Indoor environmental quality (IEQ) pertains to the quality of a building’s environment in relation to the health, well-being and comfort of occupants. It is determined by numerous factors, such as the air temperature and humidity, air quality, lighting, acoustics, workspace ergonomics, cleanliness and the presence of contaminants, viruses and mold. Research has shown that poor attention to IEQ can lead to several health conditions and maladies, including respiratory symptoms, colds, diseases and allergies. Furthermore, poor attention to IEQ can lead to decreased employee productivity, lost work time, poor employee satisfaction, lower morale and high employee turnover rates. It therefore makes good business sense to improve IEQ to keep employees happy, healthy and productive, which in turn, enhances quality output and profits for organizations. Although the control of IEQ has been traditionally done on a building-scale level, some aspects of IEQ are better controlled at a personal level. This article discusses some of the factors affecting IEQ, and how the Air Innovations MyZone system can control IEQ at a personal level.

Components of IEQ

Building owners and business managers can increase the satisfaction of building occupants and improve employee productivity by considering all aspects of IEQ. However, despite many years of research, the control of several IEQ components at a building-wide level is difficult if not impossible since many of these components are a matter of personal preference.

Temperature/air conditioning

Air temperature is the most common source of complaints among building occupants. Controlling air temperature at the building-wide level is challenging because each occupant’s comfort often varies throughout the day; a person may be too cold in the morning but too warm in the afternoon, even if the temperature remains constant. Furthermore, individual comfort varies widely from person to person. In a typical office building, a single thermostat may control the temperature for 50 people or more

Typically, buildings are subdivided into zones where the temperature within each zone is controlled by a single thermostat. Chilled or heated air is then supplied to each zone by one or more air handling units, which are switched on and off to maintain a pre-defined set point temperature within each zone. Many potential problems can arise that may compromise the effectiveness of such systems. For example, air filters may become clogged, limiting airflow, or drafts may occur near the supply or return air registers. Poorly designed systems may not be capable of properly distributing conditioned air or adapting to additional thermal loads during certain times of the day.

Acoustics/noise

Poor acoustics is another common complaint among building occupants. In rooms with excessive reverberation, sound will echo freely, making speech sound garbled, causing occupants to speak louder, exacerbating the noise problem. Unwanted noise may also enter a room from HVAC fans, outdoor traffic, adjacent manufacturing facilities, music or the conversations of others. Apart from being obnoxious and distracting, noise pollution can be detrimental to human health and has been linked to hypertension, high cholesterol levels, irregular heartbeats and hearing loss. A space featuring good acoustics could potentially solve these issues. In a building, this can be accomplished through the use of acoustic absorbing treatments throughout the workspace, such as acoustic baffles or panels, acoustical ceilings, carpeting or sound masking devices, such as so-called white noise generators.

Air filtration

Airborne particulates, comprised of solid or liquid particles suspended in air that are 10 micrometers (microns or μm) or less in diameter, are cause for concern, as these are inhalable. Once inhaled, these particles can affect the heart and lungs and may result in cardiopulmonary ailments and diseases. In some instances, indoor particulate levels have the potential to exceed outdoor levels. Indoor particulate matter can include dust from adjacent manufacturing operations, smoke generated through cooking, combustion activities (the burning of candles, use of fireplaces or cigarette smoking), or of biological origin (pollens, mold, dust or bacteria).

Airborne particulates can be captured using filters placed within the HVAC system. In general, standard pleated fabric or filament filters are capable of trapping particle sizes greater than 3.0 μm in diameter. More advanced HEPA (high efficiency particulate air) filters can remove up to 99.97% of all particles 0.3 micron and larger. Filter effectiveness is rated according to the minimum efficiency reporting value, or MERV. A filter may have a MERV rating from 1 to 16, where the higher the MERV rating, the denser the filter and the more efficient it is at removing small particles in the air. While higher MERV ratings are desirable from an air filtration standpoint, additional energy is needed to push air through the filter. The MERV-rated filter should therefore be selected based on the capability of the fan(s) in the air handling units. The effectiveness of filters according to their MERV ratings is provided in Table 1 below.

