Where do you start as an installation company
You start with the invoices already in your administration: the energy bill for your business premises, fuel receipts or fuel card statements for your company vehicles, and possibly a lease contract showing the fuel type and mileage. These documents account for most of your direct emissions. For an installation company, there is something else that does not apply in office-based sectors: travel to customers and the materials you purchase for processing.
A CO2 calculation does not weight everything equally and not everything belongs in your own figures. What you consume directly — gas for the premises, fuel for your own vehicles, electricity you purchase — counts most directly. What others in the supply chain consume, such as the manufacturing of materials you process, is treated differently and is often (still) not what a customer of a smaller company is permitted to request.
The vehicle fleet: the largest item for most installers
For most installation companies, the largest part of their own emissions lies in the vehicle fleet: vans, service vehicles, sometimes a single truck for material transport. The source is straightforward: fuel receipts, fuel card statements or invoices from the leasing company. From these you extract the number of litres of diesel or petrol per year, or for electric vehicles the kWh charged. If part of the vehicle fleet is leased with a fixed fuel budget, the consumption is usually shown per quarter on the fuel card invoice.
It is important that you do not make an estimate based on kilometres alone, unless that is your only source. A fuel receipt is more accurate than an estimated consumption per kilometre, and the entrepreneur confirms themselves what has been read from the receipt before it is recorded in a file.
Materials: what does and does not belong in your own calculation
Installation companies process pipework, cables, sheets, pumps and equipment manufactured elsewhere. The emissions from that manufacturing do not belong in your direct figures (scope 1 and 2), but in the broader supply chain around it. Whether and how detailed you must report this depends on what the voluntary standard for smaller companies requires, and that is exactly where the boundary lies between what a customer is permitted to request and what is not. A screening of the questionnaire you received shows per question whether it falls within that boundary.
Materials that are often useful to keep separate: purchase invoices for major items such as heat pumps, solar panels or specific installation materials. Not because every questionnaire requests this, but because the file you are building now will be reusable for the next questionnaire.
On-site work: where things often go wrong
Some of your employees do not work in an office but at the customer's location: installing, maintaining, fixing faults. The fuel for the trip to the customer falls under the vehicle fleet and is already included in the fuel receipts. What is often overlooked is energy used on site — a generator, a compressor, tools connected to the customer's power supply on the construction site. The latter typically does not count in your own figures, because the consumption and invoice are with the customer, not with you.
If you operate a generator or mobile power supply yourself, the fuel consumption from it is indeed your own item and belongs with the vehicle fleet or a separate line for equipment, depending on how you can distinguish it separately in your administration.
From invoices to an initial figure
The conversion of liters of fuel or kWh to a CO2 figure is done using established emission factors that are updated for each reference date. You don't need to look up or keep track of these factors yourself; that's precisely the work behind a dossier. What you do handle yourself is providing and confirming the source: this receipt, this consumption, this period.
On topics per sector and situation you can see which documents are specifically requested for the installation sector, in addition to the general list of energy bills, fuel receipts and payroll administration. If you first want to know whether the questionnaire you received falls within the limit that has applied since March 2026, you can read about that in the frequently asked questions, or you see how the dossier is built up before you start with anything.
A first indication of where your business stands, without filling in anything, you get with the quick scan.
Do the free quick scan of a few questions or read first the answers to the most frequently asked questions to see whether and when this applies to your business.