The resource impacted greatest from indoor environmental quality is not energy, water, or physical materials themselves; it’s the occupants that live in and utilize the space. IEQ is composed of more than just indoor air quality (IAQ); acoustics, illumination, thermal comfort, and the ability to control surrounding environmental conditions to personal preferences also impact how occupant interact with the built environment. Optimizing these components can lead to significant benefits for the world’s most valuable resource: people. To discover how IEQ impacts human health and comfort see the Human Impacts section.
Indoor Air Quality
A primary component of a successful indoor environment quality strategy is air; specifically its composition, odor, temperature, and moisture content when in contact with building occupants. IEQ is determined by a number of factors including building material selection, maintenance techniques, and thermal conditions.
Building materials, such as paints, sealants, adhesives, office equipment and furnishings, can emit invisible, odorous, and potentially harmful gasses, such as volatile organic compounds (VOCs) or formaldehyde, through off-gassing. VOCs are a class of chemicals that evaporate into the air at ambient (room) temperature and can cause eye, skin and throat irritation among other health complications. Formaldehyde, a human carcinogen from resins used to make wood composite materials, and VOCs should be limited in the office environment to the greatest extent possible. The Explore Section's Spaces include information on low-emitting alternative building materials and the EPA has guidance regarding VOCs and low-emission product labeling.
Ventilation is the process of "changing" or replacing air in any space to remove airborne contaminants such as moisture, odors, emissions from building products and materials (e.g. VOCs and formaldehyde), combustion byproducts, dust, airborne bacteria, and carbon dioxide; and to replenish oxygen. Ventilation systems typically include both the exchange of air with the outside and the circulation of air within the building, and as a result is critical for maintaining acceptable indoor air quality levels. Filters, which trap airborne particulates being circulated through the ventilation system, remove potentially harmful or irritating substances from the air and prevent them from being further distributed. Some green building rating systems recommend that HVAC designs incorporate filters with a minimum efficiency reporting value (MERV) of 13 and that the HVAC system is sized to accommodate such a filter.
Locate outdoor air intakes away and upwind (if applicable) from pollutant sources such as idling vehicles, building exhaust vents, cooling towers, and other exterior pollutant sources. Ventilation rates should at a minimum follow the rate procedure of ASHRAE Standard 62.1-2010. Increased ventilation rates can lead to a more pleasant environment but may demand additional energy. Further integrate CO2 sensors for densely occupied spaces to control ventilation levels. Learn more in the Human Impacts section.
Higher ventilation rates use more energy. Ventilation systems that minimize energy use should be selected, such as mixed mode ventilation, which uses a combination of natural (from operable windows and doors) and mechanical ventilation, or fully natural ventilation where appropriate. See the HVAC System for more information on the benefits of various ventilation strategies. When using natural ventilation approaches, they must be carefully designed and maintained to ensure they do not negatively affect occupant satisfaction or indoor air quality and are appropriate given local environmental conditions. See ASHRAE’s IAQ Guide for more detailed information on HVAC selection for IAQ.
Diagram of mixed-mode ventilation http://www.cbe.berkeley.edu/mixedmode/aboutmm.html
Research has shown that environmental tobacco smoke (ETS), or secondhand smoke, from cigarettes, pipes, and cigars has cancer-causing airborne particulates that can cause detrimental health effects when inhaled.1 Smoking should be banned from within the building and nearby (25-50 feet) of building openings such as entries, outdoor air intakes and operable windows. Buildings can also install separate HVAC systems to isolate smoking areas within the facility, although it’s typically uncommon and expensive in the office setting.
Construction and renovation projects pose a unique threat to indoor air quality. IAQ management plans should be instated that emphasize the protection of building materials from moisture damage and direct the performance of a flush-out procedure to rid stagnant pollutants from the space after construction is complete. Flush-out requires constant circulation of clean outdoor air for a period of time prior to occupancy. During construction or renovation, caution should be taken to limit construction worker and building occupant exposure to potentially harmful airborne pollutants that may be generated by the construction activity, such as dust, lead, and asbestos.
It is no surprise that regular upkeep is necessary to maintain a high indoor air quality, as dust, dirt, and mold accrue on materials in the space over time. Space cleanliness is a large component of IEQ. Employing a green cleaning plan is important in ensuring minimum occupant exposure to airborne particulate matter, along with HVAC filtration and entryway dirt capture systems that eliminate the pollutant source. Discover more on Green Cleaning and Integrated Pest Management in the O&M Impacts section.
Surveys of indoor environmental comfort often identify acoustics as an area of largest dissatisfaction. As the move toward open workspaces continues, effective management of noise levels become increasingly important. Planned and spontaneous interactions with coworkers are essential in the office environment. Sound absorption, zoning, and masking strategies should be taken to mitigate disturbances caused by noises like these. For more information on designing for acoustic comfort, see GSA's Sound Matters.
