Challenges on the way to a plus energy multifamily building: from planning to implementation
A climate-neutral building standard for new and existing buildings is essential for achieving climate protection targets in the residential building sector. In the BMWK-funded research project “sEnSys”, a holistic energy supply concept for multi-storey residential buildings that achieve plus energy in the annual balance is being developed and implemented in a real demonstration building. The concept focuses on energy-efficient, grid-friendly and smart building technology, a predictive control strategy and cost-effective operation via suitable operator models (e.g., tenant electricity model). Planning a plus energy building requires a holistic approach. Various aspects such as energy efficiency, the use of renewable energies, building regulations and user behavior must be taken into account. This complexity can delay or complicate implementation. When the planning is detailed, this complexity and investment costs can come to the centre of attention and cause a change in the planning that could have a negative impact on the plus energy balance. As a result, the preliminary target can be missed during implementation. This paper shows an energetic, economic and ecological evaluation of the retrofit measures in the planning process of a demonstration building. The starting point is the preliminary planning, which moves further and further away from the initial situation as the project progresses due to changes in the building class and building technology. An assessment is made throughout of how the current planning status can be reconciled with the plus energy balance. In order to be able to make well-founded statements about energy consumption and the ecological footprint, calculations were carried out in accordance with DIN TS-12831 and DIN V 18599 and the resulting boundary conditions were used in simulations in the software TRNSYS. The economic viability of the retrofit was examined over a period of 25 years using the annuity method of depreciation.