... % on running costs.Effectively a 1000 watts heater will cost approximately 6.5 cents ... square metres.20 square metres, x 100 watts = 2000 watts* Ideally suited for larger living lounge areas.eg ... square metres.15 square metres, x 100 watts = 1500 watts* Ideally suited for smaller lounge, dining, ... square metres.9.9 square mtrs, x 100 watts = 1000 watts* Ideally suited for smaller bedroom, study, ...