HEATING COLD SPACE

I am building a 3 x 2 meter grow room in an unattached shed. I am worried about the winter months. How can I keep the space warm enough when the lights are out? What is a safe and effective way?

I am building a 3 x 2 meter grow room in an unattached shed. I am worried about the winter months. How can I keep the space warm enough when the lights are out? What is a safe and effective way?
G. Grant

There are several things you can do to keep the shed warm in the winter. First, it should be insulated so that heat doesn't escape. Two easy to use materials for this are Styrofoam board and aluminized bubble pack. Either of these materials can easily be installed in the room and are also easy to remove.
If the lights are high enough above the garden so they do not have to be air-cooled, the heat they generate can be blown down to the plants in the garden. Overhead or side fans can be used and can be regulated by a thermostat, so they turn on when the temperature in the canopy decreases to a certain level, below 300 C when the lights are bright and the garden is supplemented with CO2.
Gas heaters or CO2 generators, which burn natural gas or bottled gas and release CO2, heat and humidity are good choices for both keeping the room warm and supplementing it with CO2. The generator should be regulated by the thermostat for heat. When the temperature falls, the generator is turned on. Gas heaters are economical and add humidity to dry air. However, the humidity should be maintained at a level no higher than 50%. A dehumidifier may be needed occasionally to lower the moisture level of the air. This unit also creates heat. Use a CO2 tank that is regulated by a CO2 PPM meter placed at the top of the canopy.
An electric heater is another alternative. Just plug the heater in, turn it on and set the desired temperature. The heater will maintain the temperature. When cold air is heated electrically it becomes very dry because cold air holds very little water. As it heats up and can hold more moisture, its relative humidity goes down. To maintain the relative humidity at a minimum of 40% you may have to install a humidifier regulated by a humidistat.
If you maintain the dark period temperature close to the on period you will find that the stems will be thicker and stouter. The plants will also grow and mature faster.