Table 1: Filter MERV Ratings.Pathogens, bacteria and viruses

Pathogens, bacteria and viruses (viables), such as SARS-CoV-2 (the virus that causes COVID-19) can cause illnesses resulting in lost work time, higher health insurance costs and, in some cases, death. Air filtration can be used to provide some protection from pathogens, bacteria and viruses by removing moisture particles from the mouth or nose that can be released into the air via aerosol transmission. These aerosol particles can remain in the air longer and travel greater distances than droplets. For filters to be effective, they must be capable of removing aerosol particles as small as 0.1 to 1.0 μm. This requires the use of HEPA filters with MERV ratings greater than 13. Most building central systems are not capable of handling the pressure drop associated with HEPA filters, however.

Another method to remove pathogens, bacteria and viruses involves use of ultraviolet-C (UVC) radiation, which has been known to effectively disinfectant air, water and nonporous surfaces. UVC radiation has been shown to destroy the outer protein coating of the SARS-coronavirus, which ultimately leads to its inactivation. Since direct exposure of UVC radiation to human skin or eyes may cause injuries, the safest way to disinfect air with UVC radiation lamps is to install them within air ducts. Proper design of the UVC system is critical as the results are based on intensity and exposure time to the UVC radiation. If the passing particles are not exposed to enough intensity, or for long enough, the system will be ineffective at neutralizing the viables.

Ventilation

The process of ventilation involves the “changing,” replacing or replenishing of air within a confined space to control air temperature and humidity, and to remove odors, smoke and dust. Ventilation is one of the most important factors for maintaining acceptable indoor air quality within buildings. Many modern office buildings use closed air recirculation HVAC systems, where windows cannot be opened, and only a small fraction of outside make-up air is introduced into the building. This is due to strict energy codes designed to increase building energy efficiency by eliminating leaks, thereby eliminating the introduction of fresh air into the building unless it is allowed or regulated by the HVAC system.

Buildings with poor ventilation systems can develop “sick building syndrome,” where building occupants experience acute health problems such as headaches, eye, nose, or throat irritation, dry or itchy skin, respiratory problems, dizziness and nausea, fatigue, difficulty concentrating and sensitivity to odors. Although the specific causes of sick building syndrome are not entirely known, environmental health and occupational safety professionals recommend improvements to the ventilation system, including increased air flow, additional air cleaning and filtration, and the introduction of increased outside make-up air into the HVAC system. Make-up air becomes especially important because standard air filtration cannot remove certain gases, volatile organic compounds (VOCs) and odors. Increasing the amount of fresh air introduced into the building effectively dilutes these gas contaminants to acceptable levels.

Humidity and moisture control

Humidity is a measure of the amount of water vapor (dampness) in the air at any given time. It is a factor in determining thermal comfort, as well as contributing to the formation of mold and other airborne contaminants. The optimum range for indoor relative humidity is between 40% to 60%. On one hand, high humidity levels reduce a person’s ability to cool down through the evaporation of perspiration, making the apparent room temperature feel warmer. Very high humidity levels (greater than 60%) can also create a moist environment where microbial life, such as bacteria, fungi, mold and dust mites may thrive. On the other hand, low humidity levels can aggravate allergies in some people and cause excessive thirst and dry skin, lips and eyes, and has also been associated with eye irritation and nosebleeds. High humidity air is typically treated in the HVAC system, where the incoming moist air is cooled to below the dew point temperature, allowing the water vapor to condense. The condensate is then collected and drained from the HVAC system and the drier air is re-injected back into the building. Low humidity air is treated by humidifiers, where a supply of water is heated, forming water vapor, which is re-injected back into the building.

