Codes and Standards

As an energy modeler, it is important to understand how various codes and standards apply to a building project. Codes describe requirements that must be met by projects and are enforced (typically by Authorities Having Jurisdiction or AHJs) during the design and construction process. Standards may either represent “best practices” for design (and therefore are often followed), or, in many cases, they may be adopted by a code agency and therefore are required to be followed.

In addition to specifying design characteristics that must be met, codes and standards also offer a wealth of information that can be useful for energy modelers including many numerical values that can be directly used as inputs for the models, or values that can be used to perform quality assurance on the models.

This page describes several categories of codes and standards and their relevance to energy modeling.

Building codes

The building code is a set of rules that specify how buildings must be constructed and the focus of the code is primarily to protect public health and safety for the construction and occupancy of the building. Buildings must comply with the code to obtain permits.

The scope of building codes include structural, egress, fire safety, construction materials requirements, occupancy rules, and design and construction requirements for the building systems such as mechanical, electrical, lighting, and plumbing. Energy efficiency codes and standards are also included as a building code requirement.

Energy codes and standards

Energy codes are a subset of the broader building code requirements. While building codes focus on ensuring safety, energy codes are designed to ensure that buildings are designed and built to meet a specified level of energy efficiency.

Energy codes may either be implemented following a prescriptive approach or a performance approach. The performance approach can be met by developing energy models to demonstrate that the proposed building design meets a specified energy budget, target, or other threshold. Different energy codes have different set of rules for creating the model and determining whether the modeled building passes or fails. For additional guidance on understanding modeling rules of the performance approach, refer to the page Determine the applicable energy code.

National Codes

National Codes often serve as models for state and local codes.

• American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 90.1
  • Following the publication of a new version ASHRAE 90.1, a user manual is typically developed to support the understanding and adoption of the code.
  • ASHRAE 90.1-2022: the most recent version of of ASHRAE 90.1.
  • ASHRAE 90.1-2019: the most recent version of ASHRAE 90.1 with a companion user manual.
• International Energy Conservation Code (IECC)
• National Energy Code of Canada for Buildings (NECB)

State and Local Codes

• Local jurisdictions will usually adopt the model codes with some amendments – variations of the above with requirements that may be slightly different, usually to respond to local climate conditions. Some states develop their energy code independently from the model national codes
• California Title 24
• Also, refer to the BEMcyclopedia Links Page for additional information about Codes and Standards.

Energy modeling codes and standards

• ASHRAE Standard 209 - "Energy Simulation Aided Design for Buildings" - Standard 209's purpose is to “Define minimum requirements for providing energy design assistance using building energy simulation and analysis.”. Starting in 2023 209 became a standing committee allowing continuous updates to the standard. Updated printed and PDF versions will be made from time to time.
• ASHRAE Standard 205 - "Standard Representation of Performance Simulation Data for HVAC&R and Other Facility Equipment" defines performance maps for HVAC equipment from coils and fans to chillers and VRF systems. The Standard Project Committee works with manufacturers to develop and publish performance data sets and with BEM vendors to support the use of performance maps in BEM engines.
• ASHRAE Standard 140 - “Standard Method of Test for Building Energy Simulation Computer Programs” aims to increase confidence in the use of building energy modeling (BEM) by creating standardized and citable test procedures for validating, diagnosing, and improving the current generation of BEM software.
• ASHRAE Standard 229 - "Protocols for Evaluating Ruleset Application in Building Performance Models" aims to promote consistency among BEM software tools in how they evaluate rulesets for performing code compliance modeling.
• CSA Z5020 - "Building energy modelling" focused on quality assurance.

Ventilation codes and standards

ASHRAE Standard 62.1 specifies minimum ventilation rates and other measures intended to provide indoor air quality (IAQ) that’s acceptable to human occupants and that minimizes adverse health effects. The standard provides procedures and methods for meeting minimum ventilation and IAQ requirements to engineers, design professionals, owners, and jurisdictional authorities where model codes have been adopted. For additional guidance on ventilation codes and standards, refer to the page Determine ventilation requirements.

• ASHRAE Standard 62.1 - "Ventilation and Acceptable Indoor Air Quality"
• ASHRAE Standard 170 - "Ventilation of Health Care Facilities"
• ANSI/ASSP Z9.5-2022: Laboratory Ventilation
• Local building codes - many adopt some vintage 62.1 requirements, but this is not universally true. If 62.1, be sure you know which version, and if not, consult the local code

Thermal comfort codes and standards

• ASHRAE Standard 55 - "Thermal Environmental Conditions for Human Occupancy"