Page 52 - Occupational Health & Safety, September 2017

INDOOR AIR QUALITY
requirements have been added to ensure adequate outside air is provided for ventilation whenever residences are occupied. Ideally, an airtight home designed with both continuous and intermittent ventilation will contribute to a healthy and comfortable living envi- ronment for the entire family.
Residential/Commercial Energy Codes and Standards
Another factor for builders and homeowners to consider when evaluating IAQ in their homes are the applicable local and national building codes. The International Energy Conservation Code and American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) address energy efficiency requirements for the design, materials, and equipment used in nearly all new con- struction, additions, renovations, and construction techniques. ASHRAE 62.2 is the standard most commonly referenced for home ventilation. The purpose of this standard is to specify mini- mum ventilation rates and other measures intended to provide IAQ that is acceptable to human occupants and that minimizes adverse health effects. However, complying with a building energy code is challenging for both builders and architects. If a code requires ASHRAE 62.2 compliance and a home fails to meet the ventila- tion standard, a builder faces expensive alterations to mechanical systems, fan capacities, and duct sizing.
Home Energy Ratings
The Home Energy Rating System (HERS) Index is the nationally
recognized scoring system for measuring a home’s energy perfor- mance. Ratings are calculated at the end of the construction pro- cess by a certified Home Energy Rater using diagnostic equipment and performance modeling software. The rating takes into account variables such as a home’s airtightness, level of insulation, and type of heating and cooling system. The lower the number, the more energy efficient the home.
In fact, the goal is to have a Net Zero home, which means that your home’s energy consumption is equal to the energy it is able to produce. These energy-efficient homes are more affordable to maintain, more comfortable, and have a higher value compared to regular homes. Older homes often fall under the higher ratings due to issues such as old, sagging insulation or tiny cracks and holes that have developed over time, compromising the performance and energy efficiency of the home. The U.S. Department of Energy has determined a typical resale home scores 130 on the HERS In- dex, while a standard new home is awarded a rating of 100. A home with a HERS Index Score of 70 is 30 precent more energy efficient than a standard new home. A home with a HERS Index Score of 130 is 30 percent less energy efficient than a standard new home.
However, balancing a low HERS score with a whole home ven- tilation approach is difficult. As a measure of how tightly built your home is, a HERS score will likely increase when ventilation strate- gies are employed. For manufacturers and builders, the challenge be- comes how to meet air cycle requirements as cost effectively as pos- sible. The best measure of this in ventilation is “cost per HERS point.”
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