It is rather rare for supposedly dry and technical bills to be discussed not only in parliament and the sectors concerned, but also by the general public. The Building Energy Act, particularly for existing buildings, can definitely be considered an exception in this respect.
Hardly any other amendment to the law has been discussed so controversially and passionately from the Bundestag to the kitchen table in the recent past. The reason is obvious: it not only regulates the near future of the heating transition, but also affects broad sections of the population: Building owners, tenants, landlords, planners and construction companies. It is therefore not too surprising that in times of inflation, scarce resources and climate change, even energy-related issues are the subject of particularly passionate debate.
After the Bundestag passed the final version of the law on September 8, 2013, the focus is now on very specific questions. What impact will the Building Energy Act have on old and new buildings? What will happen to existing heating systems? And are there transition periods? We provide an overview.
The most important facts in brief
The Building Energy Act (GEG ) defines energy requirements for heated and air-conditioned buildings for existing buildings.
According to the new heating law, newly installed heating systems must be operated with at least 65 percent renewable energy.
New buildings must comply with the 55 efficiency house standard.
There is no obligation to replace heating systems in existing properties.
What is the Building Energy Act?
Behind the unwieldy name lie numerous changes with far-reaching consequences for the energy planning of new buildings and existing properties.
Specifically, it defines the energy requirements for buildings. The GEG combines and replaces previous energy laws such as the Energy Saving Ordinance (EnEV 2022), the Energy Saving Act (EnEG) and the Renewable Energies Heat Act (EEWärmeG) by merging their content into a single regulation.
The original Building Energy Act has already been in force since 2020, so strictly speaking the hotly debated new version is merely a continuation and update - even if it contains far-reaching changes.
It applies to all buildings that have heating or air conditioning. Its provisions focus primarily on the respective heating technology and the thermal insulation standard and are particularly important for building services planning. For example, new buildings may only consume a certain percentage of the primary energy of a reference value, which is calculated individually for each building.
Energy balance as a benchmark
To determine the energy consumption of a building, not only space heating and cooling are taken into account, but also hot water preparation, the operation of ventilation systems and electricity consumption by devices such as heating pumps, boilers or controllers.
Furthermore, certain requirements for air exchange and the minimization of thermal bridges must be met. In addition, the Building Energy Act defines regulations for existing air conditioning technology and measures for heat protection during the summer months.
What needs to be considered for new buildings?
According to the GEG, all planned and constructed new buildings are required to meet the standards of a nearly zero-energy building from 2023. Such a building meets the requirements of an Efficiency House 55. The technical implementation of the reference building is defined in detail in Annexes 1 and 2 of the GEG.
A new building must meet the following requirements, among others:
Annual primary energy demand: The GEG takes into account the entire process chain of energy consumption. According to § 15 of the GEG, the annual primary energy requirement for heating, hot water, ventilation and cooling may not be more than 0.55 times that of a corresponding reference building.
Tightness: According to Section 13 of the GEG, the building envelope must be airtight and carefully sealed. At the same time, it must ensure a minimum air exchange rate in order to meet the needs of the occupants and the heating system.
Structural thermal insulation: The heat loss through the building envelope may not exceed 1.0 times the corresponding value of the respective reference building.
Thermal bridges: Heat losses through connections in the building envelope should ideally be minimized, although economic aspects must also be taken into account.
Heating in new buildings
According to the GEG, in future every newly installed heating system must be powered by 65% renewable energy - initially limited to new-build areas, outside of which from 2026 at the earliest.
According to the GEG, renewable energies for heating are
Geothermal energy
Environmental heat, e.g. from a heat pump (air-to-air heat pumps or air-to-water heat pumps, e.g. for underfloor heating)
Waste heat from other processes in a district heating network
photovoltaic electricity generated at the new building
heat generated on the building itself through solar thermal energy
self-generated wind power
Heat from biomass (e.g. wood pellets or biogas)
green hydrogen
What needs to be considered for existing buildings?
The energy requirements for existing buildings are significantly lower than for new buildings. As part of renovations, owners are not permitted to carry out measures that worsen the energy quality of the building.
When extending and expanding buildings, it is mandatory to comply with the minimum standards of the Building Energy Act, for example with regard to the thermal insulation of the building envelope or the energy standard of the heating system.
Border Temperature correction factor
to the ground 0,4
adjacent buildings 0,5
unheated room 0,8
to the outside via a roof 0,9
Outside air 1,0
The most important value defined by the GEG for modernization measures is the "heat transfer coefficient", also known as the U-value. It quantifies how much heat is emitted to the outside through a building component and is therefore lost. A low U-value stands for more effective insulation and thus minimizes heat loss.
Do old heating systems need to be replaced?
The rule of the Building Energy Act that new heating systems must be powered by 65 percent renewable energy in future also applies to existing properties.
In fact, however, nobody needs to worry that there is an immediate obligation to replace the heating system. The new version does not provide for a mandatory obligation to replace heating systems. Existing heating systems may continue to be put into operation and defective systems may be repaired. However, if a heating system breaks down irreparably, generous transitional periods are granted.
It is also possible to temporarily install a gas heating system, provided it can be prepared for hydrogen conversion.
In the long term, therefore, there is definitely an obligation to carry out energy-efficient refurbishment - although a corresponding heating subsidy will also apply from 2024.
What happens when existing heaters break down?
In principle, any existing heating system may continue to be repaired indefinitely. If repairs are no longer possible, the Building Energy Act for existing buildings stipulates, as already mentioned, that the newly installed heating system must be powered by at least 65% renewable energy. A transitional period is granted for this, which is five years as standard, although a longer period of up to 13 years applies for gas or oil heating systems.
If a connection to a heating network is planned as part of municipal heating planning, the transitional period can be extended to up to ten years. During the transition period, it is even permitted to install a used heating system that is operated with fossil fuels.
In exceptional cases, owners also have the option of being exempted from the obligation to use renewable energies for heating purposes.
The new Building Energy Act is merely an adaptation of existing laws
The controversial discussions in the run-up to the law almost suggested that the Building Energy Act would turn the entire construction industry and current standards for buildings and heating systems upside down. In reality, however, it is merely a (stricter) further development of the previous law.
The amendment to the law sets out strict standards which, among other things, aim to reduce energy consumption in the building sector and counteract the environmental impact. In doing so, the GEG requires appropriate evidence and takes both new and existing buildings into account.
One of the key innovations is the 65% target for new heating systems. This does not, as originally feared, mean that heat pumps will be the only legitimate source of heat in the future. The GEG is deliberately designed to be open to all technologies - which should make it easier for planners to design future heating systems.
Digital tools can provide crucial support in implementing the new requirements of the Building Energy Act. Trimble Nova is a powerful calculation software that is able to precisely visualize heating systems and building technology and harmonize them with other trades.
The integrated interface to Trimble Connect also creates a shared data environment and ensures that all relevant data is accessible to all project participants in real time. With this combined digital power, teams are ideally prepared for the stricter standards of the Building Energy Act.
