’s path. Rooms should match solar gain to the time of day the room is used.
Homes in many locations need to be equipped to handle both cold winters and hot humid summers. Depending on your climate you may need to reduce the amount of glass on the southern side to prevent high cooling bills due to overheating.
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Types of Passive Solar Designs
This section introduces the basic design principles. Current trends in housing, such as expansive glass areas, daylighting, sunrooms, great rooms, tile floors, fireplaces, and open floor plans fit well into passive solar designs. Effective designs reduce heating and cooling bills and provide greater comfort.
Heating Season
In the winter months, three primary elements interact to provide a significant portion of a home’s heating needs:
- energy efficiency features including effective insulation, airtight construction, and efficient HVAC systems, minimize the demand for heating;
- increased south-facing windows bring additional sunlight into the home which can be captured as heat energy;
- thermal mass provide a means to store heat inside the home. Concrete or tile floors; walls made of masonry materials such as brick, stone, or concrete; masonry fireplaces; or water-filled containers all provide thermal mass for heat storage and can be incorporated to enhance the aesthetic requirements of the space.
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Cooling Season
In summer months, passive solar homes in the Southeast must compensate for the hot, humid climate and the large amount of heat that can come into the home through windows. The true challenge of passive solar design is to ensure low summer cooling bills compared to those of a similar, standard home.
Many passive solar homes have significantly lower cooling bills because they:
- have energy efficient features – high insulation levels, airtight construction, and effective design and installation of air conditioning systems;
- have few, if any, windows on the east and west thus minimizing solar gain in the mornings and afternoons;
- provide shading for south-facing windows;
- incorporate thermal mass to balance temperature extremes;
- can be ventilated during milder outdoor weather with open windows and fans to help maintain indoor comfort.
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Passive Solar Design Guidelines
In passive solar design it is necessary to be sensible about your expectations of the sun. Do not assume that the solar design features will provide all of your heating and cooling needs. Some type of heating and cooling system is usually necessary to maintain comfort during colder periods in the winter and hotter periods in the summer.
Well-designed passive solar homes provide their owners with low energy bills year-round, as well as natural daylight. However, improperly designed passive solar homes may actually have uncomfortable temperature swings both in summer and in winter, thereby reducing potential energy savings. When designing the home remember rooms with large expanses of glass should include thermal storage. It is also important to consider the layout of the rooms in passive solar design. Whether adapting passive solar features to a standard home plan or designing an entirely new plan, consider the following design ideas.
Frequently-used rooms (morning to bedtime)
Family rooms, kitchens, and dens work well on the south side. Be aware of potential problems with glare from sunlight through large expanses of windows.
Day-use rooms
Breakfast rooms, sunrooms, playrooms, and offices work well on the south side of the house. They should adjoin rooms that are used frequently to take full advantage of solar heating.
Sunspaces
These rooms can be isolated from the house if unconditioned. In winter, the doors can be opened to let solar heat move into the home. At night, the doors can be closed, and the sunspace buffers the home against the cold night air. In summer, sunspaces protect the home from outside heat gain. For best performance, they should not be air conditioned.
Privacy rooms
Bathrooms and dressing rooms can be connected to solar-heated areas, but are not usually located on the south side.
Night-use rooms
Bedrooms are usually best on the north side, unless used often during the day. It is often difficult to fit thermal storage mass into bedrooms, and privacy needs may limit opportunities for installing large glass areas. However, homeowners who prefer bedrooms filled with natural light may be able to use passive solar features effectively.
Seldom-used rooms
Formal living and dining rooms, along with extra bedrooms, are best on the north side, out of the traffic pattern and air flow.
Buffer rooms
Unheated spaces such as closets, laundries, workshops, pantries, and garages work best against the north, east, or west exterior walls. They protect the conditioned space from outside temperature extremes.
Exterior covered areas
Porches and carports on the east and west provide summer shading. However, west-facing porches may be uncomfortable in the afternoon. Avoid covered porches on the south side, as they shade winter sunlight.
[top] Windows
The windows of a home produce benefits such as light, fresh air, ventilation, and attractive aesthetics. Properly sited windows contribute a significant amount of heat to a home in the winter. It is critical to choose the right windows and place them in the optimum location. Improperly sited windows can lead to unwanted glare from the sun, deterioration of finishes and fabrics, and summer time overheating which could double cooling costs.
