ASHRAE Journal - November 2010 - 54

emerging technologies
Value of Rating Buildings’ Features and Performance

Building energy labels
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By Alissa cooperman; John Dieckmann, Member ASHRAE; and James Brodrick, Ph.D., Member ASHRAE

ustainable construction comprises one-third of new construction, which is a significant increase from 2005, when it accounted for

2% of construction.1 Building energy labeling has been a major factor in this increase, by giving energy-efficient, sustainable buildings a widely recognized brand and by providing quantitative metrics to distinguish the sustainable from the not-so-sustainable.
In the United States, the Environmental Protection Agency (EPA) and the United States Green Building Council (USGBC) run two popular building rating programs. EPA’s ENERGY STAR rates commercial buildings on their energy performance, and Leadership in Energy and Environmental Design (LEED) certifies commercial buildings on their overall sustainability. Participation in both of these programs is voluntary. The systems are different enough to not be redundant. In fact, LEED is not a labeling system per se. It is a rating system that awards credits based on many sustainable features incorporated into buildings. The EPA’s ENERGY STAR for Buildings developed from the Green Lights program, which was founded in 1991 to increase the efficiency of commercial building lighting. The EPA recognized a need for a means of accurately modeling and recording energy use in commercial buildings. To meet this need, it developed Portfolio Manager ENERGY STAR software, designed to be used by the building owner to track the energy performance of a building. An approved score of 75 or greater (out of 100) qualifies a building as an ENERGY STAR building. A score of 75
54 ASHRAE Journal

indicates that the building performs better than 75% of comparable buildings in the Commercial Building Energy Consumption Survey (CBECS) database, a survey performed by the Energy Information Administration of the DOE. The first ENERGY STAR label was awarded to a building in 1999.2 LEED is a rating system for new construction, existing buildings, commercial interiors, core and shell, schools, retail, and neighborhoods. It awards credits for energy efficiency—granting credits to buildings that score above 67 on the ENERGY STAR scale. Buildings also earn credits for sustainable practices during building design, renovation, and operation.3 The energy performance baseline for a building is generated using the most current ASHRAE Standard 90.1 Energy Cost Budget approach; the energy use intensity (EUI) is relative to similar buildings in CBECS.4 Five levels of LEED certification can be obtained based on the number of credits earned: Certified, Bronze, Silver, Gold, and Platinum.3 LEED certification of a building has come to denote that a building is sustainable and is becoming standard practice in the design and construction of new buildings.
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The European Union (EU) adopted the Energy Performance of Buildings Directive in 2003, which requires new construction and buildings sold or leased to have an energy label. Since then, members of the EU have established and implemented building labeling programs.3 These labels indicate a building’s performance relative to peer buildings operated in a similar climate and under a similar load. The rating is displayed as a color-coded letter grade. Both an asset rating (as designed and built) and an operational rating are provided where available. For example, the UK has Energy Performance Certificates (EPC) required for residential and commercial buildings, as well as display energy certificates (DECs) required for publicly used commercial buildings. The DEC label must be publicly visible; it displays the building’s previous ratings, CO 2 emissions, and a basic breakdown of energy use. It is accompanied by a certificate that indicates how well the building is doing and recommends energy saving suggestions.5 ENERGY STAR focuses on the operational energy performance of buildings while LEED covers the overall sustainable practice of a building and its construction. Though ENERGY STAR distinguishes buildings performing in the top 25%, neither it nor LEED truly rank the energy performance of a building relative to buildings of similar types and in similar climates. Likewise, ASHRAE Standard 90.1 sets minimum energy requirements for buildings, but again does not specifically differentiate the extent to which performance is better than the minimum.3
November 2010

ASHRAE Journal - November 2010

Table of Contents for the Digital Edition of ASHRAE Journal - November 2010