- Aesthetic Challenges
- Aesthetic Opportunities
- Air Barrier Systems in Buildings
- Assessment Tools for Accessibility
- Balancing Security/Safety and Sustainability Objectives
- Designing Buildings to Resist Explosive Threats
- Electric Lighting Controls
- Electrical Safety
- Energy Analysis Tools
- Energy Codes and Standards
- Energy Efficient Lighting
- Evaluating and Selecting Green Products
- Facility Performance Evaluation (FPE)
- Glazing Hazard Mitigation
- High-Performance HVAC
- Life-Cycle Cost Analysis (LCCA)
- Natural Ventilation
- Passive Solar Heating
- Psychosocial Value of Space
- Reliability-Centered Maintenance (RCM)
- Retrofitting Existing Buildings to Resist Explosive Threats
- Seismic Design Principles
- Sun Control and Shading Devices
- Sustainable O&M Practices
- Threat/Vulnerability Assessments and Risk Analysis
- Windows and Glazing
Energy Codes and Standards
Last updated: 06-11-2010
Within This Page
Energy codes provide minimum building requirements that are cost-effective in saving energy. The energy saved is a cost savings to the building owner through lower monthly utility bills, and smaller and thus less expensive HVAC equipment. More than 2/3rds of the electricity and 1/3rd of the total energy in the U.S. are used to heat, cool, and operate buildings. This means that implementing and enforcing energy codes will result in fewer power plants and natural resources being used to provide electricity and natural gas. It also means fewer emissions to the atmosphere. Emissions have been linked to smog, acid rain, and global warming. In the U.S. most buildings are constructed to meet minimum energy code requirements; therefore energy codes contribute to sustainability by saving energy and protecting the environment.
Energy codes are effective in reducing per capita energy usage (energy use per person). The per capita energy use in California has remained steady due to its active use and enforcement of energy codes for buildings, while energy use in the rest of the U.S. has increased.
Fig. 1. Total Electricity Use, per capita, 1960-2001 (estimated for California for 2000 and 2001)
(Courtesy of Art Rosenfeld)
A. Commonly Used Energy Codes
The U.S. Energy Conservation and Production Act (ECPA) requires that each state certify that it has a commercial building code that meets or exceeds ANSI/ASHRAE/IESNA Standard 90.1-1999. In this sense, "commercial" means all buildings that are not low-rise residential (three stories or less above grade). This includes office, industrial, warehouse, school, religious, dormitories, and high-rise residential buildings. The process is administered by the Department of Energy. ASHRAE 90.1 is the most commonly used energy code for commercial and other non-residential buildings. The Model Energy Code (MEC), now the International Energy Conservation Code (IECC), is the most commonly used residential energy code by states. The IECC also has a commercial section that allows the use of ASHRAE 90.1 for compliance. The International Residential Code (IRC) is also used by some states. The NFPA has commercial and residential energy codes based on ASHRAE Standards 90.1 and 90.2 (low-rise residential). The status of energy codes by states is available from the Building Codes Assistance Project (BCAP). Some states, such as Florida and California, have independently developed and adopted their own energy codes. Some states and jurisdictions do not yet have energy codes despite the federal requirement.
Table 1. Energy Codes in Order of Frequency of Adoption by States
|ASHRAE 90.1||IECC (MEC)|
|NFPA 5000³||NFPA 5000³|
²The IECC allows the use of ASHRAE 90.1.
³NFPA 5000 is based on ASHRAE 90.1 and 90.2.
Table 2. Residential Energy Code Adoption – Autumn 2004
|MEC Version or Equivalent State Code||States Adopted or Adopting|
|2003 IECC, IRC||10 States (AR, CT, KS, MD, NE, NM, PA, RI, PA, VT)|
|2000 IECC, IRC or equivalent state code adopted or under review or in rulemaking for statewide adoption/equivalence||18 States and DC (AL, CA, DC, DE, FL, GA, ID, KY, NC, NH, NY, OH, OR, SC, TX, VA, WA, WI, WV)|
|1998 IECC||1 State (OK)|
|95 MEC, Mandatory statewide adoption/equivalence||6 States(AK, HI*, MA, MN, NJ, VT)|
|95 MEC, Partial adoption/equivalence||1 State (LA)|
|93 MEC, Mandatory statewide adoption/equivalence||1 State (ND*)|
|92 MEC, Mandatory statewide adoption/equivalence||3 States (IA, IN, TN)|
|No statewide residential code or residential code is not EPAct compliant||10 States (AZ*, CO*, IL*, ME, MI, MO, MS*, NV*, SD, WY*)|
(Source: Building Codes Assistance Project)
Table 3. Commercial Energy Code Adoption – Autumn 2004
|ASHRAE/IESNA Standard or Equivalent State Code||States Adopted or Adopting|
|2003 IECC/ASHRAE 90.1-2001||13 States (AR, CT, FL, GA, KS, ME, MT, NM, NE, SC, UT, PA, RI)|
|ASHRAE/IESNA 90.1-1999, Statewide or equivalent state code adoption or in adoption process||21 States and DC (CA, DC, DE, ID, IL, KY, LA, MA, MD, MI, NC, NH, NJ, NY, OH, OR, TX, VA, WA, WI, WV)|
|ASHRAE/IESNA 90.1-1989, Mandatory statewide adoption/equivalence||5 States (HI, IA, MN, ND*, OK)|
|No commercial code or commercial code is not EPAct compliant||10 States (AK, AL, AZ*, CO*, MO*, MS, NV, SD, TN*, WY*)|
(Source: Building Codes Assistance Projects)
New federal commercial and multi-family high-rise residential buildings must meet standards in 10 CFR 434, based on the ANSI/ASHRAE/IESNA Standard 90.1-1989. The U.S. Department of Navy (DON) and Department of Defense (DOD) use ANSI/ASHRAE/IESNA 90.1-1999 rather than 10 CFR 434. Government low-rise residential energy standards generally comply with ENERGY STAR. The U.S. Department of Energy's Federal Energy Management Program (FEMP) oversees the efforts to reduce energy and impacts to the environment at federal sites.