When selecting a window, you should make good quality a high priority. In most locations, double-paned low-e glazing, solid construction, and effective weatherstripping are minimum requirements.
The most controversial window design consideration is the solar heat gain coefficient for southern windows. As explained in the sidebar on Basic Window Terminology, higher solar heat gain coefficients allow more solar energy to enter the home, which saves more energy during the winter but increases cooling needs in the summer. In most of the southeastern United States, windows with low solar heat gain coefficients, typically 0.40 or less, are recommended as the energy savings during the summer months exceed the increases in energy bills in winter. One major advantage of low-e windows with low solar heat gain coefficients is that they reduce the required size of the air conditioning system. Windows with high solar heat gain coefficients, typically over 0.50, are suitable in passive solar homes without air conditioning systems or in climates with mild summers.
Window shading is recommended in climates with hot summers. Some homeowners choose to install movable window insulation, which can dramatically decrease energy bills in both summer and winter when used effectively. For more information on different types of windows, refer to the North Carolina Builders Guide to High Performance Homes and the following sidebar.
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Thermal Mass
Thermal mass materials, including concrete, tile, masonry, stone, water-filled containers, and other heavy building materials, absorb and store heat. Thermal mass is a key element in passive solar homes. Homes with substantial south-facing glass areas and no thermal storage mass do not perform well.
Providing adequate thermal mass is usually the greatest challenge to the passive solar designer. The amount of mass needed is determined by the area of south-facing glazing and the location of the mass. Sun-tempered homes, having less than 7 percent of the floor area in south facing glass, rely on incidental mass in the construction of materials and furniture. The following guidelines will help ensure an effective design.
Guideline 1: Locate the thermal mass in direct sunlight.
Thermal mass installed where the sun can reach it directly is more effective than indirect mass placed where the sun’s rays do not penetrate. Houses that rely on indirect storage need three to four times more thermal mass than those using direct storage. |
Guideline 2: Distribute the thermal mass evenly.
Passive solar homes work better if the thermal mass is thin and spread throughout the living area. The surface area of the thermal mass should be at least 3 times, and preferably 6 times, greater than the area of the south windows. Slab floors and masonry walls that are 3 to 4 inches thick are more cost effective and perform better than those that are 6 to 12 inches thick. |
Guideline 3: Do not cover the thermal mass.
Carpeting with a carpet pad substantially reduces the energy savings from the passive solar elements. It is generally acceptable to cover no more than 5 percent of the area with carpet or furniture. Masonry walls can have drywall or plaster finishes, but should not be covered by large wall hangings or lightweight paneling. The drywall should be attached directly to the mass wall, not to purlins fastened to the wall that create an undesirable insulating airspace between the drywall and the mass. |
Guideline 4: Select an appropriate mass color.
For best performance, thermal mass elements should be a dark color. A medium color, which absorbs 70 percent as much solar heat as a dark color, may be appropriate in some designs. A matte finish for the floor reduces reflected sunlight, thus increasing the amount of heat captured by the mass and having the additional advantage of reducing glare. |
Guideline 5: Insulate the thermal mass surfaces.
In climates where local energy codes do not require slab insulation, at least 1-inch of perimeter insulation should be installed for slabs used as thermal mass. In general, slab insulation levels should be considered a bare minimum. Insulating the vertical edge of the slab is the highest priority. Slabs that serve as thermal mass should also be insulated underneath with 1/2 to 1-inch of foam insulation. Make sure to follow local requirements regarding termites and foam insulation. Exterior masonry walls used as thermal mass should be insulated on the exterior with at least 2 inches of foam insulation. |
Guideline 6:
Make thermal mass multipurpose.
For maximum cost effectiveness, thermal mass elements should serve other purposes as well. Tile-covered slab floors store heat and provide a finished floor surface while masonry interior walls provide structural support, divide rooms, and store heat. Thermal storage walls are one type of a passive solar design that is often cost prohibitive because the masonry walls only function as thermal mass. |
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Thermal Mass in the Heating Season
10:00 am to 5:00 pm
Sunlight enters south-facing windows and strikes the thermal mass inside the home. The sunlight is converted to heat energy, which heats both the air and thermal mass materials. On most sunny days, solar heat maintains comfort during the mid-morning and late afternoon periods.
