Indoor air quality: Air movement needed in supply chain facilities
That comforting feeling created by an outdoor breeze on a hot summer day is equally satisfying to workers within a warehouse setting where fluctuating temperatures and stagnant air are the norm. Considering your equipment is only as good as the people using it, creating a comfortable work environment with the simple addition of air movement improves the health, safety, and sanity of those within.
Supply chain facilities are prone to these fluctuating temperatures; it’s an unfortunate reality of warehouse design. Air-conditioning and ventilation systems, while effective up to a certain point, can be greatly enhanced by the addition of proper air movement. When interior conditions are such that workers can no longer concentrate on the job at hand, personal comfort must be addressed.
In terms of employee comfort, it’s important to understand that the sensation of feeling comfortable is not dependent on air temperature alone. Human thermal comfort takes into account numerous environmental factors including temperature, thermal radiation, humidity, and air speed as defined by ASHRAE Standard 55-2010, along with personal factors including activity level and clothing type. Studies have shown that improved occupant comfort leads to increased productivity, with worker productivity decreasing as temperatures rise above 77 F.
In warmer months, operating between 60% and 100% of maximum speed, 6- to 24-ft-diameter fans improve comfort with either an evaporative cooling effect or the added effect of heat transfer—when skin temperature is warmer than air temperature. Although fans do not lower the air temperature in a space, the perceived cooling effect can make a person feel up to 10 degrees cooler.
In the winter months, operating at 10% to 30% of the maximum speed, large-diameter, low-speed fans successfully destratify tall spaces, mixing the warm air at the ceiling level with the cooler air at the occupant level, creating a more uniform temperature.
The addition of air movement offers multiple benefits that improve the well-being of occupants and, in some cases, of products and machinery as well, by aiding in the following:
- Reducing heat stress on employees
- Reducing condensation to preserve product integrity
- Improving indoor environmental quality (IEQ), when mold or toxic fumes are airborne
- Providing year-round comfort
OSHA standards indicate temperatures of 100.4 F and above are dangerous for workers while air temperatures that exceed 95 F significantly increase the heat load on the body. When temperature and humidity rise, the body’s ability to cool itself decreases, severely affecting worker productivity.
In the manufacturing industry, reducing activity level is generally not an option, but applying gentle, nondisruptive airflow from large-diameter, low-speed fans bring about the evaporative cooling process.
A Texas-size problem
A Texas-based McGraw-Hill textbook distribution center faced up to 15 heat-related incidents each summer in its 900,000-sq-ft facility. The 200 workers who boxed and shipped textbooks needed to ramp up productivity during this time in preparation for the fall semester, but the extreme Texas heat made this a tricky proposition.
Thirty 24-ft diameter fans were installed to help circulate the air. “It was an oven in this concrete building, and when workers were hot, they slowed down,” said Mike Price, maintenance manager. “We’ve noticed a big difference (installing the fans). One hundred and five is still hot, but it’s manageable inside with the fans.”
Blowing condensation to bits
Condensation within a warehouse space can prove detrimental to employee safety (e.g., forklifts on wet concrete) and negatively affect product integrity. Dehumidification systems (air conditioning) can decrease moisture content of the air, while heating systems help increase air or surface temperatures to help reduce moisture buildup.
The downside however, is that large industrial spaces are often impractical, or at the very least expensive to heat and cool. Air movement, on the other hand, does not depend on any external conditions to be effective.
Properly designed large-diameter fans with airfoils and winglets disturb the thin film of stagnant air on the metal surface, which in turn dramatically reduces the likelihood of condensation. This is highly beneficial in areas of high humidity where moisture buildup can result in mold and mildew.
Where condensation is a concern, the temperature of a concrete slab will trail the air temperature by about a month. For example, as April’s air warms to 70 F, the concrete is still stuck at roughly 50 F, from the month before. This warm, moist air sits on the cold slab and deposits moisture as it cools.
Given the vastness of most facilities, the steady, even air movement from large-diameter, low-speed fans helps move the stagnant warm air off the cold surface before it has a chance to cool down enough to leave puddles. Fans with additional blade-ending fins can help direct the fan's airflow toward the floor, maximizing the fan’s coverage area.
Annual Salary Survey
After almost a decade of uncertainty, the confidence of plant floor managers is soaring. Even with a number of challenges and while implementing new technologies, there is a renewed sense of optimism among plant managers about their business and their future.
The respondents to the 2014 Plant Engineering Salary Survey come from throughout the U.S. and serve a variety of industries, but they are uniform in their optimism about manufacturing. This year’s survey found 79% consider manufacturing a secure career. That’s up from 75% in 2013 and significantly higher than the 63% figure when Plant Engineering first started asking that question a decade ago.