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The QNG is a state quality seal for buildings. The prerequisite for awarding the quality seal is proof of the fulfilment of requirements for the ecological, socio-cultural, and economic quality of buildings.

The quality seal is awarded by independent bodies on behalf of the Federal Ministry of Construction after certification. The quality seal is awarded in the requirement level 'PLUS' or 'PREMIUM' for residential and non-residential buildings. For residential buildings, set benchmarks exist depending on the ambition level:

QNG-PLUS is awarded in cases where the total life cycle carbon footprint is no higher than 24kg CO2e/(m²*year) and the calculated non-renewable primary energy requirement of the building is no higher than 96 kWh/(m²*year).
QNG-PREMIUM is awarded in cases where the total life cycle carbon footprint is no higher than 20kg CO2e/(m²*year) and the non-renewable primary energy requirement of the building is no higher than 64 kWh/(m²*year).

For non-residential buildings, the QNG-PLUS and QNG-PREMIUM benchmarks are determined on a project-specific basis, as detailed in Annex 3 of the QNG manual.

The scope of building elements includes building parts from Kostengruppen (KG) 300 and KG 400 according to DIN 276 (2018). Outdoor components according to KG 500 are to be taken into account if they are necessary to maintain building operations.

All building materials with a share of more than 1% of the total mass of the building, more than 1% of the (PEne) or more than 1% of GWP100 must be taken into account. Small parts such as nails and screws or minor quantities (≤ 1 kg) can be neglected.

The life cycle stages included in the assessment are A1-A3 (product phase), B4 (material replacements), C3-C4 (end-of-life processing and disposal) for materials and additionally B1 for refrigerant leakages and B6 for energy consumption.

For your calculations with the QNG tool, we recommend the following workflow:

Create a Project and Select a Tool

Create a building project and select the ' LCA for Qualitätssiegel Nachhaltiges Gebäude (QNG)' tool as the chosen calculation tool.

Create Your First design and Select LCA Parameters

Ensure that the 'Product specific service life' is selected for the default service life value.

Calculation Period

Set the calculation period to 50 years in the ‘Calculation Period’ tab.

Building Area

Fill in the Building area question by entering the appropriate area in 'Netto-Raumfläche, NRF'.

Building Materials

Fill in your project information in One Click LCA by entering the design information either manually or by importing your data (see guidance for data import here).

Only generic QNG data ("Rechenwerte") is available in this tool as per the QNG requirements.

To correctly include KG 400, add the base value (“Sockelbetrag”) representing some of the HVAC components based on the correct LCA class, and the ambition level. Add this under the “Building technology” section of the material query and assign the correct KG from the list (“400 - TGA Sockelbetrag”). The base value includes defaults for systems such as electrification, heat distribution, and piping. In addition, the large equipment not included in the value must be added. See the list in the manuals for residential and non-residential building to confirm which items to add.

For complete modernisation, add the materials and tick the “reused” box. This will disregard product phase emissions but include the replacements after required service life of the material, as well as the end-of-life emissions from processing and disposal.

Energy consumption

Input the building annual energy consumption for one year. This value will be multiplied by the calculation period for full life-cycle results.

In the QNG calculation, energy consumption in use (B6) is divided into three subclasses:

B6.1: The regulated energy consumption (kWh).
- The total B6.1 values for consumed electricity and heat originate from the  GEG model. This includes the loads from heating, cooling, ventilation, and de-/humidification of the building according to the planned envelope, building services and zonal conditioning.
- For electricity, use the datapoint “Usage - 1 kWh national grid electricity mix, version 1.2” and assign KG B6.1
- For heating, choose the data set based on the actual energy carrier and assign KG B6.1.
B6.2: The unregulated energy consumption for the operation of the building (Only for non-residential buildings). It includes the use of elevators and central services (low voltage systems & video surveillance). The corresponding resources can be found in section 1 of the energy consumption tab.
- Elevators: Use Tables 11 and 12 in the QNG guides to determine the resources based on the elevators specified for the building.
- Low-voltage systems: Reported per NRF. You will need to enter an additional low-current asset resource for each low-voltage system used.
- Video surveillance: CCTV is reported per surveillance area.
B6.3: The user's energy consumption. For residential building, this is described by a default value of 20 kWh/(m²*year). For non-residential buildings values are defined per zone. The input is m² of applicable zone.
PV impact: The self-generated and self-used energy is defined by an emission factor of zero. To represent the savings gained from this renewable energy use in the tool, add the kWh produced as a negative value and assign it to the classification "Eigengenutzter Anteil erneuerbarer Energie". This reduces the project’s B6 module according to the renewable energy generated and used. If your building produces renewable energy, the equipment required for this must be added to the material query.
Exported energy: Any self-generated energy that is exported outside the building/site boundary is reported in module D2. Input your kWh values in section 4, “Exported energy”. Enter the energy as a positive kWh value – the calculation automatically converts it to a negative to represent benefits in module D2. According to QNG, you need to use the data set with 550g CO2 equivalents/kWh called “Specification of exported energy from PV systems (displacement current mix for PV from DIN 18599-1:2018-09, Table A.1)”.

