When you’re shopping for a through-the-wall air conditioner, one of the first things you’ll notice on product listings (besides BTUs and price) are the acronyms: EER, CEER, and sometimes even ENERGY STAR® certified.
They look technical — and they are — but understanding them can save you hundreds of dollars a year on your electric bill.
I’m Jake from The Furnace Outlet, and in this guide, I’ll walk you through exactly how to interpret efficiency ratings for wall AC units, how they impact your comfort and wallet, and what to look for when comparing brands like GE, Friedrich, and LG.
By the end, you’ll know how to:
✅ Understand EER vs. CEER (and when each matters)
✅ Identify ENERGY STAR-certified wall units that qualify for rebates
✅ Calculate your potential energy savings before you buy
Let’s jump in.
⚙️ 1. Efficiency Is the New Comfort
A through-the-wall air conditioner is a powerful and permanent way to cool a room — but just like cars, not all models are created equal when it comes to efficiency.
The higher your unit’s efficiency rating, the less electricity it uses to produce the same amount of cool air. That means:
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Lower monthly bills
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Less strain on the power grid
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Longer system lifespan
In other words, efficiency = comfort without waste.
According to Energy.gov, room and wall ACs account for nearly 10% of all U.S. home energy usage during summer months. Choosing a high-efficiency model can make a noticeable dent in your annual utility bill.
🔋 2. Why Efficiency Ratings Matter
Every air conditioner converts electricity into cool air — but not all do it equally well. Efficiency ratings are like the “miles per gallon” (MPG) rating on your car: they show how much cooling you get per unit of electricity.
If two ACs both deliver 10,000 BTUs of cooling power, but one has an efficiency rating 20% higher, it will consume roughly 20% less electricity to do the same job.
That difference adds up fast, especially in hot climates or during extended use.
“A more efficient wall unit doesn’t just save money — it runs quieter, lasts longer, and stays cooler under pressure.”
(Reference: Energy.gov – Room Air Conditioners)
📊 3. What Is EER (Energy Efficiency Ratio)?
Let’s start with the foundation: EER, or the Energy Efficiency Ratio.
📘 Definition:
EER measures how efficiently your AC converts electricity into cooling under standardized test conditions.
The equation looks like this:
EER = Cooling Output (BTUs per hour) ÷ Power Input (Watts)
In plain English: it tells you how many BTUs of cooling you get for every watt of electricity used.
🧠 Example:
A 10,000 BTU wall AC that draws 1,000 watts has an EER of:
10,000 ÷ 1,000 = 10.0
That’s a solid number — the higher, the better.
🧩 Why It Matters
EER is tested under fixed conditions (outdoor temp = 95°F, indoor temp = 80°F, 50% humidity). It’s a controlled, lab-style measurement that helps you compare models fairly.
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EER 9.0 → Standard performance
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EER 10.5–11.0 → Excellent (ENERGY STAR range)
The higher the EER, the more efficient and cost-effective the unit.
(Reference: ENERGY STAR Room AC Product Finder)
⚙️ 4. What Is CEER (Combined Energy Efficiency Ratio)?
EER is a great baseline, but it doesn’t tell the full story of real-world efficiency.
That’s where CEER — or Combined Energy Efficiency Ratio — comes in.
Introduced by the U.S. Department of Energy in 2014, CEER improves upon EER by factoring in standby and off-mode power consumption — the small but constant draw that happens even when your unit isn’t actively cooling.
🔍 CEER Formula:
CEER = Cooling Output ÷ (Active + Standby Power)
So if your unit is energy efficient when running but wastes electricity while idle, the CEER score will drop.
⚡ CEER vs. EER at a Glance
| Rating | Measures | Includes Standby Power? | Ideal Use |
|---|---|---|---|
| EER | Cooling efficiency under full load | ❌ No | Comparing models’ base performance |
| CEER | Cooling efficiency + standby energy | ✅ Yes | Real-world daily energy use |
For most homeowners, CEER is the better metric because it reflects actual usage.
(Reference: EnergyStar.gov – CEER Standards)
🌟 5. ENERGY STAR® Certification — What It Really Means
When you see the ENERGY STAR logo on a through-the-wall AC, it means it meets strict federal guidelines for energy performance set by the EPA and DOE.
