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Analysis of ASHRAE 90.1

Energy Savings Analysis of ASHRAE Standard 90.1

The objective of this project was to assess the energy and energy cost impact on commercial buildings of the 1999 revision to the ASHRAE Standard 90.1, which according to the Energy Policy Act of 1992, requires every state in the U.S. to adopt a commercial building energy code equivalent to or more stringent than ASHRAE Standard 90.1.  The extensive assessment used a large number of building energy simulations using the DOE-2 energy analysis software suite in ten climate zones to evaluate eight different commercial building types, each of two different sizes by floor area, to estimate the annual gas and electrical energy consumption for the building as a whole.  Six different combinations of wall and roof types were modeled along with several different glazing fractions to represent the characteristics of the commercial building stock within the U.S. Each building model was also simulated with the six most common combinations of heating and cooling equipment used in commercial buildings.  The results of these simulations were weighted by using the Commercial Building Energy Consumption Survey (CBECS) data from the U.S. Department of Energy and new commercial construction data from the U.S. Census Bureau to determine the national impact.  Using the CBECS database, commercial buildings constructed between 1980 – 1995 were characterized and weighting factors based on square footage developed to allow the simulation results to be projected regionally and nationally for:
Type of commercial building

  • Size of commercial building
  • Type of wall and roof constructions
  • Exterior glazing percentages
  • Type of heating and cooling equipment

Almost 94% of the U.S. commercial building inventory was characterized using the following eight building types:

  • Office
  • Mercantile & Service
  • Warehouse & Storage
  • Education
  • Lodging
  • Health Care
  • Public Assembly
  • Religious Worship