Plus minus zero: carbon dioxide emissions of plus energy buildings in operation under consideration of hourly German carbon dioxide emission factors for past, present and future

Abstract

Abstract The energy supply of private household buildings accounted for 16 % of the total German CO2-emission in 2020. To fulfil the targets of a climate neutral building sector in 2045, both, energy efficiency as well as on-site use of Renewable Energies in buildings are needed. One concept of a climate neutral building is the so-called Efficiency House Plus, that features large photovoltaic systems making it seemingly energy self-sufficient and CO2-negative by feeding in more electric energy into the grid than needed for its operation on a yearly basis. In fact, houses of this type are highly grid dependent especially during winter months due to their solely electrically based energy supply and a missing long term energy storage. This paper analyses the CO2 -emission of Energy Efficiency Plus houses more in detail on a timely resolved basis for the German electric supply system of the year 2013, 2021 and a perspective one 2030. An alternative calculation approach for simplified normative evaluation of such buildings is proposed.