Modifications to existing buildings often need to meet new building requirements or ANSI/ASHRAE/IESNA Standard 100-1995 – Energy Conservation in Existing Buildings. A common method of reporting energy performance for existing and new buildings is described in ANSI/ASHRAE Standard 105-1984 (RA 99) –Standard Methods of Measuring and Expressing Building Energy Performance.
B. Scope of Energy Codes
Energy codes generally dictate requirements for the building's envelope, mechanical, and lighting (nonresidential only) requirements. Energy codes must be easy to understand for architects and builders to use and code officials to enforce. For this reason codes cannot incorporate all good design practices and should not be confused with good practice. For instance, significant energy can be saved by considering building orientation, limiting infiltration, planting trees, and using passive solar design strategies. Yet these are not mandated in most energy codes at this time. Also, if durability of building materials were considered, energy could be saved in the manufacturing and installation of replacement materials throughout the life of the building. But durability is not considered in energy codes at this time.
Energy codes strive to provide cost-effective criteria. For example, commercial building criteria in ASHRAE 90.1 generally has a payback period of less than 10 years and residential building criteria in ASHRAE 90.2 generally has a payback period of less than 20 years. See resource page Life-Cycle Cost Analysis.
Building envelope requirements in codes generally include minimum insulation levels for walls, roofs, and floors, as well as window requirements. These generally vary with climate region, since more insulation is cost-effective in cold or extremely hot regions.
Mechanical system requirements include minimum equipment efficiency requirements, insulation requirements for ducts and piping, and controls for off-hours and dead bands (commercial).
Commercial building requirements for lighting include total building wattage requirements for interior and exterior lighting. Controls are generally required to assure lighting is turned off when facilities are unoccupied. This can be achieved through programmable controls or occupancy sensors.
C. Prescriptive versus Performance Criteria
Codes generally have prescriptive and performance paths for compliance. Prescriptive paths are easy-to-use tables that contain required minimum or maximum values. Performance paths are used to trade one energy saving measure for another. For instance, if the wall insulation does not meet the prescriptive requirements, but the ceiling insulation exceeds the prescriptive requirements, then using a performance method may show compliance of the whole building with the code. Prescriptive paths are commonly used for typical buildings in states with newly adopted codes. Once designers become familiar with performance software, these become more popular. Some performance methods can be used to show energy savings beyond code, and are used for sustainability programs or state tax credits.
In prescriptive tables, opaque elements such as walls and roofs will have requirements in terms of thermal resistance (R-values) and thermal transmittance (U-factors). The U-factor includes the effects of insulation as well as framing members and interior and exterior finishes. The "overall" R-value is the reciprocal of the U-factor. The "added" R-value is the R-value of the added insulation, which is a simpler way of stating the requirement since insulation materials are labeled for R-value. The effect of framing and building materials other than insulation does not have to be calculated for prescriptive tables with "added" R-value requirements. For fenestration (windows and associated frames) the requirements are in terms of U-factor and solar heat gain coefficient (SHGC). Some codes have pre-calculated U-factors for walls, roofs, or windows so that the pre-calculated values can be easily compared to the prescriptive requirements.
For walls with thermal mass (such as concrete, masonry, adobe, or logs) R-values are not a true indicator of energy performance. These materials have a relatively low R-value, yet buildings constructed with these materials perform well and are comfortable in many climates. Thermal mass absorbs heat, thereby reducing and delaying the effects of outdoor temperature extremes on the HVAC system, especially when temperatures fluctuate with highs or lows between 50 to 75°F (10 to 25°C). In most climates, buildings with insulated mass walls will save energy compared to buildings without mass with the same R-value. In many southern and western climates, mass walls without insulation will perform as well as non-mass walls with insulation. In commercial buildings where cooling demand often peaks in the afternoon due to the loads from people and equipment, walls with thermal mass can absorb and lessen this peak. Since the mass reduces peaks in mechanical system loads, first costs for HVAC equipment may also be reduced in some climates. Most energy codes allow an adjustment for wall thermal mass in the prescriptive portion.
