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Find out how to calculate your scope 1, 2 and 3 emissions.
This article gives businesses the guidance to calculate their carbon emissions.
Calculating carbon emissions involves determining the amount of greenhouse gases (GHGs) that are directly or indirectly associated with the organisations’ activities and operations.
Any business looking to calculate their carbon emissions be it for mandatory or voluntary reasons, must first identify all their records pertaining to energy & utility consumption, travel, and other supply chain factors.
Once a business has identified all the records pertaining to their activities, they can begin to categorise the emissions sources and their obtained data for calculations to be made. Emissions are calculated from the data using GHG conversion factors which calculates the number of emissions from each source based on the relevant data obtained, and ensures they’re converted to a standard unit so a total emissions figure can be reached.
GHG Conversion factors are numerical values used to estimate the amount of greenhouse gas emissions associated with a specific activity or process. Conversion factors cover a wide range of activities and emissions sources, including energy use, transportation, waste management and more.
Conversion factors are typically expressed in terms of carbon dioxide equivalent (CO2e) and are used to calculate emissions from all activities, to provide a total emission value for the business.
Typically, a conversion factor is used in a formula that looks like:
Company A is an online shop that has five of its own diesel delivery vans that can each hold a gross weight of up to 3.5 tonnes, classing them all as class III (1.74 to 3.5 tonnes) vans.
Company A has data on each of the van’s distance travelled (km) and knows they have all travelled 1,200 km.
Using this data, company A can calculate the emissions by identifying in the DEFFRA table the conversion factor applicable to a class III diesel van, and using that figure as the multiplier for the distance travelled by each van:
1,200 (km) * 0.25346 (conversion factor) = 304.152 kg CO2e
304.152 * 5 (vans) = 1520.76 kg CO2e total emissions generated by the vans
To better understand conversion factors, visit the UK government website to find the DEFRA GHG conversion factors full set spreadsheet.
According to the Greenhouse Gas Protocol itself, the concept of the three scopes enables firms to “understand their full value chain emissions and focus their efforts on the greatest reduction opportunities.”
It’s crucial that each scope is understood individually and the differences between the three are clear before starting to record carbon emissions.
Scope 1 emissions cover GHG emissions that your company makes directly. An example of these emissions could be running a boiler to heat a company office.
Scope 2 emissions are emissions your company makes indirectly. An example of these emissions could be electricity or energy purchased to power a company office.
Scope 3 emissions are quite different to scope 1 and 2 emissions, and some can find these emissions harder to understand. Scope 3 emissions are not produced by the company itself and are not the result of activities from assets owned or controlled by them, but by those that it’s indirectly responsible for up and down its value chain. An example of this is when we buy, use and dispose of products from suppliers.
Fuel emissions can be calculated using data on the litres of primary fuel combusted at a site or in an asset owned or controlled by the organisation. The activity data (litres) is multiplied by the appropriate fuel conversion factor to produce the organisations fuel emissions.
Emissions from bioenergy usage can be calculated using data on the combustion of bioenergy fuels from recently living sources at a site or in an asset under direct control of the organisation. For a company reporting emissions from standard biodiesel use in its delivery vehicles, it should record the litres consumed to publicly report scope 1 emissions. The activity data (litres of fuel) is multiplied by the appropriate conversion factor to produce its scope 1 biodiesel emissions.
Refrigerant emissions that can come from leakage of air conditioning and refrigeration units can be calculated by identifying how much the refrigerant was topped up by in the past year. The refrigerant top up data (in kg) can then be multiplied by the applicable factor to their refrigerant type to produce their direct scope 1 emissions from refrigerant.
Emissions from delivery vehicles can be calculated by keeping up-to-date records on the distances travelled by vans, LGVs and HGVs. This activity data (km) for each vehicles multiplied by the relevant conversion factor to produce the emissions.
Organisations required to report under SECR should use SECR kWh pass & delivery vehicle factors to calculate the energy use in kWh from road vehicles where they only have mileage or km data. Activity data (miles is multiplied by the appropriate kWh factors to produce the passenger vehicle energy use in kWh).
