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Efforts are being made worldwide to address the environmental challenges we face as a global population. Everyone aims to maximize environmental benefits while still trying to meet or exceed expectations for performance and cost. However, not all decisions are easy—sometimes it feels like being stuck between a rock and a hard place when trying to reach a successful conclusion. In this blog post, our expert, Luca Filippetto, Product Manager for Cooling & Heating, will explain how to make heat pump operations smarter.
For years, designers and end users have debated the economic sustainability of heat pump solutions, often with comparisons made to traditional alternatives. From our perspective, the key to minimise the operating costs of a heat pump solution, comes down to two critical factors:
- Maximise heat pump efficiency, should be measured and calculated in coefficient of performance (COP), or even better, in seasonal COP.
- Minimise energy price, since heat pumps are powered by electricity.
How can heat pump efficiency be improved?
The efficiency of a heat pump primarily depends on its design - some units are simply more advanced and smarter than others. However, several factors significantly influence efficiency, some less controllable, some can be adjusted immediately:
- Actual outdoor temperature - efficiency improves with higher outdoor temperatures since the temperature difference between source and sink side decreases.
- Operating set point - efficiency increases when the set point temperature is lower. For instance, setting the water set point to 45°C Celsius instead of 50°C will enhance efficiency.
- Service and maintenance - efficiency increases when the unit works as intended, simple actions like keeping the heat exchanger clean, both on source and sink side, will boost efficiency.
And what about the energy price?
To reduce energy price can be more challenging, but there are a few strategies worth to explore:
- Is there an opportunity to utilise local electricity production, such as a solar power system? Modern heat pumps can operate in response to the availability of locally produced energy. The heat pump , in the case that there is a surplus of domestic energy, will operate to fill up warm water tanks as thermal energy storage.
- Is the heat pump capable to operate in a price-sensitive mode, and perhaps in combination with dynamic energy prices? If so, the heat pump can be scheduled to operate during time periods when the energy price is lower , usually during night time. Additionally, heat pumps might be eligible for special tariffs as they can function as stabilisers on the grid and this may allow for a special energy price during those time periods.
The ideal scenario
In an ideal scenario, it would be possible to maximise efficiency and minimise energy price simultaneously. However, this is usually easier said than done. For example, temperatures are normally lower during night time, which reduces the COP. There might even be a need for more frequent defrosting during night time. On the other hand, energy prices are usually lower at night. Another example. In times when there is a surplus in domestic solar energy, warm water tanks may be loaded at higher temperatures which probably sounds good. However, an increased heat pump set point will affect its efficiency negatively. So, is it then better to operate the heat pump during the day or at night?
To determine the optimal control strategy for heat pump solutions is complex because it depends on so many variables. To address this challenge, a smart heat pump that can cope with the below is a good way forward:
- The heat pump should be able to estimate real time COP on hourly and daily basis as this is the parameter that defines unit efficiency.
- It should register operating data, such as external temperature, required indoor temperature, COP etc. which helps to fine-tune operations.
- It should exchange data and integrate with building automation systems, or other software solutions, for improved control and optimisation.
- It should allow for remote control and for external sources ( such as electrical energy network or building management system ) to change operating mode as well as temperature set point according to given input data in order to ensure an optimal operation.
If a heat pump features these smart characteristics, designers and users will be helped in their data collection, analysis and planning of the heat pump operation - and the economic sustainability of a heat pump solution will be much clearer.
