Climate-neutral building stock Dovetailing of efficiency, building technology and renewables is necessary

The decision has now been made: The Council of the European Union has also confirmed the amendment to the European Buildings Directive (EPBD). It aims to increase the efficiency of the building stock in the EU. By 2030 and 2033, the average primary energy consumption of the residential building stock is due to fall by 16 and 20-22 per cent respectively. Minimum energy performance requirements will be created for non-residential building stock. To achieve this, threshold values must be set at national level so that 16 or 26 per cent of non-residential buildings with the worst energy performance are below these. These buildings must then be retrofitted by 2030 or 2033.  

The importance of taking a holistic view of a building is therefore once again taking centre stage. Most recently, the debate surrounding the Building Energy Act and the associated obligation to gradually switch to at least 65 per cent renewable energies in the heating supply in Germany has focused heavily on building technology. An ambitious efficiency policy fell by the wayside. The retrofitting rate in German building stock is currently stagnating at less than one per cent.

The 65 per cent rule is a paradigm shift towards the use of renewable energies in the building sector. The just under 25 million heat generators, of which around 80 per cent are still operated using fossil fuels, are a major lever. However, it is only possible to cover the required energy demand of buildings by taking a holistic view of each individual building: Only if all components are fulfilled will a climate-neutral building stock be achievable by 2045 - system technology, renewable energies and the building envelope should be given equal consideration.

The greatest potential for energy savings, which is usually also very economical, lies in efficient existing buildings. At the same time, inefficient buildings can pose a high risk of energy poverty for building owners and tenants. High and volatile fossil fuel prices are already a threat to an affordable and secure energy supply. The rising price of CO₂ as a result of EU emissions trading is likely to exacerbate this situation going forward. Nevertheless, renewable energies are also finite and not available free of charge.

Exactly what a future-oriented heat supply might look like depends on various planning components. Integration into the existing supply structure and thus municipal heat planning, including the local conditions, is of central importance. Plans for the transformation of heating networks play a key role. Local authorities must clarify the path to be taken as early as possible in order to provide guidance for building owners. The tool for this is municipal heat planning. At the same time, experts with a building-centred view are required when it comes to planning the retrofitting of an individual building. This is where the individual retrofit roadmap (iSFP) with its integrated approach comes in, which also enables a step-by-step retrofit over a number of years with simultaneous coordination of all individual measures.

Not every building is suitable for all technologies. To this end, dena, together with @ITG Dresden and @FIW Munich clearly presented 14 different options for meeting requirements for detached and semi-detached houses in the existing building stock as part of the Climate-Neutral Building Forum. As districts offer particular potential for grid-connected supply, dena has also developed various supply options based on local heating for four different types of residential area at district level together with engineering company @Megawatt, in order to provide reference points for the implementation of renewable heat supply.

There are no technical obstacles to the installation of heat pumps in new residential buildings. This is also a mature technology that can be used in many buildings with existing radiators and can replace fossil-fuelled heating systems. But heat pumps should be used sensibly and efficiently. Where this is the case can be clarified through a professional energy consultation, preferably with a company on the the list of energy efficiency experts for federal funding programmes. This helps, preferably using an individual retrofit roadmap drawn up on the basis of the consultation, to decide whether a heat pump can be installed without additional measures or which additional efficiency measures would make sense.

This is because poorly insulated buildings require higher flow temperatures, which can have a negative impact on the efficient operation of a heat pump because the amount of electricity required and therefore the energy costs increase. Generally speaking, however, even after a heat pump has been installed, the energy requirement can still be gradually reduced so that the need for renewable energy and the operating costs of the heat pump continue to fall.

The fact is: In order to achieve the climate action targets, we need measures in all areas. Switching to and using renewable energies is just as important as energy efficiency measures that reduce energy requirements. Taking the life cycle aspects of individual components into account further reduces the proportion of grey energy and ensures greater climate action.