Home working emissions - general factors or survey results?

I have a question on home working emissions for the team there please.

I have a client who has asked their employees to complete a home working survey, which gives us their fuel type, house size, whether they heat their whole home (or just the room they work in) and numbers of days worked from home.

I have worked through this using some estimations on average household energy consumption, and the numbers are way higher than they would be by just using the generic emissions factors for home working estimations.

Do you have any advice on thoughts here on the best method to use? Obviously basing this off their own specific data is usually the best way to go, but this is making their home working emissions way higher than previous years using the DEFRA factors with a previous consultancy.

Any thoughts welcomed.

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Hello Chantelle

I appreciate the question. It is a very important topic!
I’m curious to see where those differences between your calculations and the official ones come from.

DESNZ (DEFRA/UK.gov) homeworking emission that you are referring to mention in their methodology that it is based on the “Homeworking emission Whitepaper” (EcoAct,2020)

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I see 3 reasons why your emissions might be a lot higher than the ones from GovUK:

1) multiplying with total number of working hours
The DESNZ department’s factors are “per FTE working hour”. So it represents the GHG emissions from one hour of work from home (but averaged out by one full-time employee for a year, averaging out seasonal fluctuations)

To get to the end result, you have to multiply the factor by the number of hours the employee works at home in a year. Taking the example from the pdf: 1920 hours per full time working year /employee.
So a full full time home-working employee would result in:
1920x(0.33378) = 640.9 kgCOâ‚‚e
for office equipment and heating in a year.

Which also feels about the right amount.
Did the previous consultant take that correctly into account?

2) multiply with all months, not only heating months

This one is best explained by the remark on the DEFRA spreadsheet:

heating conversion factor has already taken into consideration both heating months and non-heating months. Users should multiply the heating conversion factor simply by the total “annual FTE (full-time equivalent) working hours”, instead of just the months that require heating.

If the previous consultant multiplied the heating factor only with the heating months, you might be a factor 2 off for emissions. (heating accounts for 90% of homeworking emissions)

3) Quite strict scope of the GovUK assumptions
In the 2023 methodology , the assumptions behind the GovUK factors are disclosed.

The assumption for which appliances are counted are quite limited

  • only energy for a laptop or PC, monitor, phone, printer and lighting are taken into account
  • 140W for workstation, 10W for lighting

And additionally, they assume

  • 1/3 of the homeworking employees dont cause any additional emissions (would have stayed home anyway)

If you dont follow these assumptions, you might end up in quite a different place I would assume.

Did this help to get a more complete picture?

Where do you think the major differences come from?
Curious to hear what causes the discrepancy!