For Growers, the key to heating is to ensure the temperatures are stable, accurately controlled, and evenly distributed within the greenhouse. There are certain temperature bands to consider.
What temperature do you need?
A good place to start is to identify bands of temperature. They are called the Target Air Temperatures.
Frost Free 5 Deg C
Low Temperate 10 Deg C
High Temperate 14 Deg C
Hot Stove House 18 Deg C
Propagation 22 Deg C
Factors to consider
What is the target temperature you require? This will depend on what you intend to grow, and what temperatures these plants require to flourish. Is the greenhouse also to be used for people? If lunches, parties and social occasions are to be held in the greenhouse, it would be good to have the flexibility to turn the heating up to a comfortable level.
Bear in mind what you will be doing with the greenhouse in the future, if you want the greenhouse for propagation, but it is designed around a frost free house, you won’t be able to achieve higher temperatures. You can always turn the heating down.
Temperature lift is the difference between the internal target temperature and the minimum external temperature. E.g. if you have an internal temperature of 10 Deg C, and it gets to -5 Deg C external in the winter, this gives a temperature lift of 15 Deg C.
Temperature lift is important because we use this to calculate the amount of power the greenhouse needs, to achieve the desired internal temperature. This can affect the type of heating system that would be most appropriate for you.