Enhance Occupant Satisfaction
Make The Most of Your Environment,
INDOORS and Out.
Are you looking for ways to enhance occupant satisfaction within your building? Studies show that people prefer the comforts and pleasures associated with most green facilities. Findings reveal higher levels of occupant satisfaction in buildings where green practices are utilized.
An unpleasant sensation of being too hot or too cold (thermal discomfort), or bad indoor air quality can distract people from their work and disturb their well being. This may lead to reduced concentration and decreased motivation to work. The consequence of such a state is usually reduced productivity.
If there’s one thing facility managers agree on across the board, it’s probably that occupant comfort complaints are their biggest routine operational headache. If one person is too hot, someone else nearby is too cold, and tomorrow both complaints may be reversed. Even a young building may have trouble keeping most of the people happy most of the time, and if your building is old, well, good luck. But all is not lost. Even though comfort is an intensely personal experience for each occupant, there’s lots of science illuminating the best ways to provide it. Sadly, the best techniques don’t often get implemented in practice, possibly because this knowledge is not widely known or understood. Keeping your occupants more comfortable will have the obvious benefit of reducing trouble calls, and therefore O&M costs. More subtle are the other benefits that can accrue: higher workforce productivity, better health, and in some cases lower HVAC energy costs.
What Is Thermal Comfort?
As facilities managers know, most occupant comfort complaints will boil down to “I’m too hot” or “I’m too cold”, because typically we think of thermal comfort only in terms of temperature. Those vague but common perceptions actually only scratch the surface of a much larger set of factors that combine to drive the fundamental physical phenomenon: the human body’s heat balance. Our bodies are constantly generating metabolic heat at rates that depend on who we are and what we’re doing, and we constantly lose that heat depending on what we’re wearing and what our surrounding conditions are like. If those rates of heat gain and loss get imbalanced for some reason, we feel uncomfortable. Comfort researchers have identified several separate drivers of the heat balance:
Traditional Environmental Comfort Factors
(all are well-known, and facility managers can readily influence them)
- Temperature of the room air, ignoring moisture content (i.e., the dry-bulb temperature)
- Relative humidity of the room air
- Speed of any room air that’s hitting the occupant
- Average temperature of the solid surfaces surrounding the occupant (i.e., the mean radiant temperature)
- The amount of solar heat directly hitting the occupant through windows
Other Comfort Factors
(relatively new options, &/or areas where facility managers have little influence)
- Occupant activity level and clothing level
- Adaptive factors, such as the amount of control we have over our comfort conditions
- Variability, i.e., whether letting space conditions fluctuate somewhat is more comfortable than rigidly constant conditions
To some degree facility managers’ hands are tied when it comes to thermal comfort: they usually inherit the buildings they run, and building systems are not necessarily designed and installed to provide optimum thermal comfort conditions. Within those constraints facilities staff have some latitude, however, and can take action in either operational areas or as part of facility renovations.
Operational strategies typically focus on air temperatures: setpoints can be adjusted, and the HVAC distribution system can be repaired, adjusted, or rebalanced as needed to ensure the supplied heat or cool match the space loads. Beyond that are more approaches that should be explored, including adjustment of sequences of operations to change the humidity of the supply air, which can correct space humidity problems as well as reduce mold in building structures. Leaks in the building shell can also be repaired, and terminal registers can be repaired or adjusted to avoid stratification or undesired air circulation within rooms. Retro-commissioning your system periodically is a great way to discover unknown problems and prioritize maintenance needs. For buildings implementing setback or setup temperatures during off-work hours, think carefully about how far in advance of the early morning arrivals to have your occupied setpoints kick in: the closer the building’s thermal mass is brought to the target temperature, the more comfortable the occupants will be (because of radiant temperature effects).
Renovations bring several other opportunities into play. One recent trend is “breathable” office chairs that allow air movement through the chair seats and backs. Individual temperature controls can be explored if the HVAC system is within the renovation scope. Building thermal mass (concrete or steel structure) can be exposed, coupling it to the room air, which reduces temperature swings (be cautious if considering this in conjunction with a setback strategy, as the two approaches can conflict with each other). A complete gutting and refit can be especially beneficial for perimeter areas if you install new windows: they can dramatically improve the shell’s air tightness, they can be opened during mild weather if appropriate, and they can have high “insulation” value. The comfort benefits of a high insulation value (i.e., a low U-factor) are definite but easy to overlook; it happens because the glass surface temperature becomes closer to the room air temperature, which allows comfort to be improved and likely maintained with reduced HVAC setpoints (cooler in winter, warmer in summer).
More Reasons to Act
Many studies have indicated that poor indoor environmental quality (IEQ) has a negative effect on employee health and productivity. Each year, millions of work hours are lost due to minor symptoms, such as headaches, nausea, fatigue, and eye irritation. Most often the cause is unknown, but the literature suggested a possible connection between indoor environmental quality and these symptoms. If health is affected by poor indoor environmental quality, then it is likely that increased health related absences would cause productivity at work to decrease.
Building owners have often been reluctant to have their buildings studied, fearing that if something were detected, they could be held accountable for housing employees in unsafe environmental conditions. What these owners may not realize is that by ignoring what the literature suggests, they could lose large amounts of money every year on employee productivity alone. In addition, if the owners of buildings continue to ignore the signs of an unsafe environment, they could spend additional money on potential lawsuits.
Many building owners are simply not aware of the large amounts of money that can be saved by creating quality indoor working environments. Building occupants often do not demand quality indoor environments when choosing office spaces, so building owners have little incentive to invest in them. Most owners tend to invest more in building appearance than in the environmental mechanics of a building, because that is what people see; so too little attention is paid to the functional aspects of a building. As building owners become more aware of how much money can be saved by having quality indoor environments, purchasing decisions will begin to change.
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