Enhance Indoor Environmental Quality (IEQ)  

the WBDG Sustainable Committee


When constructing cost-effective buildings, it is easy to forget that the success or failure of a project may rest on its indoor environmental quality (IEQ). Healthy, comfortable employees are often more satisfied and productive. Unfortunately, this simple truth is often lost, for it is easier to focus on the first-cost of a project than it is to determine the value of increased user productivity and health. Salary expenses are generally a high proportion of the operational expenses of a building. Even a small percentage gain in productivity, multiplied by the number of employees, can result in considerable savings. Facilities should be constructed with an appreciation of the importance of providing high-quality, interior environments for all users.

As a species, we have progressed from an outdoor hunter-gatherer existence to one where 90% of the typical American's life is spent indoors. Many of us have adapted to the indoor realm as our "natural" environment.

IEQ encompasses indoor air quality (IAQ), which focuses on airborne contaminants, as well as other health, safety, and comfort issues such as aesthetics, potable water surveillance, ergonomics, acoustics, lighting, and electromagnetic frequency levels. IEQ improvements to an existing building can occur at any point during the use of a building.

teaching lab in the Kendeda Building for Innovative Sustainable Design

At the Kendeda Building for Innovative Sustainable Design, an AIA COTE Top 10 2021 award winner, the teaching labs use extensive daylight harvesting and have operable windows and ceiling fans for comfort and connection to the campus.
Photo Credit: Lord Aeck Sargent

During the facility/renovation design and development process, federal projects must have a comprehensive, integrated perspective that seeks to:

  • Facilitate quality IEQ through good design, construction, commissioning, and operating and maintenance practices;
  • Value aesthetic and wellness concerns such as the importance of views or the integration of natural and man-made elements;
  • Provide thermal comfort with a maximum degree of personal control over temperature and airflow;
  • Supply an adequate quantity and quality of ventilation and intake of outside air to ensure acceptable indoor air quality;
  • Prevent airborne bacteria, mold, and other fungi, as well as radon, through building envelope design that properly manages moisture sources from outside and inside the building, and with heating, ventilating, air-conditioning (HVAC) system designs that are effective at controlling indoor humidity;
  • Use materials that do not emit pollutants, or are at least low-emitting;
  • Assure acoustic privacy and comfort by employing sound-absorbing material and equipment isolation;
  • Control disturbing odors through contaminant isolation and removal, and by careful selection of cleaning products. Pursue energy efficient strategies to remove harmful odors and recover energy used in conditioning the interior environment;
  • Create a high-performance luminous environment through the careful integration of natural and artificial light sources; and
  • Provide high quality potable water.


Facilitate Quality IEQ through Good Design, Construction, Renovation, and O&M Practices

  • Acceptable IEQ is easier to achieve if "source control" is practiced, not only during building construction but also over the life of the building. For example, the designer may select building products that do not produce noxious or irritating odors or contain volatile organic compounds (VOC), and design exterior entrances with permanent entryway systems to catch and hold dirt particles.
  • Refer to the ASHRAE Indoor Air Quality (IAQ) Guide: Best Practices for Design, Construction, and Commissioning for guidance on addressing IAQ during building design and construction. The ASHRAE IAQ Guide was developed by an ASHRAE appointed team of building professionals and world class IAQ experts with funding support from the U.S. Environmental Protection Agency.
  • Refer to the Indoor Air Quality Scientific Findings Resource Bank (IAQ-SFRB) for scientific information about the effects of IAQ on people's health or work performance. The IAQ-SFRB is being developed by the Indoor Environment Department of the Lawrence Berkeley National Laboratory with funding support from the U.S. Environmental Protection Agency.
  • Operations & Maintenance (O&M) and cleaning staff can avoid creating IEQ problems by choosing less noxious materials during repair and cleaning activities. While HVAC systems may be designed to isolate certain operations (e.g., kitchens, dry cleaners, etc.) from other occupancies, the O&M staff ensures that pressure differentials are maintained to avoid the undesirable flow of contaminants from one space to another. See also WBDG Sustainable O&M Practices.

