Healthy Indoors Magazine
Issue link: https://hi.iaq.net/i/793014
Healthy Indoors 15 in response to space conditioning needs may impair contaminant removal. Define minimum ventilation rates by air cleanliness and distribu- tion, as well as temperature and humidity. • Vent placement. Air supply vents located near sources of pollution, such as exhaust vents, heavy traffic areas and trash dumpsters, pro- vide a pathway for contaminants to enter into the ventilation system. Carefully evaluate the location of all air supply vents. • Scheduling. Ventilation system scheduling is crit- ical to maintaining good indoor air quality. Install controls to operate the ventilation system based on occupancy levels or building hours. De- mand-controlled ventilation using CO 2 sensors can optimize indoor air quality and save energy. Close attention to these system design fea- tures will help you spot potential sources of in- door air pollution and create a clean, healthy indoor environment. ASHRAE 36P is a proposed guideline to provide uniform sequences of opera- tion for HVAC systems to maximize HVAC system energy efficiency and performance, provide control toms without clearly identifiable causes. Symp- toms include dry mucous membranes and eye, nose and throat irritation. These disorders lead to increased employee sick days and reduced work efficiency. The World Health Organization estimates that as many as 30 percent of new or remodeled buildings may have unusually high rates of health complaints. The National Institute for Occupational Safety and Health identifies poor ventilation as an important contributing factor in many sick building cases. Proper commissioning of the building man- agement system (BMS) is critical to ensuring appropriate ventilation and minimizing indoor air pollution. IECC 2012 and ASHRAE 90.1-2010 now require a commissioning plan for most large HVAC systems. Commissioning is mandatory for both LEED and Green Globes certification. ASHRAE Standard 202-2013, Commissioning Process for Buildings and Systems, describes how to plan, conduct, and document a commis- sioning process. ASHRAE Guideline 0-2013 pres- ents best practices for applying whole-building commissioning to facilities in order to make sure that the owner's project requirements are met. Ventilation system problems and solutions Ventilation is a combination of processes that move air into and out of buildings. Indoor air qual- ity may deteriorate when one or more of these processes is inadequate. Increasing the supply of outdoor air is the most commonly used method to fix indoor air problems, but a number of system design strategies can impact indoor air quality. • Air distribution. Locate air supply and return air vents at a reasonable distance to ensure bal- anced air distribution. • Variable airflow. Designs specifying HVAC sys- tem operation at reduced or interrupted flow Poor indoor air quality is costly in terms of health problems and lost productivity. A well-designed and maintained ventilation system can optimize comfort and well-being.