Control smartness of a smart control system coupled with inertial thermal system: defining the future frontiers through an experimental analysis

Defining a control solution for the building energy system is a task that has continuously been exploited by researchers over the years. Different control approaches can introduce advanced functionalities in building energy systems. However, it remains unclear how suitable each technique is for different levels of control complexity. A field experiment was conducted using a radiant floor system in a fully monitored test room to assess the control quality of both an analogue and a commercial smart control system across two different heat pumps. The key novelty of this work lies in the field assessment of the “smartness” level of a commercial smart control solution, introducing a methodology for evaluating the effective control quality decisions in building energy systems, particularly in HVAC systems. The study found that a “smart” controller, solely focused on precise indoor temperature control, did not guarantee energy savings and potentially jeopardized equipment due to frequent cycling. This highlights the lack of a clear definition for “smart” controllers, leading to the mislabelling of commercially available systems that often rely on basic control strategies. Furthermore, the study revealed that the heat pumps under investigation performed significantly lower than manufacturer specifications, operating at up to 30% lower efficiency under high thermal loads. Surprisingly, efficiency decreased instead of increasing at part load, contradicting both literature and manufacturer claims. This discrepancy poses challenges to the reliability of declared equipment's performance by manufacturers.