HVAC Savings Calculator

What this calculator does

The calculator above is a screening tool. It estimates how much electricity a cooling system uses in a year, applies an improvement percentage that you choose, and converts the result into dollars, a simple payback period, and avoided greenhouse gas emissions. It is meant to answer one question quickly: is a project worth a closer look? It is not a substitute for measured results on your own equipment.

The math is deliberately simple:

• Baseline annual kWh = cooling capacity (tons) × equivalent full-load hours (EFLH) × efficiency (kW/ton)
• Annual kWh saved = baseline annual kWh × assumed % improvement
• Annual $ saved = kWh saved × electricity rate ($/kWh)
• Simple payback (years) = treatment or project cost ÷ annual $ saved
• Avoided tCO2e = kWh saved ÷ 1,000 × emission factor (lb CO2e/MWh) ÷ 2,204.62 lb per metric ton

For a deeper walk-through of each formula, including demand charges, see how to calculate HVAC energy savings.

The default values are placeholders

The calculator opens with example inputs so that it shows a result immediately. None of them describes your building. Replace each one before you rely on the output.

How to find each input

Cooling capacity (tons)

One ton of refrigeration equals 12,000 Btu per hour of cooling. Chillers usually list capacity in tons on the nameplate or submittal. Rooftop and split units often encode capacity in the model number in thousands of Btu per hour (MBH); divide MBH by 12 to get tons. A unit rated at 120 MBH is a 10-ton unit. Include only the equipment you are evaluating, and leave out standby units that rarely run, since they contribute little to annual consumption.

Equivalent full-load hours (EFLH)

Equipment rarely runs flat out. EFLH compresses a year of partial-load operation into the number of hours the system would need to run at full capacity to use the same energy. It depends on climate, building type, operating schedule, and how well the equipment is sized.

Published values give a sense of scale. Texas efficiency programs use deemed EFLH values by climate zone for residential central air conditioners and heat pumps; working-group notes prepared for the Public Utility Commission of Texas list 1,142 hours for Amarillo, 1,926 for Dallas, 2,209 for Houston, 2,958 for Corpus Christi, and 1,524 for El Paso. Commercial buildings differ: an office that runs weekdays may land below those figures, while a hospital, data room, or 24/7 process load can run far more hours. The absolute ceiling is 8,760 hours, the number of hours in a year.

The most reliable approach is to back EFLH out of your own data. If you can isolate cooling electricity from submetering or from the difference between summer and shoulder-season bills, divide annual cooling kWh by (tons × kW/ton). For example, 250,000 kWh ÷ (100 tons × 1.0 kW/ton) = 2,500 EFLH.

Current efficiency (kW/ton)

kW/ton is the electrical input, in kilowatts, needed to produce one ton of cooling. Lower is better. If your equipment is rated in EER (Btu of cooling per watt-hour), convert with kW/ton = 12 ÷ EER. An EER of 10 equals 1.2 kW/ton. For a fuller explanation of the metrics, see kW/ton, EER, SEER2 and COP explained.

Federal purchasing requirements give a floor for what new equipment achieves at rated conditions:

Three cautions apply. First, these are ratings for new equipment at standard test conditions. Older equipment, equipment with fouled heat-transfer surfaces, and equipment running in extreme heat can perform worse. Second, a chiller rating covers only the chiller; a whole-plant figure adds pumps and cooling-tower fans. One long-standing industry rule of thumb holds that a chilled-water plant running continuously above about 1.0 kW/ton is in need of improvement. Third, packaged-unit and chiller ratings are measured under different test procedures, so compare like with like. If a building automation system already trends kW and tons, use measured values instead of ratings.

Electricity rate ($/kWh)

Use the rate you would actually avoid paying for each kWh saved. On most commercial bills that is the energy charge plus any per-kWh riders and delivery charges, not the total bill divided by total kWh. The total-bill average blends in demand charges, which an energy-only calculation should not count. For context, the U.S. Energy Information Administration reports an average commercial-sector price of 8.47 cents per kWh in Texas for July 2026, against a U.S. average of 14.53 cents. Those are averages across all commercial customers and include all charges, so your own marginal rate can be higher or lower. Your retail electric provider contract or utility tariff sheet is the authoritative source.

Assumed % improvement

This is the input that moves the answer most, and it is the one you know least before a test. Treat it as a range rather than a point. Run the calculator at a low, middle, and high value; if the project only works at the high value, you need measured data before you commit. After a pilot, replace the assumption with the measured improvement.

