Key Takeaways

• EER = run-time; CEER = all-day use. Look for EER ≥ 12, CEER ≥ 10.

• Only the top 10% of ACs meet ENERGY STAR® 5.0 (since Oct 2023).

• Inverter units save up to 40% and run quieter.

• Size AC to room—too big or small wastes energy.

• Use foam seals, clean filters, and smart plugs to cut bills.

Why Efficiency Counts for Window & TTW ACs

Picture a hot July afternoon in Phoenix: every room AC in the neighborhood is cranking at once. That peak demand spikes electricity prices and strains the grid. The same scene plays out from Miami to Milwaukee—U.S. room air-conditioners burn roughly $29 billion in power each year and dump over 100 million metric tons of CO₂ into the air. (energy.gov)
This guide dives into the energy efficiency of window and through-the-wall air conditioners—units popular in apartments, hotels, and retrofitted homes. You’ll learn how to read efficiency ratings, pick an ENERGY STAR® 5.0 model, size it correctly, and run it smarter. By the end, you can keep cool for less money and less carbon while staying within The Furnace Outlet brand’s U.S. focus on reliable, cost-effective comfort.

Explore ENERGY STAR® 5.0 Units

EER vs. CEER: Decoding the Numbers

Energy Efficiency Ratio (EER) is simply BTUs of cooling divided by the watts required when it’s 95 °F outside. Modern high-performance window units hit 9.9–15.7 EER, with GE Profile’s inverter models topping the chart. (pickhvac.com)
Combined EER (CEER) adds standby/off-mode watts to that same calculation, typically knocking 0.1–0.2 off the raw score but giving owners a realistic yearly view. (energystar.gov)

Rule of thumb: For every single point increase in EER, you can save about 10 % on cooling costs over the unit’s life.

Need a deeper dive? Our Highest-BTU Window AC guide breaks down rating tables by size and climate zone.

ENERGY STAR® 5.0: What Changed in 2023?

The Environmental Protection Agency tightened its Version 5.0 specification on October 30 2023, raising required CEER by 15-35 % depending on class. Any model shipped after that must meet the new bar to wear the label. (energystar.gov)

Why the shake-up? The agency wanted to push manufacturers toward inverter compressors, eco-friendlier R-32 refrigerant, and Wi-Fi controls that curb waste. Early adopter units—like those in our wide-window AC explainer—already meet or exceed the spec. When shopping, verify the yellow EnergyGuide tag lists CEER, not just EER, and double-check the manufacture date so you don’t pick up last year’s clearance model.

Inverter Compressors: The 40 % Saver

Traditional compressors are either full blast or off. Every restart pulls a surge of current and overshoots the thermostat setpoint. An inverter ramps smoothly—think of dimming a light instead of flicking it. Field studies on variable-speed scroll compressors show 10 – 40 % less cooling energy across a season, plus longer part life and softer noise. (aceee.org)

Yes, upfront cost is higher—often $60-$120 more—but payback comes in two to three summers for most U.S. electricity rates. For real-world picks, see our Best 6,000 BTU Window AC guide, where every top contender is inverter-driven.

Correct Sizing: Nailing the BTUs

A 7,000 BTU window unit may cool a 250 ft² bedroom, but drop that same model into a 450 ft² living room and it labors nonstop, guzzling watts. Overshoot the opposite way and you’ll feel cold but sticky because the compressor shuts off before it wrings out humidity.

Follow the Department of Energy sizing table (approx. 20 BTU per square foot, adjusted for shade, sun, and occupancy). For wall units, our room-by-room TTW sizing guide walks you through load math with plain examples. Add 10 % capacity for kitchens and subtract 10 % for shaded north-facing rooms.

Smart Controls & Schedules: Tiny Chips, Big Savings

Find Smart-Controlled Units

A plug-in smart outlet or built-in Wi-Fi board lets you:

• Program run times around school or work hours
  

• Track kWh in real time
  

• Geofence so the unit shuts off when you leave the bloc
  

Data from early ENERGY STAR® Connected Appliance pilots shows average 8-12 % savings just from better scheduling. Pairing with voice assistants keeps setup easy.

Curious how hotel managers automate dozens of PTACs? See our through-the-wall AC overview for commercial case studies you can copy at home.

Seal & Insulate: The $5 Fix

Even a top-tier 15 EER unit can leak cold air if the sleeve gap is the size of your thumb. Grab a roll of closed-cell backer rod and exterior-grade caulk:

1. Stuff the foam around the chassis.
   

2. Caulk both sides.
   

3. Add a light-duty storm panel in winter
   

Tests show this simple job knocks 10-15 % off seasonal energy use and stops rain intrusion that ruins drywall. For deeper envelope tips, cruise our master HVAC Tips blog hub.

Maintenance Checklist: Filters, Coils & Drains

Dirty filters raise fan power draw and freeze the evaporator coil. Spend five minutes each month to:

• Rinse or replace the filter
  

• Vacuum the coil fins with a brush attachment
  

• Flush the drain pan so algae doesn’t clog the outle
  

Annual pro service—often under $100—checks refrigerant charge and motor amps. According to field data, maintained room ACs retain up to 95 % of their nameplate efficiency over ten years, while neglected units can drop below 70 %.

Cut your cooling bills with smart, efficient tech in 2025.
Shop Energy-Saving AC Systems Now

Frequently Asked Questions

Q: Do I really need to tilt a window AC?
A: Yes—about ¼ inch per foot toward the exterior so condensate drains outside.

Q: Can I install a TTW unit in a brick wall?
A: Absolutely. Use a masonry bit, insert a corrosion-resistant sleeve, and seal all edges.

Q: How often should I clean the filter?
A: Every 30 days during heavy use; more often if you have pets or live near pollen sources.

Q: Is an inverter worth the extra money?
A: In most states, the energy it saves pays back the price difference in 2 to 3 years.

Q: What’s the easiest way to lower bills right now?
 A: Add a weather-strip around the chassis and set the thermostat to 78 °F when home.