HVLS Fans As A Complem
By Dan Anderson, Rite-Hite Fans
Distribution centers, manufacturing facilities, and other large, open warehouse
environments face a host of unique
design and maintenance challenges.
These challenges include energy costs,
temperature control, air quality, and
employee safety/comfort issues.
In an effort to mitigate these challenges,
more and more facilities are installing high
volume, low speed (HVLS) fans as a complement to their HVAC system. HVLS fans can
significantly improve employee comfort and
health and can save building operators substantial amounts of money by making existing heating and ventilation systems more
efficient, while providing additional benefits
in buildings with no air conditioning.
Two Common Challenges:
SSS and SBS
Sweating Slab Syndrome (SSS) and Sick
Building Syndrome (SBS) are two common
air quality and employee safety/comfort
issues that building managers face.
SSS is a phenomenon that occurs when
moisture intermittently develops on the
surface of an interior concrete slab, such
as a warehouse floor. SSS can increase the
slipperiness of the concrete surface and
pose a serious risk to the safety of workers
and materials handling operations. Dew
point condensation is a common cause of
this moisture accumulation. This happens
when warm, humid air enters the structure
through open doorways, windows, and
vents. As that warm air diffuses throughout the structure, it will condense on any
surface that is at or below dew point temperature, which is often the floor surface.
When warm, humid air enters a structure, it
takes far less time to change the interior air
temperature than it does the temperature of
the slab. With such a rapid change in conditions, the slab temperature can easily be
found at or below dew point.
Many large facilities provide little air
movement and may exhaust interior air
through roof vents, creating negative pres-
sure in the building. Negative pressure
within a structure quickly allows exterior
air and other conditions to enter the build-
ing when loading dock doors are open.
HVLS ceiling fans can help reduce or
eliminate slab sweating by minimizing
ceiling-to-floor temperature differentials
and increasing the surface evaporation rate.
In addition, commercial dehumidification
units can alter the interior building environ-
ment to help reduce or eliminate SSS.
ventilation system can result in a buildup
of pollutants within the building, in which
case the indoor environment can often have
air quality much lower than the outdoor air.
Interior design factors, such as the arrangement of individual offices and cubicles,
may also interfere with efficient functioning of ventilation systems. Humidity may
also be a factor. While high relative humidity may contribute to biological pollutant
problems, an unusually low level may
worsen the effects of mucosal irritants and
may even prove irritating itself. Other contributing elements may include poor lighting and adverse ergonomic conditions, temperature extremes, noise, and psychological
stresses that may have both individual and
interpersonal impact. The complaints may
be localized in a particular area, or may be
widespread throughout the building.
Increasing ventilation rates and air distribution often can be a cost effective means
of reducing indoor pollutant levels. HVAC
systems should be designed to meet ventilation standards in local building codes;
however, many systems are not operated or
maintained to ensure that these design ventilation rates are provided.
Although SSS and SBS have different
causes, they have similar solutions, at least
to some degree. In both cases, increasing
air movement and ventilation often provides
dramatic relief. HVLS fans can help reduce