How do you estimate emissions from employees working from home (WFH) ?

Overview of the estimation approach

Working from home (WFH) emissions represent the additional energy used in an employee’s home due to working hours. This covers electricity and heating used in homes that would not otherwise occur if employees were working in an office.

These emissions fall under GHG Protocol Scope 3, Category 7: Employee Commuting which includes emissions from:

• Transportation used by employees to travel to and from work

• Energy used when employees work from home instead of commuting

The inclusion of WFH emissions reflects the fact that remote working shifts energy consumption from office buildings to employee homes.

Working from home energy consumption typically includes:

• Work devices (laptop, monitor, chargers)

• Internet router

• Lighting

• Incremental heating or cooling during working hours

Since this information is not normally available at an individual household level, emissions are estimated using average electricity consumption per WFH day.

The calculation process is:

1. Estimate electricity consumption per WFH day 

2. Multiply by number of WFH days

3. Apply regional electricity emission factors

Note that we calculate electricity consumption for all regions, but only include Gas usage when employees have completed the Trace WFH and specified that they use Gas.

Capturing working from home activity data

We calculate working from home emissions using two input methods, depending on the level of data available.

1. Employee survey data (read more about our Survey here)

This is the most granular approach. Employees provide information on their working from home setup and behaviour including

• number of days per week worked from home
• where they live (which informs the emission factor we apply)
• Type of home (e.g. apartment, 4 bedroom house)
• Air conditioning and Gas (heating) behaviour patterns

This allows emissions to be calculated at a more detailed level and better reflects actual employee behaviour. Where participation is <100%, we extrapolate the data by location.

Gas usage is only included where it is explicitly reported in the survey. This is because it is often unclear whether home gas consumption can be directly attributed to working from home, and including it by default can lead to overestimation.

2. Employee working from home patterns by location

Where survey data is not available, we use a higher level approach based on:

• number of employees per location
• working from home proportion per location

Gas usage is not included in this method unless supported by survey data, due to uncertainty in attributing household gas consumption to working from home.

Industry guidance used for the methodology

There is limited public research on emissions from working from home, and companies rarely have direct access to household energy data. As a result, industry methodologies rely on publicly available guidance that provides reasonable assumptions for home energy use during working hours.

Two widely referenced sources are:

• UK DEFRA Environmental Reporting Guidelines

• EcoAct (now SE Advisory) Homeworking Emissions Whitepaper

These sources are used because they provide transparent, publicly available methodologies for estimating homeworking energy consumption when primary data is unavailable.

The guidance recognises that it is difficult to isolate the exact energy consumption attributable to working from home, so organisations should use reasonable standard assumptions for device usage and incremental household energy demand.

3. Trace methodology

Trace applies the same methodology but extends it globally by defining regional average electricity consumption per employee per WFH day.

The regional values reflect differences in 

• Residential electricity consumption patterns
• Typical working device setups

• Heating and cooling requirements

Each region therefore has a default kWh value per WFH day.

The estimate includes electricity used by:

Trace assumes a typical office device setup used at home, unless company specific data is available.

Calculation method

WFH emissions are calculated in two stages.

Electricity emission factors are sourced from recognised datasets such as:

• DEFRA emission factors

• National grid emission factors

• International energy databases (for example IEA)

Read more about our emissions factors here.

Regional energy usage assumptions used by Trace

Trace defines average electricity consumption per employee per WFH day by region using a combination of:

• Device electricity consumption benchmarks

• Climate driven heating or cooling needs

• Residential electricity consumption statistics

• Trace assumes the typical working day is 8 hours.
  

Assumptions are derived from publicly available regional energy research and appliance technical specifications

Trace electricity usage assumptions by Region

where:
low = up to 4 kWh/day
moderate = 4.1 kWh/day to 8 kWh/day
high = above 8 kWh/day

Trace gas usage assumptions by Region

The regional assumptions are reviewed periodically to reflect updated research and device efficiency trends.