If you are considering heating a room, or a new extension, it may be more economic in the long term to install air conditioning rather than extend your existing central heating system. Apart from the heating aspect the air conditioning will also give you the benefit of cooling in the summer.
Many people are adding a conservatory to their home to give them an extra room. Often they find that the conservatory is too hot in the summer and too cold in the winter so they can only enjoy their conservatory in the spring and autumn when the weather is temperate. Some people install a fan in their conservatory for cooling in the summer and a heater for warmth in the winter but an air conditioning system would do both jobs and be far more controllable and efficient.