Value Aesthetic Concerns

  • Appreciate the importance of providing windows in all occupied spaces, for views and for natural ventilation. See also WBDG Aesthetics and Productive—Promote Health and Well-Being. Ensure that windows have proper solar glare control, and encourage occupants to adjust to align with outdoor environmental conditions.
  • Design spaces around basic human needs, proven preferences, and connections to the patterns of nature and the mind. See also WBDG Psychosocial Value of Space.
  • Design circulation spaces with natural light and views that encourage interaction among building occupants. Where possible, use open stairways conveniently located which encourage people to use them instead of elevators both for health and energy savings.
  • Require that individual buildings or facilities be consciously integrated into their natural and man-made context. See also WBDG Sustainable—Optimize Site Potential.

Provide Thermal Comfort

Provide Ventilation and Maintain Acceptable Indoor Air Quality

  • Design the ventilation system to meet or exceed ASHRAE Standard 62.1 Ventilation for Acceptable Indoor Air Quality. Work closely with the Mechanical Engineering team to strike a balance between optimal fresh air and energy efficiency using either the ventilation rate procedure (VRP) or the indoor air quality procedure (IAQP). Also, consider surveying building occupants to determine their satisfaction with the interior air quality.
  • Implement a construction management program that ensures key ventilation components are protected from contamination during construction. Ensure that construction filters placed in ductwork and mechanical equipment are routinely inspected and replaced as needed. Do not install carbon filters until all construction work, including dry wall and painting, has ceased.

    650 California Street in San Francisco

    Built in 1964 by SOM, the property owners of 650 California Street in San Francisco recently undertook the replacement of the existing MERV 7–8 filters that are now the equivalent of MERV–16. Upgrading the buildings' filtration was a major step to improving the overall indoor air quality for their tenants wherever feasible across their portfolio.
    Photo Credit: Urban Land Institute

  • Commission HVAC systems to validate and document design performance intent. Review commissioning report to ensure that adequate ventilation rates have been achieved prior to initial occupancy. One Commissioning technique that can be employed over the life of the building is the use of a well maintained carbon dioxide monitoring system that will continually provide diagnostic feedback on the actual amount ventilation provided in the most densely occupied spaces. HVAC system should be installed with filters with a Minimum Efficiency Reporting Value (MERV) of 11 for residential, commercial, telecommunications and industrial facilities. MERV 13–16 is preferred for smoke removal, general surgery, hospitals, and other healthcare facilities. MERV–15 is recommended for residential applications, especially if Net Zero ready is the goal.
  • Consider a building design with a natural ventilation or hybrid component to both reduce energy consumption and to make some provisions for ventilation even if external power were not available (a measure of resiliency). Use of natural ventilation component is dependent on relative humidity being within an acceptable range.
  • Investigate the use of separate outside air and conditioned air distribution systems. A good description of various types of heating and ventilation systems can be found at: WBDG High-Performance HVAC and Natural Ventilation.
  • Ensure fresh air intakes are located away from loading areas, exhaust fans, and other contamination points, preferably on roofs.
  • If building is close to a large roadway source, consider the location of the fresh air intakes or possible breaks that may help reduce impact of the outdoor air on the indoor environment.
  • Ensure parking lot/garage usage cannot generate pollutants that affect fresh air intake or pedestrian traffic. Prevent vehicles from idling near the facility during normal operations. If there is a below grade parking garage, consider using monitored values of both carbon monoxide and carbon dioxide to control the fans to reduce exposures to not only the carbon monoxide but also the respiratory irritants of oxides of nitrogen and unburned hydrocarbons.
  • Investigate the use of a permanent air quality monitoring system. ASHRAE acceptable level of carbon dioxide (CO2) for an indoor office environment at 20 cfm per person equates to no greater than 530 ppm greater than outdoors. While outdoor CO2 levels used to range from 300 to 400 ppm many years ago, increasing atmospheric CO2 levels in the last few decades are now at least 400 ppm. Even remote locations, such as on a mountain top in Hawaii, exhibit CO2 levels above 400 ppm. If Demand Controlled Ventilation is employed, either rely on sophisticated algorithms to automatically review and interpret the monitoring data and/or have it periodically reviewed by an IAQ expert. Carbon monoxide (CO) levels in office environments should be below 9 ppm. OSHA regulates levels of CO for industrial locations.
  • Coordinate ventilation and air filtration with chemical, biological, and radiological concerns and locate outside air intakes so they do not conflict with physical security requirements. See also WBDG Air Decontamination.
  • During operation, either develop a plan for identifying needed filter media replacement or replace filter media on a regular schedule.
  • Provide Energy Recovery Ventilation systems for needed ventilation air as a standard feature in new construction which is typically highly insulated and extremely airtight.

