The Energy in Buildings Act - abbreviated to LENB - sets out the energy requirements for new and existing buildings in the private and public sectors in Germany: it imposes guidelines on thermal insulation, heating and air-conditioning technology, the use of renewable energy and heat protection. It also regulates the issue and use of the energy certificate. Breaches of the Energy in Buildings Act can be punished by the authorities as administrative offences, and can result in fines of up to €50,000.
Sounds important? It is! Read on and find out everything you need to know about the JIT requirements for :
The first amendment to the GEG Act came into force at the beginning of 2023, and a further amendment is planned for 2025 to help achieve the climate protection objectives and implement the mitigation package adopted in 2022 in response to the energy crisis.
What is the U-value?
The U-value is expressed in watts per square metre per kelvin (W/(m²K)) and measures the heat loss of a building element or material. It indicates the amount of heat output for a temperature difference of 1°C over one square metre - depending on the thickness and thermal conductivity of the building element or material. The lower the U-value, the better the insulation properties.
What does transmission heat loss mean?
Transmission heat loss is the energy that escapes through the building envelope. The level of transmission heat loss (H'T) depends on the U-values (thermal transmittance) of external building elements such as the roof, walls, windows or doors. The lower the U-values, the lower the energy loss from the building.
What is the annual primary energy requirement?
Annual primary energy demand is the amount of energy required for heating, hot water, ventilation and cooling (for non-residential buildings, also for lighting) - including consumption for the production, transformation, storage and distribution of energy. Primary energy demand is calculated from the reference building.
What does reference building mean?
The reference building is a "virtual auxiliary building" which, in terms of geometry, usable surface area and orientation, corresponds to the planned new building or the existing building to be renovated. The building envelope and installation techniques are selected here as prescribed by the LPE for residential or non-residential buildings.
In accordance with the Building Energy Act, new buildings must be built as energy-efficient houses 55 and meet the following requirements:
Part of the application for planning permission is proof of thermal insulation in accordance with GEG. The architect, specialist planner or energy consultant thus proves that the construction of the planned building complies with the prescribed annual primary energy requirement, heat loss through transmission and thermal protection in summer to limit the energy required for cooling. Once the building has been completed, it serves as the basis for drawing up the energy performance certificate.
For residential buildings, ECE can be demonstrated using either a simplified method or the reference building method. For non-residential buildings, the reference building method is compulsory.
The aim is to prove that the elements of the building envelope comply with certain U values over the entire surface area, and that a certain installation concept has also been implemented for heating and air renewal.
U values to be respected for each building element
| Component/system | Maximum permitted U-values for the reference building |
|---|---|
| Roofs, upper storey ceilings, dormer windows | U ≤ 0.14 W/(m²K) |
| Outside walls, floors downwards against outside air | U ≤ 0.20 W/(m²K) |
| Other opaque building elements (cellar ceilings, walls and ceilings overlooking unheated rooms, wall and floor surfaces against the ground, etc.) | U ≤ 0.25 W/(m²K) |
| Doors (cellar doors and external doors) | UD ≤ 1.2 W/(m²K) |
| Skylights and similar construction elements | U ≤ 1.5 W/(m²K) |
| Special patio doors (with flap, folding, sliding or lifting mechanism) | UW ≤ 1.4 W/(m²K) |
| Windows and other transparent construction elements | UW ≤ 0.90 W/(m²K) |
| Roof windows | UW ≤ 1.0 W/(m²K) |
| Thermal bridges | ΔUWB ≤ 0.035 W/(m²K) |
Authorised installation concepts
The open reference building procedure allows other installation concepts to be implemented - for example, the use of cogeneration, waste heat, liquid or gaseous biomass. The installation technology of choice is then also compared with a reference standard. However, the justification can be optimised thanks to the manufacturer's characteristic data and the exact lengths of the pipes, which can result in significant savings on the calculated annual primary energy requirement.
The quality of the building envelope is measured by the transmission heat loss (H'T), which balances the U-values of the building components and thus attests to the average insulating capacity of the building envelope. In this method, however, the U-values of the reference building (see above) are only used as suggestions and may or may not be exceeded. This makes it possible to create more economical solutions for the building envelope.
The Building Energy Act (GEG) requires homeowners to bring their properties up to standard, and sets out minimum standards that they must meet when extending or modernising. Minor measures that fall below the bagatelle limit are exempt, in other words work that involves renovating or refurbishing less than 10% of a building element, such as repairing cracks in façade rendering or replacing damaged tiles.
Tip: the EEG does not impose any requirements for façade painting, but if painting and scaffolding costs are involved anyway, it's often worth taking the opportunity to insulate the façade!
Obligation to prove that upgrades comply with ECE
The ECE sets out requirements for the U-value of individual measures. If the renovation is comprehensive, an overall energy balance must be drawn up using the primary energy or greenhouse gas method.
