The U-value represents the rate of heat transfer through a material. A lower U-value means better insulation and less heat loss. This calculator uses typical U-values for common greenhouse materials.

Does this account for air leaks?

This calculation is for heat loss through the surface material. It does not account for heat loss from air infiltration (leaks). A well-sealed greenhouse will be more efficient. Consider increasing the result by 10-20% to account for minor leaks.

What size heater do I need?

Choose a heater with a BTU rating that is equal to or slightly higher than the calculated requirement. It's better to have a slightly oversized heater that cycles off than an undersized one that runs constantly and can't keep up.

Greenhouse Heating Calculator

Estimate the heating requirement (BTU) for your greenhouse.

Frequently Asked Questions

Embed this Calculator

Want to use this calculator on your own website? Copy the code below to embed it anywhere.

Greenhouse Heating Calculator

Frequently Asked Questions

What is a U-value?

Does this account for air leaks?

What size heater do I need?

Embed this Calculator