How Do You Know If You Need a Medium Combustion Plant Directive Permit?

The Medium Combustion Plant Directive (MCPD) permit came into effect in 2018. Nevertheless, many local authorities, the bodies supposed to implement the legislation, are unaware of the regulations and are not taking any action.

The MCPD Permit Explained

Let’s first examine the need for a wood machining process permit. If a company processes or purchases more than 1,000m3 of wood or wood-based products, it must obtain a Part B permit. This comes under guidance note PGN 602.

The Part B permit, overseen by the Environment Agency, regulates emissions from wood machining processes to the atmosphere. For companies exclusively involved in timber sawing (sawmills), the allowable annual limit is raised to 10,000m3. This permit system has been in place for 33 years (since 1990).

 If a company holds a Part B permit, it is comprehensively covered for both their dust extraction system and any wood-burning appliances, with no additional charges. Notably, all sizes of wood-fired heaters require a permit or exemption, without exceptions or a minimum size requirement (unless located on Crown Property).

 If you burn waste wood on industrial premises, even kiln-dried virgin timber, this will still be classified as industrial waste and as such will need a Medium Combustion Plant Directive permit or an exemption. The table below from the MCPD denotes the burn rates and permit boundaries.

 If the rate is up to 50kgs per hour for burning waste wood, a company must obtain an exemption from the Environment Agency. This process can be completed online and currently there are no associated costs.

A Part B permit is required if the burning rate exceeds 50kgs/hour but is less than 90kgs/hour. This permit is specifically for a Small Waste Incineration Plant (SWIP) and is applicable if the facility processes less than 1,000m3 of wood and wood-based products. In this scenario, a permit for wood machining processes is not needed. However, all plants up to this size are still covered by the Clean Air Act. The only exception is if the system is claiming RHI payments, in which case the boiler must adhere to stricter emission limits set by Ofgem.

It is important to note that wood burned in these processes must not contain Halogenated Organic Compounds or heavy metals, essentially excluding demolition or strip-out waste.

In the initial stages of the RHI scheme, there were three tariff bands: less than 200kW, less than 1MW and over 1MW. Many wood-working companies opted for 199kW boilers without being informed by suppliers about the requirement to obtain a permit for a SWIP or a Part B wood machining permit. This is because 199kW exceeds the 189kW limit that requires a permit.

Presently, Ofgem and the BSL are conducting inspections, and any installations without the required permits or not satisfying other conditions are being removed from the RHI, resulting in halted payments. If a boiler is listed as having a 199kW output on the RHI, it is imperative that a SWIP permit is obtained.

Furthermore, all chimneys connected to an industrial furnace (such as a wood burner) must either have planning consent or written permitted development rights. It is a prerequisite that the Environment Agency must approve the height of all chimneys.

Secure the Necessary Permits

In order to ensure smooth and compliant operations, companies must be able to navigate the regulatory landscape for wood-related industrial processes. From the enduring Part B permissions for wood machining to the newer MCPD permits, having the correct paperwork in place is akin to having a reliable compass for your business journey.

 At Ranheat, we design, manufacture and install UK-compliant biomass wood-burning systems. If you require any expert assistance, please do not hesitate to visit or contact our team on 01604 750005 or via email at [email protected].


  • 4 January 2024
  • Alexander Franklin