Prevent Radon Entry, Airborne Bacteria, Mold and Other Fungi

Prevention of mold and fungi is dependent upon effective HVAC and building envelope design and construction. The HVAC system must be able to control interior humidity throughout a wide range of outdoor conditions. The system must be designed to have the capacity to dehumidify at the 1% Humidity Ratio and mean coincident dry bulb temperature, and control interior humidity at both extreme and low load conditions. The building envelope must be carefully designed to prevent intrusion of water and to dry if intrusion should occur. It must also incorporate barriers that control vapor and air infiltration.

  • Carefully consider the envelope of the building to prevent moisture infiltration. See ASHRAE IAQ Guide.
  • Investigate and remediate immediately when there is a mold or moisture problem, either from high humidity, a leak, or flood. See EPA Guidance.
  • Ensure the number of spores in the indoor air is less than the outdoor air. It is recommended that there should be less than 700 spores in a cubic meter of air.
  • In areas where it is prevalent, include measures to test for radon and control and mitigate radon buildup.

Limit the Spread of Pathogens

For health care facilities:

  • Implement proper maintenance procedures to prevent nosocomial infections.
  • Consider removing restroom doors to reduce the chance of acquiring infections.

Use Safer Materials that have Less Hazardous Ingredients and are Low-emitting

  • Look to EPA's Recommendations for environmental performance standards and ecolabels
  • Limit the use of volatile organic compounds (VOCs) in such products as cleaners, paints, sealants, coatings, and adhesives. See also WBDG Evaluating and Selecting Green Products.
  • Avoid products containing formaldehyde (i.e., carpet, wall panels, or prefabricated cabinetry).
  • Remove asbestos-containing material, or contain it in a manner that precludes the possibility of future exposure.
  • Carefully follow lead-safe work practices during renovations by enforcing thorough clean-up. Follow EPA's Renovation, Repair, and Painting regulatory requirements, using certified contractors and lead-safe work practices.
  • Create safe, convenient, and secure storage spaces for housekeeping chemicals. See also WBDG Sustainable O&M Practices.
  • If an area in an occupied building is being renovated, then consider isolating and negatively pressurizing the construction area whenever work is being performed that would produce dust, fumes, or odors. If conditioned air is required due to high end finishing work, then air should be directly exhausted to the exterior environment and not returned to the fan.
  • Ensure that office equipment emits minimal odors or pollutants and is contained in an unoccupied, enclosed space.

Assure Acoustic Privacy and Comfort

  • Minimize noise through the use of sound-absorbing materials, high sound transmission loss walls, floors, and ceilings, and equipment sound isolation. See Architectural Graphic Standards, 12th Edition, section on Acoustical Design for more information. See also WBDG Productive—Provide Comfortable Environments and Acoustic Comfort.
  • Minimize noise distractions by shared proximities (grouping similar functions together) and through controlled circulation patterns.
  • Consider sound masking systems, where feasible. These systems introduce an unobtrusive background sound that reduces interference from distracting office noise. Note that some level of HVAC "noise" can serve as a background white noise source, eliminating the need for sound masking systems.
  • Avoid the use of small diameter ducts with high velocity airflow.

Control Disturbing Odors through Contaminant Isolation and Product Selection

  • Directly exhaust copying and housekeeping areas, and provide added return air grills in these areas. This will help limit lower atmosphere ozone generation, commonly associated with duplicating and printing processes. Ozone acts as a power oxidant. It can attack surfaces of certain elastomers, plastics, paints, and pigments; and aid in sulfide and chloride corrosion of metals. Possible health hazards caused by ozone include eye and mucous membrane irritation as well as chronic respiratory disease.
  • Minimize disturbing odors through contaminant isolation and careful selection of cleaning products.
  • Ensure maintenance procedures are in place to remove all trash and recyclables from the building on a regular basis rather than storing them within the building for prolonged periods of time.
  • Prohibit smoking in all areas of the building. Environmental Tobacco Smoke (ETS) is a known carcinogen.
  • In special cases where smoking is permitted, e.g., federal judge's private chambers, ensure that the spaces:
    • Have lower pressure than adjacent areas;
    • Comply with ASHRAE Standard 62.1 for proper ventilation;
    • Are isolated from the return air system of surrounding areas to prevent pollutants from spreading to other areas.
  • Use and effectiveness of Air Cleaners.

