Green Power

LEED projects that do not install renewable energy on-site can purchase green power, which is renewable energy generated by another company or organization off-site.
Photo credit: Timothy Tolle via Flickr

Green power refers to purchasing renewable energy generated off the project site.  Projects that cannot or do not want to install renewable on-site can buy green power, which encourages investment in renewables and offsets some or all of the carbon emissions generated by the building.


There are a few specific types of green power that firms or people can purchase to offset their emissions:


Green power: Green power can be used as an umbrella term that applies to any renewable energy generated off-site that is eligible for purchase.  However, it is also used to describe the purchase of renewable energy through a utility.  So, when a person or firm purchases green power from their utility, they pay extra on their electricity bill, which funds the utility’s renewable energy projects.


Renewable energy certificates: A renewable energy certificate (REC), also known as a green tag or a tradeable renewable certificate (TRC) represents 1 megawatt-hour of electricity generated from a renewable source.  RECs can be sold or traded.


Purchasing renewable energy certificates allows buildings that use non-renewable power to create a market demand for renewable energy.


Carbon offsets:  Carbon offsets are credits for reducing green house gas emissions, typically measured in carbon dioxide equivalents (CO2e).  Firms or people can purchase carbon offsets, which represent that a renewable energy or energy efficiency project elsewhere is offsetting the firm or person’s carbon emissions.  While renewable energy projects are the most popular form of carbon offset, other energy or emissions projects, such as the destruction of landfill methane, may be used to generate credits.


LEED 2009 awards 2 points for projects that engage in at least a 2-year contract with a green power provider.  The contract must meet at least 35% of the building’s energy needs, either determined by the annual electricity consumption determined by a whole building energy simulation or the U.S. Department of Energy’s Commercial Buildings Energy Consumption Survey.


To qualify, the green power must be either Green-e certified, or it must meet current green power performance standards and be verified by a third party.  Green-e is a certification program for green energy developed by the Center for Resource Solutions.  It verifies that the green power provider is producing quality renewable energy and offsets, and gives the consumer confidence that their purchase is truly doing environmental good.


LEED v4 awards up to 2 points for projects that engage in a contract for qualified resources, such as green power, RECs or carbon offsets, for a minimum of five (5) years, to be delivered at least annually. The contract must meet at least 50-100% of the project's energy, including both electricity and non-electric energy. To calculate the project's annual energy consumption, the project team must use either the calculation from EA Prerequisite Minimum Energy Performance, if Option 1 (whole building energy simulation) was performed, or use the U.S. Department of Energy's Commercial Buildings Energy Consumption Survey (CBECS) database to estimate total energy use.


Green power and RECs must be Green-e Energy certified or the equivalent. If the provider is not Green-e Energy certified, the provider must provide confirmation of the date on which the qualified resources came online, the contract must outline the required purchasing goals and the time period during which the purchases will occur. For LEED buildings in the U.S. seeking greenhouse gas (GHG) offsets, the emissions reduction projects must be also located within the U.S.  


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