Thermal Management Calculator

Everything running in a grow room turns electricity into heat — the lights most of all. This tool adds up that heat plus the heat leaking in through the walls and roof, and tells you how much cooling and airflow you need to hold your target temperature. "BTU/hr" is a rate of heat; a "ton" of cooling is just an air-conditioner size (1 ton = 12,000 BTU/hr); "CFM" (cubic feet per minute) is how much air your fans need to move.

When sizing or sanity-checking the HVAC for any indoor grow room or greenhouse — planning a build, adding lights, or diagnosing why a room runs hot. Applies to any crop; it is about the room, not the plant. Do it before you buy a cooling unit so you do not undersize it.

Total Heat Load is the heat you must remove; Required Cooling converts that to tons (round UP when buying — a 4.3-ton load needs a 5-ton unit). Required Airflow is the fan capacity to carry that heat away at a 20°F supply-air difference. Heat from Lights vs Envelope Heat Gain shows where the load comes from: if lights dominate (they usually do), better insulation barely helps and you are cooling-bound; if Envelope Heat Gain is large, adding R-value or shade pays off. Improve insulation or ambient conditions and re-run to see the load drop.