IAQ

WHAT IS IAQ

Working Definition

Indoor Air Quality (IAQ) describes the condition of air inside a building. The condition of the air is a combination of the chemical, biological, and particulate matter in the air and air temperature and humidity. IAQ is important because the condition of the air affects the comfort and health of the people in a building. That means IAQ can affect people's productivity and well being. If the condition of the air is unacceptable, complaints and even law suits can result.

Formal, ASHRAE Definition

One important definition of IAQ is found in ASHRAE Standard 62.1. This definition indicates what acceptable indoor air quality is. Note that ASHRAE avoids the words "good" and "bad" as they apply to IAQ. You should do the same. Here is the ASHRAE definition:

Acceptable indoor air quality: air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80% or more) of the people exposed do not express dissatisfaction.

The first part of this definition has to do with the health of occupants. Contaminants are usually present at low concentrations, but some kinds of chemical, biological, and particulate matter in the air at high concentrations can hurt people. The second part has to do with comfort. Comfort relates to temperature, humidity, odor, and irritation. Acceptable indoor air quality is a combination of the chemical, biological, and particulate matter in the air and air temperature and humidity that keeps people both healthy and comfortable.

WHY HVAC OPERATIONS AND MAINTENANCE IS IMPORTANT FOR IAQ

HVAC systems are a key part in determining the condition of the indoor air. Heating and air conditioning determine the indoor temperature and humidity conditions. Ventilation determines how much, and how effectively outdoor air is delivered to occupants. Outdoor air is used to dilute the concentration of chemical, biological, and particulate matter in the air and to reduce odor and other irritants. The systems must be designed and installed properly to have acceptable IAQ. But even well designed and installed systems will not provide acceptable IAQ if they are not properly operated and maintained.

HOW DOES HVAC AND TABB WORK CHANGE WITH IAQ CONSIDERATIONS

Often the first time technicians go through an IAQ class, they say, "I've been stepping around these problems my whole career - I never even noticed a lot of this stuff." IAQ is an eye-opener. Your work with HVAC maintenance or test and balance is typically focused on making mechanical systems work to a specification. Once you open your eyes to IAQ, you'll see that specifications are an important starting point. They are not the end of the story. The end of the story is consistently and efficiently delivering acceptable IAQ to the building occupants.

SCOPE AND LIMITATIONS OF THE IAQ TECHNICIAN ROLE

Your Front-line Responsibilities

Technicians have a big role in IAQ, probably bigger than you think. Your initial reaction might be that an HVAC technician really can't do that much about IAQ. You might think the science is too complicated and the occupants want people with professional credentials. In some ways that is true. You will need to know the limits of your role in IAQ. But the other side of the coin is that you are often the only person who looks inside HVAC systems and ducts, mechanical rooms, crawl spaces, outdoor air intakes, and basements. That makes you the only person likely to find something that might be causing an IAQ problem.

Your Daily Tasks

Every day, you operate, maintain, test, adjust, and balance HVAC systems. Your decisions and the actions often determine the quality of the air inside a building. You may adjust the outdoor air, decide to change a filter, or adjust air flow in a supply or return. Each of these actions has an impact on IAQ. You may see a dirty or wet drain pan under a cooling coil, mold growing on a duct, or a chemical spill in a mechanical room. Reporting and recommending action on these items can help your supervisor or the building owner make good decisions about managing IAQ in a building.