2021 International Energy Conservation Code – ICC IECC-2021

2021 International Energy Conservation Code® (IECC)

Scope:
The 2021 IECC® establishes minimum energy efficiency requirements for the design and construction of new residential and commercial buildings, as well as additions and alterations to existing buildings. It is divided into separate Commercial and Residential provisions and is coordinated with the full suite of 2021 I-Codes.

Key Features and Updates in the 2021 IECC:

• Commercial and Residential Provisions:
  Two standalone sections regulate buildings based on occupancy and height. Low-rise residential buildings (≤3 stories) are addressed separately from commercial buildings and taller residential structures.
• Energy Performance Options:
  Expanded compliance paths including prescriptive, performance-based, and Energy Rating Index (ERI) methods, with updates to criteria and modeling requirements.
• Climate Zone Adjustments:
  Updated definitions and assignments based on revised climate data, affecting insulation and system requirements by region.
• Building Envelope:
  New requirements for air barrier detailing, insulation materials, and U-factor/Solar Heat Gain Coefficient (SHGC) values for windows and skylights.
• Mechanical Systems:
  Enhanced efficiency requirements for HVAC equipment, economizers, ventilation controls, and demand control ventilation (DCV) systems.
• Lighting and Electrical:
  Updates to lighting power densities, controls, and daylighting requirements; expanded use of lighting sensors and high-efficiency luminaires.
• Service Water Heating:
  Revised insulation and system efficiency requirements for hot water systems, including recirculation controls.
• Existing Buildings:
  Clear provisions for additions, alterations, and changes of occupancy; special considerations for historic structures.
• Commissioning and Documentation:
  Expanded requirements for system commissioning, construction documentation, and closeout deliverables.
• Solar-Ready and Zero Energy Appendices:
  Optional appendices (CB, CC, RB, RC) provide frameworks for solar-ready zones and net zero energy buildings in both commercial and residential sectors.

This edition also includes alignment with ASHRAE 90.1 and expanded definitions for key terms such as “conditioned space,” “continuous insulation,” and “thermal envelope.”