Medium Combustion Plants (MCPs) are used to generate heat and for power generation.  MCPs are a significant source of air pollution and many are not currently regulated in Northern Ireland.  The main driver for action on reducing air pollution from MCP is the impact it can have on health and the environment.  A cleaner, healthier environment benefits people and the economy.

The Pollution Prevention and Control (Industrial Emissions) Regulations (Northern Ireland) (Amended) 2018 transpose the requirements of the Medium Combustion Plant Directive into law in Northern Ireland. It sets out the limitation of emissions of certain pollutants into the air from MCP. This will mean that MCP will be a ‘regulated facility’ and will need to comply with the requirements in the legislation. This also includes emission controls on specified generators as further detailed below.

The new regulations are expected to provide 43% of the sulphur dioxide emissions reduction, 9% of the reduction for particulate matter, and 22% of the nitrogen oxides emissions reduction needed to meet the UK’s 2030 targets.

The definition of a medium combustion plant is “any technical apparatus in which fuels are oxidised in order to use the heat generated.” This applies to any combustion plant that has a rated thermal input between 1MW and 50MW such as:

  • combustion plants covered by Chapter III and Chapter IV of the Industrial Emission Directive;
  • waste incinerators and waste co-incinerators;
  • combustion plants designed to purify waste gases;
  • gas turbines;
  • diesel engines;
  • combustion plants designed to provide heat within indoor spaces;
  • plant that will dry, heat or provide other treatment of objects or materials; 
  • mobile combustion plant;
  • on farm combustion plant;
  • boilers; and
  • specified generators.

(This is a list of some of the typical types of combustion plant and should not be seen as all types).

Significant dates (MCP)

Operators are required to have an environmental permit for all MCP. The date by which a permit will be required depends on the date of installation of the plant:

  • from 20 December 2018 all new MCP will need an environmental permit;
  • for existing MCP (operating before 20 December 2018) with a rated thermal input greater than 5MW, a permit is required after 1 January 2024; and
  • for existing MCP (operating before 20 December 2018) with a rated thermal input less than 5MW, a permit is required after 1 January 2029.


The operator must carry out monitoring of emissions after granting of a permit, and then at the following frequency:

A reduced frequency is allowed for plant operating under the limited hours exemption but monitoring will be required no less than once every 5 years.


There are a number of exclusions from the scope of Medium Combustion Plant Directive (detailed in Article 2(3)) e.g. combustion plant used to propel a vehicle, ship or aircraft; turbines and engines used on offshore platforms; some driers; and thermal oxidisers.

There are also a number of exemptions listed (Article 6). Plants subject to these exemptions will still need permitted/registered but are exempt (sometimes on a temporary basis) from compliance with ELVs e.g. plant operating under a certain number of hours, plant at gas compressor stations, small and micro isolated systems etc.

Specified generators

A specified generator (SG) is any combustion plant used for the purpose of generating electricity; or any group of such combustion plant located at the same site, operated by the same operator, and having the same purpose, between 1MW and 50MW. If the SG is used to meet a capacity agreement or an agreement to provide balancing services then all plant less than 50MW is included.

Excluded generators

Generators in sites permitted under Chapter II and III of the Industrial Emissions Directive and emergency back-up generators operated for the purpose of testing for no more than 50 hours per year are exempt from these controls.

A backup generator means a generator that is operated for the sole purpose of providing power at a site during an onsite emergency. Operators can test their backup generators to ensure they can be relied on. Operators should maintain records of annual hours of testing for each individual generator to ensure the exclusion criteria can be demonstrated.

Mobile generators do not fall within the definition of “generator” under the Regulations, with two exceptions –

  • if they are connected to an electricity transmission system or distribution system, or
  • if they are connected to other apparatus, equipment or appliances at a site and are performing a function that could be performed by generator that is not mobile.

Mobile, in relation to a generator, means it is designed to move or be moved from place to place. Whether a generator is mobile will be determined by taking account of how long it has been on a site, the nature of the site and whether it is under construction or finished.

Significant dates (SG)

The regulations make an important distinction between ‘new generators’ and ‘existing generators’. An ‘existing generator’ is a generator with a rated thermal input 1-50MW which came into operation before 1 December 2016. A ‘new generator’ is a specified generator which is not an existing generator.

All new generators are required to be permitted and comply with ELVs by 1 January 2019. In the case of existing generators you will need to have obtained a permit and comply as follows:


All applicable MCP and SG are required to obtain a permit either from their District Council or NIEA, unless they are an excluded generator.

Plant located on Part A and Part B sites will be dealt with by the NIEA, while plant not on already regulated sites will be dealt with by the District Council of the area in which the plant is located.

Contact details

For further detail please contact Environmental Health Service Unit using the contact details below:

Environmental Health Service Unit,
Lisburn & Castlereagh City Council,
Civic Headquarters,
Lagan Valley Island,
BT27 4RL
Tel: 028 9244 7397