How Efficient Are 6–10 Ton Commercial Packaged Units in 2025? SEER2, EER, IEER & Energy Cost Breakdown

Commercial building owners always ask Tony the same question when shopping for a 6–10 ton packaged rooftop or ground-mounted HVAC unit:

“What’s the efficiency? What will this thing cost me to run?”

The problem?
Most people only look at SEER2, which barely scratches the surface for commercial HVAC efficiency.
Commercial equipment doesn’t behave like residential units. Cooling cycles are longer, ventilation loads are heavier, internal heat gains are higher, and staging is different.

A commercial system must be judged by SEER2, EER, and IEER — not one number.
If you understand what these mean, you’ll know EXACTLY how much a unit will cost you each month, whether an upgrade is worth it, and which performance ratings actually matter for your building type.

This is Tony’s no-BS deep dive into how efficiency is measured, how to interpret those numbers, and how much you should expect to pay in energy bills when running a 6–10 ton commercial packaged unit in 2025.

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1. First Rule: SEER2 Alone Does Not Define Commercial Efficiency

Residential units rely heavily on SEER2.
Commercial units? Not so much.

Commercial units run:

• longer cycles

• higher static pressure

• more ventilation

• more mixed-air conditions

• heavier internal heat load

This is why Tony says:

“SEER2 is nice. EER is honest. IEER tells the full story.”

If you judge a commercial system only on SEER2, you’re reading the wrong metric.

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2. SEER2 — Good for Basics, Not Enough for Commercial Loads

What SEER2 Measures:

Seasonal Energy Efficiency Ratio (version 2)
= cooling output across a full season divided by energy used.

It’s useful for:

• comparing base efficiency

• meeting minimum efficiency codes

• estimating average annual energy cost

Typical SEER2 ratings in 2025 for 6–10 ton units:

• 13.4 SEER2 (minimum compliant)

• 14.8–15.2 SEER2 (efficient)

• 16+ SEER2 (high efficiency, premium models)

SEER2 is based on varying temperatures and airflow but DOES NOT reflect:

• ventilation

• economizer use

• part-load operation

• high rooftop ambient temperatures

• real internal loads in commercial spaces

That’s why Tony uses SEER2 as a starting point, not the final metric.

*(Reference: [Commercial SEER2 Compliance & Efficiency Interpretation Guide])

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3. EER — The Most Honest “Peak Day” Efficiency Metric

EER (Energy Efficiency Ratio) measures efficiency at full load, at 95°F outdoor temperature, and at a fixed indoor temperature.

This is the metric Tony trusts most.

Why?
Because most commercial buildings run long cooling cycles during the hottest hours of the day — exactly the conditions EER simulates.

Typical EER for 6–10 ton units:

• Standard units: 10.0–11.2 EER

• High-efficiency models: 11.5–12.5 EER

• Premium models: 12.5–13.0+ EER

Why EER matters so much:

• shows “worst-case scenario” efficiency

• reveals performance under high rooftop heat

• tells you how the system handles heavy internal loads

• instantly predicts peak energy costs

SEER2 looks pretty in brochures.
EER tells you if the unit is actually strong.

*(Reference: [Commercial EER Rating])

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4. IEER — The Most Important Commercial Efficiency Rating of All

IEER = Integrated Energy Efficiency Ratio

It measures:

• part-load efficiency

• varying outdoor temps

• staging

• fan modulation

• economizer interaction

• real mixed-air scenarios

IEER is the most realistic commercial efficiency metric.

Typical IEER values for 2025:

• Standard: 13.5–15.0 IEER

• Efficient: 15.5–17.0 IEER

• High performance: 17.5–20.0 IEER

This is where high-end commercial units shine — especially units with:

• variable-speed compressors

• modulating outdoor fans

• advanced economizer systems

• multi-stage cooling

IEER is essential because commercial systems rarely run at 100% capacity all day.
Most of the time, they operate at 40–75% load, which IEER captures beautifully.

*(Reference: [Commercial IEER Part-Load Operation & Testing Protocol])

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5. How Internal Heat Load Changes Real Efficiency

Efficiency ratings give you a baseline, not a guarantee.
Your building load completely changes real operating cost.

Internal Loads That Increase Energy Use:

• high occupancy (gyms, restaurants, retail)

• big glass storefronts

• lighting intensity (track or halogen lights)

• computer/server heat

• kitchen equipment

• poor insulation

• sun-facing exterior

A 10-ton unit with good ratings can still struggle if:

• humidity is high

• fresh air intake is excessive

• ductwork is undersized

• heat load is underestimated

Commercial equipment MUST be matched to building behavior — not just square footage.

