With three-foot snow drifts still lining parking lots across Massachusetts, many commercial heating systems have been running around the clock. Add to that weeks of sub-freezing temperatures, many facility managers are reviewing heating runtime data and noticing longer operating hours than last year.
For nearly two decades, Harold Brothers Mechanical Contractors has helped commercial facility managers and building owners identify inefficiencies in their HVAC systems. With 17+ years in business and hundreds of customers served, we’ve seen firsthand how small operational adjustments can lead to major cost savings.
In this article, you’ll learn how strategies like variable frequency drives (VFDs), setpoint resets, optimized scheduling, and demand limiting can reduce energy consumption, without sacrificing occupant comfort or system reliability.
Runtime hours measure how long a piece of HVAC equipment is operating during a given period.
When runtime increases year over year, it usually means one of three things: the building load has increased, the system efficiency has decreased, or the control strategy has changed.
The goal is to determine which of those factors is driving the change in your building.
One of the biggest drivers of longer runtime is increased outdoor air.
Over the past several years, many commercial buildings adjusted ventilation settings to improve indoor air quality. That often meant bringing in more outside air than before.
The system now has to heat that air in the winter and cool and dehumidify it in the summer. Even if occupants feel the same level of comfort, the equipment may be conditioning significantly more air than it did last year.
If ventilation settings were adjusted but never re-optimized, runtime hours will increase.
Commercial HVAC systems rarely fail overnight. They gradually lose efficiency.
As systems age, you may see:
The equipment still operates. But it must run longer to produce the same heating or cooling output.
A chiller that once satisfied the load in six hours may now need seven or eight. Nothing feels broken, but runtime data shows the difference.
Control strategies evolve over time.
New tenants move in. Operating hours shift. Temporary overrides get left in place. Morning warm-up schedules start earlier than they used to.
Even small changes, like tightening temperature deadbands or lowering supply air temperatures, can significantly increase runtime. Because these adjustments often happen gradually, they rarely trigger alarms. They simply extend equipment operation little by little.
Over the course of a year, those small changes add up.
Simultaneous heating and cooling is one of the most expensive and overlooked causes of extended runtime.
In some buildings, the central system cools air while terminal units reheat it to maintain zone comfort. The building feels stable, but the system is working against itself.
You may notice boilers running during mild weather or pumps operating continuously even when demand appears low. When this happens, runtime increases dramatically because multiple systems are active at the same time.
Sometimes the HVAC system is operating exactly as designed. The building itself has changed.
Additional occupants, new office layouts, extended operating hours, added equipment, or expanded data loads all increase internal heat gain. Even lighting upgrades can alter heat balance in ways that affect system performance.
If the building load increases but the control sequence does not adapt, runtime rises in order to maintain comfort.
Preventive maintenance directly affects how long equipment must operate to meet demand.
Dirty filters restrict airflow. Fouled coils reduce heat transfer. Dampers stick. Actuators fail to modulate properly.
When efficiency drops, runtime increases. In many cases, longer runtime hours are the first measurable indicator that maintenance adjustments are needed.
Comfort is what occupants feel. Runtime is how hard the equipment works to achieve that comfort.
A building can hold 72 degrees consistently while equipment operates 15 to 20 percent longer than it did the previous year. That difference may not show up in complaints, but it will show up in energy bills, wear on components, and long-term equipment life.
Runtime is often the earliest warning sign that something has shifted.
If you are seeing longer runtime hours, the solution is not guessing. It requires a structured review.
Start by:
The goal is to determine whether the increase is driven by load changes, efficiency loss, or control strategy adjustments. Each cause requires a different solution.
Energy reduction in commercial HVAC systems isn’t about replacing everything, it’s about optimizing what you already have. With the right adjustments, your system can operate more efficiently while maintaining performance.
If you’re dealing with rising utility costs, aging equipment, or inconsistent comfort levels, those aren’t just annoyances, they’re signs your system may not be running as efficiently as it could.
To understand exactly how these strategies work and when they make sense for your facility, your next step is to read our guide on commercial HVAC energy reduction strategies. It breaks down VFDs, setpoint resets, scheduling optimization, and demand limiting so you can evaluate what’s right for your building.
For nearly 20 years, Harold Brothers Mechanical Contractors has helped commercial properties improve HVAC performance, reduce energy waste, and extend equipment life. If you’re ready to explore what smarter system optimization could look like for your facility, our team is here to help.