Ventilation for human health and safety in schools and offices

Providing indoor air quality to meet the safety of the occupants is a daunting task—at best.

Ventilation –that is—supplying both outside air and re-circulated are at a rate that the majority of occupants of a classroom, gymnasium, office, or sports arena, would find safe and comfortable has been undertaken by such professional groups as ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) and CDC particularly when it comes to Covid-19.

Air change rates for various types of buildings and occupancy can be found in the 2015 ASHRAE Handbook, “HVAC Applications.”  This document provides guidance on the amount of air movement—both outside air and re-circulated air—that is intended to achieve good—and safe—air quality for the occupants.

Another ASHRAE publication that addresses the need for the amount of outside air for achieving reasonable air quality is:  ASHRAE Standard 62.1-2016 titled, “Ventilation for Acceptable Indoor Air Quality.”  This document provides information on the amount of recommended outside air per person and air volume rates per unit area of floor space.

ASHRAE Guidance for COVID-19

ASHRAE has also developed detailed guidance on occupancy or re-occupancy of facilities to address COVID-19 concerns.

This can be found at www.ashrae.org\technical-resources\building-readiness#uvgi.  It is quite extensive and will require the involvement of numerous individuals to determine if your systems are operating as efficiently as possible and/or can be expanded to meet concerns over COVID-19.

The most significant position of ASHRAE andAtlantic Environmental, Inc. is to use the maximum amount of outdoor air that the system will allow while maintaining the comfort of the occupant (i.e. ability of the system to adequately heat/cool the increased outside air.

Temperature for Human Comfort

The recommended comfort range according to ASHRAE is 67°F to 82°F but a more specific range depends upon relative humidity and other factors.  It is our recommendation that the temperature range is kept between 68°F and 74°F.

Relative Humidity for Human Comfort

The relative humidity is also a very important factor in maintaining acceptable air quality.  The recommended range is 30% relative humidity to 60% relative humidity.  Below 30% may cause dry skin, dry burning eyes, static electricity, and upper respiratory irritation.  Above 60% may encourage mold growth.

ASHRAE lists about 80 different occupancy categories where a minimum ventilation rate has been established.  The following are some examples from the ASHRAE Standard 62.1: