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Improving Air Quality: Combustion Plant Directives

16 October, 2019

Regulation of emissions to air from large combustion processes is well established; The Large Combustion Plant Directive (LCPD), issued in 2001, was a European directive which required member states to limit flue gas emissions from all combustion plant having a thermal capacity of 50MW (thermal) or greater. The LCPD was superseded by the Industrial Emissions Directive (Directive 2010/75/EU) on integrated pollution prevention and control, referred to simply as the ‘IED’.  This covers large power plants regardless of the fuel used e.g. oil, gas, biomass, refuse derived fuels (RDF) or municipal solid waste (MSW).

Smaller boiler plant, less than 1 MW capacity are covered by the Ecodesign Directive and the Ecodesign product/energy efficiency label will be familiar to most as it covers virtually all domestic products in one form or another.

More recently the Medium Combustion Plant Directive (MCPD) was introduced to fill the gap between 1MW and 50MW with an estimated 143,000 such plants installed in the EU; an estimated 30,000 of these being within the UK.

The emission limit values set in the MCPD (see summary table) applied from 20th December 2018 for all new plants and 2025 or 2030 for existing plants, depending on their size.


Solid biomass

Other solid fuels

Gas oil

Liquid fuels other than gas oil

Natural gas

Gaseous fuels other than natural gas


200 (19)


350 (20)

35 (21)  (22)


300 (23)

300 (23)


300 (24)




20 (25)

20 (25)

20 (26)

Emission limit values for new medium combustion plants

The limits set by all of these regulations are designed to protect the environment and reduce the chance of the general public developing health issues. According to DEFRA, “The combined impact of Nitrogen Dioxide and Particulate Matter pollution in the UK is estimated to lead to the equivalent of approximately 50,000 premature deaths per year, at a cost of around £30 billion per year.”

Compliance with the directives

Complying with any of these directives should not be difficult.

The MCPD in particular has been designed to be affordable for SMEs, and provides long-term certainty for all economic operators concerned whilst minimising the administrative burden for both industry and Member States. Manufacturers, installers and operators simply have to ensure that the plant is appropriately maintained and is operating efficiently at all times. Maintaining efficient combustion and settings in accordance with manufacturers recommendations will ensure prescribed emissions will be kept to a minimum. Key to compliance is the fundamental understanding of the processes involved and interpreting emission and performance results during routine monitoring. Further, the need to have the underpinning knowledge to be able to optimise the process and minimise unwanted emissions.

Next steps

In order to ensure your business is both compliant with the directives and using it to drive sustainable improvement in your business begin making changes now within your organisation.

Simple steps such as putting in place a clear monitoring and reporting structure as well as educating your staff on the importance of properly operating your combustion plant will ensure that the MPCD is an agent for change and not simply a box-ticking exercise.

Added Benefits

Apart from avoiding hefty fines and the justifiable negative publicity, keeping boilers running efficiently at all times has financial benefits too.

As an example a 200 bedroom hotel using gas fired boiler plant could save as much as £3,000 per annum on its fuel bill by improving the overall efficiency of the plant by just 1%.

Further, this would also reduce the carbon footprint of the same hotel by approximately 15 tonnes per annum!

Online learning

There are two online modules available from Ditto Sustainability to support people working with medium combustion boilers.

The first module lays the foundation by introducing the principles of combustion using practical examples and visual techniques. The aim is to provide the learner with an appreciation of controlled combustion and why this is necessary in operating an efficient and compliant boiler plant. The second module provides the learner with the underpinning knowledge and scientific understanding to be able to achieve improved boiler plant performance in terms of efficiency and environmental compliance.

Further information on the Fundamentals of Combustion modules is available here.