ASHRAE Journal - November 2010 - 76

engineer’s notebook
humidity) gets too high, it enables the growth of mold. Molds can produce spores and mycotoxins that are, at best, unpleasant; it is generally a good idea to avoid the conditions that will enable mold growth. People can experience discomfort if the water vapor level becomes too high or too low. Water vapor is qualitatively different from the other chemicals discussed. Unknown Stuff is all around us. According to those who study IAQ extensively, there is more danger from the stuff we don’t know about than the stuff we do know about. There is all sorts of talk of plasticizers, endocrine disruptors, ultrafine particles and phthalates. Whether this unknown stuff is a significant problem is unknown.13 remove the products of combustion before they can spread indoors. For example, use the kitchen exhaust hood when cooking. Use materials that don’t emit much stuff. Many products and materials use formaldehyde and other volatile organic compounds in the manufacturing process. Whenever possible, choose materials that emit less. Fortunately, the industry is beginning to provide information that makes that possible Contain your poisonous stuff. When you do find it necessary to kill things, do it in a controlled way. Keep poisons contained to the time and place they are needed so as to minimize their concentrations in the indoor air. Filter stuff out of the air. Cleaning chemicals out of the air can be a costly process overall, but filtering particles is pretty easy if you have an air-handling system to begin with. Use good quality filters and maintain them to reduce exposure to fine particles. I am not sure knowing what is in indoor air is actually comforting,15 but it is probably appropriate for ASHRAE members to have some idea of the stuff we breathe. Max Sherman is a senior scientist at Lawrence Berkeley National Laboratory, Berkeley, Calif., and group leader of its Energy Performance of Buildings group. He was the first chair of ASHRAE Standards Project Committee 62.2.

What to do About stuff
We’d like to take sensible precautions regarding the hazards we do know about. ASHRAE has Standards 62.1 and 62.2 to provide minimum ventilation requirements. Ventilation dilutes (indoor) contaminants, but the best approach is to minimize the contaminant sources inside first. Given the existing priority hazards,14 there are a few recommendations to consider: Don’t burn stuff indoors. Move combustion sources outside, which is what sealed combustion appliances, or sealed fireplaces, essentially do. When that is not possible, use exhaust systems to

13. This is great for researchers as it justifies further work for them. It is not, however, terribly useful for those who just want to know if there is a significant problem to be dealt with. 14. Just to stave off letters, let me state the obvious: just because something is on the priority hazards list does not mean that it is a problem for you. Similarly, just because the priority hazards are not a problem for you, does not mean that you have good IAQ. 15. I personally have decided to avoid being exposed to anything that was used as a chemical weapon during WWI…and not to play with pure cinnamaldehyde.

The IAQ Standard.
Standard 62.1 is the recognized standard for ventilation system design and acceptable IAQ. It provides the information you need to ensure that your project is designed according to the latest requirements. Here’s what’s NEW in the 2010 revision: • Minimum filtration/air-cleaning requirements • Minimum requirements for when ventilation systems must be operated • A Natural Ventilation Procedure • A more robust IAQ procedure • Demand-controlled ventilation system design requirements • Requirements for separation of intakes and exhausts • Ventilation rates and occupancy categories Price: $69 (ASHRAE Member: $59)
S N A P I T

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ASHRAE Journal - November 2010

Table of Contents for the Digital Edition of ASHRAE Journal - November 2010