By: Jake Lawson, HVAC Insights Specialist
The times of year that HVAC equipment is in the highest demand will typically be the times that property owners naturally consider PTAC systems. Often the questions are whether a unit can keep a hotel room comfortable in the middle of a July heat wave or adequately warm during the coldest nights of January. These are valid concerns because occupant comfort during extreme weather conditions directly affects guest satisfaction, tenant retention and overall property performance. What gets far less attention, though, is the big chunk of calendar that lies between those extremes.
Spring and autumn are temperate weather periods in many locations, and heating and cooling needs can vary widely from day to day. These times are often referred to as shoulder seasons as they are in between the main heating and cooling seasons. While rarely the headlines for record temperatures, shoulder seasons are often among the most important months from an HVAC efficiency standpoint. Buildings still have to be conditioned, occupants still expect comfort and equipment still has to run every day. The difference is that the outside conditions are often ideal for technologies that can take advantage of moderate temperatures.
This is precisely where PTAC heat pumps tend to distinguish themselves from conventional electric PTAC units. A heat pump can often do a much more efficient job of heating in shoulder seasons since it’s moving heat, not creating it. While this efficiency advantage may not be apparent when comparing equipment specs, it can make a meaningful impact on utility costs and overall system performance over the course of months of operation. Long-term value is what hotels, apartment communities, senior housing facilities and commercial properties should be getting much more attention for shoulder-season performance than it usually does.
🔄 What Shoulder Seasons Mean for HVAC Systems
The HVAC industry talks about shoulder season quite a bit, but many property owners aren’t aware of just how much equipment is running during these times. Most climates have shoulder seasons in spring and autumn when outdoor temperatures are relatively mild but vary widely during the day. A morning might start in the forties, climb to the upper sixties in the afternoon, then cool off again after sunset. These shifting conditions create unique heating and cooling needs that are very distinct from those experienced in the middle of summer or winter.
Shoulder seasons for PTAC systems often involve rapid changes between times of heating needs and times where very little conditioning is required. Sometimes a hotel guest may want warmth in the early morning hours, and not need any by mid-afternoon. Residents of apartment buildings can lower temperatures overnight and enjoy rapid comfort at the start of their day. Senior living facilities and hospitals tend to have more stringent comfort standards regardless of the weather, so while demand for HVAC is more constant, it tends to be moderate demand spread evenly over the course of the day.
For these are periods of moderate, not extreme, temperatures, and the manner in which a system produces heat becomes increasingly important. Conventional electric PTACs still depend on resistance heat for heating requirements. However, PTAC heat pumps can take advantage of the good outdoor conditions in shoulder seasons. This difference in operation is one of the main reasons heat pumps tend to show their strongest efficiency advantage in these months.
⚡ Limited Shoulder-Season Benefits of Conventional Electric PTAC Units
For decades, traditional electric PTAC units have been the go-to for the hospitality and multifamily housing industries as they are reliable, relatively simple, and able to deliver dependable heating performance no matter what the outdoor temperature. When heat is required, electric resistance elements are switched on and generate heat that is distributed into the occupied space. The process is simple, predictable and effective.
The problem is that resistance heating does not become significantly more efficient simply because outdoor temperatures are moderate. So if it is 50 degrees outside or 20 degrees outside the system still uses electricity to make each unit of heat that is injected into the room. In the shoulder seasons the total heating demand is lower, but the way heat is produced is the same.
For individual rooms this difference may not seem significant. But property owners rarely operate a single PTAC unit. Hotels can have dozens or hundreds of guest rooms. Often, apartment communities contain many occupied units. PTAC systems are commonly used year-round in healthcare facilities, senior living properties, and institutional buildings. In such cases, the resistance heating effect can be cumulative and of considerable magnitude.
What’s interesting about the shoulder seasons is that outdoor temperatures are typically warm enough to allow the heat pump to run efficiently. Traditional electric PTAC units, which still generate heat through resistance elements, cannot take advantage of these favourable conditions. It gives heat pumps the chance to offer similar comfort levels while using less energy.
🌱 How PTAC Heat Pumps Benefit from Moderate Temperatures
The biggest advantage of a PTAC heat pump is that it moves heat instead of creating heat. As noted by the U.S. The U.S. Department of Energy states that heat pumps can deliver significantly more heating energy than they use in electrical energy because they move heat from one place to another, rather than producing it through resistance heating. The Department of Energy explains the science behind this process at https://www.energy.gov/energysaver/heat-pump-systems for property owners who want to learn more.
