Identifying districts’ potential to become Positive Energy Districts (PED) is challenging but strategic since they are considered critical enablers for cities’ carbon neutrality. PEDs are city areas with a positive annual energy balance, achieved primarily through energy efficiency and renewable energy generation while ensuring sufficient energy flexibility. This investigation introduces a methodological framework designed to prioritise and comprehend the potential PED status of diverse districts within a city, drawing upon predetermined criteria and expert insights. The study employs a combination of Decision Making Trial and Evaluation Laboratory (DEMATEL) and Analytic Network Process (ANP) methodologies to scrutinise the city's various districts and the influencing criteria. The method's applicability is tested through to the specific case of Valencia City. The study reveals that the importance of specific criteria in attaining PED varies according to the distinctive attributes of each district. Furthermore, variations emerge based on the perspective and expertise of the contributing experts. The results of this application allowed the selection of the 19 most influential criteria, organised into technical, social, urban, environmental and economic clusters. The two economic criteria (Investement and Grant or projects), one social criterion (Interest or acceptance) and one technical (Potential for retrofitting the buildings), are the most influential overall. The evaluation of the 19 administrative districts of Valencia for each criterion allowed the identification of the districts on the city's outskirts as having the greatest potential to be energy-positive. In conclusion, the proposed methodology aids decision-making in a city's urban energy planning on a district-by-district basis.

This research raises the possibility for households in energy poverty to participate in shared photovoltaic systems in renewable energy communities (REC) to reduce their energy costs, with investment costs covered by public institutions. It begins by evaluating the current solution for vulnerable households, which relies on public subsidies to lower energy costs without addressing root causes or improving environmental impacts. The study compares traditional subsidies with REC participation for vulnerable households. By simulating a REC composed of such households, the results indicate that REC participation is more cost-effective for public institutions than energy subsidies. At the economically optimal size of 31 kWp, the cost of subsidies decreases by 58,000 €, a 50% reduction, with household savings increasing by 6%. At 58 kWp, the need for additional support checks is eliminated, increasing household savings by 65% but with a lower NPV of 22,500 €. The largest viable system, 75 kWp, increases average household savings by 82%. This approach also leads to a net reduction in GHG emissions, engaging previously excluded households in the energy transition.

This research raises the possibility for households in energy poverty to participate in energy communities to alleviate their energy costs, having their investment costs paid by public institutions. The study starts from the current solution for vulnerable households based on public subsidies to reduce energy costs, which neither addresses the problem's causes nor improves the residential energy systems' environmental profile. It compares the business-as-usual solution, energy checks, with the participation of vulnerable households in energy communities. We simulate a renewable energy community composed of vulnerable households to calculate the usefulness of this solution. he chosen vulnerable households are doubly vulnerable because they are older people experiencing social isolation and loneliness. The results show that participating in energy communities can be a better economic option for public institutions than paying energy subsidies. Moreover, most households increase their savings, and in all cases, it results in a net reduction of GHG emissions, engaging households unable to participate in their current situation in the energy transition.

The intermittent nature of the renewable energy sources with the greater potential, wind and solar, requires dealing with temporary mismatches between demand and supply. The object of this study is to assess the Spanish energy plan from a system perspective regarding the energy storage requirements to meet electricity demand with high penetrations of renewable energy generation. We use a model that builds on existing literature and commercial software and integrates features such as demand response modelling, the correlation between reserve requirements and the technology mix, and hydrogen as an energy vector. This representation is applied to the Spanish electricity system to assess the consistency of the targets of the national energy strategy. Several scenarios of costs, demand and variation of other parameters are simulated to analyse their relative influence on the solution of minimum cost, especially assessing the sensitivity of energy storage capacity. The simulation results show that the Spanish goals for decarbonising the electricity system are based on optimistic assumptions. Also, energy storage will play a more important role than expected, and the use of hydrogen for energy storage is only needed for a 100% penetration of renewable energies.

Reducing the carbon emissions of buildings and whole districts is one of the main objectives of sustainable development goals. Both policymakers and end-users need reliable information to take actions that lead to achieving those goals. For this, an innovative open access planning tool has been developed to assess the effect of energy consumption on the overall carbon emissions of districts, buildings, and house units. When it comes to the end-users, it would help them know the actual environmental impact of their homes and make environmentally and financially sound decisions before investing in new equipment. The tool is meant to be an online planning service for dwelling end-users and policymakers alike; thus responding to a still unresolved demand. For this, firstly, the study focuses on the obtention of a complete catalogue of open-source conversion factors, which convert the different energy sources to carbon dioxide emissions per unit of energy. Secondly, it presents two case studies to illustrate the use of the tool. The first case study explains how an end-user could estimate the energy savings that may result from changing his domestic energy habits, equipment, and sources. The second case study uses actual data from a district in Valencia (Spain) to show how renewable sources would affect the carbon footprint of an apartment block. Both study cases show greenhouse gas emissions savings by replacing the existing equipment with more efficient ones such as heat pumps or renewable energy-based power systems like photovoltaic panels. This study concludes that providing smart tools is pivotal to planning nearly Zero-Energy Districts (nZED).