The performance paths in energy codes generally allow the use of an easy-to-use computer trade-off program or a detailed energy budget method. Generally the more complicated the compliance tool, the more flexibility the designer is allowed. Trade-off tools also allow for innovation in design and materials. COMcheck™ is an easy-to-use program for determining commercial building compliance for ASHRAE 90.1, IECC, and many state codes. REScheck™ (formerly MECcheck) is an easy-to-use program for determining residential building compliance with the MEC, IECC, and many state codes. A detailed computer-based energy analysis program such as DOE2 and Visual DOE4.0 calculate yearly energy consumption on an hourly basis. Such programs are useful when using the energy budget method because other simpler compliance tools do not take into account special features of the building or its components. The energy budget method compares the annual energy use of a building that meets prescriptive requirements with the proposed building to determine compliance. Codes provide rules and guidelines for the energy budget method.
Energy codes provide minimum building requirements that are cost-effective in saving energy. The energy saved is a cost savings to the building owner through lower monthly utility bills, and smaller and thus less expensive HVAC equipment. Energy codes contribute to sustainability by saving energy and protecting the environment.
Relevant Codes and Standards
- 10 CFR 434 (minimum standards for energy efficiency for the design of new federal commercial and multi-family high-rise residential buildings)
- ANSI/ASHRAE/IESNA Standard 90.1 - Energy Standard for Buildings Except Low-Rise Residential Buildings
- ANSI/ASHRAE/IESNA Standard 90.1 - Energy Standard for Buildings Except Low-Rise Residential Buildings; used by the U.S. Department of Navy and U.S. Department of Defense
- ANSI/ASHRAE/IESNA Standard 90.1 - Energy Standard for Buildings Except Low-Rise Residential Buildings; basis for government standard 10 CFR 434
- ANSI/ASHRAE Standard 90.2 - Energy Efficient Design of Low-Rise Residential Buildings
- ANSI/ASHRAE/IESNA Standard 100 - Energy Conservation in Existing Buildings
- ANSI/ASHRAE Standard 105 - Standard Methods of Measuring and Expressing Building Energy Performance
- Energy Policy Act of 2005 (PDF 1.9 MB)
- Executive Order 13423, "Strengthening Federal Environmental, Energy, and Transportation Management"
- International Energy Conservation Code (IECC)
- International Residential Code (IRC)
- Model Energy Code (MEC), now the International Energy Conservation Code (IECC)
- NFPA 900 Building Energy Code
- NFPA 5000 Building Construction and Safety Code
Products and Systems
Federal Green Construction Guide for Specifiers:
- 07 20 00 (07200) Thermal Protection
- 07 30 00 (07300) Steep Slope Roofing
- 07 50 00 (07500) Membrane Roofing
- 08 14 00 (08210) Wood Doors
- 08 50 00 (08500) Windows
- 23 70 00 (15700) Central HVAC Equipment
- 26 50 00 (16500) Lighting
- 48 14 00 (13600) Solar Energy Electrical Power Generation Equipment
- 48 15 00 (13600) Wind Energy Electrical Power Generation Equipment
- 48 30 00 (13600) Biomass Energy Electrical Power Generation Equipment
- DOE's Building Energy Codes Program
- DOE's EREN: Office of Energy Efficiency and Renewable Energy
- DOE's Appliances and Commercial Equipment Standards
- Energy Star
- FEMP: Federal Energy Management Program
- ASHRAE: American Society of Heating, Refrigerating, and Air-Conditioning Engineers
- Building Codes Assistance Project (BCAP)
- BOMA: Building Owners and Managers Association
- CRRC: Cool Roof Rating Council
- ICC: International Code Council
- NASEO: National Association of State Energy Officials
- NFPA: National Fire Protection Agency International
- NFRC: National Fenestration Rating Council
- RESNET: Residential Energy Services Network
- ASHRAE 90.1 User's Manual
- ASHRAE 90.2 User's Manual
- Department of Energy, Office of Energy Efficiency and Renewable Energy [Docket No. EE-DET-02-001] "Building Energy Standards Program: Determination Regarding Energy Efficiency Improvements in the Energy Standard for Buildings, Except Low-Rise Residential Buildings", ASHRAE/IESNA Standard 90.1-1999, Federal Register, Vol. 67, No. 135, Monday July 15, 1992, Notices.
- GSA LEED® Applications Guide
- GSA LEED® Cost Study
- The New Standard 90.1 by R. Jarnagin, M. McBride, M. Schewedler, J. Howley, Jr. ASHRAE Journal, March 2000, vol. 42, no. 3.