Create a High—Performance Luminous Environment

  • Provide daylighting for ambient lighting wherever feasible.
  • Supplement natural light with integrated, high-performance ballasts, lamps, fixtures, and controls.
  • Replace magnetic fluorescent lamps with high-frequency electronic ballasts to reduce flickering.
  • Reduce direct glare from both natural and man-made sources in the field of view—particularly in spaces with highly reflective surfaces, such as visual display terminals (VDTs).
  • Use ambient lighting systems that provide reduced levels of diffuse, general illumination, and supplement with task lighting. Most people do not need lighting in excess of 300 lux.
  • Avoid dark colors on walls. Locate windows to maximize benefits of natural light and minimize glare.
  • Provide dimmable fixtures where possible, combined with task lighting for occupant control. Dimming light levels will conserve electricity and reduce heating loads which lighting imposes on the building's HVAC system. Lighting levels are often designed for the most demanding user, and all other occupants are forced to adapt to light levels that are brighter than desired.
  • Create a safer and more accommodating environments for the growing population of people with low vision (defined as a chronic visual impairment that causes functional limitations or disability) and other disease- or other age-related vision challenges.

Provide Quality Water

  • Comply with EPA Safe Drinking Water Act (SDWA) for the levels of various metals and bacteria in potable water systems.
  • For newly installed or temporarily suspended domestic water systems, follow "start-up" procedures by flushing all downstream outlets.
  • Conduct periodic 'maintenance flushing' to proactively control drinking water issues.
  • Control domestic water temperature to avoid temperature ranges where legionellae grow: keep domestic water temperatures above 140°F (60°C) in tanks and 122°F (50°C) at all taps (faucets and showers).
  • Design cooling tower and building air intake placement so air discharged from the cooling tower or evaporative condenser is not directly brought into the facility's air intake.
  • Consider a closed loop system instead of an open system to reduce the potential of exposure at the cooling tower.

Be Aware of Exposure to Electromagnetic Fields (EMF)

Electromagnetic fields (EMF) are generated by forces associated with electric charges in motion, and by microwaves, radio waves, electrical currents, and transformers. EMF are thought to cause cancer, however there is currently insufficient evidence to prove this. There are no federal standards limiting occupational or residential exposure to EMF at this time, only various U.S. and International voluntary occupational exposure guidelines. Nevertheless, facility designers and managers should consult the following resources to find out the latest scientific research and recommendations on dealing with EMF exposure:

Balance IEQ Strategies with Security Requirements

Since the terrorist attacks of 9/11, building owners and occupants have placed greater emphasis on facility security and safety. However, security and safety measures must be considered within a total project context, including the project's environmental goals. Several indoor environmental quality strategies, such as dedicated ventilation systems and tight building envelopes, can be employed to help designers achieve an integrated, high-performance facility.

Secure facilities and spaces are not inherently exempt from daylighting. As required by the applicable security criteria, consider the following fenestration design features: non-opening; acoustical protections; visual protection, via elimination of line of sight into secure areas with angles or translucent or semi-opaque glazing, curtain walls, clerestories, skylights, glass unit masonry, fiberglass panels and other lightweight plastics; minimum required elevation from the ground or platforms; and access to daylight in breakrooms and other common spaces. See also WBDG Balancing Security/Safety and Sustainability Objectives.

Healthy Buildings / Active People

Relevant Codes and Standards

Additional Resources

Facilitate Quality IEQ through Good Design and O&M Practices

Federal Agencies and Laboratories

Organizations and Associations

Design and Analysis Tools

  • IAQ Building Education and Assessment Model (I-BEAM) Computer Software—I-BEAM is computer software for use by building professionals and others interested in indoor air quality in commercial buildings. I-BEAM updates and expands EPA's existing Building Air Quality guidance and is designed to be comprehensive state-of-the-art guidance for managing IAQ in commercial buildings. I-BEAM contains text, animation/visual, and interactive/calculation components that can be used to perform a number of diverse tasks.
  • NIST Multizone Modeling—Contains software tools for performing multi-zone analysis (e.g. CONTAM), information on the applications of multi-zone modeling, multi-zone modeling case studies, and references to multi-zone modeling publications.


Provide Thermal Comfort

Supply Adequate Levels and Quality of Ventilation and Outside Air

Prevent Radon Entry, Airborne Bacteria, Mold and Fungi

Specify Safer Materials

Assure Acoustic Privacy and Comfort

Create a High—Performance Luminous Environment

Provide Quality Water

Balance IEQ Strategies with Security Requirements


Training Courses

Case Studies