As soon as cold weather sets in, a significant difference between
ceiling and floor temperatures makes working conditions very
uncomfortable in even the newest metal aircraft hangers. If the hanger's
employees are comfortable working on the floor, those working on the
upper levels of the facility broil. And if the mezzanine-level workers
are comfortable, the floor-level workers freeze. As a result, many
directors of flight operations have begun searching for a solution that
will terminate the perpetual thermostat tug-of-war. And they have found
that solution in high-volume/low-speed Big Ass Fans.
Using 10 light-weight aluminum airfoils, a single 24 ft. ceiling fan
from the HVLS Fan Company, based in Lexington, KY, moves a lot of air
(about 140,000 cfm) very slowly (about 3 mph) over a large area (up to
20,000 sq. ft.). Using a 1 hp cycloidal 230/460 3 phase gear motor, the
HVLS fan is quiet and very efficient, using just 370 watts of
electricity and operating at a cost of about $.05/hour.
Because heat rises, a situation called "stratification" exists
whereby there normally is a floor-to-ceiling temperature differential of
approximately 1 degree per vertical foot. In a typical 10,000 sq. ft.
Corporate aircraft hanger, therefore, ceilings that are 30' high will
account for about a 30 degree difference in floor-to-ceiling
temperature. By thoroughly mixing or destratifying the air, HVLS fans
can virtually eliminate the temperature differential between the ceiling
and the floor. With the fans in operation, thermostat settings can be
reduced without any loss of employee comfort. And lower thermostat
settings translate into a significant reduction in heating costs.
According to Joe Thompson, Director of Flight Operations Maintenance for
the Ohio-based Cafaro Company, the onset of cold weather made for very
uncomfortable working conditions in the company's 10,500 sq. ft.
Aircraft hanger. If the thermostat were set so that the maintenance
people were comfortable, the administrative staff working on the
mezzanine would broil. If the administrators were comfortable, the
workers on the floor froze. Thompson therefore became determined to find
a way to terminate this seasonal thermostat tug-of-war. And he found it
with a single 20' diameter high-volume/low-speed ceiling fan, designed
to move a lot of air (125,000 cfm) very slowly (about 3 mph) throughout
the entire facility.
The Cafaro aircraft hanger's 30' high ceilings accounted for a 30 degree
difference in floor-to-ceiling temperature. However, by thoroughly
mixing or destratifying the air, Cafaro's HVLS fan virtually eliminated
this temperature differential, making working conditions comfortable
throughout the entire facility.
Even more impressive was the impact of the HVLS fan on the facility's
heating costs. The Cafaro hanger's natural gas usage in November 2000
was over 47 MCF. In November 2001, the natural gas consumption was just
11 MCF, a reduction in usage of 76%. Thompson attributes this savings
solely to the operation of the HVLS fan, especially because both
November 2000 and November 2001 had the identical number of degree days,
a measure of heating energy demand. With similar savings anticipated for
the rest of the heating season, Thompson expects a record payback for
his HVLS fan.
Destratification is not the only benefit the big fan can provide. The
cooling effect of the gentle movement of air during the summer months
can create a reduction in a building's effective temperature of 6 to 8
degrees, improving summer as well as winter working conditions. And, in
the case of big metal buildings with large doors that are open much of
the time, such as aircraft hangers, the fans act like bird and bug
repellant. Once a fan is installed, the birds' nests that were present
prior to the installation of the fan will be quickly vacated, as the
birds were terrified of the slowly moving airfoils. Birds that venture
into the hanger thereafter will likewise beat a rapid retreat. Because
birds and their business are not only a nuisance, but also can dirty and
damage planes, operation of the fan will significantly reduce the
maintenance costs for the planes and the building. Even flies and other
insects seem to hate the fans and either stay far away or land on the
floor and stay there, making eradication (i.e., squashing) easy.
Making working conditions more comfortable in hangars does not have to
be expensive or complicated. At a cost of much less than other options
that might be considered, HVLS fans can create a more pleasant working
environment year round.
HVLS Fans range in size from 8 feet to 24 feet to fit in virtually any
large or small hangar.
I heard osha is concerned about this...
By bill ireland