General note: The datapoints should be added as separate inputs and then marked appropriately using the cost group options to refer to the respective B6 subclass.

Reference Values

To compare the performance of the building under assessment to QNG benchmarks, a reference building must be created. There are separate rules for a residential building and a non-residential building.

Residential Building

Select the resource “Reference value for DGNB 2023/QNG, Residential building” in section 1 of the reference values tab. This static value includes all life cycle stages and building parts.

Non-Residential Building

The reference building's performance is based on various parts. It is suggested to carefully read through the manual for calculation of the reference building before starting the assessment.

Construction-related/embodied reference value

The reference value for the materials in life cycle modules A1-A3, B4, C3-C4 of cost groups 300 and 400 is based on the LCA class of the building. Input the NRF for the correct dataset in section 1 of the ‘Reference values’ tab.
To represent the embodied (“grey”) impacts of the PV system, choose the dataset that represents 40% own use. This allocates 40% of the embodied impacts of the system to the reference building, as defined by the manual

Energy-related/operational reference value

B6.1: The QNG rules for the determination of the reference value for non-residential buildings refer to the GEG ANNEX 2 and provide further requirements on calculating the consumption in kWh:
- Take the modelled energy requirement of the reference building from the GEG model (note: the energy modelling is not carried out by One Click LCA). Electricity and heat are considered together in this first step.
- Prior to adding the values, you must apply the modified zones (as in Table 12) and the Reduction factor (as in Table 11), in this order. See the manual
- For electricity, use the dataset 'Utilization - 1 kWh national grid electricity mix - QNG' (or “Referenzwert Strombedarf, QNG 2023”).
- For heating, as per QNG rules, it is represented through natural gas, dataset “Usage - 1 kWh final energy from gas calorific value”.
B6.2: Resources for central services and elevators can be found in section 2 of the 'Reference values' tab. Only efficiency class B and A are accepted for elevators, depending on the ambition level. The usage profile must correspond the intended profile.
B6.3: You can find the resources for usage for various zones in section 2 and input them per NRF. The values are identical to the actual building (Ist-Gebäude).
PV impact: Finally, you need to subtract the energy generated on site and used in the building, which can replace purchased grid electricity. In the software, this is done by converting kWpeak to kWh:
- The kWpeak is calculated with Formula 1 in the QNG-Anhang 3.2.1.2 zur ANLAGE 3:
- Assuming a self-use share of 40% as defined by the manual, the solar energy generated by the reference building PV system is calculated as: kWpeak*0.4*1000. In Germany, the average expected yield is approximately 1,000 kWh per installed kWpeak. These figures are confirmed by various sources. (External Links: ADAC, solarwatt.de, Fraunhofer Institut).
- The resulting kWh is input as a negative value to reduce the total B6 and assigned to the KG "Eigengenutzter Anteil erneuerbarer Energie”. The resource used for this is “Utilization - 1 kWh national grid electricity mix, version 1.2”.
Exported energy: No reference values are to be determined for module D2.

General note: The datapoints should be added as separate inputs and then marked appropriately using the available options in the cost group column to refer to the respective B6 subclass. Otherwise, one risks that no values will show in the results table for these subclasses.

Results

The results summary table is used to report the impacts as per the QNG guidance (see page 20 for residential guidance and page 26 for non-residential building guidance). The tool automatically calculates both ambition levels and shows the requirement level. The rows concerning the fulfilment of QNG-PLUS and QNG-PREMIUM show 1 if they are achieved, and 0 if they are not.