5:00 pm to 11:00 pm
As the sun sets, it stops supplying heat to the home. However, a substantial amount of heat has been stored in the thermal mass. These materials release the heat slowly into the passive solar rooms, keeping them comfortable on many winter evenings.
11:00 pm to 6:30 am
The homeowner sets back the thermostat at night, so only minimal back-up heating is needed. Energy efficient features minimize heat losses to the outside.
6:30 am to 10:00 am
The cool early morning hours are the toughest for passive solar heating systems to provide comfort. The thermal mass has usually given up most of its heat, and the sun has not risen sufficiently to begin heating the home. During this period, the homeowner may have to rely on a supplemental heating system.
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Thermal Mass in the Cooling Season
8:00 am to 10:00 am
The sun’s rays strike the outside of the east walls, which have minimal glass area. Thus, the home suffers less heat gain than a comparable standard home.
10:00 am to 4:00 pm
Direct sunlight on the south windows of the home is shaded by roof overhangs. Diffuse sunlight on hazy days is blocked by interior or exterior shades. The energy efficient features minimize heat gain through walls and attics. The attention to detail in sealing air leaks keeps both heat and humidity out of the home.
On warm days in spring and fall, natural ventilation or mechanical ventilation, such as that provided by a ceiling fan or whole house fan, helps maintain comfort. On hot summer days, most homeowners prefer the comfort provided by an air conditioning system. The high capacity of the thermal mass to store heat regulates indoor temperatures so that the house is less likely to overheat during the middle of the day.
3:00 pm to 8:00 pm
Sunlight coming from the west is once again deflected because the home has little or no west-facing glass.
8:00 pm to 9:00 am
On mild nights, the windows can be opened to provide nighttime ventilation. On cool evenings, nighttime ventilation can help flush heat from the thermal mass to the outside. The cooler mass will absorb more heat the following day. On hot, humid evenings, air conditioning may be preferred.
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Incorporating Thermal Mass
Thermal mass can be incorporated into a passive solar room in many ways, from tile-covered floors to masonry walls. When selecting thermal mass materials, consider the aesthetics, costs, and energy performance.
• Slab-on-grade floor
Used in most passive solar homes. Slab floors can be stained or stamped into a variety of patterns or finished with tile, stone, or brick. Concrete floors can be expensive to install on upper stories. Floors made of brick, brick pavers, or tile on a thick bed of mortar also may be used.
• Interior mass walls
Solid mass walls between interior rooms. Since they have living area on both sides, they can be up to 12 inches thick, although thinner 4- to 8-inch walls deliver heat more quickly. Masonry fireplaces that are several feet thick store heat but are not as effective as thinner mass walls with greater surface area. Since masonry is not a good insulator, keep fireplaces on interior walls.
• Thermal storage walls
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solid masonry wall fronted by exterior double-glazed windows. Sometimes known as Trombé walls, these designs are one of the least cost-effective passive solar options in the Southeast. They are expensive to build, and many researchers question whether the mass wall has sufficient time to warm between the periodic spells of cloudy weather experienced by most of the Southeast in the winter.
• Water-filled containers
Water stores heat twice as effectively as masonry by volume and five times as effectively by weight. However, water containers look unusual in most living areas. Since they store more heat per pound, less weight is required to store the same amount of solar heat; therefore, they are easier to use in upstairs rooms. Commonly used water containers include fiberglass cylinders and 30- or 55-gallon metal drums.
• Hot tubs, saunas, and indoor pools
Some homeowners have tried to use hot tubs, saunas, and indoor pools as thermal storage mass. In most cases, these forms of water storage do not work well. The desired water temperature for comfortable use of these amenities is hotter than the passive solar contribution can possibly achieve.
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Natural Cooling
Design features known as natural cooling measures can reduce air conditioning needs. Natural cooling guidelines are especially important for passive solar homes because their large expanses of south-facing glass can cause overheating if unprotected from the summer sun.
