NBC 2025 Guide: Mechanical Ventilation & Air Exchange Rates for London, Ontario Construction
Sarah's Expert Insight
Senior Consultant at empcontracting.ca Inc.
"In Southwestern Ontario, our extreme humidity fluctuations make the NBC 2025's focus on Energy Recovery Ventilators (ERVs) a game-changer for London homeowners. By choosing empcontracting.ca Inc., you ensure that your mechanical systems are not just 'to code,' but are optimized to prevent the mold issues and heat loss common in older, poorly ventilated London builds."
The 2025 National Building Code of Canada (NBC) introduces more stringent requirements for indoor air quality and energy efficiency. At empcontracting.ca Inc. your construction contractor in London, Ontario, we stay ahead of these regulatory shifts to ensure your projects are compliant, healthy, and energy-efficient.
Understanding NBC 2025 Air Exchange Requirements
Mechanical ventilation is no longer just about removing odors; it is a critical component of building envelope integrity and occupant health. The NBC 2025 emphasizes continuous ventilation to mitigate the buildup of radon, volatile organic compounds (VOCs), and excess moisture.
Residential Ventilation Rates (Part 9)
For residential dwellings, the NBC 2025 specifies minimum ventilation capacities based on the number of rooms and bedrooms. Systems must be designed to provide a continuous exhaust and supply rate—measured in Litres per second (L/s)—ensuring the total air volume of the dwelling is exchanged frequently. The use of Heat Recovery Ventilators (HRVs) and Energy Recovery Ventilators (ERVs) is now essential to meet the tiered energy performance targets integrated into the 2025 code.
Commercial and High-Occupancy Standards
In commercial and institutional settings, air exchange rates are dictated by occupancy load and the specific use of the space. NBC 2025 mandates the use of advanced sensors for Demand-Controlled Ventilation (DCV). These systems adjust air exchange rates based on real-time CO2 levels, ensuring optimal air quality while significantly reducing energy waste during low-occupancy hours.
The Importance of System Balancing and Compliance
Improperly balanced ventilation systems can lead to negative building pressure, which causes drafts, moisture ingress, and potential structural damage. As empcontracting.ca Inc. your construction contractor in London, Ontario, we utilize precision instrumentation to balance ductwork and calibrate airflows according to the latest NBC standards, ensuring your project passes municipal inspections the first time.
Key Updates in the 2025 Revision
- Mandatory integration of high-efficiency filtration (MERV 13 or higher) in specific ventilation circuits.
- Enhanced duct sealing requirements to prevent air leakage in unconditioned spaces.
- Stricter noise level limitations for continuous-run fans to ensure occupant comfort.