Treatment or project cost

Enter the full installed cost from a written quote, including any monitoring you plan to install. If a utility incentive is likely, run the payback both with and without it, because incentives are usually paid only after savings are verified. Our guide to Texas utility commercial incentives lists 2026 programs.

Emission factor

The default is EPA's eGRID2023 total output emission rate for the ERCOT subregion: 736.6 lb CO2e per MWh. The U.S. average in the same table is 770.9 lb CO2e per MWh. If your site is outside ERCOT, use your eGRID subregion. eGRID also publishes non-baseload rates (1,247.5 lb CO2e/MWh for ERCOT), which some analysts use to approximate the emissions avoided by reducing demand on marginal generators. Use whichever factor your sustainability or reporting framework specifies; see Scope 2 emissions and HVAC for how location-based reporting works.

Worked illustration using the defaults

Illustration only. These are the placeholder inputs, not results from any building.

1. Baseline: 100 tons × 2,500 hours × 1.2 kW/ton = 300,000 kWh per year.
2. Savings at an assumed 10%: 300,000 × 0.10 = 30,000 kWh per year.
3. Dollars: 30,000 kWh × $0.11 = $3,300 per year.
4. Emissions: 30,000 kWh = 30 MWh; 30 × 736.6 lb = 22,098 lb; 22,098 ÷ 2,204.62 = about 10.0 metric tons CO2e per year.
5. Payback: project cost ÷ $3,300. A hypothetical $9,900 cost would pay back in 3.0 years.

Now change one input at a time. At 5% improvement the dollar savings halve to $1,650 and the payback doubles. At 3,500 EFLH, typical of longer cooling seasons or extended hours, the savings rise by 40%. This sensitivity check is the most useful thing the calculator can show you.

How to read the results

• Annual kWh saved is the quantity a utility custom program or an M&V report would try to verify.
• Annual $ saved reflects energy charges only. If the improvement also lowers your monthly peak, demand-charge savings come on top, but they need separate analysis.
• Simple payback ignores the time value of money and savings beyond the payback date. For a fuller picture, use net present value; see payback, ROI and NPV for HVAC projects.
• Avoided tCO2e is an estimate tied to the factor you chose. Report the factor and its source alongside the number.

What the calculator leaves out

Demand charges

Many commercial tariffs bill a separate charge per kW of peak demand. An NREL survey of more than 10,000 tariffs found that about 5 million of the roughly 18 million U.S. commercial customers can take service on rates with demand charges above $15 per kW. Lower kW/ton during the hottest afternoons can trim that peak, but whether it does depends on what else sets your peak and on ratchet clauses in your tariff. Leaving demand out keeps the calculator conservative.

Part-load operation

Equipment efficiency changes with load and outdoor conditions. That is why chiller ratings pair a full-load value with an integrated part-load value (IPLV), and why packaged units carry an IEER rating. A single kW/ton figure multiplied by EFLH is an approximation of a curve.

Weather and operations

A hotter summer raises consumption whether or not anything changed in the equipment. Occupancy changes, new loads, setpoint changes, and other projects can all mask or mimic savings. Before-and-after comparisons need to be adjusted for these factors; see baselines and weather normalization.

Interaction with other measures

If you also replace a compressor, add a variable-speed drive, or change controls in the same period, the calculator cannot separate the effects. Stagger projects or meter them separately.

Why on-site M&V is the real answer

A calculator multiplies assumptions. Measurement and verification replaces them with data. The International Performance Measurement and Verification Protocol (IPMVP), maintained by the Efficiency Valuation Organization, is the widely used framework. For a single system, an isolated approach is usually the most practical: meter power and capture the conditions that drive load (temperatures, flow, or run time) before and after the change, then compare under adjusted conditions. FEMP's M&V Guidelines Version 5.0, used for federal performance contracts, describe how to apply the same options in practice.

For a treatment such as CryogenX4, which the company describes as a one-time application installed while the system runs with no downtime, a short measured pilot on one to three representative units is a practical way to replace the % improvement input with your own number. See what a CryogenX4 pilot measures and IPMVP options explained.

Next step

Gather three things before you rerun the calculator: nameplate capacity for the units in question, twelve months of electric bills with the tariff sheet, and any trend data your building automation system already keeps. With those, the estimate becomes specific to your building, and you can decide whether a measured pilot is worth scheduling.