Why Refrigerant Matters More Than You Think for AC (or Heat Pump) Efficiency

The overlooked role of refrigerants in HVAC performance, costs, and emissions

Wherever you live, chances are you’re only a few feet away from a refrigerant-containing system — whether it’s a car, a building, a supermarket, or even a data center. Refrigerants are everywhere, working behind the scenes as invisible chemical compounds that enable comfort, preserve food and vaccines, and power digital infrastructure.

Yet despite their ubiquity, refrigerants are often overlooked. Most people don’t know what type their HVAC system uses, how much is required, or how leaks and errors can affect efficiency, costs, and the environment.

This article draws on insights from research to unpack this overlooked problem, examining why proper refrigerant levels matter and how even small refrigerant losses can impact a system’s performance and energy bills.

The hidden problem: low refrigerant charge

One of the most common issues in HVAC systems is when a system has less refrigerant than it was designed to operate with. Field studies show that both new and operational systems are frequently undercharged, often around 15 percent. But this isn’t just a symptom of aging equipment — it can happen on day one of system installation.

Most HVAC systems in the United States are charged on-site and different installation layouts require custom amounts of refrigerant. If a technician doesn’t adjust the charge to fit the specific setup, the system may be undercharged from the start, causing it to deliver subpar cooling and waste energy. One study of HVAC systems found 78 percent to be undercharged from installation, often because additional refrigerant wasn’t added to account for longer pipes.

Even correctly charged systems can leak as they age

As equipment ages, corrosion, vibration fatigue, and loose connections can create tiny pinholes in coils and joints. These small leaks often go unnoticed, but in the worst cases can cause ice to build up on the evaporator coil, blocking airflow, and eventually leading to equipment failure. The EPA estimates that on average, residential systems can leak refrigerants at around 5–11 percent per year.

Refrigerant loss decreases performance and increases operating costs

As refrigerant charge drops, performance declines. The system’s coefficient of performance (COP) — the ratio of useful cooling output to electrical energy input — begins to fall sharply, forcing the unit to run longer and consume more electricity to maintain the same comfort level.

The graph below illustrates the relationship between refrigerant charge and HVAC efficiency. Results vary by equipment type, size, and conditions, but the pattern is consistent: lower charge equals poorer performance. Even a 10 percent drop in refrigerant charge reduces system efficiency. In 2024, the average US household spent $719 on its summer cooling bill. A 10–20 percent efficiency loss could quietly add $72–$144 to that bill. One study shows that losing more than 20 percent of a system’s refrigerant charge marks a critical tipping point, causing steep performance drops. As refrigerant charge continues to decrease and the efficiency penalty grows, costs soar even higher.

In addition to efficiency loss, maintaining equipment — e.g. topping up refrigerants and scheduling service visits — costs time and money. And as supply for some of the most commonly used refrigerants, like R410A, becomes constrained in the future due to regulations, refrigerant price spikes could make topping up refrigerants a hefty burden on households.

The problem is cyclical: if leaks and other root causes aren’t addressed, efficiency losses can become recurring costs in the long run. And when condenser coils get dirty due to dust, debris, or poor upkeep, performance losses compound, leading to increased energy use, reduced cooling performance, and shorter equipment lifespan.

Efficiency loss strains grid infrastructure and creates pollution

When multiplied by millions of homes, this efficiency loss can put immense pressure on the grid. Millions of undercharged systems running harder in the summer or winter months translate into higher peak demand, straining the grid when it’s needed most. This additional electricity consumption then amplifies emissions.

Beyond straining the grid, refrigerant losses also carry a direct climate cost. The most common residential refrigerant in the United States today, R410A, has a Global Warming Potential (GWP) of about 2000 — meaning per pound of gas, it traps roughly 2000 times more heat in the atmosphere than CO₂. Since a typical home system holds 5–20 pounds of refrigerant, even a small leak can be equivalent to thousands of pounds of CO₂ emissions.

On a global scale, refrigerant emissions could add nearly 0.5°C of warming by 2050 if unmanaged. The Kigali Amendment and US AIM Act are pushing for an 85 percent reduction of Hydrofluorocarbons (HFCs) with high GWPs by 2036, but switching to lower GWP refrigerants won’t be enough alone — installation practices, maintenance protocols, and end-of-life recovery will all play a crucial role in meeting efficiency and climate goals and ensuring existing refrigerants don’t leak into the atmosphere.  

The good news: it’s fixable

If your HVAC system is running longer than usual but the indoor environment still feels stuffy, utility bills are climbing, or a technician keeps “topping off” refrigerant, these are likely signs of low charge or a hidden leak. Quick fixes like topping off may offer temporary relief, but without finding and repairing leaks, costs and energy waste will only grow over time.

Accurate refrigerant charging at installation and good user maintenance practices to catch leaks early can go a long way. While many homeowners rely on contractors for servicing, understanding the following key concepts can help you ask the right questions and keep your system performing well:

• Check the outdoor unit label to confirm what refrigerant your system uses. This affects how the system and its repairs are handled, especially as older refrigerants like R410A are phased down.
• Understand how charge levels are measured during installation or repair and whether they align with manufacturer specifications. An incorrect charge can lower efficiency and increase costs.
• If refrigerants are added, ask whether leaks were checked and fixed. Simply topping off without addressing the root cause can lead to recurring service calls and long-term inefficiencies.

Attention to these practices — by homeowners, contractors, and the broader HVAC industry — can help extend equipment life, lower emissions, and ensure comfort doesn’t come at an unnecessary cost.

 

The authors would like to thank the team at OTS R&D, Inc. for their contributions.