During the shoulder seasons, the outdoor air contains a large amount of usable heat energy. It may feel cool, but temperatures are often ideal for heat pump operation. Instead of running electric resistance elements when heat is needed, the heat pump takes heat out of the outside air and moves it into the building. Moving heat takes less energy than creating it , so the system can often keep you comfortable with less electricity .
This advantage in efficiency is most noticeable in the moderate weather that is typical of autumn and spring. Shoulder-season temperatures often allow the heat pump to perform just as it was intended to, with backup heat needed only on rare occasions in extreme winter weather. This gives property owners a chance to cut down on energy costs while still keeping occupants comfortable. The result is a system capable of delivering consistent performance while making better use of available energy resources.
🏨 The Hotels That Usually Gain the Most
One of the clearest examples of why shoulder-season efficiency is important is hotels. Many hospitality properties see great occupancy in spring and autumn travel but temperatures outside can swing dramatically during the day. Guests may want heat in the morning, no conditioning in the afternoon, and some additional comfort adjustments later in the evening. These shifting conditions generate an ongoing need for responsive HVAC performance.
From an operational perspective, every room you use has an energy cost. Small efficiency improvements can add up to a lot when applied across a property. An efficient PTAC heat pump can simultaneously reduce energy consumption in dozens or hundreds of guest rooms during shoulder seasons. In very cold weather supplemental heat may be necessary at times, but in moderate temperatures in the spring and autumn, the heat pump can provide most or all of the heat needed.
The benefit is more than utility costs. HVAC technology is usually not on guests’ minds. They think of convenience. Heat pumps are also able to respond efficiently to changes in the weather, helping to keep a more stable indoor environment. This is an opportunity for hotel operators to improve energy performance and guest satisfaction for a large part of the year.
🏢 Multi-Family Housing & Resident Comfort
Heat pumps can be just as beneficial for multifamily housing communities in the shoulder season as they are for hotels, which tend to receive the most focus in PTAC conversations. Apartment dwellers use their HVAC systems differently than hotel guests. They live with the system every day, instead of renting a room for a few days. Small comfort issues that are easy to overlook when you’re only in a hotel for a few nights can be nagging annoyances when you’re living there for the duration of a lease.
Shoulder seasons often create a unique comfort challenge in apartment communities, as residents have different schedules and different comfort preferences. One resident may leave for work in the early morning and turn down the thermostat before leaving. Another resident works from home and wants the temperature to be consistent throughout the day. The outdoor temperatures in the morning and afternoon can be quite different and thus the heating demand can change frequently. Conventional electric PTAC units provide heat using resistance elements in response to each of these heating requests. But PTAC heat pumps can often meet these modest heating needs by extracting the heat energy available in the outside air.
The benefit is more than just utility costs. One of the most important factors affecting retention and lease renewals is resident satisfaction. Property managers invest a considerable amount of money and effort in attracting and retaining residents, and comfort is a major factor in how occupants judge the quality of a property. A heating system that responds smoothly to changes and keeps the temperature constant provides a better living experience for the residents. Those incremental improvements in comfort can help to strengthen tenant satisfaction over time while reducing operating expenses.
🏘 Long-Term Stay Properties and Changing Occupancy Patterns
The extended-stay hotel exists in a strange in-between space, between conventional hospitality and residential housing. Guests often stay at the property for weeks or months instead of days, which creates different expectations for comfort and energy use. Occupants develop routines, set thermostats to their own schedules, and are more sensitive to the performance of HVAC than an average overnight guest.
These environments can be particularly challenging during the shoulder seasons when the outdoor temperature can swing wildly over the course of a day. Guests can leave in the morning when it’s cooler and come back in the warmer temperatures of the afternoon. Traditional electric PTAC systems rely on resistance heat whenever heat is required regardless of outside temperature. A heat pump, however, can take advantage of the mild weather often found in spring and autumn.
Extended-stay properties tend to have round-the-clock occupancy, so even small efficiency wins can really add up. In fact, a properly operating PTAC heat pump that serves dozens of occupied rooms for months at a time can lead to significant energy savings. And while they’re receiving that reliable comfort, they may not realise the HVAC system is working smarter behind the scenes. In many respects, that invisibility is the ultimate compliment to an HVAC system. People rarely think about the equipment that constantly keeps them comfortable.