Window Shading Options
The effectiveness of window shading options depends on the position of the incoming sunlight. On a clear day, most sunlight is direct, traveling as a beam from the sun to a home’s windows without obstruction. In winter, most of the direct sunlight striking a window is transmitted. However, in summer, the sun strikes south windows at a steep angle, and much of the direct sunlight is reflected. In developing a strategy for effectively shading windows, both direct and indirect sources of sunlight must be considered. |
Landscaping and Trees
According to the U.S. Department of Energy report, “Landscaping for Energy Efficiency”, careful landscaping can save up to 25% of a household’s energy consumption for heating and cooling. Trees and vines are effective means of shading in the summer and, combined with a lawn or other ground cover, can reduce air temperatures as much as 9 degrees F in the surrounding area. When located in the front of open windows on the windward side of the house, bushes and other vegetation can cool the air coming in. Trees must be located to provide shade in summer and not block the winter sun. Even deciduous trees that lose their leaves during cold weather block some winter sunlight; a few bare trees can block over 50 percent of the available solar energy. |
Overhangs
Overhangs shade direct sunlight on windows facing within 30 degrees of south. Overhangs above south-facing windows should provide complete shade for the glazing in midsummer, yet still allow access to winter sunlight. Overhangs above tall, south-facing windows should generally extend 2 to 2½ feet horizontally from the wall. It is not necessary for south windows to extend vertically all of the way to the overhang because the top one to two feet will be shaded year round. |
Shades and Shutters
Exterior window shading treatments are effective cooling measures because they block both direct and indirect sunlight outside of the home. Solar shade screens are an excellent exterior shading product with a thick weave that blocks up to 70 percent of all incoming sunlight. They should be removed in winter to allow full sunlight through the windows.
Shutters and shades located inside the house include curtains, roll-down shades, and Venetian blinds. More sophisticated devices such as shades that slide over the windows on a track, interior movable insulation, and insulated honeycomb shades are also available. Interior shutters and shades are generally the least effective shading measures because they try to block sunlight that has already entered the room. However, if passive solar windows do not have exterior shading, interior measures are needed. The most effective interior treatments are solid shades with a reflective surface facing outside. |
Reflective Films and Tints
Reflective film, which adheres to glass and is found often in commercial buildings, can block up to 85% of incoming sunlight. It is not recommended for south windows as it blocks sunlight all year in passive solar homes. |
[top] Ventilation
In spring and fall, ventilation measures can help cool a house and bring in fresh air. Air movement keeps people cooler by evaporating moisture from the skin. Research has shown that people feel as comfortable in rooms at 85° F with air movement as in rooms at 75 degrees F with still air. Both natural ventilation and mechanical ventilation measures are important for low cost cooling.
All houses need ventilation to remove stale interior air and excessive moisture and to provide oxygen for the inhabitants. There has been considerable concern recently about how much ventilation is required to maintain the quality of air in homes. While it is difficult to gauge the severity of indoor air quality problems, most experts agree that the solution is not to build an inefficient, “leaky” home. Research studies show that standard houses are as likely to have indoor air quality problems as energy efficient ones. Most building researchers believe that no house is so leaky that the occupants can be relieved of concern about indoor air quality. They recommend mechanical ventilation systems for all houses.
Natural Ventilation
Breezes can generate air movement inside the house. All rooms used frequently should be designed for ventilation; however, natural breezes are unpredictable throughout most of the Southeast. They usually do not blow from any one direction reliably in summer and are not very strong. It is important to place windows on opposite sides of a space to allow for cross ventilation because they can capture cooling, flow-through breezes. However, do not rely on natural ventilation as the only source of air movement.
Another form of natural ventilation, called the stack effect, occurs when hot air can exit the house through a high opening. A low opening lets in outside air to replace the exiting air. The stack effect does not provide sufficient air flow to provide comfort during hot summer weather. |
Mechanical Ventilation
Mechanical ventilation provides an inexpensive means of creating a cooling air flow. In addition, ventilation systems can expel stale air from the home to improve indoor air quality.
Portable fans or ceiling fans can provide comfort inexpensively, even when the air conditioner operates. For each degree that the thermostat is raised, air conditioning costs drop 3 to 8%. By setting the thermostat between 80 and 85 degrees Ferinheit and using fans that blow directly on room occupants, homeowners can save 20 to 50 on cooling bills.
