45 ICI Bucharest © Copyright 2012-2020. All rights reserved ISSN: 1220-1766 eISSN: 1841-429X 1. Introduction Presently people all over the world continue to witness the advent of a new energy crisis of our era. The energy shortage is evident by the ever- increasing price of fuel. The impact on average citizens takes diferent forms: unbearable heating costs, an increase in food prices, hijacked gas prices, etc. The main concern of this work is to contribute to fnding engineering practical solutions to lower the District Heating (DH) running costs by tapping into the solar free energy. National and International agreements such as the Paris Agreement (French: Accord de Paris: it is an agreement within the United Nations Framework Convention on Climate Change (UNFCCC)), which deal with the greenhouse gases emissions mitigation, adaptation and fnance starting in the year 2020, request countries to target and facilitate practical implementation of measures. The agreement included 195 countries, which adopted the frst-ever universal, legally binding global climate deal (COP21, 2015). Unfortunately, the energy consumption of the building sector is rising monotonically at the moment, where it constitutes more than 30% of the end energy consumption of most societies. On the other hand, the building sector is responsible for the largest amount of Greenhouse Gas Emissions (GHG) of all sectors. This is caused by their utilization of fossil fuels for the diferent combustion processes, which are used to satisfy the heating demands of their building stock. District Heating (DH) strategies may signifcantly enhance the use of energy resources and provide better integration of renewable energies techniques into the heating sector (i.e. solar, geothermal, biomass, and industrial waste heat). Low-temperature District Heating (DH) in cold winters could be one of the vital solutions for both the generation and the demand sides (Schmidt et al., 2017) (Werner, 2017) (Abdalla et al., 2019). Scientists and Engineers believe that the solution to the current energy crisis has to be a collection of elusive engineering actions. These measures comprise of developments in structural materials, energy control, and management, sustainable energy technology, corrective actions, etc. This work focuses on the energy control, modeling, and management for District Heating (DH) applications. For designing robust and smart controllers one needs to establish rigorous mathematical models of the dynamical thermal solar systems. Consequently, heat transfer based modeling of the DH thermal solar system is essential for the designing, verification, and validation of their synthesized controllers (Equa, 2013) (Abdalla, 2015). District Heating research objectives may be categorized in few areas; dynamical modeling, hydraulic network design, and operation, balancing valves efects on DH systems, control and operation strategies of DH systems, and optimization of DH systems (Delmastro et al., 2016) (Mazhar et al., 2018). DH dynamical modelling is essential for simulations, control and analyzing the efciency of district heating systems. Typically, DH has consisted of several component models such as boiler, distribution network, single or multi-zone, building enclosure, Studies in Informatics and Control, 29(1) 45-53, March 2020 https://doi.org/10.24846/v29i1y202005 Modelling and Simulation of Solar-Thermal DH Systems Musa O. ABDALLA Mechanical Eng. Dept., The University of Jordan, Amman, 11942, Jordan admin@mechatronix.us Abstract: Currently, dynamical heat transfer models of the District Heating (DH) systems are needed to synthesize diferent types of smart building controllers. Such controllers are designed in such a way as to increase energy savings and provide highly fexible and more efcient DH systems. In this work, the complete analysis, the modelling, and the simulation of a DH thermal solar system have been investigated. A Complete mathematical modelling of the DH system components has been carried out for both the transient and steady state parts. The generated mathematical heat transfer model of the DH system has been frst verifed and validated through computer simulations, and it has been complemented by real collected environmental data in order to validate the derived heat transfer model. Finally, a small-scale DH system has been built and tested to validate the computer simulations, which has also been used to test a simple ON/OFF as a control strategy for the DH thermal solar system. Keywords: District Heating, DH, Thermal solar Modelling, Heat Transfer Model, Switching Control, Transient Response.