Green Means

Improving Indoor Environmental Quality

By Shannon Scott

            Indoor environmental quality (IEQ) encompasses indoor conditions needed for human health and comfort.  Two factors affecting indoor comfort are clean, non-toxic air, and comfortable room temperatures.  I’ll discuss other IEQ factors such as lighting, acoustics, and views in coming weeks.  IEQ factors prove critical for a comfortable, safe, and pleasant home and work environments.

            Commercial building operators may do well to improve occupied spaces for maximum employee comfort.  Many recent studies show that when employees are more physically comfortable, have fresh outdoor air, easily controlled thermal settings, a view of nature, good acoustics, and natural day lighting, they are far more productive and take fewer sick days. 

Fresh Air

            Allowing fresh air to infiltrate indoor spaces is one of the best ways to improve indoor air quality.  Opening windows to allow fresh air in is called natural ventilation.

            Carpets, cabinets, composite lumbers, gas ranges, cleaning products, moisture in bathrooms, and so forth can contribute to indoor toxins.  Many products off-gas or emit volatile organic compounds (VOC), indoor air contaminants than can cause or contribute to short- and long-term problems, like asthma, respiratory infections, allergies, headaches, congestion, eye and skin irritations, coughing, sneezing, fatigue, dizziness and nausea. 

            Agencies such as the Environmental Protection Agency (EPA) and others have conducted research that showed that the quality of indoor air can be many times more polluted, up to nine times, than that of the outdoor air, and has been a growing cause of health related litigation.  Indoor air pollution, building-related illness, and "sick building syndrome" have received increased attention over the last several years.  On average people spend as much as 90 percent of their time indoors, so health risks caused by indoor air pollutants are a significant concern.  Since poor indoor air quality can cause sickness and discomfort, this reduces employee attendance and productivity.  

            Poor IEQ can reduce a person's ability to perform mental tasks requiring concentration, calculation, or memory.  Think of this in work situations, and in school environments. 

            Growing numbers of elite preparatory schools, like the Sidwell Friends School, one of the world’s top tier K-12 schools, leads in more ways than academics.  Sidwell has become world-wide models of indoor environmental health, energy efficiency, and ecological conservation.  In feel-good school and work environments people can think better and function more effectively. 

            Operable windows allow in fresh air, dilute toxins, and make inhabitants feel better, perform better, and take fewer sick days because they are better. 

            In our climatic region, with hot summer days and cool nights, opening windows at night invites in cooling breezes, reducing or eliminating the need for artificial air conditioning methods – provided a building is well insulated with a tight building envelope or shell.  This passive cooling strategy freshens air and saves energy. 

            Homes should be designed with breeze pathways in mind.  Breeze pathways allow fresh air entering through windows to blow through throughout a house without being blocked by walls or room closures. 

            While replacing carpets and cabinets might be cost prohibitive, opening windows more often and venting exhaust fans to the outside can make drastic improvements in air quality. 

                         

Thermal Comfort

            Indoor ambient temperatures affect human comfort more than any other factor. 

            When constructing or upgrading a home, floor radiant heat zones are one good way to establishing area comfort.  They can be plentiful for few, but more zones means more control over individual room temperature.   Adjusting temperature based upon frequency and type of use, makes energy bills go down. 

            In commercial buildings, where energy costs effect the bottom line, the more individual thermostatic controls the better for employee productivity and reduced operating costs.  Since employee comfort drastically effects productivity, green building design experts strongly recommend that employees be able to control their own cubicles’ or rooms’ thermal comfort levels. 

            The type of heating or cooling, air movement velocity, and humidity levels all effect indoor comfort.  Passive heating methods and mechanically supported radiant heat often make inhabitants feel better than forced air type thermal systems.  

            Radiant heat from the sun or mechanical systems warms objects within a room, floors for example, and maintains more even temperatures than forced air or space heaters.   With convection, or forced air type systems, warm or cold air often is not evenly distributed and tends to cause discomfort due to the air velocity, or lack thereof, to sufficiently heat or cool a space.  

            Air movement should be nearly absent within rooms, but sufficient to circulate temperatures without causing drafts or drastic temperature fluctuations.  This is one reason radiant systems tend to feel more comfortable as no drafts or blasts of air from ducts occur.  We all know of work places or commercial buildings where we’ve tried to duck away from cold blowing air.

            Humidity is most comfortable when it hovers around 50%.  In our high desert, we’re lucky to have 10% outdoor humidity and maybe 20% indoors which causes mucous membranes to dry out, and static electricity.  Comfortable humidity levels in homes and offices reduce respiratory problems and skin rashes, and make thermal conditions simply feel better.  Too much humidity without adequate ventilation may cause harmful molds and mildews to grow and create other health problems.

            Open windows to breathe fresh air.  Adjust your personal radiant heat zone, so you feel good and do well in the environments in which you live and work.