|
GREEN Construction The following sub-topics detail some of the ways Green Building:
LOT DESIGN, PREPARATION, AND DEVELOPMENTWith a goal to lower environmental impact and improve energy performance, factors considered are:
RESOURCE EFFICIENCY Material selection occurs at the design phase. A resource efficient design incorporates materials to maximize function while optimizing the use of natural resources. In addition, resource efficiency reduces job-site waste and recycles generated waste where appropriate. An average 2300 ft2 home is estimated to generate between 7,000 and 12,000 lbs of waste during construction. An effective waste management recycling plan may reduce construction material waste by two-thirds, realizing a cost savings for the builder and owner while reducing the burden on local landfills. In addition, using locally stocked new building products and incorporating salvaged materials where applicable, reduces the transportation cost associated with job site delivery. FRAMING TECHNIQUES By incorporating advanced framing techniques builders maximize the use of materials thereby reducing waste and costs. These techniques in conjunction with engineered materials improve value, durability, and safety of the homes walls. Many engineered framing materials provide a superior strength product and use less old growth timber. For example Structural Insulated Panels (SIP) contain a core of rigid foam expanded polystyrene insulation (EPS) sandwiched between two sheets of composite oriented strandboard (OSB). These panels may be used in roofs, walls, and floors to replace conventional sheathing. They have a higher R-value, reduced air leakage, resist moisture, transmit less sound, and are stronger and more earthquake resistant than conventional framing. In addition, EPS does not out-gas harmful chemicals nor does it sustain a flame. Since these engineered panels are pre-cut, job site waste is reduced and the completed wall contains about 75% less raw wood than a conventional stick framed wall. They are factory manufactured and can be custom sized for each home, resulting in a structure that is stronger and more energy efficient, while requiring less labor to complete. Another eco-friendly framing method uses manufactured steel, which is recycled, strong, lightweight, and less labor intensive. Steel is inherently rot and insect proof and resistant to moisture damage. It is fastened, not nailed, so it can be disassembled and reused with minimal scrap. Concrete Masonry Framing offers strong resistance to natural and man-made disasters. It is fire resistant and offers protection from wind, termites, rot, and mildew. Reduced structural flexing minimizes cracks and nail pops on interior walls and lowers routine maintenance. This stronger envelope also lowers insurance premiums with many carriers. FOUNDATIONTo improve thermal losses via the foundation walls, manufacturers have developed a variety of ways to reduce conductive heat loss through concrete. For example, cladding the exterior with foam board, or filling block voids with foam increases the foundations R-values and reduces air infiltration. To improve the foundations performance further, manufacturers have created Insulated Concrete Forms (ICF). There are several systems currently being manufactured. Most use (EPS) blocks or panels that are laid up, installed with rebar, and filled with concrete. There are other systems that use a recycled foam or shredded waste wood mixed with concrete to create the blocks. These (ICF) concrete filled block walls are very strong and offer superior thermal performance. A masonry home can offer up to 50% in energy savings to its inherent thermal mass. Since it is a recycled product, it is naturally eco-friendly. CRAWL SPACESThe traditional vented crawl space is a haven for moisture and mold. While the intent of foundation vents is to dry the moisture introduced by the dirt crawl space floor, in reality they introduce new problems to the overall home environmental system. In the winter while they may indeed lower the humidity in this space, the outside air entering creates colder floors and a corresponding energy penalty. In summer, they introduce warm moist air to a cooler area, raising the relative humidity and under certain conditions, cause condensation. Mold will start to grow when the relative humidity on organic materials (i.e. Wood Framing) is above 60%. This is often easily achieved in vented crawl spaces. The solution to both these conditions is to totally seal the crawl space, separating the house from the ground under it. This both reduces the homes energy requirements and improves indoor air quality.
INDOOR ENVIRONMENTAL AIR QUALITY
Air Quality, often the most-cited important feature of certified high performance homes, is achieved through controlling the source, diluting the source, and capturing the source through filtration. The first step involves correct sizing of the buildings heating and cooling requirements using Manual J calculations. Next using Manual S calculations, the type and size of HVAC equipment is determined to meet the Manual J BTU load. Finally, Manual D is incorporated to size and layout supply and return ductwork for the structure. When installing gas furnaces or fireplaces use direct vent equipment and / or install induced mechanical draft in a combustion closet to minimize the quantity of combustion-generated pollutants entering the home and the unnecessary loss of indoor air to support these devices. Tip: Look for Energy Star certified HVAC units with high SEER, HSPF, and AFUE ratings to minimize utility expenses and reduce consumption of natural resources involved in energy generation. INSULATION
Foamed-in-place insulation is sprayed out of an applicator. It is superior to batt insulation as it stops air circulation within the wall cavity. It may be used in walls, attics, surrounding gaps, and sealed crawl spaces. Applied to the bottom of the attic roof decking, foam insulation also performs excellent as a radiant barrier. ENERGY EFFICENCY Energy consumption occurs during the operation, construction, and indirectly in the production of the materials that go into the home. A Green Built home reduces all these impacts and can make the home 20% more efficient thereby reducing the homeowner’s utility expenses.
WATER EFFICENCY Today’s average home per capita daily water use is slightly over 64 gallons. Implementing water conservation measures can reduce this usage to 45 gallons or less. Green Homes conserve water indoors and outdoors by:
OPERATION, MAINTENANCE, AND HOME OWNER EDUCATION A homeowner’s instruction manual supplied by the builder provides information on the proper operation and maintenance procedures for the home. This assists the owner in areas such as knowing which toxic cleaning chemicals to avoid, water and energy saving practices, filter change intervals, and maintenance of mechanical equipment enabling the owner to maintain the durability of the home.
The preceding information was gathered in part from the following sources
|