ENERGY STAR models must have CEER values at least 10% higher than federal minimum standards.
💠 ENERGY STAR CEER Benchmarks (2025):
| Cooling Capacity (BTUs) | Minimum CEER for Certification | Typical Efficiency Gain |
|---|---|---|
| ≤ 8,000 | 10.0 | 15% improvement |
| 8,001–14,000 | 9.8–10.3 | 10–15% improvement |
| ≥ 14,001 | 9.4 | 8–10% improvement |
Beyond CEER, ENERGY STAR units also include smart features like:
✅ Eco Mode (cycles fan off when compressor rests)
✅ Sleep Mode (reduces speed gradually overnight)
✅ Inverter Compressors (variable-speed for precise cooling)
✅ Improved insulation to prevent energy loss
(Reference: ENERGY STAR Certified Room Air Conditioners)
🔍 6. EER vs. CEER vs. SEER2 — What’s the Difference?
If you’ve shopped for HVAC systems before, you’ve probably heard of SEER2 as well. Here’s how they all connect.
| Rating | Applies To | Includes Standby Power | Seasonal Measure? | Typical Range |
|---|---|---|---|---|
| EER | Window & Wall ACs | ❌ | ❌ | 8.5–11.5 |
| CEER | Wall & Room ACs | ✅ | ❌ | 9.0–11.5 |
| SEER2 | Central & Mini Split Systems | ✅ | ✅ | 13.4–22+ |
🔧 Simple Summary:
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EER = Efficiency snapshot under ideal test conditions
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CEER = EER + real-world energy usage
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SEER2 = Full-season efficiency (used for ducted or ductless systems)
(Reference: Energy.gov – SEER2 Standards Update)
⚡ 7. How Efficient Are Today’s Wall AC Units?
Through-the-wall ACs have improved dramatically in the last decade thanks to better refrigerants, smart sensors, and inverter technology.
Here’s how efficiency levels compare across common categories:
| Model Type | Typical CEER | Annual Energy Use (8,000 BTU) | Estimated Yearly Cost* |
|---|---|---|---|
| Basic Wall AC | 9.0 | 1,000 kWh | ~$150 |
| ENERGY STAR Model | 10.5–11.0 | 850 kWh | ~$120 |
| Inverter-Driven Smart Unit | 11.5–12.0+ | 750 kWh | ~$105 |
*Based on national average of $0.15/kWh electricity rate.
“That’s about $40–$50 a year saved — and over a 10-year lifespan, nearly $400 in energy savings.”
(Reference: Energy.gov – Calculating Appliance Energy Use)
🌿 8. Why Refrigerant Type (R-32 vs. R-410A) Affects Efficiency
One of the biggest efficiency changes in recent years comes from new refrigerant technology.
Most older through-the-wall ACs use R-410A, but many 2024–2025 models now use R-32, which is:
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12% more efficient at transferring heat
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Requires 20% less refrigerant per system
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Has 68% lower Global Warming Potential (GWP)
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Easier to recycle and maintain
R-32 units also typically score higher CEER ratings because they run at lower pressures, reducing compressor workload.
(Reference: EPA – Transitioning to Climate-Friendly Refrigerants)
💰 9. How Efficiency Impacts Your Wallet
Let’s put the numbers into perspective.
| Efficiency Level | CEER | Annual Energy Cost | Lifetime (10-Year) Cost | Savings vs. Base Model |
|---|---|---|---|---|
| Standard Wall AC | 9.0 | $150 | $1,500 | — |
| ENERGY STAR® Model | 10.7 | $120 | $1,200 | $300 |
| Inverter Model (R-32) | 11.5 | $110 | $1,100 | $400 |
While an ENERGY STAR or inverter-driven unit may cost $100–$200 more upfront, the long-term payoff makes it the smarter buy — especially when combined with tax credits or rebates.
