A Note from Samantha
One of the most common things I hear from homeowners shopping for a new HVAC system is, “I want the most efficient air conditioner I can get.”
On the surface, that sounds like a smart approach. Who doesn’t want lower utility bills, better comfort, and equipment that can operate efficiently for years? It’s easy to understand why cooling efficiency often becomes the center of the conversation, especially when manufacturers promote impressive SEER2 ratings, potential energy savings, and advanced cooling technologies.
But for homeowners in colder climates, there is an important part of the efficiency equation that can easily be overlooked: heating efficiency.
In many northern areas of the United States and Canada, the heating system operates for significantly more hours each year than the air conditioner. An air conditioner may operate heavily for three or four months during the summer, while a furnace may run for six, seven, or even eight months during the heating season.
For example, a system such as this Goodman R-32 air conditioner and gas furnace package combines cooling and heating equipment into one matched system:
Goodman 2-Ton R-32 Air Conditioner & Gas Furnace System
That difference in operating hours matters. Even relatively small improvements in heating efficiency can add up over time when the equipment operates for thousands of hours each year.
In a cold-climate home, the furnace can account for a much larger share of annual heating and cooling energy use than the air conditioner. As a result, focusing only on the air conditioner's SEER2 rating may cause homeowners to overlook one of the biggest opportunities to reduce long-term HVAC operating costs.
The key takeaway: If you live in a colder climate, don't evaluate an HVAC system based on cooling efficiency alone. Look at the complete heating and cooling system, including both the air conditioner's SEER2 rating and the furnace's heating efficiency.
Understanding the relationship between climate, heating demand, equipment efficiency, and total energy consumption can help homeowners make better HVAC decisions. In some homes—particularly those in colder climates—the efficiency of the furnace may have a greater impact on annual energy costs than the efficiency of the air conditioner.
Why Climate Plays Such a Large Role in HVAC Costs
One of the biggest factors affecting HVAC operating costs is climate. The more frequently an HVAC system operates, the more its efficiency can influence overall energy consumption and utility costs.
In warmer parts of the United States, homes typically experience long cooling seasons and relatively mild winters. Air conditioners may operate for extended periods, making cooling efficiency an important consideration when evaluating annual energy use.
In colder regions, the situation can be very different. States such as Minnesota, Wisconsin, Michigan, North Dakota, Montana, Vermont, and Maine can experience long heating seasons and extended periods of freezing temperatures. Furnaces may operate regularly from fall through spring, including during both daytime and overnight hours. During particularly cold weather, a furnace may cycle frequently for extended periods to maintain comfortable indoor temperatures.
The U.S. Department of Energy provides extensive information about residential heating and cooling, energy efficiency, and ways to reduce household energy consumption.
Because heating systems in cold climates can operate for substantially more hours than air conditioners, heating may represent a larger share of annual HVAC energy use. In these situations, furnace efficiency can be one of the most important factors affecting long-term utility costs.
Put simply: the equipment that operates the most can have the greatest influence on your annual energy budget. That's why homeowners should evaluate HVAC efficiency based on their local climate and actual heating and cooling needs—not simply choose the highest cooling efficiency rating available.
Comparison Chart: Warm Climate vs Cold Climate HVAC Priorities
| Consideration | Warm Climate Home | Cold Climate Home |
|---|---|---|
| Cooling Season | ✅ Long | ⚠ Moderate |
| Heating Season | ⚠ Short | ✅ Long |
| Air Conditioner Runtime | ✅ High | ⚠ Moderate |
| Furnace Runtime | ⚠ Lower | ✅ Very High |
| Furnace Efficiency Importance | ⚠ Moderate | ✅ High |
| Cooling Efficiency Importance | ✅ High | ✅ Important |
This is one of the main reasons homeowners in colder regions should pay close attention to furnace efficiency when comparing replacement systems.
Understanding AFUE: The Furnace Efficiency Rating
When shopping for a new furnace, homeowners will often encounter a rating called AFUE, which stands for Annual Fuel Utilization Efficiency. AFUE measures how efficiently a furnace converts the fuel it consumes into useful heat over the course of a typical heating season. Trane — What Is AFUE?
