https://youtu.be/oqu5DjzOBF8 For the first time I actually understood what earth scale "greenhouse" effect is. The stupid name does so much damage.

Actual greenhouses - infrared escapes through the glass easily and heat losses are very high at night. To the extent that growers measure this with pyrgeo sensors and take actions to prevent it (closing thermal screens so that plants "see" the warm screen material instead of the -50C clear night sky.

They work by trapping warmed air (warmed either by sun or warmed by hot water pipes). Actual trapping works by greatly limiting air exchange. In fact, there is not enough air exchange capacity to even out inside temperature of an empty greenhouse and outside temperature on warm summer day. We rely on the moisture transpired by the plants to cool down the greenhouse. To achieve this we limit the air exchange - it may be 40C outside but it can be 31-33C inside.

We also enrich air with co2 to 1000ppm. Only way this affects the inside temperature is the effect it has on plant transpiration.