Aneysha Minocha: 
 

Hello, 

We are currently modelling Air-Source Heat Pumps for a non-domestic retrofit. We have CoPs available from manufacturer datasheets, which relate to various base operating temperatures (A-7, A2, A10 etc., output temperatures 35 degrees). We would like to apply these at a granular level to model seasonal carbon reduction. 

What would be the best approach for this?

a. Is there a way we can use the manufacturer data on CoPs to convert to Seasonal Performance Factor annually?

OR

b. Use the various CoPs at different base temperatures and use them for the building at seasonal / monthly levels? Would we also require information on base ambient temperatures for specific locations?

Or

c. Another methodology that would be better suited?

Would greatly appreciate any guidance on this.

Thank you.

It is best to ask current users about their experiences with heat pumps. Many domestic users are not happy with them, especially in the winter in the U.K. They claim that they do not work as well as gas fired wet central heating systems. They are slow to heat up a building. Good thermal insulation is a better investment.

Z.

You would need to calculate the total consumption (using the COP) then factor in any auxiliary power consumption  then calculate as below:

Qs is the total heat generated by the system

Eel is the kWh used by the heat pump

Eaux is the power used for any external pumps

Qf is any gas/oil used if it is a bivalent system. In a pure heat pump system this can be ignored.

Thank you @Zoomup - it is a challenge in homes which requires insulation first then some form of decarbonised heating help achieve net zero.

Thank you @Regor - appreciate your inputs from a controls perspective. You are right - the supplier datasheets tend to provide optimum COPs - not necessarily reflective of the actual performance and how that would vary with seasons. Finally, time of use (ToU) is an excellent concept - only challenges are : a) if the consumer is signed up to a ToU electricity deal (not many at the moment) and b) the grid carbon intensity does not usually align with ToU pricing - which would potentially create unintended consequences.

Thank you very much @RussellPridgeon This is very helpful. 

A follow up question - We are trying to work out performance in each season at a granular level - instead of applying a global SCOP to an entire year in a retrofit scenario. Would you consider running the same equation individually for each season? Thanks again!