For example, an 80% AFUE furnace converts approximately 80% of the fuel it consumes into usable heat, while the remaining energy is lost, primarily through the exhaust.
A 96% AFUE furnace converts approximately 96% of its fuel into useful heat, with roughly 4% lost.
At first glance, a difference of 16 percentage points may not sound dramatic. But consider how many hours a furnace can operate during a long, cold heating season. When the equipment runs for thousands of hours, even relatively small improvements in fuel efficiency can add up to meaningful differences in annual energy consumption and operating costs.
For homeowners in colder climates, AFUE can therefore be an important number to consider alongside the air conditioner's SEER2 rating when evaluating the overall efficiency of a new HVAC system.
Furnace Efficiency Comparison
| AFUE Rating | Heat Delivered to Home | Energy Lost |
| 80% AFUE | 80% | 20% |
| 90% AFUE | 90% | 10% |
| 96% AFUE | 96% | 4% |
| 98% AFUE | 98% | 2% |
ENERGY STAR provides additional information about high-efficiency heating and cooling equipment, including furnaces and other residential heating systems.
The longer and more demanding your heating season, the greater the potential impact of choosing a higher-efficiency furnace. This is why AFUE can be one of the most important specifications for homeowners in northern and colder climates when comparing new HVAC systems.
Why Heating Costs Often Exceed Cooling Costs
Homeowners sometimes assume that the air conditioner is responsible for most of their annual HVAC energy costs because they notice their electricity bills increase during the summer. However, in many colder regions, the heating system operates for significantly more hours throughout the year.
Consider a home in Minnesota. Outdoor temperatures can remain below freezing for extended periods during winter. The furnace may operate regularly in the morning, afternoon, evening, and overnight to maintain a comfortable indoor temperature. During particularly cold weather, it may cycle frequently for days or even weeks.
By comparison, the air conditioner may see its heaviest use during a much shorter cooling season, such as June through August.
In this situation, the furnace may simply do far more work over the course of the year than the air conditioner. As a result, improving furnace efficiency can potentially have a greater effect on annual HVAC operating costs than choosing a slightly more efficient air conditioner.
The U.S. Environmental Protection Agency (EPA) also notes that heating and cooling account for a significant share of residential energy use.
The important takeaway is that HVAC efficiency should always be considered in the context of your local climate and how often each piece of equipment operates. A homeowner in Minnesota may benefit from prioritizing furnace efficiency, while a homeowner in a hot southern climate may place greater emphasis on cooling efficiency.
This does not mean cooling efficiency should be ignored. Instead, homeowners should evaluate an HVAC investment based on how the equipment will actually be used in their particular climate, rather than focusing on a single efficiency rating.
The Hidden Advantages of High-Efficiency Furnaces
Most homeowners think of furnace efficiency primarily as a way to reduce fuel consumption and potentially lower heating costs. That is certainly an important benefit, but modern high-efficiency furnaces can offer advantages that go beyond energy savings.
Many newer furnaces are available with technologies such as advanced blower motors, multi-stage heating, and variable-speed operation. These features can help the system adjust its output more closely to the home's heating needs while providing more consistent airflow.
Instead of operating at full capacity whenever heat is needed, a multi-stage or variable-capacity furnace can often operate at a lower output for longer periods when conditions allow. This can help maintain more consistent indoor temperatures and reduce the noticeable temperature swings associated with traditional single-stage operation.
The result can be a more comfortable and balanced indoor environment, with fewer hot and cold spots, steadier temperatures, and more consistent airflow throughout the home.
For homeowners, this is an important distinction: a high-efficiency furnace isn't simply about the number printed on the AFUE label. The technology behind the equipment can also influence comfort, airflow, noise levels, and how consistently the system responds to changing heating demands.
Potential Comfort Benefits of a High-Efficiency Furnace
Depending on the equipment design and features, a modern high-efficiency furnace may provide several comfort-related benefits, including:
- 🔥 More consistent indoor temperatures
- 🔥 Reduced temperature swings
- 🔥 More consistent airflow
- 🔥 Quieter operation
- 🔥 Better humidity control when paired with appropriate HVAC equipment
- 🔥 Improved overall indoor comfort
For many homeowners, these comfort improvements can be just as valuable as potential energy savings. A system that maintains a more consistent temperature and distributes air more evenly can make a noticeable difference in how comfortable the home feels throughout the heating season.