Emissions from the use of electricity in the UK by organisations can be calculated by reading electricity meters and or collecting the data from utility bills. Only the emissions associated with electricity used by the organisation at sites which the organisation owns or controls should be calculated. Emissions associated with the transmission or distribution of electricity should not be calculated as scope 2 emissions. Calculate the kWh electricity usage and multiply by the DEFFRA ‘electricity generated’ figure appropriate to the reporting year to produce scope 2 electricity emissions.
To calculate the emissions from your electricity usage overseas the organisation should similarly record electricity usage (in kWh) at owned or controlled international sites. The calculations can then be made by multiplying your international electricity use data with the overseas electricity conversion factor.
Emissions from the use of electric vehicles can be calculated by obtaining data on the electricity used at sites owned or controlled by the organisation (where it is not already reported) to power EVs.
Organisations required to report under the SECR should use SECR kWh UK electricity for EVs conversion factors to calculate the energy use in kilowatt hours (kWh) from electricity vehicles where they only have mileage or km data. Activity data (km or miles) is multiplied by the appropriate kWh conversion factor to produce its passenger vehicle total energy consumption in kWh. They also need to calculate scope 1 energy consumption with use of petrol/diesel in hybrid electric vehicles using the kWh conversion factors provided in the ‘SECR kWh pass & delivery vehicles’ DEFFRA table.
The emissions from heat and steam that your organisation purchases for heating or use in specific industrial processes can be calculated by keeping track of the kWh usage of heat and steam. A figure on the kWh used in the past year can be used to calculate the generated emissions. The kWh data is multiplied by the appropriate year’s conversion factors to produce the company’s scope 2 heat and steam emissions.
There are 14 different categories of emissions in scope 3; 8 classified as “upstream” and 6 classified as “downstream”.
Category 1 upstream emissions, purchased goods and services, account the extraction, production, and transportation of goods and services acquired by organisations that are not otherwise included in the later upstream categories.
Emissions from material use should report on the consumption of procured materials based on their origin (mainly primary materials or recycled materials). Material use emissions cover extraction, processing, manufacturing, and transport for primary materials to the point of sale. For secondary materials, the sorting, processing, manufacturing, and transporting to the point-of-sale emissions are included.
To calculate material use emissions the organisation selects the materials first i.e. wood associated with construction and identify the tonnes of material procured. This data is then multiplied by its relevant factor to produce the scope 3 emissions associated.
Category 2 upstream emissions, or capital goods, describe emissions associated with the extraction, production and transportation of capital goods purchased by your organisation. To calculate these scope 3 emissions, you may use an average-product method. This involves estimating emissions for capital goods based on units of goods purchased and multiplying the figure by the relevant emission factor.
Category 3 upstream emissions, or fuel and energy-related activities emissions describe the emissions associated with the extraction, production and transportation of fuels and energy acquired by organisations, that are not already accounted for in scope 1 or 2. This category can account for emissions of purchased fuels, purchased electricity, transmission and distribution losses, and the generation of purchased electricity. The following calculations are all classed as category 3 upstream emissions:
Emissions associated with the extraction, refining and transportation of raw fuel sources to your organisations site before use, should be calculated using fuel activity data and well-to-tank fuel conversion factors. A company should select the WTT emissions associated with their use of natural gas and diesel. The activity data is then multiplied by the conversion factors to produce WTT emissions for fuels.
Well-to-tank emissions refer to greenhouse gas emissions associated with the production, processing and transportation of a fuel from the point of extraction or creation to the point where it is used. They are classed as ‘upstream’ emissions.
Emissions associated with the transmission and distribution of electricity should be calculated using electricity purchased in the past year. These calculated emissions can account for emissions associated with grid energy losses during transmission from the power plant to organisation. To calculate emissions from T&D the company must multiply the total kWh electricity purchased by the appropriate conversion factor (i.e. electricity or heat/steam).
Water emissions related to water transported through the mains supply network should be calculated using data from utility bills and water meters. The data gathered (water use in cubic meters) can then be multiplied by the appropriate conversion factor called ‘water supply’ to produce the scope 3 emissions.
Emissions associated with the refining and transportation of bioenergy sources prior to combustion can be calculated by keeping track of the litres of biofuel consumed in the past year. The litres of biofuel consumed is multiplied by the appropriate conversion factor (i.e. Bioethanol).
