When purchasing an industrial fan or commercial fan, it’s common to see various claims about cooling effect and lowering indoor temperatures. We all know breezes from a fan make us feel cooler, but we may not understand how similar sounding claims can carry very different meanings. Some of the most common industrial fan claims are:
- “Makes you feel up to 12 degrees cooler”
- “Creates up to a 12-degree cooling effect”
- Some may even claim, “Lowers temperatures by up to 12 degrees”
We should proceed with caution anytime we see a claim stating an industrial fan lowers the temperature in a room (as illustrated in the third example above), as no fan can lower measurable room temperature using airflow alone. The other two examples may be technically true, but to the average buyer, these claims can create some confusion. When a company makes a claim about feeling XX degrees cooler or creating an XX degree cooling effect, they are typically referencing Thermal Comfort.
Understanding the Basics of Thermal Comfort
Thermal Comfort is used in HVAC engineering to define whether someone (or a group) is too hot or too cold. There are 5 primary factors that make up Thermal Comfort:
- Insulation value of clothing
- Metabolic Rate
- Air Temperature (F)
- Air Speed / Air Movement
All things being equal, any adjustment made to any of the 5 factors above will result in either an increase or decrease in thermal comfort. As one may speculate, increasing air speed is how industrial fans and commercial fans cause changes to Thermal Comfort. In most cases, an increase in air speed across our skin will make us feel cooler. Below is a simple chart that illustrates the cooling effect gained from various different airspeeds (graph provided by North Carolina State University)
While the above graph is straightforward it cannot be used as an absolute rule. This is where claims made about cooling effect must be more carefully considered. The above chart illustrates the cooling effect of different airspeeds and assumes all other factors are static, so any change to one of the other factors would also change this chart. In the chart, the cooling effect of air moving 500 ft/min creates approximately 10 degrees F of cooling effect (aka wind chill). This cooling effect assumes an indoor temperature of 85F and relative humidity of 55 to 65%. If the indoor air temperature or relative humidity increases significantly, the cooling effect at each air velocity point on the graph will also decrease significantly. Temperature and humidity is something that changes on a daily basis, so we want to keep in this in mind when considering cooling effect claims made by manufacturers.
Applying The Basics
Armed with an understanding of Thermal Comfort, we can better determine the true benefits of industrial fan’s performance claims. It’s common for industrial HVLS fan companies to claim up to a 12 F degree cooling effect when using an HVLS fan during the summer months. In extreme environments, where temperatures are more than 100 F or Humidity is in excess of 85%, it will be very difficult (if not impossible) to experience 12 F degree cooling effect from increased air speed alone. If something sounds too good to be true, ask questions. Most reputable industrial fan manufactures have technical experts on staff that can help explain details of all performance claims.
The team at Super Duty Fans can answer any questions you may have about thermal comfort or questions about our fans. Feel free to call or submit a contact form.