>>2051767>Like I get that they amplify sunlight Greenhouses and tunnels don't amplify the light. If anything, the intensity and uniformity of light in them can be lower than the outdoors because the glazing material won't allow all light to enter, the structure produces shadows and the orientation of the structure (north/south vs east/west).
>but like how do you retain heat on cloudy/shitty winter days?To start make sure it is well sealed. You won't need as much heating as you think though. On a cold but sunny March day you may need to vent it to prevent it from becoming hot. If you really need heat, do not use a fuel burning heater that does not have any exhaust venting like pic related. Ethylene is released and that gas can cause ethylene damage to your plants.