Gas Natural Fenosa is the biggest gas company in Barcelona. Usually if you are buying or renting an apartment in Barcelona, you will have to either open an account or change the present account details for the gas supply. This can be done in a Gas Natural shop, or over the telephone. The meter will usually be read when you take over the apartment. Sometimes in rented flats the owner prefers that the account name stays the same and the new tenant just changes the bank account number registered to the account, so the the gas bill is paid automatically by the new tenant's bank. Visit the Gas Natural Fenosa website for more information and contact numbers. The website is in Spanish and Catalan only.