1. Maria Justo Alonso1, Rolf Ulseth2 and Jacob Stang1
Considerations and Calculations on System Efficiencies of Heating Systems in Buildings Connected to District Heating
Maria Justo Alonso1, Rolf Ulseth2 and Jacob Stang1
1 SINTEF Energy Research, Department of Energy Processes
2 NTNU, Faculty of Engineering Science and Technology,
Department of Energy and Process Engineering

2. New Legislative Documents
Directive 2010/31/EU on the Energy Performance of Buildings (recast), (EPBD), 19 May 2010.
Presupposes the use of the mandated EN-standards in the
calculation of energy system efficiencies.
EN-Standard series - Method for calculation of system energy requirements and system efficiencies.
Background documents for preparing the actual paper.

3. EPBD and mandated EN-Standards
Climate influence
Building categories
Placing of the substation

4. Method of calculation based on EN 15316-x:2007
Efficiencies to be studied
Production
Distribution
Emission (in the heated rooms)

5. Production efficiency
-> High efficiency and minor changes with the temperature level of the heating system

6. Distribution efficiency
For space heating
The losses are dependent of the temperature difference in the non-heated areas.
Distribution efficiency of space heating system ranges around 0.99
For the domestic hot water (dhw) system
The circulation loop losses are ranging up to 35 % of the total losses from the total dhw system.
Efficiency for the total domestic hot water distribution system is in the range of 0.60
OBS! For the dhw the efficiency refers to the water leaving from the discharge cocks

7. Emission efficiency in the rooms

8. Total efficiency
Total Efficiency Space Heating(radiator 80/60)
Total efficiency Domestic Hot Water
~0.86
~0.60

9. Conclusions
EPBD presupposes the use of the mandated EN-Standards for the calculation of Primary Energy use of the buildings.
The design temperature level of the hydronic heating system should always be considered.
A general lowering of the design temperature level of the hydronic heating systems in buildings should be considered.
User-friendly guiding supplements to the EN-standards should be required.

10. Thank you