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Written By: Robert E. Sheriff, MS, CIH, CSP, President
April 5, 2020
Ventilation for Human Comfort – Offices, Retail Stores
Providing indoor air quality to meet the comfort requirements 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 an office, meeting room, restaurant, sports arena or any other occupied space, would find comfortable has been undertaken by such professional groups as ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers) and regularly they publish updated standards on the subject.
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 comfortable—air quality to 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.
Although it may be obvious, it is also important to heat or cool the incoming 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:
|Occupancy||Outdoor Air Rate CFM/Person||Occupancy Density (per 1000 ft²)|
|Restaurant Dining Room||7.5||70|
|Hotel Bedroom/Living Room||5||10|
|Pharmacy (Prep Area)||5||10|
|Beauty and Nail Salons||20||25|
|Gymnasiums (Play Area)||20||7|
Start Testing With a Balometer
If a measurement is necessary, the first approach is to identify the main supply duct. Measure the airflow at each different (supply duct) in each space and compare it to the level of occupancy using the chart above.
The most direct method of measuring the CFM per person in a particular occupied space is to use a Balometer—which is a hood-type instrument placed over a ceiling, wall or floor diffuser and measures the CFM of air for each diffuser. Measure the total supply air volume for each diffuser in an area and divide by the number of occupants in the occupied space, and compare it to the rates in the above table.
CFM/person = total CFM from Diffusers
Number of occupants
For more information on Ventilation for Human Comfort in offices and retail stores, and ASHRAE, contact Atlantic Environmental.
Our primary service areas for Ventilation Testing are: New Jersey NJ, New York NY, (New York City), Pennsylvania PA, Connecticut CT, Delaware DE, Massachusetts, (Boston) MA, Rhode Island RI, Washington DC, Wisconsin WI, Maryland MD, Michigan MI, Illinois (Chicago) IL, Virginia VA, Indiana IN, Georgia (Atlanta) GA, Alabama AL, North Carolina NC, South Carolina SC, Tennessee TN, Texas (Dallas, Ft Worth) TX, Oklahoma OK, DC, Arkansas AR, Florida FL. We can service most other areas of the U.S. but with some added travel charges.