Why Air Conditioner Efficiency Still Matters
While furnace efficiency is particularly important in colder climates, homeowners should not overlook air conditioner efficiency.
Cooling efficiency remains an important consideration for both comfort and operating costs, particularly in regions with long, hot summers. SEER2 is one of the efficiency ratings used to evaluate the seasonal performance of residential air conditioning equipment. In general, a higher SEER2 rating indicates greater cooling efficiency under the conditions used for the rating.
For homeowners in hot climates, cooling equipment may operate for much longer periods during the year, making SEER2 an especially important consideration. In colder climates, however, the furnace may operate for substantially more hours, making AFUE a more influential factor in annual heating energy use.
The key is to determine which part of your HVAC system does the most work in your particular climate.
Which Efficiency Rating Matters More?
| Climate Example | Rating That May Deserve More Attention |
|---|---|
| Florida | SEER2 |
| Texas | SEER2 |
| Arizona | SEER2 |
| Michigan | AFUE |
| Minnesota | AFUE |
| Maine | AFUE |
This is a general guideline rather than a strict rule. Local weather, home insulation, system sizing, thermostat settings, energy prices, and individual household usage can all affect actual operating costs.
The best HVAC investment is one that balances both heating and cooling efficiency according to the demands of your climate and your home.
ASHRAE provides valuable information on indoor environmental quality, HVAC performance, and industry standards.
While furnace efficiency is an important part of the HVAC decision, homeowners should not overlook air conditioner efficiency—or other factors that can have an equally significant impact on system performance.
Proper Sizing Is Just as Important as Efficiency
It is easy to assume that buying the highest-efficiency furnace available will automatically deliver the best performance. In reality, even a highly efficient furnace can perform poorly if it is not properly sized for the home.
An oversized furnace may reach the thermostat setting too quickly and cycle on and off more frequently than necessary. This can contribute to temperature fluctuations, reduced comfort, and less efficient operation.
An undersized furnace has the opposite problem. During extremely cold weather, it may struggle to keep up with the home's heating demand and maintain the desired indoor temperature.
This is why proper equipment sizing is just as important as the efficiency rating.
A qualified HVAC professional should evaluate the home's heating and cooling loads rather than simply selecting equipment based on the size of the existing system. Factors such as the home's square footage, insulation, windows, orientation, local climate, air leakage, and other building characteristics can all affect the required equipment capacity.
Air Conditioning Contractors of America (ACCA) — Manual J Guidance provides industry guidance on Manual J load calculations, which are used to determine the heating and cooling requirements of a home.
The takeaway is simple: efficiency and capacity need to work together. A properly sized, well-installed system can provide better comfort and more consistent performance than an oversized or undersized system, even when the latter has a higher efficiency rating.
What Goes Into Proper HVAC Sizing?
A professional HVAC sizing assessment takes several characteristics of the home and its surroundings into account, including:
- 🏠 Home size and layout
- 🪟 Window size, location, and type
- ☀️ Local climate and outdoor conditions
- 🏡 Insulation levels
- 🚪 Air leakage and infiltration
- 👨👩👧 Number of occupants
Other factors, such as ceiling height, orientation, building materials, and internal heat gains from appliances and lighting, may also influence the calculation.
Without proper sizing, homeowners may not experience the full benefits of even a highly efficient HVAC system. The right equipment needs to match the actual heating and cooling requirements of the home.
The Often-Overlooked Role of Ductwork
Ductwork is another important part of HVAC performance that homeowners often overlook. Even a highly efficient furnace cannot deliver its full potential if conditioned air cannot move effectively throughout the home.
Leaky ducts, restricted airflow, poor balancing, undersized ducts, and inadequate return-air pathways can all reduce comfort and increase energy consumption. In some homes, ductwork problems can have a greater effect on comfort than the difference between two equipment efficiency ratings.
