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USGBC
Excerpted from LEED 2009 for Retail: Commercial Interiors
EA Credit 1.5: Optimize energy performance - building envelope
Intent
To achieve increasing levels of energy conservation beyond the prerequisite standard to reduce environmental and economic impacts associated with excessive energy use.
Requirements
Option 1. Performance compliance path
Demonstrate a 15% reduction in the heat loss and heat gain of the proposed building envelope compared with the baseline building performanceBaseline building performance is the annual energy cost for a building design, used as a baseline for comparison with above-standard design. rating per ANSI/ASHRAE/IESNA Standard 90.1–2007 (with errata but without addenda1) for the building envelope components such as glazing, insulation, roofing, and slab using a modeling protocol or overall UA (U factor x Area) calculation. Projects outside the U.S. may use a USGBC approved equivalent standard2.
OR
Option 2. Prescriptive compliance path
Comply with the prescriptive measures for building envelopes of ASHRAE Advanced Energy Design Guide for Small Retail Buildings 2006. The building must meet the following requirements:
- The building in which project is located must be less than 20,000 square feet.
- The building must be retail occupancy.
- The project must fully comply with all applicable criteria as established in the Advanced Energy Design Guide for the climate zoneOne of five climatically distinct areas, defined by long-term weather conditions which affect the heating and cooling loads in buildings. The zones were determined according to the 45-year average (1931-1975) of the annual heating and cooling degree-days (base 65 degrees Fahrenheit). An individual building was assigned to a climate zone according to the 45-year average annual degree-days for its National Oceanic and Atmospheric Administration (NOAA) Division. in which the building is located. Projects outside the U.S. may use ASHRAE/ASHRAE/IESNA Standard 90.1-2007 Appendices B and D to determine the appropriate climate zone.
1Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
2 Projects outside the U.S. may use an alternative standard to ANSI/ASHRAE/IESNA Standard 90.1-2007 if it is approved by USGBC as an equivalent standard using the process located at www.usgbc.org/leedisglobal
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2 Comments
LEED 2009 for Retail: Commercial Interiors EAc1.5
We have an existing building being renovated. The existing building envelope does not meet ASHRAE 90.1-2007 criteria. If we want to get the credit for EAc 1.5, can we use the existing building envelope as the base line, or do we have to use the building envelope coefficients in ASHRAE 90.1-2007 as the baseline for our model ?
Robert, speaking solely on the basis of my reading of the LEED requirements, I think you would need to use 90.1-2007 as the baseline. There is no mention of a different approach for existing buildings in the credit language, as there is in other LEED rating systems. Also, this is a credit, not a prerequisite, so there is an expectation of strong performance.
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