Client: Miami Mold Testing Client
Property Address: Miami Florida
Date: 10-12-06
Based on the findings of very low spore levels in all the samples taken from the interior of the townhouse, and from inside several walls. And based on no visible mold and no mold odors it appears that drying was successful in preventing any mold problems inside the walls that were tested. Another concern of the clients was the setting of the humidistat and thermostat when away. It was explained by this inspector that the thermostat should be set to 80F and the humidistat to 50% or 60%RH when away. Most experts as well as this inspector's experience agree that the humidistat's be set at no higher than 60%RH however the client received conflicting information on what humidity levels should be maintained indoors. Here is what the experts say in regards to what humidity levels are acceptable in indoor settings.
U.S. E.P.A. (Environmental Protection Agency) on controlling relative humidity
Keep indoor humidity low. If possible, keep indoor humidity below 60 percent (ideally between 30 and 50 percent) relative humidity. Relative humidity can be measured with a moisture or humidity meter, a small, inexpensive ($10-$50) instrument available at many hardware stores. http://www.epa.gov/mold/preventionandcontrol.html
U.S. E.P.A. (Environmental Protection Agency)
"By controlling the relative humidity in a home, the growth of some sources of biological can be minimized. A relative humidity of 30-50% is generally recommended for homes. Standing water, water-damaged materials, or wet surfaces also serve as a breeding ground for molds, mildews, bacteria, and insects. House dust mites, the source of one of the most powerful biological allergens, grow in damp warm environments."
http://www.epa.gov
Well Known AC Manufacturer (Carrier)
Your home comfort system should provide both comfortable temperatures and comfortable humidity levels. It should maintain your home at the recommended levels of 40-60% relative humidity, preventing growth of mold and mildew and minimizing dust-mites, bacteria and viruses.
http://www.carrierresidential.com/CarrierAlliance/NewHomeBuyer/identify3.asp
ASHRAE Standard 55-1992
They make the rules for all AC contractors and AC engineers to follow. Thermal Environmental Conditions for Human Occupancy sets guidelines intended to achieve thermal conditions that at least 80% of the occupants would find comfortable. ASHRAE humidity levels are recommended between 25-60%.
http://www.yestek.com/faq.html#Anchor-ASHRAE-8432
Humidifier & dehumidifier sales and information website
The optimum relative humidity level is generally considered to be between 40% and 50%. Levels anywhere between 30% and 60% is acceptable, however, below 50% is recommended to help control dust mites which are bad for allergy sufferers.
http://www.humidifierinformation.com/optimum-humidity-levels.php
American Academy of Allergy Asthma & Immunology
To reduce dust mites, it is important to keep humidity below 50% throughout the home by using a dehumidifier or a central or window air conditioning. Wall-to-wall carpeting should be removed as much as possible, especially if it is laid over concrete floors. Hardwood, tile or linoleum is better for people with allergies. Washable throw rugs may also be used if they are regularly washed in hot water or dry cleaned.
http://www.aaaai.org/patients/publicedmat/tips/indoorallergens.stm
Well Known AC Manufacturer (Trane)
Most designers choose a dry-bulb temperature of 72°F to 76°F as the set point. To discourage microbial growth, ASHRAE Standard 62-1999 recommends a relative humidity of 60 percent or less during cooling. Therefore, select the dedicated OA unit to limit the relative humidity in all spaces to no more than 60 percent.
Designing a dedicated ventilation system that limits the space relative humidity to a lower value (50 percent, for example) adds unnecessary cost because it requires larger equipment and increases energy consumption. http://www.trane.com/commercial/lbrary/vol30 3/implica.asp
