The Building Energy Act (GEG) only applies to Germany, the Renewable Heat Act (EWärmeG) only to the German state of Baden-Württemberg.

Both laws stipulate minimum proportions of renewable energies to cover the heating requirements of buildings. The following applies to both laws:

• The fulfilment levels of heat pumps and solar thermal systems may be added together.
• Monovalent HP systems automatically have a fulfilment level of 100 % if the heat pump exceeds a certain SPF (see below), determined by the VDI 4650.

Building Energy Act (GEG)

The GEG applies nationwide and specifies minimum proportions of renewable energies in new buildings. GeoT*SOL shows which legal requirements from the GEG the simulated system fulfils or does not fulfil. For the systems in GeoT*SOL are subject to various legal requirements.

Some systems may be subject to several laws at the same time. E.g. systems with boiler, heat pump and collectors. In this case all laws are displayed with the corresponding criteria. In the project report you can decide which law should be displayed in the project report and which law is hidden.

Heat generation

GEG Section 71 (1) for pure heat pump systems

• Heat pump, elec. drive:
  Electrical energy consumed by the heat pump during the year.
• of which renewable (electricity):
  Proportion of energy generated from renewable sources. For example, the proportion of energy covered by the photovoltaic system. Or the regenerative share of the electricity supplier’s electricity mix.
• Biomass/natural gas/oil boilers:
  Electrical energy generated by the boiler.
• *of which renewable (fuel):
  Proportion of energy generated from renewable sources. E.g. the proportion of biogas.

Hybrid system (heat pump)

GEG § 71h for hybrid systems with a heat pump

Hybrid system (solar thermal system)

GEG § 71h for hybrid systems with a solar thermal system

• Residential buildings with more than two flats:
  For residential buildings with a maximum of two residential units, an aperature area of 0.07 m² per m² of floor space is required. For residential buildings with more than two residential units, an aperature area of 0.06 m² per m² of floor space is required.  

Renewable Heat Act (EWärmeG)

The EWärmeG only applies in Baden-Württemberg and specifies minimum proportions of renewable energies in existing buildings. In GeoT*SOL the degree of fulfilment can be taking into account the heat pump and an existing solar system can be determined. The law requires a degree of fulfilment of 100 %.

Heat pump

For the heat pump, a distinction is made as to whether the energy requirement is covered by the heat pump alone or additionally by a second fossil fuelled heat generator.

• The SPF according to VDI 4650 must be greater than 2.5.
• In the case of additional fossil heat generators, the energy is calculated with:
  chargeable heat pump energy = (JAZ-3)/JAZ * energy emitted by the HP
• The degree of fulfilment is then determined with:
  15 % * creditable heat pump energy / total energy requirement

Solar system

The degree of fulfilment is 100 % if

• the solar system covers either 15 % of the total energy requirement
• the area of the solar system exceeds a minimum size (0.7 m² per m² of usable floor space for single-family houses, 0.6 m² for apartment blocks). For more efficient tube collectors, the minimum area is minimum area is 20 % less.

The individual degrees of fulfilment (heat pump and solar system) may be be added together. Other possible combinations (other energy sources, insulation measures) are not shown in GeoT*SOL.

Parameters

The parameters used in the calculation are displayed:

• The usable building area from the side Space Heating
• The design temperature of the heating system from the side Space Heating
• The performance figures of the heat pump used

 

Indicate whether the building has more than two flats (on the side of the GEG). This is used to determine the minimum area required for an solar system is determined.

Degree of fulfilment

The following values are output as results:

• The HP must have a minimum SPF. The reference is the SPF according to VDI 4650.
• In the case of bivalent/monoenergetic systems, the chargeable HP energy is output.
• The fulfilment levels for the heat pump and the solar thermal system.
• Solar installations must exceed a minimum area, which is also is also displayed.
• The total degree of fulfilment as the sum of the individual degrees of fulfilment.