Scopes 1 & 2

Office space

carbon calculation diagram

Estimates must be used for the calculation of indirect emissions associated with purchased electricity, and for direct emissions associated with the combustion of natural gas for heating when organisations are unable to access primary data such as meter readings. This is common when organisations occupy leased office space, or use a hot desking membership at a coworking space.

We estimate that each employee occupies 10 square meters, in accordance with the 2010 Employment Density Guide published by the Home & Communities Agency1. The amount of electricity and gas consumption associated with each square meter of office space is taken from the CIBSE’s 2000 “Energy use in offices” report, assuming a typical type 3 office2.

When the reporter provides information with regards to leased office space we account for energy consumption for all seven days of the week so as to preclude underestimation. When the reporter is providing information for hot desking activities, we allow them to choose the number of days per week that they use the office space.

The following formula is used for estimating energy consumption associated with heating and energy in a leased office:

kWh energy used per day = m^2 occupied by employees* kWh energy per m^2 of office space per day

Total kWh energy used= kWh energy used per day* days

The estimated kWh values are then multiplied by the appropriate conversion factors as specified in the relevant publication of UK Govt. conversion factors for company reporting of greenhouse gas emissions 3. For electricity, we account for the consumption of generated electricity, as well as losses associated with transmission and distribution, with the former being categorised as scope 2 and the latter as scope 3 (Fuel- and Energy-Related Activities Not Included in Scope 1 or Scope 2). For gas, we account for the combustion of gas for heating, which is categorised as scope 1.

The formula for calculating each of the emissions stated above is as follows:

kg CO?e = estimated energy consumed in kWh*conversion factor

 

Scope 3

 

Business Travel

The following applies to travel that takes place in vehicles that are not owned by the reporting organisation.

Distance based

distance based

Where practical and feasible, the reporter provides the mode of transport, and distance travelled for all business travel that occurred during the reporting period.

For each business travel activity, the distance is multiplied by the appropriate conversion factors as specified in the relevant publication of UK Govt. conversion factors for company reporting of greenhouse gas emissions 3.

kg CO?e = distance travelled*conversion factor for mode of transport

 

Flights

For air travel, the distance is calculated as the great-circle distance between the airports. If the flight is over 3700 km, we use the Long-haul, to/from UK factors from the UK Govt. conversion factors. Otherwise, we use the Short-haul, to/from UK factors. We pick the relevant factor based on the class specified (Economy/Business etc).

 

Spend based

spend based

Where a distance-based approach is not feasible, nor practical, the reporter provides the mode of transport, and amount spent for all business travel that occurred during the reporting period. The amount spent on each business travel activity is then automatically extracted from an expenses report exported from an expense management, or accounting tool.

For each business travel activity, the amount spent is multiplied by the appropriate conversion factors as specified in the relevant publication UK Govt Environmental Reporting Guidelines publication 4.

kg CO?e = amount spent*spend based conversion factor for mode of transport

 

Purchases

purchases

The reporter provided details of all purchases, the category of the purchase, and the amount spent during the reporting period. The amount spent on each purchase is automatically extracted from an expenses report exported from an expense management tool called Expensify. The categorisation of each purchase is done manually.

For each purchase, the amount spent, accounting for inflation, is multiplied by the appropriate conversion factors as specified in the relevant UK Govt Environmental Reporting Guidelines publication 4. Accounting for inflation is recommended in the publication as the spend based emissions factors are from 2009 and there have been price changes since then. Where the category of the purchase is not known, the emissions factor used is an average of all the aforementioned UK Govt Environmental Reporting Guidelines spend based factors 4.

UK Govt Environmental Reporting Guidelines spend based factors

Commuting

commuting

The reporter provides the mode of transport, distance commuted, and the number of days commuted for all employees during the reporting period. For each employee their total commuting distance is calculated using the following formula:

total distance travelled = daily distance travelled * days per week* no.weeks in period

For each employee their total commuting emissions are calculated using the following formula:

kg CO?e = total distance travelled during period*conversion factor for mode of transport

The distance values are multiplied by the appropriate conversion factors as specified in the relevant publication of UK Govt. conversion factors for company reporting of greenhouse gas emissions 3.

 

Homeworking

In accordance with the GHG Protocol Technical Guidance for Calculating Scope 3 Emissions, employee teleworking has been included in Scope 3 Category 7: Employee commuting. The methodology outlined in the 2020 EcoAct homeworking emissions whitepaper5 is used to calculate the homeworking emissions for the application period.

The first step of estimating the emissions is to establish an estimate of the total number of hours worked from home during the reporting period. The following formula is used to calculate this number:

total hours= no.employees * ((avg.working days – avg.holiday days) * avg.working day length)

With the number of homeworking hours calculated, we then estimated the emissions associated with energy consumption.

Given that estimation is required, we aim to preclude underestimation in accordance with PAS 2060 by making the following assumptions when using the methodology outlined in the 2020 EcoAct homeworking emissions whitepaper:

  • 100% of employees working from home result in incremental heating energy. One or more of the employees may be working in a household where one other household member would normally remain at home in the day, but we have not accounted for this.
  • No households have a green energy tariff.
  • The power consumption of each workstation is 140W as calculated in CIBSE Guide F (2012), which accounts for a laptop or PC, monitor, phone and printer, though one or more employees may not have all of these devices.

For electricity consumption by employee workstations and lighting, we use the following formula, where the details of the140W, and 10W values can be found in the EcoAct whitepaper5.

workstation kWh=(140W * total hours) / 1000
lighting kWh=(10W * total hours) / 1000

For emissions resulting from heating, we first calculate the number of total homeworking hours that fall within the northern hemisphere heating season of October to March (6 months). This number is then multiplied by 5 kWh, as stated in the EcoAct whitepaper5.

heating kWh=5 kWh * total hours in heating months

The estimated kWh values for electricity consumption and heating are then multiplied by the appropriate conversion factors as specified in the relevant publication of the UK Govt. conversion factors for company reporting of greenhouse gas emissions 3. For electricity, we accounted for the consumption of electricity, as well as losses associated with transmission and distribution. For gas, we account for the combustion of gas for heating.

The formula for calculating each of the emissions is as follows:

kg CO?e = estimated energy consumed in kWh*conversion factor

 

Waste

waste

The reporter provides the weights in kilograms for the different waste categories such as:

  • General waste (landfill)
  • Paper and card (recycled)
  • Plastics (recycled)
  • Cans and foil (recycled)
  • Food waste (composted)

The weights are then multiplied by the appropriate conversion factors as specified in the relevant publication of the UK Govt. conversion factors for company reporting of greenhouse gas emissions 3.

 

Sources

  1. Home and Communities Agency, “Employment Densities Guide” https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/378203/employ-den.pdf
  2. CIBSE. “Energy use in offices” 2000, https://www.cibse.org/getmedia/7fb5616f-1ed7-4854-bf72-2dae1d8bde62/ECG19-Energy-Use-in-Offices-(formerly-ECON19
  3. Government conversion factors for company reporting of greenhouse gas emissions https://www.gov.uk/government/collections/government-conversion-factors-for-company-reporting
  4. Environmental reporting guidelines: including Streamlined Energy and Carbon Reporting requirements https://www.gov.uk/government/publications/environmental-reporting-guidelines-including-mandatory-greenhouse-gas-emissions-reporting-guidance
  5. EcoAct Homeworking Emissions Whitepaper https://info.eco-act.com/en/homeworking-emissions-whitepaper-2020