1. As far as gas and heat are concerned, this Directive shall apply to the following activities:

(a) the provision or operation of fixed networks intended to provide a service to the public in connection with the production, transport or distribution of gas or heat;

(b) the supply of gas or heat to such networks.

2. The supply, by a contracting entity other than a contracting authority, of gas or heat to fixed networks which provide a service to the public shall not be considered to be a relevant activity within the meaning of paragraph 1 where all of the following conditions are met:

(a) the production of gas or heat by that contracting entity is the unavoidable consequence of carrying out an activity other than those referred to in paragraph 1 of this Article or in Articles 9 to 11;

(b) the supply to the public network is aimed only at the economic exploitation of such production and amounts to not more than 20 % of the contracting entity's turnover on the basis of the average for the preceding three years, including the current year.