An important consideration for any “green” building is its electric power supply. Commercial buildings currently consume more than one-third of the total electric energy produced in the United States. The U.S. Department of Energy (DOE) predicts that electric energy use by commercial buildings will increase by 75 percent between now and 2030, despite increased efficiency and conservation efforts.

Since most of the electric energy produced in the United States uses coal or natural gas as a fuel, commercial buildings contribute significantly to the production of carbon dioxide (CO2) and other greenhouse gasses and pollutants that impact the environment through their electric energy use.

As a result, the use of “green power” is becoming increasingly popular. In recognition of this, the U.S. Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED) Green Building Rating System includes the use of renewable energy sources as a part of their green building certification criteria.

The Green Building Rating System is divided into six categories, including Energy and Atmosphere (EA), which addresses the use of renewable energy sources among other issues. EA Credit 2 provides points toward certification for incorporating on-site renewable energy sources such as photovoltaics (PV) and wind generation into the project.

These points are assigned based on the amount of the building’s total energy use that is supplied by renewable energy sources as opposed to the traditional utility supply. The sliding scale assigns one point toward certification for supplying 5 percent of the building’s annual energy use from on-site renewable sources in EA Credit 2.1, two points for at least 10 percent in EA Credit 2.2 and a maximum of three points for more than 20 percent in EA Credit 2.3.

In densely developed urban areas, it is difficult to incorporate significant on-site renewable energy sources into a building due to limited space, the impact of surrounding buildings and development, zoning restrictions, and other constraints. However, there is another way that the building owner can reduce the impact of his or her building’s electric energy use on the environment.

Besides incorporating renewable energy sources into the project, the owner can purchase green power from its local utility or other regional power producer. This green power is generated using PV, wind, geothermal, biomass, low-impact hydro or other environmentally friendly power generation technology.

The LEED rating system recognizes the use of utility-supplied green power in EA Credit 6. This credit awards one point toward LEED certification if 50 percent or more of the buildings’ annual electric energy usage is supplied by utility-generated renewable energy.

To obtain this one-point credit, the owner must enter into a minimum two-year contract with the green power producer, and the renewable energy sources supplying the building must meet the Center for Resource Solutions (CRS) Green-e certification requirements.

To qualify for the LEED EA Credit 6, the energy must be supplied from an eligible Green-e renewable power source. Green-e certifies utility and other regional electric power producers through a voluntary process that verifies that the renewable power sources claimed by the supplier meet Green-e’s criteria.

Depending on the arrangement, the building owner either purchases the desired amount of renewable energy directly from the serving utility or through the purchase of tradable renewable certificates (TRCs) or “green tags” from other regional power suppliers.

With green power, there are no separate services or metering requirements that are sometimes required to take advantage of special rates for electric heat or other incentive programs. Instead, the building owner is paying a premium to the power producer either directly or through TRCs to provide renewable energy to the regional power grid.

There is no guarantee that the owner’s building will actually receive any of the energy produced by the renewable power sources. Instead, the green power produced by these renewable power sources will displace energy that would otherwise have to be produced by conventional fossil-fueled generators thereby improving the regional environment for everyone.

The impact of purchasing green power on the environment is essentially the same as if the building owner was able to install on-site renewable power sources to offset the amount of energy his or her building draws from the utility grid. EC

GLAVINICH is an associate professor in the Department of Civil, Environmental and Architectural Engineering at The University of Kansas and is a frequent instructor for NECA’s Management Education Institute. He can be reached at 785.864.3435 or tglavinich@ku.edu.