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, called 'Incremental Energy Consumption'. 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

• Heating or cooling during working hours

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

The calculation process is:

1. Estimate energy consumption per WFH day 

2. Multiply by number of WFH days

3. Apply regional electricity emission factors

Note that at the moment we calculate electricity consumption for all regions by default, but only include gas usage when employees have completed the Trace WFH survey and specified that they use gas. More detail below.

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.

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

If you do not do the survey with us, you can enter this data directly into the platform.

Gas usage

Gas is not currently included in Trace's default WFH emissions calculation, unless usage is specified in the survey, but can be added at request.

If gas heating is a meaningful part of your organisation's homeworking footprint, our team can calculate and add a gas estimate to your account, using the same country-specific data set as our electricity figures. Contact us at support@our-trace.com to request this.

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.

Trace's electricity and gas consumption estimates are based on:

• Anthesis Group, Estimating Energy Consumption & GHG Emissions for Remote Workers (February 2021) — the source for our current country-specific energy intensity assumptions. This whitepaper combines national residential electricity and gas consumption data (IEA, 2018) with a literature-reviewed ratio of incremental-to-baseline energy use attributable to homeworking, by region.

Previously, our regional electricity assumptions were based on UK DEFRA guidance and the EcoAct (now SE Advisory) Homeworking Emissions Whitepaper (2020). We've moved to the Anthesis methodology because it provides country-specific figures for a broader set of regions.

3. Trace methodology

Trace applies country-specific average energy consumption per employee per WFH day, based on the Anthesis (2021) methodology, reflecting residential electricity consumption patterns for that country.

The regional values reflect differences in 

• Residential electricity consumption patterns
• Typical working device setups

• Heating and cooling requirements

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

The estimate includes energy 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.

Emission factors are sourced from recognised datasets such as:

• Australian National Greenhouse Accounts

• UK Department of Energy Security & Net Zero (DESNZ, prev. DEFRA)

• Other government-issued emission factor databases

• International energy databases (for example IEA)

Read more about our emissions factors here.

Regional energy usage assumptions used by Trace

The table below shows Trace's default incremental electricity consumption per employee per WFH day, by country, based on Anthesis (2021). Where a customer's country is not listed, the regional average or closest proxy applies.

Trace incremental energy usage assumptions by country

*Trace derived incremental consumption leveraging country-level IEA data and Anthesis methodology.

**Gas consumption was provided in kWh in the original source data and has been converted to MJ using the factor 1 kWh = 3.6 MJ.

Why do consumption figures vary so much between regions?

All figures use the same source and method (Anthesis Group, 2021, applied to IEA national data); the difference is a genuine data-driven regional pattern. Each region has its own "incremental ratio" - the share of a household's daily energy that's additional from working at home, rather than usage that happens anyway (e.g. because someone else is home). For electricity, the ratio is much lower for Asia-Pacific (26.24%) than the Americas (62.57%) or EMEA (57.79%), because the underlying study found cooling and appliance use households already running at similar levels regardless of homeworking. Therefore, two employees with similar home setups can show quite different WFH energy figures purely because of their region's incrementalo energy ratio.

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