FANS IN AIR CONDITIONED SPACES
Fans and AC Energy Savings Increased air movement from Big Ass fans make occupants feel cooler, allowing designers and users to raise thermostat setpoints without sacrificing comfort. Each Fahrenheit degree offset reduces HVAC- related energy usage by 3 to 6 percent.* In the example below, where the cooling setpoint has been raised 5 degrees Fahrenheit while maintaining thermal comfort, HVAC cooling energy savings of 15% to 30% would be expected. Credits can also be earned for elevated airspeed in designs that exceed the minimum requirements of Standards 90.1 and 189.1.**
PIVOT
What Is Thermal Comfort? Thermal comfort is how comfortable an occupant feels in a space. Many factors influence thermal comfort — some are in your control, and some are in ours. Most notably, Big Ass fans provide cooling effects by increasing occupant-level air speed.
Measuring Thermal Comfort To comply with ASHRAE Standard 55, calculated conditions for occupants must meet the following conditions: Predicted Mean Vote (PMV), a statistical prediction of population thermal sensation should be greater than -0.5 and less than 0.5, indicating thermally neutral conditions. Predicted Percentage Dissatisfied (PPD), a statistical prediction of population thermal dissatisfaction should be less than 10%. It is worth noting that even in a perfectly thermal neutral environment (PMV = 0), that PPD will still equal 5%, reflecting the population variance in thermal comfort preferences.
Air Speed
Air Temperature
Radiant Temperature
Humidity
Clothing Insulation
Metabolic Rate
Environmental Factors
Personal Factors
Six important factors determine your overall thermal comfort, as defined by ASHRAE Standard 55.
Why Add Fans To Conditioned Spaces?
A/C ONLY
A/C AND FANS
POWERFOIL ® SERIES
Air Dry Bulb Temp = 75ºF (24ºC)
Air Dry Bulb Temp = 80ºF (27ºC)
Air conditioning is great — but it’s expensive and can be horrifically inefficient. Big Ass fans work with air conditioning systems to make them more effective and provide cooling effects that reduce AC system run-times. The fans use a fraction of the energy of an HVAC system, thereby reducing overall energy consumption. By incorporating Big Ass fans into HVAC designs and building automation systems, energy savings become easy and automatic.
Mean Radiant Temp = 75ºF (24ºC)
Mean Radiant Temp = 80ºF (27ºC)
Humidity Ratio = 0.009
Humidity Ratio = 0.009
Air Speed = 20 fpm (0.1 m/s)
Air Speed = 110 fpm (0.6 m/s)
Metabolic Rate = 1.1 met
Metabolic Rate = 1.1 met
Clothing Insulation = 0.75 clo
Clothing Insulation = 0.75 clo
PMV: -0.01 PPD: 5%
PMV: -0.01 PPD: 5%
“BIG ASS FANS HELP US CUT DOWN ON OUR AIR-CONDITIONING LOAD AND OUR UTILITY BILL. WE CUT 15 PERCENT OFF OUR BILL AT A TIME WHEN EVERYBODY ELSE IS SEEING A 20 PERCENT INCREASE.”
Source: CBE Thermal Comfort Tool
Combining A/C and fans means increased energy efficiency without sacrificing comfort
DAVE LEON Planet Fitness Owner
*US EPA & DOE Energy Savings Calculator **ANSI/ASHRAE/IES Standard 90.1 and ANSI/ASHRAE/USGBC/IES Standard 189.1
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