If you are planning individual measures such as façade insulation or window replacement, the modified or new building elements must comply with certain U-values. The required proof of thermal insulation is provided by means of the so-called building element procedure, in which the craftsman confirms, by means of a specialist company declaration, that the new U-values comply with the ECE. This document serves as proof to the inspection authorities.
These requirements do not apply to listed buildings or those whose structure is worth preserving.
| Component/system | Maximum U-value |
|---|---|
| Pitched roofs / roof slopes, dormers | U = ; 0.24 W/(m²-K) |
| Roof windows | UW= ; 1.4 W/(m²-K) |
| Flat roofs | U = ; 0.20 W/(m²-K) |
| Upper floor ceiling | U = ; 0.24 W/(m²-K) |
| External wall where layers of insulation, panels or panel-shaped construction elements, formwork or wall linings, new external rendering are installed | U = ; 0.24 W/(m²-K) |
| Windows and patio doors | UW= ; 1.3 W/(m²-K) |
| French windows with folding, sliding or lifting mechanism | UW= ; 1.6 W/(m²-K) |
| Exterior doors | U = ; 1.8 W/(m²-K) |
| Walls and ceilings against unheated cellar, floor slab | U = ; 0.30 W/(m²-K) |
| Ceilings against unheated cellars or slabs when building or renovating the floor on the heated side | U = ; 0.50 W/(m²-K) |
| Ceilings in contact with outside air downwards | U = ; 0.24 W/(m²-K) |
If you wish to renovate your building and, for example, replace windows, doors and heating and insulate the building envelope, you must - as with a new build - calculate the primary energy requirements or greenhouse gas emissions. However, the energy requirements may be higher than those of a comparable new building (reference building). Note that the submission of a greenhouse gas emissions calculation must be approved by the competent building authority.
U-values to be respected when renovating residential buildings
| Component/system | Reference house U-value |
|---|---|
| Roof, upper floor ceiling, walls to sides | U = ; 0.20 W/(m²-K) |
| Roof windows, glazed roofs and light strips | UW= ; 1.4 W/(m²-K) |
| Outside wall, first floor ceiling against outside air | U = ; 0.28 W/(m²-K) |
| Windows and patio doors | UW= ; 1.3 W/(m²-K) |
| External doors, doors to unheated rooms | U = ; 1.8 W/(m²-K) |
| Exterior wall to ground, floor slab, walls and ceilings to unheated rooms | U = ; 0.35 W/(m²-K) |
You decide what measures to take to comply with the maximum permissible transmission heat loss.
Roof
If you want to replace or rebuild your roof covering, including the battens and cladding, the Building Energy Act requires that the thermal insulation be checked and, if necessary, additional insulation installed.
Upper floor ceiling
If the upper storey ceiling of your property does not yet meet the minimum thermal protection standard in accordance with DIN 4108-2, you are obliged under the Energy Act to carry out subsequent thermal insulation. It is also sufficient for the roof above the upper storey ceiling to meet the minimum thermal protection standard. This is often already the case with wooden beam ceilings and ceilings of solid construction (from around 1969).
There are exceptions: as the owner of a detached or two-family house, you are exempt from the obligation to renovate if you were already living in the house before February 2002. If you sell it, however, the new owner must carry out the subsequent thermal insulation work within two years. You are also exempt from the obligation to renovate the ceiling of the upper floor if your building is heated to at least 19°C for less than four months of the year.
Piping
New heating pipes and hot water pipes in unheated rooms, such as cellars, must be insulated in accordance with the GEG law.
Cellar and ground floor
If you are installing or replacing external cladding, damp-proof barriers or drains, you must achieve a U-value of 0.30 W/ m²K or less for the cellar ceiling, cellar walls and perimeter insulation. If you are renovating the floor on the ground floor, you must achieve a U-value of 0.50 W/ m²K. You are exempt from this requirement if the building components mentioned were built or renovated after 31 December 1983, in accordance with the statutory energy-saving provisions.
Exemption from ECE requirements
If the renovation costs are not amortised within a reasonable period, they can be exempted from the requirements of the Building Energy Act.
In the case of an extension of less than 50 m2 of usable surface area, a simple justification of the thermal insulation using the building component method is sufficient. If the modifications do not exceed 10% of the total surface area of the building component concerned, the de minimis rule applies and no special requirements come into play. However, they must not deteriorate the quality of the building.
If you are building more than 50 m2 of floor space, you will also need to provide proof of summer thermal protection.
If you are adding heated or cooled rooms to your residential building, the requirements for new buildings apply: New external elements such as the façade, roof and windows must not exceed 1.2 times the heat loss through transmission of the reference building. For non-residential buildings, the heat transmission coefficient (U-value) must in this case remain less than 1.25 times the maximum value.