Long-Term Energy Cost Difference (LT ECD)
One of the biggest mistakes that property owners make when evaluating HVAC systems is looking only at the initial cost of the equipment. The purchase price is certainly important, but HVAC equipment often remains in service for many years. Often, the operating costs during this period are higher than the investment in the original equipment. This is particularly true for properties with large numbers of PTAC units, where even small differences in efficiency can lead to significant cumulative savings.
This long-term perspective is even more critical in the shoulder seasons. In very cold winter weather, the efficiency edge of a heat pump can be reduced because supplemental heat is required periodically. However, shoulder seasons often provide outdoor temperatures that are ideal for efficient heat pump operation. The system is frequently able to supply most or all of the necessary heat without the use of electric resistance elements.
A wealth of research from the National Renewable Energy Laboratory (NREL) shows the potential efficiency of heat pump technologies under ideal operating conditions. Actual savings will vary with climate, occupancy patterns and building characteristics, but the principle is the same: it requires less energy to move heat than to create heat in most situations.
For owners managing operating budgets for multiple buildings or hundreds of rooms, the efficiency gains can add up year after year. What appears to be a small difference in one month can add up to a big benefit over the lifetime of the equipment.
🌎 Sustainability Goals and Contemporary Property Management
Energy efficiency is no longer just about saving on utility costs. Sustainability goals are increasingly being incorporated into long-term operational plans of hotels, apartment communities, healthcare facilities and commercial properties. Investors, residents, guests and regulatory agencies are all paying more attention to energy performance than they ever have before.
PTAC heat pumps meet these goals well because they are designed to use available energy more effectively. In shoulder seasons, when outdoor temperatures are suitable for efficient operation, heat pumps can greatly reduce the amount of electricity required to keep occupants comfortable. The Environmental Protection Agency’s ENERGY STAR program continues to highlight the role of heat pump technology in building energy performance. For more information, visit the ENERGY STAR resources at https://www.energystar.gov/products/heat_pumps.
One of the most compelling arguments for using heat pump technology for properties with sustainability initiatives is often the efficiency during shoulder seasons. Not only does the equipment help achieve energy reduction goals, it does so without sacrificing occupant comfort. In fact, the technology may never be seen by many of the occupants. They simply like a comfortable environment that is maintained more efficiently.
📈 Why Shoulder Seasons May Give You the Best Return on Investment
When people think about HVAC ROI, they typically think about the hottest days of summer or the coldest nights of winter. Those periods are important, but they only account for a small fraction of the annual operating hours. Shoulder seasons mean months of equipment operation, opening a large window of opportunity for efficiency improvements.
This is when the temperature outside is not too cold and not too hot . Heat pumps are often running in some of the best conditions they will see all year . The system can easily circulate heat, without the problems of a harsh winter climate. This is where the efficiency gap between a heat pump and a traditional electric resistance system can be especially stark.
This is why a lot of experienced property owners view shoulder season performance as an important part of the overall value proposition. The savings that spring and autumn bring may not be as dramatic as the comfort needs associated with extreme weather, but they do occur regularly and predictably year after year. The recurring benefits often can account for a large share of the return on investment during the life of the equipment.
For large hospitality properties, multifamily communities and commercial facilities, shoulder-season performance should be analysed with the same level of focus that is typically applied to peak heating and cooling capacities.
🔧 Jake Lawson’s Conclusion
One of the biggest mistakes I see property owners make is to evaluate HVAC equipment based on what happens during the most extreme weather. The peak performance in summer and winter is important, but that's not all there is to it. HVAC systems spend much of their operating life performing under moderate conditions and those conditions often reveal the true efficiency benefits of heat pump technology.
PTAC heat pumps shine in the shoulder seasons because they take advantage of something that traditional electric PTAC units can’t – the ability to move heat instead of generating heat. This ability allows the system to provide comfortable indoor conditions with less energy when the outdoor temperature is moderate. These efficiencies can translate into meaningful, long-term value whether the property is a hotel, apartment community, extended-stay facility, healthcare building or institutional property.
The choice to go with a conventional electric PTAC versus a PTAC heat pump should never be made on equipment specs alone. It should be based on how the building operates year-round. When shoulder-season performance is brought into the evaluation, the case for heat pump technology frequently becomes significantly stronger.
Jake Lawson
HVAC Insights Specialist
The Furnace Outlet