Emissions associated with the extraction, refinement and transportation of primary fuels used to generate heat and steam can be calculated by keeping records of kWh used in the past year, then multiplied by the appropriate year’s factor.
For electricity generated in the UK, emissions associated with the extraction, refining and transportation of primary fuels before their use in generating electricity can be calculated. To calculate this the company uses the kWh data from its electricity meters/utility bills and multiplies it by the WTT factor – be it for generation or T&D.
Category 4 upstream transportation and distribution emissions account for emissions associated with the transportation and distribution of products purchased by the organisation between tier 1 suppliers and the organisation’s own operations. Transportation and distribution services purchased by your organisation are also accounted in this category. The following calculations describe the emissions classed as category 4 upstream emissions:
The shipment of goods by land, sea or air through a third-party organisation should be calculated to quantify upstream and downstream emissions. For upstream ‘goods in’, if the mass of items shipped to an organisation is known, the tonnage should be multiplied by the distance travelled to achieve a tonne.km value – this can then be multiplied by the appropriate cargo ship factor for its type.
Emissions generated from the extraction, refining and transportation of raw fuels before they are combusted for delivery & freight vehicles should be calculated as scope 3 emissions. To calculate these scope 3 emissions a company must, for each mode of transport (i.e WTT – freight flights), select the corresponding factor and multiply by the distance travelled or by the tonne.km measured for each of the goods freighted (where applicable).
Category 5 waste generated in operations, upstream emissions, account for the disposal and treatment of waste generated in an organisation’s operations. This category accounts the scope 1 and 2 emissions from waste management suppliers that occur during disposal or treatment:
Emissions from water returned into sewage systems through drains should be calculated using up-to-date records from utility bills and the volume of water disposed via drains (cubic metres) multiplied the appropriate year’s factor called ‘water treatment’.
Category 6 business travel upstream emissions describe emissions associated with the transportation of employees for business-related activities. To calculate these emissions, consider the scope 1 and 2 emissions of used transportation carriers:
Emissions generated from employees flying for work purposes should be calculated as scope 3 emissions. Gather the distances travelled domestically, by short-haul and long haul, and in which class of travel. Then multiply the distance (km) travelled in each travel class and in each category of journey (i.e. short haul) using the DEFFRA table. The factor set that includes indirect effects of non-CO2 emissions should be used in most cases. If the haul of the journey is known but not the class, assume the employee was an ‘average passenger’.
The emissions from the extraction, refining and transportation of air travel fuel prior to flight, should also be calculated as a scope 3 emission. Use the distance travelled (for domestic etc..) and (class data) and multiply the km travelled in each class and category by the relevant factors.
Employees staying overnight at hotels during business trips – To calculate each hotel, stay trip, the company visited and number of nights each staff member stays in a hotel for should be recorded. For each hotel stay, the number of rooms is multiplied by the length of stay (number of nights) and by the relevant conversion factor for each appropriate country.
Emissions from your employees travelling by ferries for business purposes should be calculated using data on the total km travelled. This figure should be multiplied by the appropriate conversion factor (foot passenger, car passenger, average). The company gathers the activity data (km) by the appropriate conversion factors (foot, car, average) is then gathered to ultimately produce the scope 3 emissions.
Emissions associated with business travel on land by employees should be calculated as upstream scope 3 emissions. Emissions for land travel should factor in mileage data in cars owned by employees, public transport, hire cars, and generally any assets not owned by your organisation. To calculate these emissions your organisation should account the total km travelled for each mode of transport and multiply each km data for each mode by the appropriate factor to produce the scope 3 emissions.
Emissions related to the extraction, refining and transportation of raw fuels before their use in transport vehicles should be calculated as scope 3 emissions. To calculate these emissions your company should identify the types of travels e.g. WTT – rail and locate the corresponding WTT figure and multiply by the distance travelled.
Category 7 employee commuting emissions describe the emissions generated from employees travelling between their homes and work location. The following calculations can be used to define your category 7 upstream emissions:
Energy use that enables employees to work from home should be calculated. The full-time equivalent (FTE) working hours per employee is multiplied by the conversion factor.
