New York’s new One World Trade Center, aka the Freedom Tower, achieved LEED Gold certification in September 2016. This award recognizes the many energy-saving features of the building, including daylighting to reduce electricity needs, use of recycled materials such as fly ash concrete, greywater harvesting, and elevator brakes that capture the lost energy like an electric car. The award comes in spite of a setback when Hurricane Sandy destroyed several fuel cells earmarked for the building in 2012.
LEED, which stands for Leadership in Energy and Environmental Design, was first developed in the 1990s and remains the best-recognized scorecard of a building’s impact on the planet. The United States Green Building Council (USGBC) develops the requirements and oversees the certification for LEED buildings. There are many categories, including a residential-specific category called LEED for Homes. No building receives a LEED review automatically; developers must apply for certification and pay a fee to USGBC.
The levels of certification are LEED Certified, LEED Silver, LEED Gold, and LEED Platinum (the highest). Levels are based on the number of credits a building earns for design features including materials selection, energy and water management, and connection to the neighborhood. The maximum is 110 credits. Among other things, Freedom Tower got 3 credits for its Low-Emitting Materials and 6 for Indoor Water Use Reduction. It also got lots of credits in the Location and Transportation category by virtue of its downtown location – you can’t beat having a subway and PATH station literally in your basement.
LEED for Homes rewards small footprints. A house earns incremental credits for being smaller than some benchmark (it’s 1600 square feet for a two-bedroom) and loses incremental credits for being larger. Small houses also naturally benefit from their reduced fuel requirements, in terms of both embodied energy and ongoing needs. Integration with the site is a prerequisite, so a house on wheels can’t get LEED certification… but then a house on wheels doesn’t really need a third party to verify its tiny environmental impact.