5. Until 1 January 2030, Member States may exempt existing medium combustion plants with a rated thermal input greater than 5 MW from compliance with the emission limit values set out in Annex II provided that at least 50 % of the useful heat production of the plant, as a rolling average over a period of five years, is delivered in the form of steam or hot water to a public network for district heating. In the event of such exemption, the emission limit values set by the competent authority shall not exceed 1 100 mg/Nm3 for SO2 and 150 mg/Nm3 for dust.
Until 1 January 2030, Member States may exempt medium combustion plants firing solid biomass as the main fuel, which are situated in zones where, according to assessments under Directive 2008/50/EC, conformity with the limit values of that Directive is ensured, from compliance with the emission limit values for dust set out in Annex II to this Directive. In the event of such exemption, the emission limit values set by the competent authority shall not exceed 150 mg/Nm3 for dust.
The competent authority shall in any case ensure that no significant pollution is caused and that a high level of protection of the environment as a whole is achieved.