CO2 Balance

Vue aérienne du campus EPFL en 2017

CO2 balance of EPFL


A detailed monitoring to understand the challenges of the campus and achieve CO2 emission reduction targets.

EPFL’s CO2 balance has been developed from a life cycle analysis established with the EPFL spin-off Quantis. The figure above illustrates the carbon balance from 2006 to 2021 and refers to the objectives of the Confederation (-50% by 2030 compared to 2006, except for professional mobility (-30% compared to 2006)). The balance takes into account data from the main campus in Ecublens as well as from the associated campus in Valais, Neuchâtel and Fribourg. The energy data from Geneva are not included in the balance. It includes 4 themes: energy (electricity, fuel oil and gas), business travel, commuting and nutrition (see below).

Feel free to contact us for any questions or information about the calculations/assumptions used.


EPFL purchases significant amounts of electricity each year (approximately 73 GWh in 2019). Since 2012 and until the end of 2019, the accounted carbon impact of electricity was very low thanks to the purchase of guarantees of origin (GO) certifying the purchase of renewable electricity. Thus, in 2020, the electricity mix purchased by EPFL from Romande Energie consisted of 97.5% of Swiss hydroelectricity and 2.5% of photovoltaic electricity (corresponding to what is produced on EPFL roofs). The impact factor associated with hydropower was set at 7.3 g CO2 eq/ kWh in 2012 by Quantis and used as such until the end of 2019.

According to accounting based on purchase of certificates of origin, the emission reduction target would have already been reached as early as 2019, while electricity consumption increased by 35% between 2006 and 2018.

Since 2020 and according to recommendations of the committee of experts consulted in the framework of the elaboration of EPFL’s Climate & Sustainability Plan, EPFL has chosen to calculate its carbon footprint using an emission factor that considers the place of production of electricity but also the impact linked to imports/exports and seasonal variation. This helps to reflect the true impact of campus’ electricity needs and the actions needed to reduce that impact.

The emission factor taking into account imports/exports chosen for EPFL is the one recommended by the Federal Office for the Environment (FOEN) (Verbraucher Strom-mix) in April 2021: 128g CO2-eq/kWh.


Carbon Accounting for Electricity

Carbon accounting for electricity can be very complex depending on methodologies used to convert electricity into carbon equivalents. Indeed, depending on the chosen methodological approach, considering or not the import/export of electricity, the carbon emission factor of electricity in Switzerland (Swiss mix) can vary from 30 g to 128 g CO2-eq/kWh (FOEN 2021). The choice of the highest factor considers the real consumption of electricity in Switzerland and permits to integrate the significant impact linked to importation in winter, in particular from countries using coal-fired power plants.
EPFL uses the latter approach to reflect the real impact of its campus electricity needs and the actions to be taken to reduce its GHG emissions.


The gas consumed was mainly used for heating (60%) and laboratory processes (40%). Exceptionally, due to the renovation works of the campus’ Heat Pump Power Plant (CCT), the consumption of gas for heating is higher over the period 2019-2021.

Starting from winter 2021-22, the part of gas used for heating has been strongly reduced as the heat pump power plant only use electricity as energy source.

The remaining part depends on laboratory processes.

Fuel oil

Fuel oil was used as a secondary heating source for the operation of the CCT in very cold temperatures. For information, with the renewal of the CCT, oil consumption ceased in 2019. However, the part consumed during the 2019 year-end remains.


The data are based on the mobility survey offered to employees and students. Measures implemented within the framework of the Mobility Plan, such as the new parking policy, the reinforcement of the public transport offer as well as the promotion of cycling, show positive effects with a strong decrease in the modal share of individual motorized transport.

Business and student travel

The values are calculated from data provided by EPFL’s central travel agency. Student travel data correspond to all trips abroad made as part of the university curriculum (internships, academic exchanges, Master’s projects and study trips). These data are reflected in EPFL’s CO2 balance since 2019.

The revision of the Directive for Responsible Business and Student Travel, the reinforcement and promotion of videoconferencing tools and the organization of awareness campaigns are part of the strategy to reduce travel-related CO2 emissions.


This theme is now one of the priorities for action in terms of sustainability. Values were calculated according to the number of vegetarian and non-vegetarian meals consumed on campus through the end of 2018. Since 2019, reporting is more detailed and based on restaurant purchase data as well as discarded organic waste.


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EPFL Sustainability
BS 101 (BS building)
Station 4
CH-1015 Lausanne