California Green Building Code: CALGreen – Covering of duct openings & protection of mechanical equipment during construction

Covering and protection of ducts and mechanical equipment during construction in a CALGreen mandatory measure. It is applicable to all Residential and Non-Residential projects. This measure is triggered if there is a probability of any part of the HVAC system being exposed to dust and fumes from the construction process. The code language is as follows.

CALGreen Code Section 5.504.3: Covering of duct openings and protection of mechanical equipment during construction. 

At the time of rough installation and during storage on the construction site until final startup of the heating, cooling and ventilating equipment, all duct and other related air distribution component openings shall be covered with tape, plastic, sheet metal or other methods acceptable to the enforcing agency to reduce the amount of dust, water and debris which may enter the system.


To enhance HVAC equipment efficiency and indoor air quality at building occupancy by preventing construction debris from building up in the air ducts during construction.

Compliance Method:

Engineers and designers should include the measures intended to promote air quality in the project specifications for ventilation and materials as applicable. The contractor should be responsible for employing them on the job and being able to demonstrate that the practices are being followed if requested by the enforcing agency.


Plan intake: The plan reviewer should confirm that the construction documents show directions on proper installation practices to be followed by the contractor.

On-site enforcement: The inspector should verify protections of duct openings and mechanical equipment are in place for duct systems and equipment to be installed during the construction phase. 

(Excerpted from ‘Guide to the 2019 California Green Building Standards Code Nonresidential’ – Chapter 5)

You May Also Like

CALGreen Services in Palo Alto

CALGreen – City of Palo Alto has implemented one of the most aggressive green building codes in the state of California. Due to very high value of real estate and heightened awareness for sustainable construction practices among the residents, city has succeeded in justifying the enforcement of green building code that few other cities in the state of California have enforced.

Read More »