30 May 2005
Which heating system is performing best? This question is still not easy to answer, since standardised
calculation methods for the comparison of different heating systems hardly exist. Annex 28 of
the Heat Pump Programme (HPP) of the International Energy Agency (IEA) has been initiated to deliver
calculation methods for the Seasonal Performance Factor (SPF) and the necessary comprehensive test
procedures of combined operating heat pump systems. The results of this research are continuously transferred
to the standardisation committees. Nine countries are participating in the IEA HPP Annex 28.
New system developments are often not covered by existing standard testing or calculation methods.
Thus, the application of the test procedures and the calculation methods developed in the framework of
IEA HPP Annex 28 is manifold: Manufacturers have regulations for providing precise and uniform technical
data. On the other hand, system layouts can be compared in the planning process. Moreover, energy
labels or building standards can be based upon the SPF. Hence, a uniform testing and calculation is
necessary to overcome trade barriers and enhance consumer confidence.