Healthy Indoors Magazine - USA Edition

HI May 2014

Healthy Indoors Magazine

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Page 39 of 57

40 May 2014 Spray Poly Foam Continued from previous page semi-conditioned attic. Another issue to consider here is the home's necessary ventilation rate, which is largely reli- ant on the infiltration and exfiltration rates. The infiltration rate is the volumetric flow rate of outside air into a building, typically expressed in cubic feet per minute (CFM) or liters per second (LPS). The air exchange rate (I) is the number of interior volume air changes that occur per hour, as expressed in liters per hour (l/h). The air exchange rate, also known as air changes per hour (ACHs), can be calculated by multiply- ing the building's CFM by 60, and then dividing that by the building's volume [(CFM x 60)/vol- ume]. The American Society of Heating, Refrigerat- ing, and Air-Conditioning Engineers (ASHRAE) set a residential ventilation standard in 2003. The ASHRAE 62.2 minimum ventilation rate formula was set at 7.5 cfm per person plus 1 cfm per 100 square feet, which is based on the assumption that the number of occupants in a home equals the number of bedrooms plus one. The ASHRAE 62.2 formula was also based on the assumption that all homes deserve an "air infiltration credit" of 2 cfm per 100 square feet, because homes built in and before 2003 tended to have a good amount of air infiltration. The homes built today with or without the use of SPF insulation are much tighter and have a substantially reduced air infiltration rate. So while your home's recommended minimum ventilation rate remained unchanged for many years, ASHRAE has now recognized the tighter construction of today's homes and revised the 2013 version of ASHRAE 62.2. Under the new formula, newer tightly built homes will need to be ventilated at a much higher rate, namely 7.5 cfm per person plus 3 cfm per 100 square feet. This means that for a tightly built 2,400-square- foot home with 3 bedrooms, the minimum airflow rate of the ventilation equipment has jumped 89%, from 54 cfm to 102 cfm. More specifically, the 2013 version of ASHRAE 62.2 has eliminated the air infiltration credit on new tightly built homes. Guess where SPF insulat- ed homes fall? Right smack dab in the middle of the (as designed) tightly built category. Questions to Ask Your SPF Contractor Prior to Install SPF Consumer Question Number 1: How will you determine whether or not my home will meet or exceed the minimum ventilation rate once the SPF insulation is installed? This is one of the most important questions every prospective SPF consumer must ask. It involves the necessary air changes per hour (ACHs) to ensure that your home does not ac- cumulate indoor contaminants and you have healthier air to breathe. With SPF insulation, you will most likely require a dedicated outdoor air supply to meet the minimum ventilation rate and avoid accumulation of contaminants. I've inspected homes with reported SPF nuisance odors that are well over 50 years old, as well as homes that are only a year or two old, and the most critical issues in each often relate to the ventilation rate of the home. SPF Consumer Question Number 2: How will you clean my attic and prepare it to be a semi- conditioned attic space? So, what exactly do I mean when I say "semi- conditioned attic?" Once SPF insulation is installed, your attic that was once naturally cooled through traditional outdoor air circula- tion (soffit, gable, and roof vents) is now cooled or conditioned through indoor air circulation as the soffit, gable, and roof vents are sealed. This newly un-vented or semi-conditioned state Quality Lab for Quality Professionals (888) 752-2934 One Trap to Do It All One Trap to Catch Them All AccuScience One-Trap - for Airborne Mold Sproes AccuScience One-Trap™ is the one and only multipurpose sterile spore trap with 100% collection rate for both short and long term air sampling. Why pay for incomplete results from partial mold spore collection? Ask your mold inspectors & microbial consultants for AccuScience One-Trap from QLab!

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