For operators of district heating networks and when planning new heat supply networks, it is helpful and in some cases necessary to have the primary energy factor, the CHP share and the emissions in CO2 equivalents certified in accordance with the AGFW FW-309 series of worksheets.
Primary Energy Factor
The primary energy factor of a heating network is a key figure for the ratio of primary energy used to final energy delivered, thus showing the amount of energy used from the source to the end consumer.
For buildings that are heated or cooled with energy, the Building Energy Act (GEG) stipulates requirements for total energy demand: A primary energy factor must be determined for the respective district or local heating network in order to calculate the demand.
The factor influences the prescribed construction of new buildings, in particular the required insulation quality and the efficiency requirements for the system technology. As a rule, district heating supply involves a mixture of different heat generators.
The primary energy factors of district heating networks are determined in accordance with:
AGFW worksheet FW 309 Part 1 (January 2023 edition)
DIN standards DIN V 4701-10
DIN V 18599-1
In addition, CO2 emission factors for CHP products (electricity and heat) must in certain cases be calculated using the working value and Carnot methods in accordance with AGFW worksheet FW 309-6 (May 2021 edition).
In order to determine the specific primary energy factor and emission factor of district heating, this model considers CHP and non-CHP plants and assigns the fuels to the co-products electricity and district heating. This takes into account the electricity credit method and the displacement of fossil condensation electricity.
Emissions in CO2 equivalents are mandatory information on new energy performance certificates according to GEG.
The requirements for the energy assessment of district heating and cooling and their certification are regulated in the following AGFW worksheets:
FW 309-1: Part 1: Primary energy factors and emission factors according to the electricity credit method
FW 309-5: Part 5: Degree of fulfilment and energy source indicators
FW 309-6: Part 6: Emission factors according to the work value and Carnot methods
FW 309-7: Part 7: Certificates
KWKG
Funding according to KWKG (CHP)
A CHP expert report is particularly interesting for energy producers who generate electricity and heat from CHP plants and wish to receive a feed-in tariff under the CHP Act or require priority feed-in.
Combined Heat and Power (CHP(KWK)
Combined heat and power generation is intended to make an important contribution to environmental protection in order to achieve the environmental policy goals of the German government and the EU. This requires appropriate framework conditions for CHP plants, such as the Combined Heat and Power Act (KWKG).
In order to be eligible for support under the KWKG, the share of CHP electricity must be determined. The AGFW rulebook module FW 308 has proven its worth in this regard. The aim of FW 308 is to determine the share of CHP electricity in CHP plants of any complexity. The determination of CHP electricity should be based on available measurements of external energy and material flows.
According to the KWKG, non-standard CHP plants and plants larger than 2 MW require a CHP assessment prepared in accordance with recognised rules.
How does the assessment of the heating network according to AGFW | the inspection according to KWKG work?
An independent body will check your data and calculations – based on documentation and, if necessary, on site. Once any identified deficiencies have been demonstrably rectified, you will receive an inspection report and a certificate confirming your primary energy factor or CHP electricity share.
Audit preparation
The audit programme (procedure, dates, required documents) is agreed upon jointly.
You will then receive the audit plan as an agenda for the audit.
Conducting the verification
The experts need access to the investigation methodology and data basis.
The data provided will be subject to review.
If necessary, the location of the heating network and key energy producers will be inspected.
The CHP plant is inspected.
The auditors then summarise their assessments.
Verification result
Primary energy factor:
You will receive an audit report with a summary of the findings, notes and recommendations for verification.
The assessor will issue you with a certificate in accordance with AGFW FW 309-7.
CHP report:
You will receive a CHP expert report with a summary of the findings, notes and recommendations for verification.
Upon request, the expert will issue you with a certificate confirming your CHP electricity share.
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