One of the major challenges faced in the optimization process of existing heating systems is the harnessing and integration of a higher share of renewable energy. Centralized integration at the thermic source leads to high investment costs at the first investment stage, and low values of conversion, transport, and storage efficiencies, due to high levels of heat loss from large-capacity entropic systems. This research paper presents a case study on the partially decentralized integration of thermal solar fields that are used for heat production in crowded urban areas within the optimization process of the existing heating system in the city of Oradea, Romania. A deterministic method was used as the method for the calculation of heat demand, in both stationary—hourly heat demand and dynamic regimes—annual heat demand, and the simulations within the configuration and the optimization process of the hybrid heating systems were carried out. In the case study, four representative urban areas with different thermal densities were analyzed within two working scenarios, which took into account the energy performances of the buildings inside the studied areas before thermal retrofitting, and after a usual thermal retrofit.

This paper aims to present partial results of a large study regarding the alternative energen solutions (sun, wind, hydrogen) for power supply of passive house placed on Cluj-Napoca, Romania. Five scenarios for different combinations were optimized and analyzed of hybrid energy system. The best energy and environmental performances are achieved by hydrogen technology and fuel cell, also the use of hydrogen energy is more efficient and less expensive then primary renewable energy seasonal storage by batteries.

The concept of sustainable development aims to meet the needs of the present without compromising the needs of future generations. In achieving the desideratum “low-carbon energy system”, in the domain of energy production, the use of innovative low-carbon technologies providing maximum efficiency and minimum pollution is required. Such technology is the fuel cell; as these will be developed, it will become a reality to obtain the energy based on hydrogen. Thus, hydrogen produced by electrolysis of water using different forms of renewable resources becomes a secure and sustainable energy alternative. In this context, in the present paper, a comparative study of two different hybrid power generation systems for residential building placed in Cluj-Napoca was made. In these energy systems have been integrated renewable energies (photovoltaic panels and wind turbine), backup and storage system based on hydrogen (fuel cell, electrolyser and hydrogen storage tank), and, respectively, backup and storage system based on traditional technologies (diesel generator and battery). The software iHOGA was used to simulate the operating performance of the two hybrid systems. The aim of this study was to compare energy, environmental and economic performances of these two systems and to define possible future scenarios of competitiveness between traditional and new innovative technologies. After analyzing and comparing the results of simulations, it can be concluded that the fuel cells technology along with hydrogen, integrated in a hybrid system, may be the key to energy production systems with high energy efficiency, making possible an increased capitalization of renewable energy which have a low environmental impact.

Romanian cities are facing two opposing patterns of urban development that are common worldwide: a significant number of small cities are undergoing a process of shrinkage, while large cities are experiencing dense urban sprawl. This study examines the framework of the current legislation and urban codes that impact the growth of Romanian cities. The aim is to establish a critical analysis of the current urban codes of residential areas in Romania and to create a framework for an integrated neighbourhood tool of analysis for Romanian residential areas, using urban form as a starting point. This direction starts from the fact that international documents such as the “New Leipzig Charter” recommend a resilient and environmentally friendly approach to urban development, while current Romanian normative documents on resilience and sustainability focus mostly on buildings, ignoring a broader vision that includes the urban scale of the neighbourhood or city while considering the multidisciplinary requirement for understanding urban morphology and phenomena. Existing urban legislation in Romania is characterised by several deficiencies resulting from the fragmentation of outdated regulatory bodies in the field of urban planning. Furthermore, this study has demonstrated that urban indicators can serve as a versatile tool for the assessment and enhancement of residential areas in the country.

This paper illustrates the results of analysis of the technical potential for hydrogen production and providing electrical energy by fuel cell for residential consumer, through a system that has the basic components such as photovoltaic panels, wind turbines generator, electrolyser and fuel cell. The study estimates the production of hydrogen and electrical energy of this hybrid system for five different areas of Romania, using the following parameters: daily global solar irradiations on horizontal plane and wind speed. Analysis of hydrogen production by using solar and wind resources and ensuring electrical energy by fuel cell, that resulting from proposed autonomous hybrid system was performed through the performance indicators as follows: electrolyser operating time, energy consumed by the electrolyser and hydrogen production, respectively fuel cell operation time and the electrical energy obtained. The objectives of this study include the development and simulation testing of the best situations (methods) for producing hydrogen and ensuring electrical energy by fuel cells from hybrid renewable resources available in Romania. The results show that the use of such systems for hydrogen production and electricity insurance to residential building is relatively advantageous, the total annual production of hydrogen is estimated to be around 77,87 m³ and the total annual electrical energy delivered by fuel cell is estimated to be around 779 kWh, also the equipment components that will make the best configuration of the hybrid system are dependent on the availability of renewable resources.

Currently, buildings are considered to be a continuously evolving organism that over time has to be treated, rehabilitated, and upgraded to meet the requirements set by the user at a certain stage. Buildings are a central element of the EU member states' energy efficiency policies, accounting for about 40% of final energy consumption, and 36% of greenhouse gas emissions, and about 75% of buildings are not energy efficient. Recent applications and studies establish that green retrofitting has maintained older existing buildings to increase energy efficiency, optimize building performance, increase occupants' satisfaction, and boost economic return while decreasing greenhouse gas emissions. In this regard, this chapter aims to address the main factors that negatively affect the performance of residential buildings and presents the common green retrofitting measures that can be taken to ensure the state of human well-being in residential buildings.