*(Reference: [Commercial Building Heat Load])

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6. Economizers & Ventilation Can Make or Break Efficiency

Tony always checks fresh air intake settings because ventilation load has a DIRECT impact on kWh usage.

When economizers save energy:

• mild outdoor temperatures

• dry conditions

• low humidity days

• spring and fall

• early mornings and evenings

When economizers destroy efficiency:

• humid climates

• polluted or dusty locations

• summer afternoons

• improperly calibrated sensors

• stuck dampers

Many buildings unknowingly run with fresh air dampers stuck open, pulling hot outdoor air inside and killing efficiency.

Tony tests:

• damper minimum position

• outdoor air sensors

• mixed-air temperature

• actuator response

IEER accounts for this. SEER2 does not.

*(Reference: [Commercial Ventilation & Economizer Energy Impact Guidelines])

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7. How Much Will a 6–10 Ton Commercial Unit Cost to Run? (Real Numbers)

Tony always breaks energy cost down based on:

• tonnage

• EER rating

• ventilation requirement

• operating hours

• climate zone

• rooftop temperature impact

Here’s what owners should expect.

Typical Daily Operating Cost at Full Load (95°F day)

Assuming $0.14/kWh and 10-ton capacity:

That’s $600–$900 per month depending on:

• climate

• internal loads

• operating hours

• staging

IEER further reduces costs during part-load operation.

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8. IEER Savings Breakdown — This Is Where Money is Actually Saved

A high IEER system may cost more upfront but saves a LOT more over time.

Example:

• 13 IEER “standard unit”

• 18 IEER high-efficiency unit

Assuming 2000 cooling hours:

• Standard: ~17,600 kWh/year

• High-efficiency: ~12,700 kWh/year

Savings:
~4,900 kWh/year
= ~$686 per year
= ~$6,800 over 10 years

This is why Tony tells owners:

“Don’t pick the unit with the lowest bid — pick the one with the lowest lifetime cost.”

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9. Climate Zone Changes EVERYTHING

Efficiency ratings must be matched to climate.

Hot & Dry (AZ, NV, NM, Inland CA)

→ EER matters most
→ rooftop temps extremely high
→ static pressure + ventilation = heavy load

Hot & Humid (FL, GA, TX Gulf Coast)

→ moisture removal load high
→ economizers often disabled
→ IEER becomes highly important

Mild West Coast (CA coastal, OR, WA)

→ economizers shine
→ high IEER = big savings
→ part-load cycles common

Mixed Climate (VA, TN, NC, MO)

→ SEER2 + IEER both matter
→ humidity + moderate temps

Tony ALWAYS looks at climate first.

*(Reference: [Commercial Climate Zone Efficiency Selection Guide])

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10. Dirty Coils, Bad Ductwork & High Static Pressure Kill Efficiency Completely

Even the highest-rated unit becomes inefficient if:

• coils are dirty

• duct leaks exceed 10%

• return air is undersized

• static pressure exceeds 0.6 in. w.c.

• economizer is stuck

• supply air temperature is too high

• building envelope is weak

Efficiency is NOT just an equipment rating.
It’s the sum of:

• installation

• airflow

• ventilation

• maintenance

• building design

The unit is just one piece of the system.

*(Reference: [Commercial HVAC Installation Quality])

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11. Tony’s Real-World Efficiency Recommendations (Straight Talk)

Here’s what Tony recommends for commercial buyers:

✔ For hot, brutal climates:

Pick the highest EER you can afford.
EER saves money on peak summer days when it matters most.

✔ For mild climates or coastal regions:

Pick the highest IEER you can afford.
You will save huge money on part-load performance.

✔ For humid climates:

Choose a unit with strong moisture removal
and good mixed-air control.

✔ For buildings with high heat load:

Prioritize EER + strong airflow design.

✔ For buildings with heavy ventilation requirements:

Focus on IEER + economizer efficiency.

✔ For long-run-hour buildings (gyms, restaurants, retail):

High IEER pays for itself faster than any other upgrade.

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Tony’s Final Verdict: SEER2 Is Just the Starting Line

Here’s Tony’s breakdown:

✔ SEER2 tells you basic seasonal efficiency

✔ EER tells you peak-day performance (most important in hot climates)

✔ IEER tells you real-world all-day efficiency (most important overall)

✔ Internal heat load and ventilation change everything

✔ Climate determines which rating matters most

✔ Installation quality determines whether ratings even matter

✔ Operating cost depends more on EER + IEER than SEER2

If you choose a commercial packaged unit based solely on SEER2, you’re missing the real picture.

Efficiency is a system, not a number.

Noise levels will be discussed in the next blog.