Leadership in Energy & Environmental Design is a program developed by the U.S. Green Building Council to integrate all aspects of the design, construction, and maintenance of a building in order to minimize environmental impact and maximize energy efficiency. Through LEED certification, the USGBC provides third-party verification of green goals.

In a traditional design process, the pieces of the project (i.e. structural, landscape, architectural, etc.) are divided and worked on separately by different specialists. In a LEED project, all participants work collaboratively from design inception, beginning with analysis of the owner’s program in light of the rating requirements.

The role of the LEED Accredited Professional is to interpret the rating system for the project team, coordinate the certification process, verify compliance, and participate in technical analyses.

Building categories defined by the USGBC include rating systems for new construction, commercial interiors for tenant improvements, core and shell, existing buildings, homes, neighborhood development, and schools K-12 including acoustics, master planning, and mold prevention.

Each rating system describes requirements unique to the project type, and provides technologies and strategies for meeting them. The certification process involves documenting achievement of measurable and verifiable criteria. The formal review will evaluate performance over the life cycle of the building. The level of LEED certification depends upon on the total number of credits achieved in each credit category. Some are mandatory; others are elective. A project qualifies for certification if it meets a minimum of 40% of the requirements. A silver rating means the building qualifies for 50% of available credits; gold means 60%, platinum 80%.

In the LEED for New Construction rating system, these categories are:

Sustainable Sites: Minimizes pollution from the construction of the building, and gives the design team criteria for site selection. Credits can be earned by controlling soil erosion, waterway sedimentation and airborne dust during construction. Discourages building on farmland, parkland, wetlands, habitat for endangered or threatened species, or in close proximity to bodies of water. Encourages cleanup and reclamation of “brownfields” – areas where there is hazardous waste. Building footprints are minimized to protect surface habitat. Preferred sites are in urban areas within walking distance of community and commercial centers and public transportation. Encourages installation of bike racks and paths. Parking ideally goes underneath the building. Tenants are encouraged to car pool. Open space is maximized. Impervious site surfaces are kept to a minimum to encourage filtration of stormwater. Vegetated or reflective rooftops help keep the air temperature above buildings consistent with temperatures outside the city (protects wildlife habitats and reduces strain on cooling systems.) Light pollution at night may be reduced or avoided through the use of low lighting and downlighting. Lights may be programmed to turn off when not needed.

Water Efficiency: Reduces the quantity of water needed for building operations; provides water management criteria. Limits use of potable water. Encourages harvesting and reuse of storm water for irrigation, custodial purposes, and toilet flushing. Native plants are preferred because they require less or no irrigation. Water-efficient fixtures with automatic turnoffs are preferred. Dry fixtures such as composting toilets may be used.

Energy & Atmosphere: Minimizes energy use; provides criteria for renewable and alternative energy sources. Specifies methods for designing, installing, and operating energy systems and building envelope systems. This section requires an analysis of energy costs through whole building energy simulation. Includes looking at the energy needed to run equipment, elevators, escalators, computers, cooking, refrigeration, laundry washing and drying. Renewable energy (solar, wind, geothermal, biomass, bio-gas) is preferred. Ozone-depleting substances are discouraged in refrigeration and fire prevention equipment.

Materials & Resources: Requires establishing a plan for recycling on the site during construction. Recycling efforts are to be tracked throughout the construction process. Encourages re-use of existing materials. Credits can be earned by maintaining high percentages of existing walls, floors, roofs, and interior non-structural elements. Materials to be removed are redirected for re-use or recycling. Encourages use of post-consumer recycled content (materials made from recycled, not just recyclable, materials.) Must provide for safe removal of hazardous materials. Preferred building materials are obtained through regional sources (to avoid burning fuel to transport over long distances) and/or are made from rapidly renewable resources (fast growing plants such as bamboo.)

Indoor Environmental Quality: Ventilation methods and reduction of indoor pollutants. Smoking rooms are negatively pressurized to cause air to flow in instead of out when a door is opened. Transfer of environmental tobacco smoke must be contained with proper sealing in walls, ceilings, floors, and vertical chases. Requires the installation of permanent monitoring systems that provide feedback on ventilation systems performance. Requires monitoring of carbon dioxide levels. During construction, workers are protected from exposure to toxic fumes emitted by carpeting, adhesives, caulking, sealants, foams, ceiling tile, paint, etc. Prior to occupation, air quality must be tested for formaldehyde, volatile organic compounds, and other harmful substances. Product testing requirements are included in construction documents.

Innovation & Design Process: Encourages unique solutions to regional sustainability issues. This can be for performance above the requirements, or for innovations outside the scope of the rating system. For a building to qualify for LEED certification, it must meet a minimum of 40% of the requirements (earn 40% of the available points.) A silver rating means the building qualifies for 50% of available credits; gold signifies 60%, and a platinum rating requires 80%. Most LEED concepts are common sense, but require detailed knowledge, proven results, and thorough documentation.

Recommended reading:

Books by Jerry Yudelson

Green Building A-Z

The Green Building Revolution

Green Building Through Integrated Design

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