From certificate to physics - Paths to net-zero compatible buildings

Abstract

The role of heat pumps in a decarbonised (thermal) energy system is pivotal. This technology is often in competition with other technologies such as district heating or boilers. When comparing different heating technologies in respect to their CO2 footprint and their costs, the calculation method of future greenhouse gas emission factors of the different energy carriers and energy prices is decisive. Emission factors need to be based on technical and physical fundamentals as (international) green certificates are not a satisfactory proxy for physical emissions, especially for the case of electricity. Currently the Swiss electricity generation system is mostly decarbonised with its high share of hydropower and nuclear energy. However, Switzerland, located in the heart of Europe, has the highest relative shares of cross border capacities, which are relevant for energy trading. In a still fossil dominated European power system, the high volatility of wholesale power prices is entailing a high (temporal) volatility of power related emissions. Thus, the overall carbon footprint of consumed electricity changes significantly over time. Heating demand also shows a dynamic behaviour. It is therefore likely, that a CO2 footprint based on annual averages in heating demand and emission factors could lead to significant errors. The aim of the research was to draw a comparison of the resulting annual CO2 emissions applying different time step aggregation levels (yearly, monthly, typical days) with the results calculated based on a complete year in hourly resolution. The aim was to determine the relative error made through aggregation.