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Executive SummaryThis analysis was conducted by Pacific Northwest National Laboratory (PNNL) in support of the U.S. Department of Energy's (DOE) Building Energy Codes Program (BECP). DOE supports the development and adoption of energy efficient and cost-effective residential and commercial building energy codes. These codes set the minimum requirements for energy efficient building design and construction and ensure energy savings on a national level. This analysis focuses on one and two family dwellings, townhomes, and low-rise multifamily residential buildings. For these buildings, the basis of the energy codes is the International Energy Conservation Code (IECC). This report does not address commercial and high-rise residential buildings (four or more stories). This technical support document provides additional detail and documents the specific assumptions used in applying the cost-effectiveness methodology. iv The analysis is conducted using DOE's EnergyPlus simulation software. PNNL developed two prototype building models to represent the single-family and the multifamily buildings defined in the methodology. These two prototypes were then expanded to a suite of 32 energy models to represent four commonly used heating systems in homes (i.e., gas furnace, oil furnace, heat pump, and electric furnace) and four commonly used foundations (i.e., vented crawlspace, slab-on-grade, heated basement, and unheated basement). Different versions of the models are created to match the requirements of the 2006, 2009, and 2012 IECC for each location. The entire set is simulated across 119 locations to represent the different climate-zone and moisture regimes in each state across the country. The annual energy consumption for space heating, cooling, domestic hot water heating, and lighting is extracted for each case. The energy use is converted to energy cost using fuel costs in the different states. Incremental first costs are calculated for each location for the energy provisions of the 2009 and 2012 IECC over the baseline code, as applicable, using the Building Component Cost Community (BC3) data repository. 1 These first costs are adjusted for variation in construction and material costs across the country using location multipliers developed by Faithful+Gould for PNNL. 2 The energy costs and first costs are aggregated based on new housing construction starts from the U.S. Census data 3 , weights of the different foundation types from the Residential Energy Consumption Survey data 4 , and heating system weights based on National Association of Home Builders data (NAHB 2009). Life cycle cost (LCC) analysis is then conducted for each case to assess cost effectiveness. DOE uses LCC as the primary measure of cost effectiveness.

This report was completed by Pacific Northwest National Laboratory (PNNL) in support of the U.S. Department of Energy (DOE) Building Energy Codes Program. DOE supports the development and adoption of energy efficient and cost-effective residential and commercial building energy codes. These codes set the minimum requirements for energy efficient building design and construction and ensure energy savings on a national level. This report focuses on enhancements to prototype building models used to determine the energy impact of various versions of ANSI/ASHRAE/IES 1 Standard 90.1 (herein referred to as Standard 90.1).

This project was conducted by Pacific Northwest National Laboratory (PNNL) in support of the U.S. Department of Energy's (DOE's) Building Energy Codes Program (BECP). DOE's BECP supports the upgrading of the building energy codes and standards, and the states' adoption, implementation, and enforcement of those codes and standards as they are incrementally upgraded. Building energy codes and standards set minimum requirements for energy-efficient design and construction for new and renovated buildings, and impact energy use and emissions for the life of buildings. They are part of a broader set of documents which govern the design and construction of buildings for the health and life safety of occupants. Energy codes and standards set a baseline for energy efficiency in construction by establishing minimum energy-efficiency requirements. Improving these documents generates consistent and longlasting energy savings.When the model energy codes and standards for buildings are being updated, BECP reviews the technical and economic basis of these documents. For commercial and multi-family high-rise residential buildings, which are the subject of this report, the basis for the energy codes is the ANSI/ASHRAE/IES 1 Standard 90.1.

iv including plug and process loads. Chapter 5 and Appendix C of this report present these energy simulation results as used in the cost-effectiveness analysis. The energy saving analysis of Standard 90.1 in the report described above utilized a suite of 16 prototype EnergyPlus building models. Prototypes were simulated in 17 climate locations representing all eight U.S. climate zones. The cost-effectiveness analysis in this report used a subset of prototypes and climate locations, providing coverage of nearly all of the changes in Standard 90.1 from the 2007 to 2010 edition that affect energy savings, equipment and construction costs, and maintenance, including conventional HVAC systems used in commercial buildings. Each prototype building was analyzed in each climate location for a total of 30 cost-effectiveness assessments. The following prototype buildings and climate locations were included in the analysis: Prototypes Climate Locations Small Office 2A Houston, Texas (hot, humid) Large Office 4A Baltimore, Maryland (mixed, humid) Standalone Retail 3A Memphis, Tennessee (warm, humid) Primary School 5A Chicago, Illinois (cool, humid) Small Hotel 3B Albuquerque, New Mexico (hot, dry) Mid-rise Apartment A primary input to the cost-effectiveness analysis was the incremental costs for the addenda to 90.1-2007 that were included in 90.1-2010. Of the 109 total addenda to 90.1-2007, 41 had quantified energy savings that were modeled in the 90.1-2010 energy savings analysis. The remaining addenda were not considered to have quantifiable savings, or do not affect the sections of 90.1 that directly impact building energy usage. Of the 41 addenda with quantified energy savings, 38 were modeled in the six prototypes and were included with the cost estimate. The remaining three addenda affect building systems that were not included in the prototypes. vi Table ES-1 Summary of Cost-effectiveness Analysis Prototype Climate Zone