What is LEED?

Leadership in Energy and Environmental Design (LEED) is the leading green building rating system in the United States. It is primarily a voluntary system, and was designed by the U.S. Green Building Council to measure the environmental aspects of newly constructed buildings, and environmentally sensitive operation of existing buildings. There are several rating systems under the LEED umbrella, among them LEED for New Construction, and LEED for Existing Buildings: Operations and Maintenance.

LEED Certifications for buildings are achieved by managing environmental aspects of a building in five categories, including Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, and Indoor Environmental Quality. By meeting specific benchmarked goals, operating to appropriate policies, and installing specific technologies, a building achieves “LEED Points”. The number of LEED Points a building has earned determines the level of LEED Certification at which a building is rated. In order of increasing LEED Point achievement, the levels are LEED Certified, Silver, Gold, and Platinum.

Submetering of both electricity and water are critical technologies referenced in the LEED system, with opportunities in four credit areas each. Many LEED Points are earned only when a specific performance target is met, which requires the adoption of at least one but potentially many technologies and solutions to achieve the necessary result. Submetering is one of those few technologies in LEED that the simple installation and monitoring of meters immediately results in points awarded. For good reason it is an

Why LEED?

There are numerous reasons to achieve LEED certification for a building, and LEED adoption has increased exponentially over the last decade from dozens of buildings per ear, to thousands of buildings per year. It is sought for many buildings out of a sense of responsibility, or the prestige, or the marketing value it creates for the organization that owns the building. In addition to these benefits, there are numerous municipalities and states in the U.S. that have adopted LEED as code for some buildings. Additionally, tax credits and other incentives are offered by some jurisdictions. As of 2009, over 75 municipalities have adopted LEED as either code, or providing incentives for its adoption.

The goal of this credit, worth one or two points, is to reduce potable water use consumed by cooling towers. A credit is achieved if cooling towers use 50% reclaimed water or more, and submetering of both potable water and reclaimed water entering the tower is required to demonstrate compliance.

Water Submetering Benefits in LEED

WE Prerequisite 1: Minimum Indoor Plumbing Fixture and Fitting Efficiency
WE Credit 1: Water Performance Measurement
WE Credit 3: Water Efficient Landscape
WE Credit 4: Cooling Tower Water Management

Electricity

EA Prerequisite 2: Minimum Energy Efficiency Performance
EA Credit 1: Optimize Energy Efficiency Performance
EA Credit 2.1: Existing Building Commissioning- Investigation and Analysis
EA Credit 3.2: System Level Metering

Water Submetering

WE Prerequisite 1: Minimum Indoor Plumbing Fixture and Fitting Efficiency

The goal of this prerequisite is to ensure faucet plumbing water use is reduced. It is a general prerequisite that requires determination of water saved after retrofitting a building with water efficient fixtures. Submetered fixture plumbing is specifically referenced as a technology that helps meet this requirement.

WE Credit 1: Water Performance Measurement

This credit is earned specifically by installing water submetering units, with one or two points available. For the first credit, applicants must monitor potable water use for the entire building and grounds are encouraged to meter clean water and grey water separately.

A second credit is earned in this category by submetering 80% of expected water consumption for “process type end uses, such as humidification systems, dishwashers, clothes washers, pools and other systems using process water”, or by installing metering systems that cover 80% of expected water use on irrigated grounds, or by metering 80% of indoor plumbing fixtures.

WE Credit 3: Water Efficient Landscape

There are up to five points available for water efficient landscaping under this credit, the specific number of which are achieved based on the percentage reduction in water used for landscaping. Submetering is specifically referenced as a key method to demonstrate compliance, and achieve the credit.

WE Credit 4: Cooling Tower Water Management

The goal of this credit, worth one or two points, is to reduce potable water use consumed by cooling towers. A credit is achieved if cooling towers use 50% reclaimed water or more, and submetering of both potable water and reclaimed water entering the tower is required to demonstrate compliance.

Electricity Submetering

EA Prerequisite 2: Minimum Energy Efficiency Performance

This requirement in the LEED system compels applicants to establish a minimum level of operation efficiency, so that existing buildings can be benchmarked against performance of a “typical” building of that type. The level of performance required for LEED Certification is EPA Energy Star rating of 69. Submetering is mentioned as the most effective solution to demonstrate compliance.

For buildings that are eligible for the EPA’s Energy Star rating, metering 100% of electricity use throughout the performance period is required. Submetering of major mechanical systems is also specifically mentioned as an effective solution to ensure all energy consumption is taken into account.

EA Credit 1: Optimize Energy Efficiency Performance

Energy and Atmosphere Credit 1 is very closely related to EA Prerequisite 2. The prerequisite requires establishment and measurement of a specific minimum building performance of 69. However EA Credit 1 provides credits for buildings that achieve performance beyond the minimum set forth in the prerequisite. Up to eighteen credits are available for buildings, depending on how far the prerequisite Energy Star level is exceeded.

Like EA Prerequisite 2, one full year of metered data is required to establish qualification for extra energy efficiency credits. Energy meters must record all energy use associated with the building throughout the performance period. Again, submetering of major electrical and gas machinery and subsystems is recommended to ensure all energy is accounted for.

EA Credit 2.1: Existing Building Commissioning- Investigation and Analysis

The Investigation and Analysis credits are achieved by analyzing the major energy using systems (gas and electric) of a building, their performance, and identify areas where savings can be achieved. It is a significant credit worth two LEED points.

To achieve the Investigation and Analysis credit, submetering of energy consuming systems is required. It is necessary to understand where and how energy is used in a building in order to monitor, control, and improve energy efficiency.

EA Credit 3.2: System-Level Metering

One or two points are available under EA Credit 3.2, the goal of which is to provide additional energy-use information to support energy management and identify opportunities for improvements that will save energy.

There are two levels for this credit, each achieved by a different level of submetering. One point is achieved when at least 40% of the annual energy consumption of a building is submetered. A second point is achieved when 80% of the annual energy consumption is submetered. Furthermore, metering must be continuous and data must be logged such that time trends can be analyzed.

References

U.S. Green Building Council Web Page: http://www.usgbc.org/DisplayPage.aspx?CMSPageID=222