Plant Services Q&A: HVAC and indoor air quality

Oct. 2, 2013
Here are a few questions from the recent Plant Services HVAC and Indoor Air Quality webinar.

Workplace comfort impacts a lot of locations, where operators are simply performing more efficiently if they’re in a more comfortable environment. Measuring temperature, humidity, and air flow is a good start, but inspecting and testing of the ventilation, heating, and air conditioning systems should be performed, too. Here are a few questions from the recent Plant Services HVAC and Indoor Air Quality webinar with Jeff Hess and Christian Taber.

What is the difference between IAQ and IEQ?

Per the CDC, “Indoor Environmental Quality (IEQ) refers to the quality of a building’s environment in relation to the health and wellbeing of those who occupy space within it.” The IEQ of a space is determined by several factors, including lighting, air quality, temperature, humidity and air speed. Indoor Air Quality (IAQ) is a very important part of IEQ and is primarily concerned with the properties of the air in the building and the impact the air has on the health of the occupants of the building.

How can I control my increase in energy cost often associated with improved IEQ?

Improving IEQ often means adding or repairing mechanical equipment including fans, heaters, air conditioners, louvers, etc.  Properly controlling these systems so that they operate efficiently and only when necessary can greatly decrease their impact on building energy consumption.

What are some of the major indoor air pollutants that might be found in a building?

Indoor air pollutants include products of combustion (burning natural gas, propane, kerosene, oil, wood, etc.), mold, mildew, volatile organic compounds (VOC’s – paint, adhesives, etc.) and pesticides.  Please see the EPA or CDC websites for additional information.

Would big oversized doors (open ambient) be equal to big fans being installed to circulate fresh air?

Large ceiling fans provide circulation of whatever air is in the space.  This circulation can help to dilute localized concentrations of pollutants, bring fresh air down to the occupant level and generally increase IEQ.  An open door (oversized or not) is a passive way of allowing fresh air (as well as other things) to enter the building.  Without some driving force such as wind or an exhaust fan, air exchange between the inside and the outside of the building is generally localized and not sufficient to meet IAQ or IEQ needs.

What is the best way to address a negative building pressure in terms of creating a comfortable temperature in a shipping dock area?

Negative pressure is caused by exhausting more air from the building than is brought in by the mechanical system.  If large amounts of infiltration occur when the doors are open because of pressurization issues, the pressure in the building should be balanced by increasing the amount of treated outdoor air that is brought into the building. 

Any recommended air distribution guidelines to improve air movement at the floor or personnel level (e.g. elevation, locations of intake and exhausts, diffuser types, etc.)?       

Generally speaking, creating air movement via diffusers and intakes/exhausts is not an efficient or effective means of creating air movement.  Having a HVAC system that creates high air speeds at the occupant level in the summer might be desirable, but that same system would cause undesirable drafts during the winter months.  Allowing the mechanical systems to exchange the air in the building as well as heat or cool the air in tandem with using circulator fans to create air movement is more cost effective and more efficient.  For recommendations on increasing the distribution effectiveness of HVAC equipment, please refer to the recommendations contained in the ASHRAE handbooks, ASHRAE Standard 62.1, and the Advanced Energy Design Guides.