Acoustic ceiling tiles, carpeting, furniture finishes, curtains and hanging acoustical plasters can be implemented to mitigate the distribution of sound in the space. Absorption technologies block sound transmission from one space to another and require a relatively low financial investment. Choose materials with a high noise reduction coefficient (NRC).
Acoustical zoning supports both workers that need concentrative quietness to complete tasks and those in need of vocal interaction. Separate noise generating activities, such as conference rooms, away from work that needs a quieter environment and provide specialized areas for conversations demanding privacy to occur.
Blocking sound waves prevents noise from traveling to undesired ears but requires more than simply blocking line of site. For example, research shows that higher cubicle partitions provide small amounts of additional acoustical shielding. But this increase in ‘visual privacy’ may encourage people to talk louder because they believe they have more privacy. As a result this could lead to even more disruptions.
Masking strategies "cover" the unwanted sound by providing a low and uniform level of background noise to contrast sporadic and distracting interruptions to the quiet workplace. Often perfect silence can be distracting in the working environment. Sound masking technologies may be electronic, with speakers providing artificial white noise, or part of a well-planned ductwork and diffuser system.
Thermal conditions, which include air temperature, relative humidity, and velocity, greatly impact overall occupant comfort and associated productivity. ASHRAE Standard 55 – Thermal Environmental Conditions for Human Occupancy should be met and maintained at a minimum to achieve adequate indoor environmental quality. Reductions in the size of thermal zones in the workspace allows for more specialized control over thermal conditions. However, be sure zones are homogenous in activity and thermal loads to ensure the needs of most occupants can be met. Special attention should be given to material moisture dynamics, as building moisture from rainwater or excessive humidity facilitates mold growth leads to occupant discomfort and poor indoor air quality. Discover more in the HVAC whole building section.
Lighting Environment and Views
Providing access to uniform general lighting, daylight and views has demonstrated beneficial returns in occupant morale, comfort, and productivity. See the Lighting whole building section for more information.
An effective daylighting strategy sufficiently illuminates the building space without subjecting occupants to inconvenient glare or light level fluctuations. Daylight can be reflected into the interior of the space using light shelves at the building’s perimeter or light tubes from the roof. Daylighting reduces the overall lighting energy consumption and provides a visually stimulating and productive environment for occupants.
Supplementing natural light with a combination of direct and indirect light sources creates a consistent and well dispersed indoor lighting level for occupants to complete visual tasks. Potentially irritating glare should be avoided along with overbearing shadows on the walls and ceiling. Personal controllability and integration of task lights should be part of a successful lighting strategy.
Views to the outdoors provide building occupants with not only natural daylight but a visual connection to the environment. This visual connection has demonstrated increased morale in workers over the period of a work day and is an important part of a comprehensive indoor environmental strategy.1 Locating private office spaces away from the building envelope, implementing lower partitions, and providing open office space adjacent to exterior-facing windows are all strategies to optimize views for building occupants. However, employing these strategies to increase views must be balanced with acoustical and HVAC zoning objectives.
IEQ is all about health and comfort. The optimum indoor comfort "settings" for one individual is never the same as his neighbor. As a result, providing controllability over indoor environmental conditions, namely thermal comfort, luminance levels, and acoustics, allows occupants to tailor their surroundings to what works best for them. In the process, utility costs are reduced and productivity is improved.
Providing thermal comfort controllability can be achieved in a number of ways. Individual controls, such as thermostats, local diffusers, variable volume air distribution, fans, and radiant panel control, can be integrated in an HVAC zoning strategy. Operable windows may be used in lieu of individual controls for occupants positioned near exterior walls.
Incorporating task lights into the overall lighting strategy allows occupants to customize their ambient light conditions on a personalized basis. Task lights can be hard-wired into a cubicle / desk or come simply in the form of a desk lamp. All automated controls, including occupancy sensors, should allow for occupant override. Occupants should also be given control over natural light levels through effective, adjustable shading.
Modern office policies and technologies enable mobility as a means for the occupant to seek out desirable environmental conditions. Mobile laptops and Wi-Fi internet allow users to take work to more conducive areas for their task at hand, including the exterior of the building. Distracting acoustics can be avoided altogether by simply moving location. Consider corporate telecommuting programs that incentivize occupants for working in more beneficial areas. Mobility further increases individual control, which is essential to high indoor environmental quality.
Green Tips and Strategies
|Limit the use of products containing volatile organic compounds (VOCs). Specify low or no-VOC alternatives.||Create a green cleaning maintenance plan utilizing less-toxic cleaning materials and strategies.||Prohibit smoking within the facility or near building entrances and ventilation intakes.|
|Regularly clean and replace air filters.||Create acoustical protocols to make workers more aware of behavior that interferes with others.||Directly exhaust disturbing odors from kitchen and bathroom areas to the outdoors.|
|Implement absorption, blocking, and masking strategies to limit sound disturbances.||Optimize views to the outdoors and provide mobility to access it.||Consider long-term IAQ effects of construction and renovation projects and take actions to remediate those effects.|