Commissioning the Ventilation System

We’re in the final few weeks of construction, and our HVAC contractor is busy commissioning the various systems.  This is a two-part process: first, the contractor gets each piece of equipment working within its design specifications, and second, for many systems an outside rater tests each system to verify proper operation.  We’ll need to test many aspects of the HVAC system, particularly airflows and pressure differentials between rooms, to meet the LEED and Indoor airPLUS requirements.  We got a start on this a few days ago with the first testing of our Zehnder ERV system.  As discussed in earlier posts, the ERV brings a continuous supply of fresh air into the house through high-efficiency filters and a heat exchanger, to help keep the best possible indoor air quality.

Our outside commissioning agent, Mike, started with a thorough visual inspection of each of the three ERV systems.  Then, using a sophisticated ventilation flow hood, he measured airflows at each register. The next step will be to adjust the internal dampers so that the pressures and airflows at each register match the design guidelines.  Once that’s done the system will just run quietly in the background, removing odors and moisture and supplying fresh air to bedrooms and living spaces.

Mike measuring airflow out of a supply register

The main house ERV in the basement mechanical room