Category 8 upstream leased assets emissions, describe the emissions generated from the operation of assets leased by the organisation, that are not included in scope 1 or 2. The following calculations are all classed as category 8 upstream emissions:
Category 9 downstream transportation and distribution emissions account for emissions associated with the transportation and distribution of products sold by your organisation, between your organisation’s operations and the end consumer. The following calculations allow you to total these category 9 emissions:
For category 9, calculate the emissions associated with grid losses during T&D of electricity for electric vehicles. Multiply the EV activity data by the appropriate conversion factor (i.e. sports car – plug in hybrid electric vehicle).
Emissions associated with the shipment of goods by land, sea or air through a third-party organisation should be calculated as downstream scope 3 emissions. To calculate them your organisation should quantify its upstream and downstream emissions (these emissions can be upstream for goods in and downstream for goods out). For ‘goods in’, if the mass of items shipped to an organisation is known, the tonnage should be multiplied by the distance travelled to achieve a tonne.km value – which can then be multiplied by the appropriate cargo ship factor for its type (if the shipment travelled by sea at any point).
Category 10 downstream processing of sold products emissions account for the emissions associated with the processing of intermediate products sold by an organisation, for example, from energy use. To calculate the emissions from downstream processing of sold products, your organisation should first collect relevant activity and GHG emissions data from value chain parties, such as fuel data. This fuel data would then be multiplied by the life cycle emission factor for fuel to generate an emissions figure.
Category 11 use of sold products downstream emissions describe the emissions generated from end of use goods and services sold by an organisation. For this calculation, calculate the lifetime uses of each product by the number of products sold and an emission factor per use. The emission factor used can be either a lifecycle emission factor for fuels, electricity, or refrigerants.
Category 12 end-of-life treatment of sold products can also be included in these calculations. Category 12 describes the emissions associated with waste disposal and treatment of products sold by an organisation. The following calculations enable you to calculate category 11 and 12 downstream emissions:
Emissions associated with the end-of-life disposal of different materials using a range of waste disposal methods should be calculated as a downstream scope 3 emission. To calculate these emissions, the emissions sub totals should be added up. For example, a company that sends 0.5 tonnes of food waste to a landfill each year and has a white paper recycling scheme in place should first calculate the emissions from food waste using the ‘organic: food and drink waste’ category and select the appropriate landfill factor.
This figure is then multiplied by the 0.5 tonnes of food waste to get a waste disposal subtotal. For the white paper it will select ‘paper and board: paper’ and the closed-loop factor, which can then be multiplied by the mass of white paper recycled to give another waste disposal subtotal. The total waste emissions are then added together to get a total of the associated scope 3 emissions.
Category 13 downstream leased assets, describes the emissions associated with the operation of leased assets or entities. The following calculations enable you to calculate your category 13 downstream emissions:
Emissions associated with vehicles that are used by an organisation but are not explicitly owned by the organisation (or don’t appear on balance sheets) should be calculated as downstream scope 3 emissions. To calculate these emissions, for example with a 12-tonne gross vehicle weight rigid HGV, a factor of ‘rigid (>7.5 tonnes-17 tonnes factor’ should be used. The total km travelled is multiplied by the appropriate factor to produce the emissions data.
Emissions associated with electricity used at a site or at an asset not owned or operated by an organisation (i.e. space in a data centre) should be calculated as scope 3 downstream emissions. To calculate the emissions of, for example, electricity used in a data centre (hosted by a third party), a company should gather consumption data from its monthly bill in kWh. This total annual kWh consumption figure is then multiplied by the electricity generation factor to produce the scope 3 emissions figure.
Category 14 franchises emissions, accounts for the emissions associated with the operation of franchises, that are not already reported in scope 1 and 2 by the franchisor.
Category 15 investments emissions, accounts for the emissions associated with the operation of investments (including equity, debt investments, and project finance) by your organisation.
Calculating carbon emissions can be a lengthy process, comprised of rigorous identification, data collection, and calculations. Depending on the size of the organisation, and the data available on company assets, owned, or associated, it can be a simple or complicated process. But sticking to the key tenants of carbon emissions calculation can ensure that emissions are calculated correctly:
Elisabeth is an Associate Consultant and Associate Tutor of the British Standards Institute (BSI), a BSI qualified Lead Auditor and member of the Standard Committee responsible for the publication of the BS 10008 Standard.
Elisabeth can help you decide if ISO 14001 is for you and support you through its implementation, all the way to certification.