What SEER Ratings Mean and Why They Matter for Your Heating and Cooling System

December 2, 2025

What SEER Ratings Mean and Why They Matter

If you're in the market for a new air conditioning or cooling system, you've probably come across the term SEER rating. SEER stands for Seasonal Energy Efficiency Ratio, and it's one of the most important factors to consider when choosing a system for your home. A higher SEER rating means greater efficiency—and that translates into lower utility bills and better overall performance. At Modern Heating & Plumbing Co. in Gurnee, IL, we help homeowners understand SEER ratings so they can make informed, cost-effective decisions.


Choosing the right SEER-rated system can significantly affect your home's energy use, comfort levels, and long-term savings. Here’s what you need to know about what SEER ratings are and why they should matter to you.

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What Is a SEER Rating?

A SEER rating measures how efficiently a cooling system operates over an entire season. It’s calculated by dividing the total cooling output (in BTUs) by the total energy consumed (in watt-hours). The higher the SEER number, the more efficiently the unit cools your home. For example, a system with a SEER rating of 18 is significantly more efficient than one with a rating of 13.

  • SEER = Seasonal Energy Efficiency Ratio
  • Measures cooling efficiency over an entire season
  • Higher SEER = lower energy usage and better performance
  • Required minimum SEER ratings vary by region

Why SEER Ratings Matter for Homeowners

The SEER rating directly impacts your monthly energy bills. High-SEER systems use less electricity to cool your home, which means you spend less over time. In addition, efficient systems reduce wear and tear, helping them last longer and operate more quietly. If you're replacing an older system, upgrading to a higher SEER model can provide substantial energy savings.

  • Reduces long-term cooling costs
  • Lowers energy usage and environmental impact
  • Improves indoor comfort and system longevity
  • May qualify for energy rebates or tax incentives
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What's a Good SEER Rating?

The minimum required SEER rating varies by state and climate zone. In Illinois, the current standard is SEER 14 or higher for new systems. However, many homeowners opt for systems rated between 16 and 20 to achieve better efficiency and comfort. While higher-rated systems cost more upfront, the added efficiency can pay off in utility savings within just a few years.

  • Minimum SEER in Illinois is 14
  • SEER 16–20 systems offer superior energy savings
  • Ideal SEER depends on budget, usage, and home size
  • Higher SEER = higher initial cost but lower operating costs

SEER vs. Other Efficiency Ratings

SEER is specific to cooling systems, but it's not the only rating to consider. Furnaces, for example, are rated by AFUE (Annual Fuel Utilization Efficiency). While SEER measures seasonal cooling efficiency, AFUE measures how efficiently a furnace converts fuel to heat. Both ratings help homeowners compare systems based on energy performance.

  • SEER applies to cooling systems
  • AFUE is used for furnace efficiency
  • Understanding both helps with full-system efficiency decisions
  • Helps you select the right balance of comfort and savings
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When to Upgrade Based on SEER

If your system is over 10–15 years old and has a low SEER rating, it may be costing you more than you think. Older units often operate at SEER levels below today’s minimum standards. Upgrading to a newer, higher-rated system can immediately improve comfort, reduce monthly bills, and offer peace of mind with updated warranty protection.

  • Older systems often have SEER ratings under 10
  • Newer systems offer significant performance upgrades
  • Upgrades reduce energy waste and increase reliability
  • Consider replacement if facing frequent repairs and high bills

Why Choose Modern Heating & Plumbing Co.?

Modern Heating & Plumbing Co. offers expert guidance in selecting high-efficiency systems with optimal SEER ratings for your home. We assess your property, comfort needs, and budget to recommend the most effective solution. From professional installation to routine maintenance, our team ensures you get the most from your investment. Serving Gurnee and nearby communities, we deliver reliable, honest service backed by years of experience. When you’re ready to upgrade, trust us to help you save energy and stay comfortable year-round.

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