4.2 Indicate the type of fuel or power that feeds the heating system in the dwelling (more than one answer is possible)
[] 1 Methane, natural gas
[] 2 Diesel
[] 3 Liquid propane gas
[] 4 Wood
[] 5 Electricity
[] 6 Fuel oil
[] 7 Coal
[] 8 Solar energy
[] 9 Other types of fuel or energy