IAQ Ventilation Basics - Indoor air pollution can be reduced and possibly eliminated by taking corrective action using a defined plan. The first step is called an IAQ audit and often requires the services of both an HVAC Test and Balance (TAB) Company and an industrial hygienist.
First of all, it must be determined where the source of pollution is coming from and then steps taken to eliminate it. Vapor barriers and foundation sealant can often be the source of indoor air pollution but other areas need to be studied to ensure they are not allowing pollution into the structure.
IAQ Ventilation Basics
Other types of pollutants are carbon dioxide (produced by people), moisture, tobacco smoke, carbon monoxide, formaldehyde, ozone, and other volatile organic compounds (VOC’s) which cause issues with the health and safety of the building’s occupants. After the source of the pollutants is determined then a plan of action can be implemented to ensure these issues are corrected. There are different levels of IAQ that range from very thorough to just a cursory look at the building and the building’s HVAC systems.
A TAB company can check to ensure that the building is getting proper ventilation. That all the control systems are calibrated, ventilation fans are ventilating the proper amount of CFM’s, and that the correct amount of dilution air is introduced through the make-up or outside air system. Building pressure can be tested to ensure infiltration problems are eliminated.
Kitchen range hoods have been found in some cases to cause a negative pressure in the building and this will create many problems associated with too much infiltration air so it is important that all ventilation systems be checked and adjusted as necessary to eliminate this problem.
If all ventilation systems meet the specifications as required by Mechanical Code and/or ASHRAE standards then the further steps in the IAQ Audit process can begin. This will require checking the foundation and other parts of the building for pollutant sources.
It will also require a check of CO2 levels in the building. CO2 is naturally produced by humans and ASHRAE recommends a maximum limit of 1000 parts per million (PPM) to meet IAQ comfort and safety standards.
IAQ Ventilation Basics - Moisture Issues
Moisture can cause severe problems with mold, mildew, and bacteria, and steps need to be taken to eliminate excessive moisture. Sources of moisture can be too much infiltration air in high humidity regions, condensation pans not draining properly, leaks in the structure, leaks in the plumbing, steam leaks or steam from kitchens and bathrooms, and overcooling the spaces.
In areas where humidity levels are high oversized air conditioning systems can cause moisture problems by infrequent cycling. The system short cycles and cools the space too fast. This causes the air not to have consistent conditioning where it is necessary to remove humidity from the air. Modern controls and the proper HVAC equipment set-up can help maintain the proper humidity levels year-round and reduce IAQ problems associated with moisture.
IAQ Ventilation Basics
Energy Efficiency and Gas Furnace AFUE
Just because you spend extra money to buy a high AFUE gas furnace does not mean you will have true energy efficiency. There are many factors to getting true energy efficiency. Among these factors are:
- Proper installation of the gas furnace
- Ductwork Integrity
- Home Insulation including energy-efficient doors and windows
- Home humidity levels
For more information see our article on Gas Furnace Efficiency Factors