🔍 10. Finding Your Unit’s Rating (Where to Look)
You can find the EER and CEER ratings for your through-the-wall air conditioner on:
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The yellow ENERGYGUIDE label (attached to the unit or box)
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Lists estimated yearly energy cost and CEER rating
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Manufacturer spec sheet (in product description)
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ENERGY STAR Product Finder online database
📘 Example Label Breakdown:
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Cooling Capacity: 10,000 BTU
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CEER: 10.7
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Estimated Annual Cost: $120
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ENERGY STAR Certified ✅
(Reference: Energy.gov – Room Air Conditioner Labeling)
🧰 11. Jake’s Quick Efficiency Checklist
Here’s how I help homeowners quickly identify efficient through-the-wall units:
| Step | What to Check | Ideal Target |
|---|---|---|
| 1️⃣ | CEER Rating | 10.0 or higher |
| 2️⃣ | ENERGY STAR Certification | Required for rebates |
| 3️⃣ | Refrigerant Type | Prefer R-32 |
| 4️⃣ | Smart Modes | ECO, Sleep, or Wi-Fi control |
| 5️⃣ | Estimated Annual Energy Cost | Under $130 for 8,000–10,000 BTUs |
If your current wall AC doesn’t meet at least three of these, you’re likely overpaying for power.
(Reference: EnergyStar.gov – Room Air Conditioner Efficiency Standards)
🔋 12. Tips to Boost Efficiency (Even Without Replacing)
Even if your unit’s a few years old, you can improve its performance with a few easy tweaks:
✅ Maintenance Habits:
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Clean or replace the air filter every month during summer.
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Keep the coils free of dust and lint.
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Ensure the wall sleeve has proper outward tilt for drainage.
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Check for gaps or leaks around the sleeve and seal them with weatherstripping.
🧠 Smart Usage:
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Set thermostat at 78°F for comfort and savings.
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Use Energy Saver mode during mild days.
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Close curtains during peak sun hours.
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Run a ceiling fan to help circulate cool air more evenly.
(Cross-link: Maintenance Tips to Keep Your Through-the-Wall AC Running Like New)
🌞 13. Rebates, Tax Credits & ENERGY STAR Perks
Did you know your efficient wall AC might qualify for federal or state rebates?
Under the Inflation Reduction Act (IRA), homeowners can claim up to 30% off qualified ENERGY STAR-certified systems, depending on income and efficiency tier.
Some utility providers also offer rebates of $50–$150 per unit when upgrading from older models.
To check eligibility:
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Enter your ZIP code
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Filter for “Room Air Conditioners”
(Reference: Energy.gov – Energy Efficiency Tax Credits)
⚙️ 14. Comparing Brands: LG vs. GE vs. Friedrich
Efficiency isn’t just about numbers — it’s also about engineering.
| Brand | Typical CEER Range | Strength | Best For |
|---|---|---|---|
| LG | 10.3–11.5 | Smart inverter technology, Wi-Fi control | Energy-conscious homes |
| GE | 9.8–10.7 | Reliable build, easy installation | Apartments & rentals |
| Friedrich | 10.5–11.8 | Commercial-grade design, quiet operation | Long-term homeowners |
Friedrich tends to dominate in durability and long-term efficiency, while LG leads in smart features that optimize cooling cycles automatically.
(Cross-link: “Top Through-the-Wall Air Conditioner Brands Compared: LG vs. GE vs. Friedrich”)
🧠 15. How to Calculate Real Savings
Want to estimate your own savings?
Use this quick formula:
Savings per Year = (Old CEER ÷ New CEER – 1) × Annual Energy Cost
Example:
If your old wall AC has CEER 9.0 and you’re replacing it with CEER 11.0:
(9.0 ÷ 11.0 – 1) × $150 = $27 saved per year
Multiply that by 10 years, and you’ve saved $270 — not including rebates or reduced maintenance.
(Reference: Energy.gov – Estimating Energy Use)
🏁 16. Jake’s Final Take
At the end of the day, EER and CEER ratings aren’t just numbers — they’re indicators of how efficiently your wall unit turns power into comfort.
“If you remember one thing from this guide, make it this: Look for CEER 10 or higher, ENERGY STAR certification, and R-32 refrigerant. Those three together guarantee comfort that’s efficient, affordable, and future-ready.”
Whether you’re upgrading an older system or comparing new models, efficiency ratings help you make decisions that pay you back — month after month.
In the next topic we will know more about: Is a Through-the-Wall AC Unit Right for Your Home? Pros, Cons & Common Use Cases
