{"id":57834,"date":"2025-11-26T10:26:34","date_gmt":"2025-11-26T09:26:34","guid":{"rendered":"https:\/\/www.deos-ag.com\/?p=57834"},"modified":"2024-01-11T08:46:03","modified_gmt":"2024-01-11T07:46:03","slug":"energy-optimisation-in-existing-buildings","status":"publish","type":"post","link":"https:\/\/deos-ag.com\/en\/blog\/energy-optimisation-in-existing-buildings\/","title":{"rendered":"Energy optimization in existing buildings"},"content":{"rendered":"

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Table of contents<\/h2>\n
    \n
  1. Obligation to refurbish in accordance with the Building Energy Act<\/a><\/li>\n
  2. Requirements for existing buildings<\/a><\/li>\n
  3. Requirements for technical building systems<\/a><\/li>\n
  4. Building optimization<\/a><\/li>\n
  5. Savings potential in buildings<\/a><\/li>\n
  6. Thermal insulation<\/a><\/li>\n
  7. Efficient building technology<\/a><\/li>\n
  8. Building digitization<\/a><\/li>\n
  9. Digitization in existing buildings<\/a><\/li>\n
  10. Advantages of energy optimization of buildings<\/a><\/li>\n
  11. State support<\/a><\/li>\n<\/ol>\n

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    Obligation to refurbish in accordance with the Building Energy Act<\/h2>\n

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    Energy consumption in German buildings is too high! The German government has therefore set itself the goal of reducing heating requirements in buildings by 80% by 2050. If this goal is to be achieved, there is no way around the mass refurbishment of existing buildings. Therefore, the Building Energy Act (GEG) has been in force since November 1, 2020. This leads requirements for the energy quality of buildings. It also obligates the declaration of the building-specificCO2 footprint<\/sub> in the energy certificate and prescribes the purchase of renewable energies for public buildings. The requirements of the GEG for buildings are regularly renewed and tightened. Here it is worthwhile to introduce efficiency measures at an early stage. Compliance is verified by the chimney sweep and the local building department.<\/p>\n

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    Requirements for existing buildings<\/h2>\n

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    Minimum standards must be met<\/h3>\n

    When renovating the exterior of a building, minimum thermal insulation standards apply, which are defined in Annex 7 of the GEG. Alternatively, the requirements are also considered to be met if both the annual primary energy demand and the heat transfer coefficient of a reference building defined in the GEG are not exceeded by more than 40%.<\/p>\n

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    Minimum thermal protection<\/h3>\n

    The GEG prescribes a minimum thermal insulation according to DIN 4108-2:2013-02. If this is not met, the floor slabs or roof must be subsequently insulated so that a maximum heat transfer coefficient of 0.24 W\/m2K<\/sup>is ensured.<\/p>\n

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    Energy certificate<\/h3>\n

    When selling or renting the building, an energy certificate must be given to the buyer or tenant. In highly frequented buildings, the energy certificate must also be displayed in a clearly visible manner. This applies to official buildings with a usable floor area of 250m2 or<\/sup> more and to other buildings with a usable floor area of 500 m\u00b2.<\/p>\n

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    Renewable energies<\/h3>\n

    Public buildings should act as role models for climate protection. Therefore, it is true that the energy demand after renovation must be partially covered by renewable energy. Alternatively, the requirement can be met through the use of waste heat, a CHP plant, the purchase of district heating or cooling, or through measures to save energy.<\/p>\n

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    Requirements for technical building systems<\/h2>\n

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    Replacement of oil and gas heating systems<\/h3>\n

    Old oil or gas heating systems with an output of 4 to 400 kW must be replaced if they were installed before 1991.<\/p>\n

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    Automatic controls for central heating systems<\/h3>\n

    Since October 2021, central heating systems must be able to automatically control heat supply and the switching on and off of electric drives depending on the outside temperature and time.<\/p>\n

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    Automatic controls of room temperatures<\/h3>\n

    Heating systems must have automated control of individual room temperatures. Group regulations are permissible for rooms of the same type and use.<\/p>\n

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    Insulation on pipes<\/h3>\n

    Freely accessible heating and hot water pipes and their fittings must be insulated in unheated rooms.<\/p>\n

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    Controls for air conditioning and ventilation systems<\/h3>\n

    In newly installed air conditioning systems with a cooling demand of more than 12 kW and in room air conditioning systems with a supply air volume flow of more than 4000m3\/h<\/sup> applies:<\/p>\n