Lighting

Lighting provides numerous benefits for the health, well-being, productivity and safety of employees. Effective lighting can allow employees to see sufficiently to carry out tasks with minimum eye strain, and enhances the aesthetic appeal of the office, thereby improving employee mood, behavior and morale. Light intensity is typically measured in units of foot-candles or lux, which are often used interchangeably. A 1 ft candle is defined by the illuminance of 1 sq ft from a uniform light source, whereas 1 lux is defined by the amount of illumination supplied by one candle at a distance of 1 sq m on a 1 sq m surface. The color temperature of light, which is measured in degrees Kelvin, affects the appearance and illumination of light. Cooler temperatures (below 3000 K) will have a yellow hue, whereas hotter temperatures (above 5000 K) will have a blue hue. Lighting experts recommend that the lighting should be distributed evenly throughout an office workplace with a light intensity level of 500 lux at temperatures of 3500 K to 4500 K.

Ergonomics

Ergonomics concerns the layout and design of a workspace and use of equipment or furniture to minimize the potential for musculoskeletal disorders (MSDs) and injuries that may affect a person’s muscles, nerves, blood vessels, ligaments and tendons in the performance of their work. Work-related MSDs are among the most frequently reported causes of lost or restricted work time. An ergonomically designed workspace will accommodate user preferences, allow customized comfort settings, minimize stress and fatigue on the body, eliminate the likelihood of injury, and increase an employee’s efficiency and productivity while reducing discomfort. Ergonomics in an office environment considers several factors, including the layout and arrangement of desks and chairs, the adjustment of height and orientation of desktops, chair seats, arms and backs, computer keyboards and monitors, footrests and document holders.

Air Innovations MyZone System

IEQ incorporates several factors that may affect the health, well-being and comfort of building occupants and employees. While building owners and operators have traditionally controlled many of the factors at the building level, some of these are more effectively controlled on a personal level, as they are a matter of personal preference.

Air Innovations, a world leader in the design and manufacturing of building and equipment environmental control systems, has addressed this need through the development of their MyZone personal desk environment control device (Figure 1). This device can manage several parameters that could be contained to the immediate vicinity of an individual in an open office environment to provide customized environment settings according to the user’s personal preferences. The MyZone system can be attached to a personal work surface and combines several functions that can be operated by a centralized control module.

Figure 1. Air Innovations MyZone System. Source: Air Innovations

Heating and cooling

The MyZone system provides variable heating and cooling, with the air intake located below the desk surface and adjustable louvers on top of the desk to allow conditioned air to be directed at the user. The system utilizes a patented Reflective Arc Technology, which maximizes the heat produced by the system while utilizing a smaller heating source. In addition, the unit contains fans with multi-level outputs.

Air filtration

The MyZone system includes a standard MERV 7 filter, which can capture about 66% of particulates sized 3.0 μm to 10.0 μm. An optional HEPA filter can be installed on the unit to provide better air quality and greater personal protection to employees at their desks by allowing the user to direct purified air to their own breathing zone independent of the rest of the space.

Desk height adjustment

The MyZone system incorporates an integrated leg lift system that can precisely adjust the desk height for sitting or standing operation.

Acoustics/noise control

The MyZone system comes standard with a white noise generator that can be operated at different volume levels to mask unwanted noise in the personal workspace.

Modular controller

The MyZone system utilizes color touchscreen monitors to control various functions, such as temperature, airflow, acoustics, lighting, a clock and a calendar. The controller has presets for up to 15 users and can be positioned anywhere on the desk surface for maximum flexibility.

Air Innovations

Air Innovations was founded in 1986 in Syracuse, New York, and is a world leader in designing and building environmental process control systems for several industries. Their primary business involves the development of customized packaged systems and solutions for temperature, humidity, filtration, pressurization and with direct-expansion, chilled-water or thermoelectric capabilities. The company maintains a research and development department dedicated to continuous growth and improvement in the creation, testing and validation of their engineered solutions. More information about the MyZone system can be found on the Air Innovations’ website.