OBC 9.7.3.3 Guide: Energy Efficiency Standards for Windows and Doors in London, Ontario
Sarah's Expert Insight
OBC Compliance Specialist
"Adhering to the U-value requirements of Section 9.7.3.3 is critical for managing heat loss in regions like London and Oakville, where winter temperatures frequently dip into the -15°C to -30°C range. As empcontracting.ca Inc. your construction contractor in London, Ontario, we emphasize that choosing NAFS-compliant products is not just about passing inspection; it's about preventing condensation issues that are common in high-moisture areas and Muskoka-style cottage builds."
Navigating the 2024 Ontario Building Code (OBC) is essential for any successful residential or commercial build. Section 9.7.3.3 outlines the specific thermal performance requirements for windows, doors, and skylights, ensuring that structures are energy-efficient and resilient against the Ontario climate.
Thermal Performance and U-Value Requirements
According to the code, windows, doors, and skylights installed in buildings with low moisture generation must adhere to strict thermal transmittance (U-value) or temperature index (I) standards. These requirements vary based on the 2.5% January Design Temperature of your specific location.
Regional Temperature Standards
- Between -15°C and -30°C: Windows and doors must have a maximum U-value of 2.0 and a minimum temperature index of 68. Skylights are capped at a 3.0 U-value.
- Colder than -30°C: Standards become more stringent, requiring a maximum U-value of 1.7 and a temperature index of 77 for windows and doors.
Exemptions to Thermal Break Requirements
Per Sentence (2), a thermal break is not mandatory for specific components, including:
- Vehicular access doors
- Storm windows and storm doors
- Windows and doors required to have a fire-resistance rating
High Moisture Generation Environments
For portions of buildings where interior use results in high moisture generation, simple U-value compliance is insufficient. These installations must be designed in conformance with Subsection 5.3 to prevent structural damage and mold growth, a critical consideration for indoor pools or specialized industrial spaces.
Manufacturing and Installation Standards (NAFS)
Section 9.7.4 mandates that all manufactured windows, doors, and skylights must conform to the North American Fenestration Standard (NAFS) (AAMA/WDMA/CSA 101/I.S.2/A440). This ensures that products are tested for air leakage, water penetration resistance, and structural strength. When you partner with empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every product installed meets these harmonized standards and the applicable Canadian Supplements.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.