Fresh Air – Ventilation is the essential process of replacing stale air with fresh air. Proper ventilation in buildings helps curb the spread of allergens and toxins in the air. It helps to moderate internal temperatures, internal humidity, replenishing oxygen, reducing the accumulation of moisture, odours, bacteria, dust, carbon dioxide, smoke and other contaminants that can build up during occupied periods. Mechanical (or forced) ventilation is driven by fans or other mechanical plant. Natural ventilation is driven by pressure differences between one part of a building and another, or pressure differences between the inside and outside.
CALGreen Code Section 5.506.1: Outside air delivery.
For mechanically or naturally ventilated spaces in buildings, meet the minimum requirements of Section 120.1 (Requirements for Ventilation) of the 2019 California Energy Code or the applicable local code, whichever is more stringent, and Division 1, Chapter 4 of CCR, Title 8.
The purpose of this code section is to point building designers and contractors to the ventilation requirements in the California Code of Regulations that are intended to improve indoor air quality for building occupants. Ventilation requirements are in Sections 120.1(a) through 120.1 (e) and ventilations flow rates are in Table 120.1-A of the 2019 California Energy Code, Part 6, Title 24, CCR. Local jurisdictions may have more restrictive requirements in their local ordinances.
Most engineers and contactors are familiar with following the provisions of the California Energy Code that specify requirements for naturally and mechanically ventilated spaces, and may comply with this provision by using energy code compliance tools currently in place. Division 1, Chapter 4 or the California Code of Regulations, Title 8, may have additional regulations that emphasize air quality for workers in particular environments, which should be followed as applicable.
Plan intake: The plan reviewer should verify that the construction documents show compliance with the building ventilation requirements as specified in the California Energy Code and, if applicable, Title 8.
On-site enforcement: The inspector should verify the natural ventilation features and mechanical ventilation systems that are installed on the project, requesting results of any testing of ventilation rates. Adequate building ventilation before occupancy shall be verified.
(Excerpted from ‘Guide to the 2019 California Green Building Standards Code Nonresidential’ – Chapter 5)