How do you estimate electricity used to calculate work from home (WFH) emissions?

1. 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

2. 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

• Average working hours

• 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.

4. Calculation method

WFH emissions are calculated in two stages.

Step 1: Estimate electricity consumption

Electricity consumption (kWh) =
Number of WFH days × Average kWh per WFH day (region)

Step 2: Calculate emissions

Emissions (kg CO₂e) =
Electricity consumption (kWh) × Regional electricity emission factor

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.

5. Regional assumptions used by Trace

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

• Device electricity consumption benchmarks

• Typical working hours

• Climate driven heating or cooling needs

• Residential electricity consumption statistics

Here is a summary of the assumptions used per region:

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