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An epic effort to get the sums right for waste reporting

On 1 December 2014 an 18-month journey came to an end when McGrath Group launched its new waste report.

The format now quotes net and gross carbon emissions for the period concerned, and gives an accurate breakdown of the destination of all clients’ materials by waste hierarchy categories.

In doing so, the report is now compliant with the Waste Regulations and the Scope 3 Green House Gas (GHG) reporting protocol.

Waste Hierarchy

The waste hierarchy has been around for many years, but its implementation became a legal requirement when it was included in amendments to the Waste Directive in 2011.   

This ranks waste management options in order of environmental preference – for example, prevention and minimisation should be considered before reuse, which is preferable to recycling and energy recovery, with landfill the last resort. Clients must be able to demonstrate that they have applied the hierarchy in handling their waste materials.

Previously, they were provided with a certificate to confirm that we used the hierarchy in our waste management processes. But our waste report now gives customers accurate data about how their materials have been processed and their ultimate destinations.

Data gathered in-house and from reprocessing partners en- abled our environmental team to allocate factors for each category to each waste type (EWC Code), which is then processed and tallied to create a summary of all materials handled across a period. The data is presented in a table and pie chart (shown above).

The integration of waste categories into our reporting systems was relatively simple compared with the epic task of developing a system to calculate the CO2 emitted during collection and recycling of wastes. The 18-month journey was fraught with a number of technical and academic hurdles, but we believe we have developed the world’s first waste report that is compatible with Scope 3 GHG reporting.

Since October 2013, all UK quoted companies have been required to report on their GHG emissions as part of their annual directors’ report. The GHG Protocol defines three scopes of emissions:

  • Scope 1: direct emissions from in-house sources, for example, owned or controlled boilers, furnaces and vehicles.
  • Scope 2: emissions from the generation of purchased electricity.
  • Scope 3: an optional reporting category which allows for the treatment of all other indirect emissions such as third party deliveries, business travel activities and use of sold products and services. Waste management which is carried out by a third party falls under Scope 3.

Although Scope 3 reporting remains voluntary for all types and sizes of organisation, many are taking a lead and seeking ways to gather data to report such emissions. To respond to this growing need for accurate data on indirect emissions, our in-house environmental team looked into developing a way of calculating the energy expended during each stage of the waste process.

There are basically three distinct stages involved in the collection and recycling or disposal of wastes – transport, sorting and reprocessing – so we needed to determine the energy consumption for each.

Transportation of wastes from client sites to their point of destination typically involves two journeys. First, from the collection site to an MRF, where it is sorted into individual material streams and then on to a reprocessing facility where it is processed into raw materials for the manufacture of new products.

This arrangement is typical for mixed wastes and part-segregated recyclables, which form the vast majority of waste generated from commercial and residential sources. Even wastes that have been pre-segregated will usually be taken first to a MRF to be inspected for quality control purposes and/or bulked, awaiting reprocessing.

There are, of course, exceptions. Some waste materials are taken directly from site to their ultimate destination missing out the MRF altogether: hazardous waste such as asbestos will be removed straight to a licensed landfill site. Organic wastes such as food collected on-site in special caddies will usually be taken directly to a specialist food processing facility.

And some MRFs may have reprocessing capabilities themselves. For example, at our Barking MRF, rubber, timber and concrete are processed on-site which removes the need for a subsequent journey.

To determine the energy expended during transportation, we needed to calculate the distance travelled and fuel consumption of our vehicles. We asked the developers of our in-house electronic waste management system to integrate a postcode application, which would calculate distance based on site and destination postcodes, while our environment team gathered data on the average fuel consumption of the vehicles in our fleet.

However, each waste consignment is not transported in isolation; to reduce the cost and environmental impact of the collection process, many waste contractors typically combine several collections in one journey. To account for this, we made a number of assumptions based on average payloads, weight and volumes of consignments.


Determining the energy expended during the sorting phase was less problematic. Our MRF uses an integrated system in which a series of mechanical, magnetic and manual processes segregate mixed waste streams into individual material types.

Mixed waste consignments typically pass through the entire sorting system while others, such as pre-segregated items, may just require one or two of the sorting processes. Each waste type was assigned a combination of sorting processes and, using in-house and published sources, it was possible to calculate the average energy consumption of each consignment.

By using standard carbon conversion factors, we converted the energy consumed in the transport and sorting process into equivalent carbon emissions for each waste transaction.

The final stage of the waste management process involves converting individual material streams into raw materials for the manufacture of new products. The methods differ for each material type but, typically, this will involve removing contaminants then shredding or crushing the materials into fine particles ready for reconstitution using a manufacturing process.

Fortunately the calculation of the carbon emitted during reprocessing had already been estimated, and we were able to use carbon factors published by Zero Waste Scotland, which included carbon emissions for almost all waste types. For those that were not available we made assumptions and used data for similar material streams.

The data was combined with the calculations from transport and sorting to produce a figure for carbon emissions for each waste transaction. This can be aggregated across a series of transactions such as on a project basis or for a fixed duration such as a monthly summary report.

McGrath Group decided to approach the carbon consultancy Carbon Action to independently verify the efficacy of the methodology, and to check that our assumptions were based on sound environmental principles.

Its auditors scrutinised our processes to ensure they were capable of producing fair, accurate and representative GHG data in compliance with the principles and requirements of the international standard. They analysed the logic and assumptions behind the methodology for all three waste processes, as well as the accuracy of our arithmetic in converting energy consumption into equivalent carbon emissions.

This included requests for clarifications that our carbon reporting system was granted accreditation against the international standard for GHG reporting, ISO 14064 part 3, in March 2014. This gave our methodology the independent seal of authenticity required to build client confidence in the accuracy of our data.

Following this, our algorithms and workings were passed to the software developers to integrate the new data into our electronic waste management system and prepare a report format.

After a four-month period of testing during the summer, a trial report was ready to send to a select group of industry experts and influencers to gauge reaction, which was resoundingly positive.

The report provides two carbon data sets: a figure for gross carbon emissions and one for net CO2 emissions which factor in the carbon benefits of recycling wastes compared with landfilling them.

For those organisations that are going the extra environmental mile and volunteering to submit their Scope 3 emissions, our data can be simply extracted and inserted into their own environmental reporting systems.

Now that we have established methodology that has been independently endorsed, the challenge is to improve the accuracy of the data. In 2015 we plan to introduce more scientific methodology to challenge and replace some of the assumptions we needed to make in order for the report to become a reality.

Tara Donaghy is business director of the McGrath Group

A sample report is available to download from:

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