How do you calculate CO2 emissions from your energy bill?
Your energy bill itself does not provide a CO2 figure. What appears on it is consumption: kilowatt-hours of electricity, cubic meters of gas, sometimes gigajoules of heat. To convert this into an emissions figure, you multiply that consumption by an emission factor: an established figure that indicates how much CO2 is released per unit of energy. That factor does not appear on your bill, but in an official source that is maintained separately.
The calculation itself is straightforward: consumption times factor equals emissions. The difficulty lies in two other matters: namely which consumption you must precisely include and which version of the emission factor applies to your situation. The rest of this article addresses these points.
What appears on the bill and what you need
An annual invoice for electricity and gas typically shows total consumption over the billing period, broken down by day and night rates for electricity and sometimes by hot water or cooking gas consumption for gas. For a CO2 calculation, you add those line items together into one annual consumption per energy carrier: total number of kilowatt-hours of electricity, total number of cubic meters of gas.
If you have multiple locations or multiple connections, you need one invoice per connection, or a consolidated invoice in which the energy supplier breaks down consumption by address. If part of the year is missing because you switched suppliers, you add together the consumption from both invoices, provided the periods do not overlap and together cover the entire year.
Where the official emission factors come from
The emission factors used in the Netherlands for this type of calculation are centrally established and reviewed annually. They have a reference date: the factor you use corresponds to the year you are reporting on, not the year in which you perform the calculation. If you use the factor from the wrong year, the sum adds up, but the premise does not.
The factors themselves differ per energy carrier and, for electricity, per procurement method. For gas there is generally one factor per cubic meter of natural gas. For electricity the situation is more nuanced, and that deserves separate explanation.
Electricity: grey power, green power and the distinction that matters
With electricity it matters whether you consume power without a guarantee of origin, or whether you have specifically purchased green power with a certificate demonstrating its origin. For grey power, a factor applies that reflects the average Dutch production mix. For power with a valid certificate, a lower factor may apply, down to a factor based on virtually no emissions, depending on what the certificate precisely covers.
Whether you have a certificate and what it states is usually not shown on the energy bill itself but in a separate declaration from your supplier. If you do not have that declaration, the starting point is generally the factor for grey power, even if your supplier markets itself as sustainable in advertising.
Gas and other energy carriers
For natural gas, the calculation is more straightforward: consumption in cubic meters times the established factor for natural gas. If your company has its own fleet of business vehicles or uses fuel for machinery, the same principle applies but with different documents: fuel receipts or a fuel card statement instead of an energy bill, and a separate factor per fuel type. Heat that you draw through a district heating network works slightly differently again, because the supplier often has already accounted for part of the generation.
This means that a complete overview of your building's CO2 emissions usually comes from multiple sources at once: the energy bill for gas and electricity, and separate documents for everything outside that. Which line items are relevant for your situation depends on what you actually consume and which questionnaire you are answering; the overview of topics per situation provides a starting point for that.
What you can do with the figure, and what you cannot
The result of this calculation is an estimate based on consumption, not measured emissions. This is precisely what most questionnaires and the VSME standard also request: a calculation according to a recognized method, with a source you can point to. It is not an audit or assurance, and there is no body that certifies or approves this type of SME calculations.
What the calculation is sensitive to, however, is the source of the factor and the year it relates to. If the established factor changes for the next year, your result changes too, even if your consumption has not changed. This is not an error in your calculation, but a consequence of an updated source.
Do it yourself or have it documented
For most businesses, the calculation itself is straightforward: one or two invoices, a few fuel receipts, and a table of factors. The work lies in keeping track of which factor applies to which year, in keeping the underlying documents for when the same question comes back next year, and in maintaining an overview once you have multiple locations or energy sources.
On esgia.eu you can document those documents as soon as you have them; the platform links your consumption to the emission factor that applies to the correct reference date, and keeps the file so that the next questionnaire requires less work. If you want to first see whether this is relevant for your business, then the free quick-scan with a few questions gives a first indication, and the explanation of where the information comes from shows how the sources are maintained. If you have doubts about a specific part of your invoice, you may find the answer in the frequently asked questions about files and figures .