Common Ductwork Problems
- 🔧 Air leakage – Conditioned air escapes before reaching the rooms where it is needed.
- 🔧 Restricted airflow – Blockages or undersized ducts can limit the amount of air the system can move.
- 🔧 Poor balancing – Some rooms may receive too much air while others receive too little.
- 🔧 Undersized ductwork – Ducts that are too small can increase resistance and reduce airflow.
- 🔧 Blocked or inadequate returns – Poor return-air pathways can make it harder for the system to circulate air effectively.
Because most ductwork is hidden behind walls, ceilings, floors, or in attics and crawl spaces, homeowners may not think about it when replacing an HVAC system. However, a qualified contractor should consider the condition and design of the duct system as part of a comprehensive replacement evaluation.
A highly efficient furnace paired with poorly designed or leaky ductwork may not deliver the comfort or energy performance homeowners expect.
Think Beyond the Purchase Price
When comparing HVAC systems, it is easy to focus on the initial installation cost. Budget is certainly important, but homeowners should also consider the system's total cost of ownership.
The least expensive system to purchase is not necessarily the least expensive system to own. A higher-efficiency furnace may consume less fuel over its operating life, potentially helping offset a higher upfront investment. Depending on the equipment, homeowners may also gain access to features such as variable-speed operation, advanced controls, improved comfort, and enhanced system monitoring.
Initial Cost vs. Long-Term Value
| Consideration | Lower-Efficiency Furnace | Higher-Efficiency Furnace |
|---|---|---|
| Initial Cost | ✅ Typically lower | ⚠ Typically higher |
| Fuel Consumption | ⚠ Generally higher | ✅ Generally lower |
| Comfort Features | ⚠ May be more basic | ✅ Often more advanced |
| Operating Costs | ⚠ Potentially higher | ✅ Potentially lower |
| Long-Term Value | ⚠ Depends on usage and energy prices | ✅ May be stronger over time |
The actual financial benefit of a higher-efficiency furnace depends on factors such as climate, annual heating demand, fuel prices, equipment efficiency, installation quality, and how long you plan to own the system.
Looking at HVAC equipment through the lens of total ownership cost—not just the installation price—can give homeowners a much clearer picture of the value they are getting from their investment.
Homeowner Furnace Efficiency Checklist
Questions to Ask Your HVAC Contractor
Before approving a replacement HVAC system, consider asking your contractor these questions:
- ✔ What is the furnace's AFUE rating?
- ✔ Was a Manual J load calculation performed for my home?
- ✔ Is the complete system AHRI certified?
- ✔ Will my existing ductwork be evaluated?
- ✔ How significant is my home's heating demand based on the local climate?
- ✔ What operating cost differences might I expect between the equipment options?
- ✔ What comfort and control features are included?
- ✔ How will airflow and system performance be verified after installation?
The answers can help homeowners compare more than just equipment prices and efficiency ratings. They can also provide a better understanding of how the system is designed, installed, and expected to perform in the home.
Final Thoughts
When homeowners think about HVAC efficiency, air conditioners often get most of the attention. However, in colder climates, the furnace may operate for substantially more hours each year than the cooling system. Longer heating seasons and greater heating demand can make furnace efficiency an especially important factor in annual fuel consumption and operating costs.
That doesn't mean cooling efficiency should be ignored. Instead, homeowners should evaluate HVAC efficiency in the context of their local climate and how their system will actually be used. For many homes in northern climates, investing in a higher-efficiency furnace may provide greater long-term value than focusing on SEER2 ratings alone.
Ultimately, the best HVAC decisions involve the entire system, not a single specification. Proper sizing, professional installation, effective ductwork, appropriate airflow, comfort features, reliability, maintenance, and equipment efficiency all contribute to long-term performance.
By looking beyond cooling efficiency and giving appropriate attention to furnace efficiency, homeowners can make a more informed HVAC investment—one that is designed to provide reliable comfort, efficient operation, and long-term value for years to come.
Samantha Reyes
The Smart Shopper
Factory Furnace Outlet
Next Blog: The Hidden Benefits of Variable-Speed Blowers Even with Single-Stage Equipment