M id A tlantic Real Estate Journal — 2021 Forecast — January 22 - February 18, 2021 — 11A 2021 F orecast
www.marej.com
By William Amann, PE, LEED Fellow, M&E Engineers Ventilation & Filtration for COVID-19
A
little speck of protein wrapped in fat has killed over 400,000 people in
air and exhaust, install MERV 14 or better filters, reduce the population density and open the windows. If the minimum venti- lation rates cannot be achieved, then they recommend supple- mental filtration units to provide
a minimum of 2 air changes per hour with HEPA filters, and to consider using Ultraviolet C lamps for disinfection. In buildings where we have been asked to help with reopen- ing plans, we have performed
inspections of the HVAC sys- tems to verify the fan opera- tion and determine the level of filtration. The intent was to see where filter efficiencies could be upgraded. The reality was we found units with outside air dampers wired shut and units with collapsed filters. Obviously to provide a safe environment the systems need to be properly operating and maintained. LEED certified buildings typically provide a safer envi- ronment, requiring compliance with ASHRAE 62.1. However we have found many buildings
that do not comply, despite it being a code requirement. LEED also requires MERV 13 filters for the IAQ credit, as well as an increase in the outside air rate by 30%. M&E Engineers is first and foremost concerned with public safety, followed by sustainability, and can provide HVAC assessments as well as LEED and WELL building cer- tification assistance to ensure improved indoor environmental quality. William Amann, PE, LEED Fellow, DCEP - President M&E Engineers. MAREJ
t he Un i t ed States, and it is not going to go away. So while we hope that the vaccines will bring an end to this pan- demic some-
ASHRAEhas publishedCOVID recommendations which include: maximize the outside air and exhaust, install MERV 14 or better filters, reduce the population density and open the windows. If the minimum ventilation rates cannot be achieved, then they recommend supplemental filtration units to provide aminimum of 2 air changes per hour with HEPA filters, and to consider using Ultraviolet C lamps for disinfection.
William Amann
time this year, we still have a ways to go until we get to that point. We need to learn from this tragedy in order to protect ourselves in the meantime and to implement strategies that will protect us from other virus strains in the future. There are three major vari- ables that affect the risk of exposure: occupant density, ventilation rate, and exposure time. Minimum ventilation rates are established by ASHRAE Standard 62.1, and are based on three principal factors: the space size, the density of occu- pants in that space, and what the occupants do in that space. What they do is relevant because of their respiratory rate. The minimum amount of outside air required in an office is 5 Cubic Feet of outside air per minute (CFM) per person, plus an ad- ditional 0.06 CFM per square foot. The occupant density levels are greater in spaces like break and conference rooms, so these spaces need higher ventilation rates or reduced occupancy levels. Outside air reduces the con- centration of virus particles by dilution. Secondarily, high efficiency filters can capture con - taminated particles. Virus par- ticles themselves are extremely small (~140 nm), but they are typically attached to mucous or other larger particles. Therefore there is a wide range of par- ticles which we want to capture. Most typical HVAC units have MERV 7 or lower filters, which are not even rated for smaller micron particle ranges. MERV 13 and higher provide increas- ingly better rates of efficiency in these smaller ranges. The best are HEPA filters which have a minimum efficiency of 99.5%, but these are generally only used in operating rooms and other critical spaces, and are now also being deployed in portable units to provide supplemental air cleaning. ASHRAE has published CO- VID recommendations which include: maximize the outside
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