Abstract
Operational control strategies for the heating system and “smart” utilization of energy storage were developed and analyzed in a simulation based case study of a single-family house with exhaust air heat pump and photovoltaic system. Rule based control algorithms that can easily be implemented into modern heat pump controllers were developed with the aim to minimize final energy and maximize self-consumption by the use of the thermal storage of the building, the hot water tank and electrical storage. Short-term weather and electricity price forecasts are used in some of the algorithms. Heat supply from an exhaust air heat pump is limited by the ventilation flow rate fixed by building codes, and compact systems employ an electric heater as backup for both space heating and hot water. This heater plays an important role in the energy balance of the system. A typical system designed for new detached houses in Sweden was chosen for the study. This system, together with an independent photovoltaic system, was used as a base case and all results are compared to those for this base case system. TRNSYS 17 was used to model the building and system as well as the control algorithms, and special care was taken to model the use of the backup electric heater as this impacts significantly on final energy use. Results show that the developed algorithms can reduce final energy by 5–31% and the annual net cost for the end user by 3–26%, with the larger values being for systems with a battery storage. Moreover, the annual use of the backup electric heater can be decreased by 13–30% using the carefully designed algorithms.
Highlights
Heat pumps (HP)s for residential applications are becoming more popular in the European Union (EU) and to date have reached more than ten million installed units according to the European Heat Pump Association (EHPA) [1]
In the Nordic climate, and in Sweden the main heating method used for space heating (SH) and domestic hot water (DHW) in detached houses is electricity and accounts for 47% of the total annual use of energy [2]
It is noticeable that the thermal mode TH for the medium photovoltaic system has significant impact on the system performance, with solar fraction increase of 5%, final energy use reduction of 6% and cost savings of 6% even when increasing the space heating set point by only 1 K
Summary
Heat pumps (HP)s for residential applications are becoming more popular in the European Union (EU) and to date have reached more than ten million installed units according to the European Heat Pump Association (EHPA) [1]. In the Nordic climate, and in Sweden the main heating method used for space heating (SH) and domestic hot water (DHW) in detached houses is electricity and accounts for 47% of the total annual use of energy [2]. The extent to which the total electrical load can be met either seasonally or on an annual basis by the electricity produced on-site is highly affected by more or less sophisticated control of the components in the Applied Energy 249 (2019) 355–367 Nomenclature Abbreviations.
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