“The vast majority of U.S. offices utilizes constant speed HVAC systems to heat and cool these occupied spaces. Whether we’re talking about large commercial office buildings using chillers and boilers or low-rise office suites with rooftop units, these systems are by and large fixed speed, meaning they operate at either 100% or 0% capacity with no in-between. In this scenario, these systems turn on when the condition the space to thermostat’s set point and click off when that set point is reached. When the system is off there is no air flow occurring.
This approach worked in the pre-pandemic world because offices were mostly full and ventilating beyond what building codes required was unnecessary. In the middle of a pandemic, however, it presents problems. These constant volume systems are designed to heat and cool during the hottest and coldest days of the year, which occur roughly 2% of the time. The other 98% of the time, the system is oversized. Bringing more outside air into the building, which then needs to be heated or cooled, drives up system usage and utility bills. Not to mention that this oversized system is operating more than usual to condition outside air and ventilate the building for only a handful of people. In this context it makes sense that even as office occupancies cratered by 70% or more in 2020, energy use in those offices had decreased by just under 25% (according to at least one April 2020 snapshot of energy use in offices across the U.S.).”
Read more about the differences in HVAC systems here.
Variable-speed HVAC systems typically have the ability to run between 20% and 100% capacity. This feature allows the demand of the building to be met without unnecessary waste. It also means that there is a steady flow of air at any given time unlike the on/off method of constant speed HVAC systems. Building managers using variable-speed systems can choose to ramp up or wind down climate settings as they see fit.
Temperature Control Specialties offers variable-speed HVAC systems for purchase and installation to businesses and homeowners. Check out our services page to learn more or call us at (317) 247-7663 with any questions.