Whole house fans, also called attic fans, blow hot room air into the attic and pull supply air into the home from outside. They generate substantial air flow within the home and cost 4 to 6 times less to operate than a central air conditioning system. Their primary disadvantage is that they bring in outside air containing dust, moisture, pollen and other allergens. Whole house fans are primarily recommended for houses without air conditioning or for homes whose occupants are committed to saving energy and are willing to control the operation of their home carefully. |
Estimating Passive Solar Savings
The following rules of thumb estimate the annual heating savings of passive solar homes:
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Each square foot of double-glazed south-facing window that is unshaded in the winter will save 40,000 to 60,000 Btu per year on a home’s heating requirement, if sufficient thermal mass exists.
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Low-emissivity glass will increase the savings 15 to 30 percent.
Thus, an energy efficient home with 200 square feet of passive solar windows and sufficient thermal storage mass could save 8 to 12 million Btu of energy on home heating needs each year. Movable insulation or low-e glass would save an additional 2 to 4 million Btu. Annual energy savings could range from $70 to $160.
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Key Energy Efficiency Steps:
Key Feature Checklist: - Moisture barrier system
- Air barrier system
- Continuous insulation system
- Design heating and cooling system
- Ductwork design and installation
- Minimize hot water costs
- Choose energy efficient appliances and lighting
- Provide intentional ventilation
(the pdf download of the entire Planbook has a complete checklist)
[top] High Performance Building Programs
ENERGY STAR Home Program
ENERGY STAR , an innovative energy efficiency program sponsored by the U.S. Environmental Protection Agency (EPA), is a voluntary partnership that includes more than 2,400 builders, developers, retailers, and product manufacturers nationwide who are working to build homes that use energy more efficiently.
ENERGY STAR qualified homes are independently verified to be at least 30% more energy efficient than homes built to the national Model Energy Code or 15% more efficient than state energy code, whichever is more rigorous. These savings are based on heating, cooling, and hot water energy use and are typically achieved through a combination of:
- building envelope upgrades
- high performance windows
- tight construction and controlled air infiltration
- upgraded heating and air conditioning systems
- tight duct systems
- upgraded water-heating equipment
To have a home certified ENERGY STAR, an independent contractor must verify that there is minimal air leakage and duct leakage by testing homes with special equipment. The contractor, called a Home Energy Rating Service (HERS) rater, then evaluates the overall efficiency of the insulation, windows, and heating and cooling systems to make sure the home meets ENERGY STAR guidelines. The HERS rater provides the certification and label for the home if it meets ENERGY STAR. ENERGY STAR certification can also be achieved through a Builder Option Package (BOP), which is a set of construction specifications for a particular climate. After certification, the home has the many benefits of an ENERGY STAR home, which include:
Some electric utilities offer a 5% reduction in electricity rates for homes that qualify as ENERGY STAR. Thus, the energy-saving features of the homes will reduce heating, cooling, and hot water bills, and the utility rate reduction will reduce the total cost of all electricity use. In addition to the efficiency requirements, some states, such as North Carolina, recommend an effective home ventilation system along with other measures that help provide for quality indoor air. Visit Energy Star or NC Energy Star for more information. |
What are Builder Option Packages (BOPs)?
Builder Option Packages (BOPs) help to simplify the process of constructing an ENERGY STAR qualified new home. BOPs represent a set of construction specifications for a specific climate zone. They specify performance levels for the thermal envelope, insulation, windows, orientation, HVAC system and water heating efficiency for a specific climate zone that meet the ENERGY STAR standard.
Though constructing a home to BOP specifications eliminates the need for a full HERS rating, third-party verification that BOP specifications have been met is still required. Similar to HERS ratings, BOP ratings typically entail at least one on-site inspection of the home to test the leakiness of the envelope and ducts. However, unlike the HERS rating, the scores derived from these tests are compared with the pre-determined specification of the BOP to either pass or fail the house as an ENERGY STAR qualified new home. |
What is a HERS rating?
A HERS Rating is an evaluation of the energy efficiency of a home as compared to a reference house (same size and shape as the rated home) that meets the requirements of the national Model Energy Code (MEC). It provides objective, standardized information on the energy performance of a home. A HERS rating evaluates the performance of the thermal envelope, glazing strategies, orientation, HVAC system and other efficiency criteria. Information is obtained either by an on-site inspection or a review of construction plans. HERS rating calculations incorporate estimates of both annual energy performance and of energy costs.
