MCS Standards

MCS Technical Working Groups develop the MCS standards, which are predominantly based on international and European standards already in existence.

Biomass Systems

Biomass heating systems burn wood in the form of pellets, chips or logs to provide heating and hot water for the home.

Below are the standards required to be met to be able to install Biomass systems under the MCS scheme. Approved guidance and reference materials to be used with the standards can also be found below.

Technology Specific Scheme Requirements
Biomass Systems
MIS 3004 Biomass Standard 4.2 06.05.2015
MCS Domestic RHI Metering Guidance Document 1.1 01.05.2015

70kWth Application Guidance* 1.0 15.05.2014

Installer standards that have been withdrawn are available for reference here.

Biomass Reference Materials

The following reference materials have been approved for use alongside MIS 3004:

Document Download here Version Date
MCS biomass calculator Download here 1.7 27.03.2017
BFMCA flue and chimney guide Download here

MCS biomass calculator

The MCS biomass calculator provides a method for carrying out the design calculations required by MIS 3004 v4.2 Appendix C. Its use is optional and installers may choose to use their own calculations as long as these comply with the requirements of MIS 3004. Please note that the calculator is compatible with Microsoft Excel and if you are using alternative software we cannot ensure compatibility. If you are experiencing compatibility issues then you may wish to open the document using the free online version of Excel.

Please note a few points of frequently asked questions:

  • All yellow cells must be filled. White cells cannot be altered.
  • If you have less than 20 rooms to calculate, select “No Room” in row 12 in the relevant column. If no room is selected then please ensure that you enter any inputs as 0.

  • Numbers on the Design Calculations page in column G and P in the format [101] refer to page 25-27 of MIS  3004. The corresponding box explains exactly how to make the calculation.
  • All yellow cells must be answered with a number. If letters or “0” is entered, an error will be returned and the compliance certificate will say #VALUE! or #DIV/0!
  • If no additonal heat sources is required, do not input “0” into the cell. Rather, select from the drop down box “No Aux Heat Source”.

  • The Compliance Certificate (CC) is filled in from the HC Calculations page. Once the information has been filled in, the CC will be automatically be filled in. You can then export the CC page as a PDF to attach it back to the MID for the relevant MCS Certificate.

MCS welcomes all feedback on the calculator. We will then collate any feedback and issue periodic updates. If you do have any feedback on the calculator please submit this to:


*The MCS Standards Management Group (SMG) has prepared a guidance document (found above) to assist installers and the wider industry in understanding the intent of how the thresholds, set within each MCS Installation Standard for the heat technologies, shall be practically applied to design, installation and commissioning work under the MCS scheme.

This document has been prepared by the MCS SMG, taking into account the views of the industry to ensure that systems can be adequately designed and installed under the scheme, whilst reinforcing with installation companies the need to ensure they have the relevant competencies to undertake the tasks associated with these systems.
An MCS certified Installation Company should ensure they follow this guidance, and MCS reserves the right to amend the guidance as necessary through periodic review without prior notice.
The 70kWth threshold was noted by the Scheme as a threshold which aligns with the existing competency criteria set out by the Scheme, and other industries such as oil and gas.