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Buildings

1. Context

The carbon footprint considered in the Buildings module includes the impact associated with the following two sub-modules:

  • The Rooms sub-module covers emissions relating to heating, cooling, ventilation and lighting of the various building locations related to the data entered in the internal database relating to rooms location.
  • The Energy Combustion Emissions sub-module is available to account for other energy combustion emissions in cases where a unit uses a non-centralised energy source. Emissions related to energy combustion in laboratories stem mainly from the on-site combustion of fuels used for heating, ventilation, hot water and specialized equipment.

The Buildings module aims to capture these energy-related emissions. The Rooms sub-module covers indirect emissions and therefore Scope 2. The Energy Combustion Emissions sub-module covers direct emissions and therefore Scope 1.

2. Data collected

Rooms sub-module

The internal database on floor location provides a list of the rooms used by a unit and their floor locations.

Data on energy consumption (in kWh/m²) and room types (DIN/SIA standards) are provided by the Vice-Presidency for Operations at EPFL (VPO). Consumption data is then redistributed according to the types of rooms used by a unit.

Energy Combustion Emissions sub-module

Data on centralised thermal energy consumption for the ‘Energy Combustion Emissions’ sub-module is entered manually.

3. Emission factors

Rooms sub-module

For electricity, the emission factor 0.097 kg CO₂-eq/kWh (BAFU, 2025) is used in this module.

Energy Combustion Emissions sub-module

For centralised thermal energy consumption, the emission factors are taken from the Corporate Footprint Calculator, and in particular from the BAFU database (2025).

For energy combustion emissions from non-centralised systems, the emission factors from Labos1point5 (2021, 2022) are used (see Section 7, Appendix).

4. Methodology

Rooms sub-module

The carbon footprint of each room \(CF_{rooms}\) is calculated as the product of the room’s floor location in m² and the consumption of heating, cooling, ventilation and lighting in kWh per m² by room type and by building as well as the emission factor for Swiss electricity as follows:

\[ CF_{rooms} = Surface \cdot \left( Cons_{heating, building, room_{type}} + Cons_{cooling, building, room_{type}} + Cons_{ventilation, building, room_{type}} + Cons_{lighting, building, room_{type}} \right) \cdot EF_{electricity} \]

Where:

  • \(buildings\): the building in which the unit’s rooms are located
  • \(room_{type}\): type from the categories office, miscellaneous, laboratories, archives, libraries and auditoriums
  • \(Surface\): floor occupation in m²
  • \(Cons_{heating, building, room_{type}}\)
  • \(Cons_{cooling, building, room_{type}}\)
  • \(Cons_{ventilation, building, room_{type}}\)
  • \(Cons_{lighting, building, room_{type}}\): electricity consumption for heating, cooling, ventilation and lighting of the room in kWh/m² extrapolated from VPO data, depending on the buildings and room type
  • \(EF_{electricity}\): emission factor for electricity consumption (0.097 kg CO₂-eq/kWh (BAFU, 2025))

Energy Combustion Emissions sub-module

\(CF_{combustion}\) carbon footprint is calculated as the product of the amount of fuel consumed in kg or kWh and the corresponding emission factor, as follows:

\[ CF_{combustion} = Q_{fuel_{type}} \cdot EF_{fuel_{type}} \]

Where:

  • \(fuel_{type}\): type of fuel used: natural gas, domestic fuel oil, biomethane, wood pellets, wood chips and logs
  • \(Q_{{fuel}_{type}}\): amount of fuel used for a non-centralised heating source in kg or kWh, entered manually.
  • \(EF_{{fuel}_{type}}\): emission factor for each fuel in kg CO₂-eq/kWh or kg CO₂-eq/kg.

5. Limitations

  • The floor location in m² provided by the internal database on rooms may not reflect reality in cases where rooms are shared or loaned.
  • Electricity consumption for heating, cooling, ventilation and lighting of the rooms is extrapolated from a single consumption value per building provided by the VPO to derive a specific value per use (heating, cooling, ventilation and lighting) and per type of room (office, miscellaneous, laboratories, archives, libraries or auditorium) based on the SIA standard.
  • The emission factor of 0.097 kg CO₂-eq/kWh represents a Swiss annual average, not the electricity mix at the time the equipment is in use.
  • Fuel consumption for estimating energy combustion emissions from a non-centralised heating system must be entered manually. The quality of the results therefore depends on the quality of this input data.

6. References

7. Appendix

Energy combustion emission category Unit Name Year Emission factor Unit of the emission factor
Natural gas kWh (net calorific value) Natural gas, average mix 2022 0.24 kg CO₂-eq / kWh PCI
Heating oil kWh PCI Heating oil 2014 0.3243 kg CO₂-eq / kWh PCI
Biomethan kWh PCI Biomethane – Injected into the networks – Average mix 2020 0.0444 kg CO₂-eq / kWh PCI
Wood pellets kg Wood pellets – 8% of humidity 2014 0.1108 kg CO₂-eq / kg
Forest chips kg Forest chips – 25% of humidity 2022 0.0503 kg CO₂-eq / kg
Wood logs kg Wood logs – 20% of humidity 2014 0.1138 kg CO₂-eq / kg 
Table 2 : Energy combustion emissions from non-centralised systems (Labos 1point5, 2021, 2022)