A HERS rating results in a score between 0 and 100. This rating indicates the estimated annual energy use of a rated house relative to a reference house built to the Model Energy Code (MEC). The reference house is assigned a score of 80. A rated home with identical annual energy use would also receive a score of 80. For each five percent reduction in energy use (compared to the reference house) the score increases by one point. Thus, an ENERGY STAR home that is 30% more energy efficient than the reference house has a minimum HERS rating of 86. Annual energy use is based on the heating, cooling and hot water heating requirements. |
Advanced Energy – SystemVision
The SystemVision initiative was launched by Advanced Energy in 2000 for affordable homes in North Carolina. The program now offers its own guarantee for homeowners of more modest means. The SystemVision guarantee lasts for two years. The guarantee promises that energy used to heat and cool the home will not exceed a specified amount and the temperature in the center of any conditioned room will not vary more than three degrees from the thermostat setting. If those conditions are not met, Advanced Energy will pay for the energy cost overrun and for identifying problems with the original equipment or construction.
The program treats the building as a system. The initiative helps building professionals improve the durability, energy efficiency, and environmental impacts of a house while emphasizing the health, comfort, and safety of the occupants. Advanced Energy’s involvement begins with reviews and necessary modifications to house plans and specifications. Also, on-site quality control monitoring and actual performance testing occurs before the guarantee is issued. |
Masco Contractor Services – Environments for Living
The Environments for Living Program includes a Heating & Cooling Energy Use Guarantee that calculates the amount of energy required to heat and cool the new home. While the program has no control over local utility rates, the combination of special framing techniques, improved insulation, and efficient ductwork helps ensure that the energy usage remains at a manageable level.
The program also provides built-in advantages such as pressure balancing, moisture management, and fresh air ventilation to help you and your family enjoy a higher level of consistent comfort throughout your new home. Another feature of the program is that it filters and delivers fresh air more efficiently to help create an environment that contains less dust, fewer odors and remarkably comfortable temperatures. Combined with interior moisture management and advanced combustion safety features, this should help reduce potential health risks. |
North Carolina Solar Center – NC Healthy Built Home Program
The NC HealthyBuilt Homes Program provides visibility and certification of homes for residential builders who practice sustainable, high performance building practices. The HealthyBuilt home is a comfortable, healthy, and affordable house that reduces energy and water usage and helps protect the environment. Building materials and processes are selected to reduce pollution and the waste of natural resources both during the manufacturing and construction phases and throughout the life of the home. Careful attention is given to energy efficiency and indoor air quality. Because the quality, amenities, and energy savings are evident, these homes have a higher value.
The program has been launched in North Carolina with a focus on providing support for small to medium-size home builders who may not have the resources to compete in the rapidly emerging field of green building. The program is designed with two tiers. The first is a statewide umbrella organization that administers the overall program, sets statewide guidelines, provides technical support, and coordinates training, marketing and certification. The second tier consists of local partnerships with organizations such as home builder associations that administer and promote the program in their community, tailoring it to local conditions and code requirements. |
Other Green Building Programs
Many other states have active green building programs. In the Southeast, the Earthcraft Home Program is available in several locations. Find out more at Southface. The organization know as LEED, Leadership in Energy and Environmental Design, is developing a green building program for residences. The Web site US Green Building Council has information on LEED and other green building programs. |
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North Carolina’s Renewable Energy Tax Credit
North Carolina provides a tax credit for the construction or installation of a renewable energy system to heat, cool, or provide hot water or electricity to a building located in state. The credit is 35 percent of the installation and equipment costs of a system, including passive and active space heating ($3,500 maximum per system), active solar water heating ($1,400 max) and residential electricity generating systems such as photovoltaics, wind, and micro-hydro. At present, the passive solar tax credit applies only to windows with Solar Heat Gain Coefficients of at least 70%. There are no low-e windows and virtually no double-paned windows that meet this requirement. Plans are underway to seek changes in the requirement. The tax credits are distributed over five years. The NC Solar Center can provide details and guidelines to determine the income tax credit, or visit The Database of State Incentives for Renewable Energy.
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