Ventilation Summaries

Recent Ventilation Assessments

Background

NES was retained by Peralta Community College District (PCCD) to evaluate the performance of the HVAC systems servicing buildings located at Berkeley City College, Merritt Community College, Laney College, and College of Alameda, following the district-wide replacement of air filters. The purpose of the assessment is to document ventilation adequacy and potential impact to air flow following the installation of MERV 13 filters.

The first phase of the return-to-campus effort consisted of a qualitative HVAC assessment to evaluate the condition of 175 air handling units for issues that may negatively impact indoor air quality and effective dilution ventilation. Sub-optimal observations related to structural and component integrity, contamination sources, insulation material, filter conditions, condensate drainage and overall cleanliness were reported, and the appropriate recommendations were furnished for each inspected unit. Units that were significantly damaged were highlighted and it was recommended that an appropriately qualified HVAC professional determine repair vs. replacement of components/units. Furthermore, recommendations were categorized based on in-house immediate mitigations or required professional intervention. Sources of contamination such as exhaust roof penetrations close to outdoor air intake were categorized under required professional intervention, whereas crawling plants and stagnant water were categorized under immediate mitigation.

An assessment workbook was created to evaluate spaces prioritized for re-occupancy. The purpose of the assessment was to measure effective air changes per hour (ACH) for the selected spaces using the equivalent outdoor air tool developed by ASHRAE and published on their technical resources website. The measured effective ACH were compared to a minimum target of 3 ACH (95% removal of airborne contaminants) or higher based on the minimum requirements for outdoor air, calculated using the number of occupants and square footage of the assessed functional space, as per ASHRAE standard 62.1-2019. The minimum outdoor air requirement is reported in cubic feet per minute (cfm) and converted to ACH. Spaces were labeled as “Meets the target” or “Does not meet the target”. For spaces that did not meet the target, a recommended minimum clean air delivery rate (CADR) of HEPA-filtered air was calculated as a supplemental mitigation to achieve the desired target ACH.