Installing solar photovoltaic panels on building rooftops can help property managers generate renewable energy and reduce electricity costs. However, the existence of multiple efficiency indicators and ambiguity in interpreting these metrics limits the comparison of the performance of individual installation projects. This paper presents a methodology using data envelopment analysis to evaluate suitable candidates for rooftop solar panel installation. This approach integrates rooftop area, solar irradiation, temperature, costs, energy yield, and revenue to evaluate the relative efficiency of each building. To demonstrate the methodology, it was applied to rank 22 residential buildings, revealing the top performers for installation in 2022. The approach was subsequently adapted to assess potential outcomes under deferred implementation up to 2030, encompassing a diverse range of climate and pricing scenarios. Five installations were found to be optimal irrespective of the future scenarios. In addition, a super-efficiency approach was applied to overcome the low level of discrimination among the possible installations and to rank each individual unit uniquely. The analysis is designed to guide property owners in identifying favorable solar photovoltaic investments within their portfolios under changing conditions.

The evolution of district heating and cooling systems into sophisticated energy networks is essential for global decarbonization. However, a fundamental tension exists between rapid innovation in advanced control algorithms and the slow replacement cycle of physical infrastructure, making intelligent system-wide control the primary enabler of network modernization. Despite this critical role, the existing literature remains fragmented and lacks a comprehensive synthesis of control strategies across the production, distribution, and end-user levels. This analysis confirmed a definitive shift from isolated, single-level control to holistic frameworks that unlock system-wide flexibility. This review establishes that successful implementation requires addressing distinct objectives at each operational level, from multisource management in production to occupant-centric control at the end-user level. A critical finding is the credibility gap between the demonstrated potential of advanced control and its limited practical application. This disparity is rooted in systemic challenges, including intensive modeling requirements, computational scalability limits, and unresolved human-in-the-loop problems. To bridge this gap, this review presents a structured framework that synthesizes the current state of district heating and cooling control and proposes a forward-looking research roadmap. This roadmap prioritizes the development of hybrid intelligent controllers that integrate learning-based methods with model predictive control, creating persistent digital twins for human-centric applications, and designing secure and decentralized coordination architectures for next-generation thermal networks.

In recent years the demand for cooling in buildings has grown steadily due to factors such as climate change and increased use of technology in Sweden. The increase of cooling demand occurs mainly during peak demand periods, where there is limited cooling capacity combined with limited distribution capacity in the district cooling network. Sweden has experienced considerable growth in the solar energy market in recent years, though its utilization has been mostly limited to power generation. To fulfill the cooling demand increase, solar driven cooling is a viable solution alternative to traditional cooling methods. The use of solar cooling is still in its early stages in Sweden. The aim of this work is to design a simulation model of a solar absorption cooling system for a full-service restaurant prototype building. The system layout consists of photovoltaic/thermal collector, storage tank, single-effect absorption chiller, auxiliary heater, and cooling tower. The results revealed the system ability to meet the cooling load while delivering sufficient hot water for the establishment. Higher solar fraction confirmed that using photovoltaic/thermal collector is more competitive than solar thermal collectors based on restaurant operational activities. A levelized cost of cooling of 0.164 €kWh⁄ indicated the system cost-effectiveness in comparison to similar setups in other favorable European locations for solar energy utilization.