LEED, Passive House, Net Zero Energy and NAHB: Which Standard is Right For You?
Even for those who make their living in the green building industry, navigating the world of energy-efficient building standards and certifications can seem overwhelming. While these standards share many of their underlying principles, each one is unique in its objective, scope and mandates. The following four programs and design standards represent some of the strongest trends in energy-efficient building in the United States today.
Passive House
The objective of a Passive House, or Passivhaus in its native Germany, is to build a home that improves energy efficiency at least 90% relative to the average new home. In the United States, the Passive House Institute U.S. trains and certifies Passive House consultants and verifies performance of homes built to the Passive House standard. The principle strategies for reducing energy use in a Passive House are an airtight envelope, well-insulated walls and windows, passive solar heating using optimal window orientation to minimize heating and cooling load, and an energy recovery ventilation system that provides fresh air with minimum energy consumption. All of these strategies seek to implement the goal of using "passive" natural resources efficiently and minimizing the need for "active" systems. The Passive House standard focuses specifically on minimizing energy consumption.
LEED for Homes
The Leadership in Energy and Environmental Design (LEED) is a Green Building Rating System developed and administered by the U.S. Green Building Council. LEED for Homes is a set of performance standards for certifying the design and construction of new homes and residential remodels. LEED's objective is to stimulate the home construction market toward more sustainable practices. The LEED Home Rating System evaluates the performance of new homes in eight categories: indoor environmental quality, energy efficiency, water efficiency, site selection, site development, materials selection, residents' awareness and innovation. To achieve LEED certification a home must submit to inspections during construction and a final certification at the conclusion of the project. During this process the home wins points for achievements in each category and finally is awarded Certified, Silver, Gold or Platinum certification. LEED takes a broad-based approach to sustainability and aims to promote energy and environmental performance across the board.
National Green Building Standard
In 2007 the National Association of Home Builders (NAHB) partnered with the International Code Council (ICC) to develop the National Green Building Standard (NGBS). The goal of this process was to establish definitions and standardize metrics for "green building" in single- and multi-family homes and residential remodeling projects. The NAHB Research Center certifies homes to this standard by evaluating the incorporation of features in the following five areas: resource efficiency, energy efficiency, water efficiency, indoor environmental quality, and operations, maintenance and owner education. The NAHB has four levels of certification: Bronze, Silver, Gold and Emerald. The category with the lowest score determines the overall certification level of the home, and to achieve Emerald certification a home must attain at least 60% energy savings.
Net-Zero Energy
A Net-Zero Energy Home (NZEH) is a home that annually produces as much energy as it consumes. NZEH homes combine state-of-the-art energy efficiency measures with onsite renewable power generation, usually through solar photovoltaic and/or solar thermal production. While these homes connect to the electricity grid and may draw from it when the renewable power source does not meet its daily needs, when production exceeds consumption the house sends the excess back to the grid. NZEH play an important part in the Department of Energy's (DOE) vision for the future of the built environment. The DOE began the Builders Challenge program to promote the advancement of energy efficiency in new homes with the ultimate goal of making NZEHs available throughout the United States by 2030. An NZEH can be measured an certified with the Home Energy Rating System (HERS) Index, which measures energy performance of homes in relation to the average new home. On the HERS Index a score of 100 corresponds to the energy consumption level of the average new home and each point represents a reduction of 1% in relation to that benchmark. A score of 0 or below corresponds to an NZEH.
Many other regional, national and international standards exist in the area of green building. However, these four trends represent some of the most influential and cutting-edge achievements in the green building space. All of these standards can apply to both new construction and retrofits of existing homes. While all of these programs promote more efficient and sustainable building practices, each retains an unique perspective in terms of goals and approaches.
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SeriousWindows http://www.seriouswindows.com can help both residential and commercial buildings drastically improve energy efficiency, reduce heating and cooling loads and save money. SeriousWindows are top-of-the-line windows that use suspended film technology and inert gas fills for optimal insulation performance. They feature high R-Values, low air leakage and custom glazing packages perfect for retrofits or new construction.
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