How HVAC Right-Size Works

Your Thermostat Knows the Truth

Instead of guessing how much heating or cooling your home needs, we look at what actually happened. Your thermostat tracks exactly how long your system ran each day. On the hottest and coldest days, this tells us exactly how hard your system had to work.

Simple Math, Powerful Results

Here's an example: If your 3-ton air conditioner runs half the time (50%) on the hottest day while keeping you comfortable, you really only need about 1.5 tons of cooling. It's like finding out your car's engine is twice as big as you need for your daily driving.

What We Analyze

• We look at the extreme 10% of your temperature data — the hottest days for cooling, coldest for heating
• We calculate how long your system ran during those conditions
• We multiply your system's capacity by the runtime percentage to find the actual load
• We add a 20% safety factor to recommend the right size

Benefits of Getting the Size Right

• More Comfortable: Steady temperatures with better humidity control
• Lower Energy Bills: Right-sized systems use less electricity and gas
• Equipment Lasts Longer: Less cycling means less wear and tear
• Save Money: Buy only what you need and pay less to run it

What Data Do You Need?

Export your runtime data from your Ecobee thermostat as CSV files. Go to ecobee.com → Home IQ → Download Data and select monthly exports.

The more data you share, the better the recommendation. Ideally, upload a full year so we can see both summer and winter performance. But even a few months during the hottest or coldest season can give you valuable insights.

Your Privacy

All analysis happens right in your browser. Your data is never sent to any server. It's stored locally on your device so you can come back and re-analyze without re-uploading.