High-Volume, Low-Speed Fans
A high-volume, low-speed (HVLS) fan up to 24 feet in diameter, capable of displacing many smaller constant speed fans.
Synopsis:
A High-Volume, Low-Speed (HVLS) fan is a large fan with sizes in diameters that range between 6 and 24 feet. A single HVLS fan is capable of displacing several smaller conventional propeller, box or panel fans to improve the de-stratification of warm air. Benefits include improved comfort, quieter operation, and energy savings, especially since HVLS fans are equipped with variable speed motors and temperature controls which can adjust fan speed in response to changes in air temperature. Energy savings are obtained by: displacing multiple fans with a fewer number of HVLS fans; increasing air movement in occupied spaces; increasing temperature setpoints of HVAC equipment in the cooling season, and; through a reduction in heat energy needed due to de-stratification.
A single HVLS fan can displace several conventional high-speed fans, while still providing the same airflow, thus saving energy. The metric used for comparing HVLS fans to conventional fans is the airflow per Watt of fan power, in cubic feet per minute per watt (CFM/W). A conventional high-speed 48” fan could produce 29,000 CFM with a 1-hp motor (40 CFM/W), whereas a HVLS fan could produce 140,000 CFM with the same 1-hp motor (194 CFM/W). This comparison demonstrates how a single HVLS fan can replace several fans of similar total horsepower. Energy consumption also depends on the operating time and fan speed. Manufacturers of HVLS fans estimate that their cooling systems can save up to 30% to 70% of the energy used by conventional fans.
During the cooling season, HVLS fans provide comfort through the convective cooling effect when airflow comes into direct contact with human skin. This cooling effect allows occupants to perceive an ambient temperature reduction of 4-8°F, which can allow building operators to increase the temperature setpoint. For many of the HVLS manufacturers, this is the default mode of operation, sometimes called 'forward mode' or 'cooling mode.' During the heating season, HVLS fans “de-stratify” or mix warm air that is trapped near the ceiling, and circulate it down to occupant level. Heating savings occur due to reduction of the temperature gradient from floor to ceiling, allowing thermostats to sense higher temperatures and thus reduce heating unit runtime.
Energy Savings: 96%
Energy Savings Rating: Limited Assessment
What's this?
| Level | Status | Description |
| 1 | Concept not validated | Claims of energy savings may not be credible due to lack of documentation or validation by unbiased experts. |
| 2 | Concept validated: | An unbiased expert has validated efficiency concepts through technical review and calculations based on engineering principles. |
| 3 | Limited assessment | An unbiased expert has measured technology characteristics and factors of energy use through one or more tests in typical applications with a clear baseline. |
| 4 | Extensive assessment | Additional testing in relevant applications and environments has increased knowledge of performance across a broad range of products, applications, and system conditions. |
| 5 | Comprehensive analysis | Results of lab and field tests have been used to develop methods for reliable prediction of performance across the range of intended applications. |
| 6 | Approved measure | Protocols for technology application are established and approved. |
Simple Payback is one tool used to estimate the cost-effectiveness of a proposed investment, such as the investment in an energy efficient technology. Simple payback indicates how many years it will take for the initial investment to "pay itself back." The basic formula for calculating a simple payback is:
Simple Payback = Incremental First Cost / Annual Savings
The Incremental Cost is determined by subtracting the Baseline First Cost from the Measure First Cost.
For New Construction, the Baseline First Cost is the cost to purchase the standard practice technology. The Measure First Cost is the cost of the alternative, more energy efficienct technology. Installation costs are not included, as it is assumed that installation costs are approximately the same for the Baseline and the Emerging Technology.
For Retrofit scenarios, the Baseline First Cost is $0, since the baseline scenario is to leave the existing equipment in place. The Emerging Technology First Cost is the Measure First Cost plus Installation Cost (the cost of the replacement technology, plus the labor cost to install it). Retrofit scenarios generally have a higher First Cost and longer Simple Paybacks than New Construction scenarios.
Simple Paybacks are called "simple" because they do not include details such as the time value of money or inflation, and often do not include operations and maintenance (O&M) costs or end-of-life disposal costs. However, they can still provide a powerful tool for a quick assessment of a proposed measure. These paybacks are rough estimates based upon best available data, and should be treated with caution. For major financial decisions, it is suggested that a full Lifecycle Cost Analysis be performed which includes the unique details of your situation.
The energy savings estimates are based upon an electric rate of $.09/kWh, and are calculated by comparing the range of estimated energy savings to the baseline energy use. For most technologies, this results in "Typical," "Fast" and "Slow" payback estimates, corresponding with the "Typical," "High" and "Low" estimates of energy savings, respectively.