Glossary · Heating, cooling & ventilation
Variable-speed (inverter) compressor
Also called: variable-speed compressor · inverter compressor · inverter-driven · variable-capacity
A compressor that ramps its speed up and down to match the heating or cooling needed, instead of switching fully on and off.
What it means
An inverter drive lets the compressor run slowly for long periods in mild weather and speed up when it's very cold or hot. This avoids short cycling, keeps temperatures steadier and helps cold-climate heat pumps keep capacity in deep cold. Two-stage units are a simpler middle ground.
Why it matters in an audit
NEEP's current cold-climate specification requires variable capacity, so it's a quick marker of a heat pump built for cold weather.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| NEEP ccASHP v4.0 | Requires a variable-capacity compressor (more than three distinct operating speeds); the v5.0 proposal would drop this as a prescriptive rule | neep.org ↗ |