COP bzw. JAZ plausibility check

[kuhnal]

A yearly weighted COP (or rather JAZ) of 6.2 for a GSHP as calculated with the simulation framework is not realistic. A more realistic JAZ is between 4.0 and 5.0.

Assumption COP (efficiency) = 1 for non HP systems might lead to an underestimation of operational emissions. Real efficiencies for fossil systems move between 80 and 95% (depending on kind of conversion process (oil, gas, pellet), as well as the age of the heater)

[kuhnal]

Why not simplify it, taking "Standard-Nutzungsgrade von Heizkesseln ..." "... von Wärmepumpen..." from SIA 380 p.54?

[Linwal]

There are pros and cons for using default values given by standards. For example, the standard JAZs for heat pumps do not seem to be suitable to investigate future systems, as better models are constantly coming onto the market. And this can be represented indirectly via the WP machine efficiency. For technologies that have already passed their peak in 2015, like oil burners, this can, however, definitely make more sense.

The efficiency of 1 for combustion systems is certainly not correct. A decision would have to be made on how to input the GHG emission values. If I see this correctly, the values are already available per heat produced in SIA380 Tab6, for example. If necessary additional distribution could also be considered.

ToDo for @Linwal

• Add temperature dependent efficiency drop of the heat pump system.
• Check heat source temperature assumption in GSHP
• Check out in more detail if it makes sense to include efficiencies on the energy scale and then calculate emissions from this or directly calculate emissions from delivered energy (after conversion).

[Linwal]

Ground Temperature:
Bodentemperatur für GSHP in CH ab 5m 10-13°C [1]
Grundwasser/Seewasser nicht kleiner als 4°C [1]
Nicht wissenschaftliche Quellen sprechen von tieferen Temperaturen (3-8°C) [2]
Bodentemperatur zwischen 50 und 200m 8-15°C [3]
Oft ergeben sich Absenkungen um die Bohrung von 1-4°C [3]
2Sol sagt 100-500m führt zu 10-25°C [4]
--> maybe 12°C is too high as a standard assumption

Heat pump efficiency:
There are efficient low-lift heat pumps that reach very high COPs [5]
However, I did not find citable literature that shows the performance of heat pumps below a temperature lift of 15°C
--> I would argue, it makes sense to cap the COP at 12 or 15°C instead of 10°C
What do you think? @hillias
It has to be considered that the output file heating COP is only for heating and the COP for DHW is substantially lower. A total COP could be added if that helps.

Cooling
To me the cooling COPs are an even bigger question. Also sources on that are hard to find. However, eth internal measurements show that cooling JAZ of >13 are possible for cooling, [6]
--> Ultimately I think reducing the HP efficiency to 0.45 or 0.5 already leads to more realistic (comparable to currently built) results.

Combustion and additional efficiency losses
Here I would generally prioritize model simplicity. That means that if we have the possibility to directly have emissions/UBP per delivered heating/cooling energy I would use those. @kuhnal : let's discuss on Thursday if that is applicable for you