• Energy Research

Abstract European and Italian standards establish high levels of energy performance of buildings that have to be designed considering their energy balance near zero. To achieve this goal, the reduction of energy demand, attainable by improving energy efficiency of the construction, and the use of renewable energy available both on site and off site are effective solutions to be applied. In particular, in buildings that use energy produced from renewable sources, due to their unstable and unpredictable nature, having the right strategy to compensate the variations is essential. A technical solution reevaluated as a consequence of passive design principles, is to provide an adequate thermal inertia in order to store energy when it is offered and to use it when the source is not available. In these cases, the ability of construction elements to retain heat becomes fundamental as they contribute to maintain internal comfort conditions. This paper aims to investigate how various types of heating and cooling systems, based on different modes of heat transfer, are able to interact differently with the thermal mass of the building, producing a different level of its activation. The investigation considers a case study used to carry out dynamic simulation by means of DesignBuilder which is a user interface of EnergyPlus. The model consists of a building with elementary geometry and a single thermal zone, delimited by walls with outside thermal insulation and a heat accumulation layer inside. The variation of the internal temperature by using different types of conditioning system is analyzed in order to individuate the technology that takes the greatest advantages from the thermal mass.

“Are ICFs suitable building envelope solutions for Mediterranean climatic conditions? A critical analysis concerning thermal properties and cooling energy performances”

The global construction industry significantly contributes to energy consumption and greenhouse gas emissions, necessitating immediate action for sustainable development. Recognizing the impact of buildings on emissions, the United Nations has set ambitious energy-related goals for 2030. Retrofitting buildings emerges as a strategic method for reducing energy consumption, offering lower environmental impact and life cycle costs. However, retrofitting is a complex process influenced by diverse factors such as policies, available resources, techniques, building-specific data, and uncertainties. Thus, this paper reviews the existing literature on retrofitting strategies for tropical and humid climates to identify effective approaches for enhancing energy efficiency, thermal comfort, and overall building performance in these regions. Through comprehensive analyses, including bibliometric analysis using VOSviewer version 1.6.18 and systematic assessments, this study investigates various retrofitting strategies. This study categorizes tropical climates into Af (Tropical Rainforest Climate) and Aw (Tropical Savanna Climate) based on the Köppen climate classification. It reveals distinct emphases, with Af climates concentrating on office buildings and Aw climates prioritizing residential structures. Passive strategies were predominantly favored in office buildings, with glazing being the most commonly implemented approach. Residential structures, on the other hand, adopted a combination of passive strategies such as phase change materials along with active methods like appliance replacement. Educational buildings tended to rely on passive strategies, including roof covers, shading, and glazing. The absence of specific cost values underscores the importance of establishing baseline metrics, revealing significant challenges in retrofit techniques. This study further highlights an opportunity to explore passive methods in educational buildings, stressing the need for comprehensive guidelines, especially in institutional settings. Moreover, it emphasizes the urgency for ambitious regulations to address carbon emissions and optimize energy efficiency in tropical climates.

To achieve sustainable cities and communities, it is necessary to decarbonize existing buildings. Actions need to be taken to reduce the buildings’ energy demand and ensure that the low remaining demand is met by energy produced from renewable sources. This leads to Net Zero Energy Buildings (NZEBs), whose impact on energy consumption is zero or positive, meaning that they are able to produce more energy than they require. The “zero” objective may be difficult to reach in hot and humid climates, where the cooling demand is prevalent. In this case, a combination of active and passive measures, together with appropriate interaction with users, is a viable way to obtain NZEBs. The present study aims to explore technological solutions for renovating existing buildings to NZEBs in a tropical climate. The analysis is developed through a parametric analysis, a sensitivity analysis, and an optimization directed at minimizing the site’s net energy and hours of discomfort. Evaluations are conducted for a case study consisting of a single-family house located in Panama City. The results showed that photovoltaic size, cooling operation schedule, and cooling set-point temperature are the most influential variables for the attainment of NZEBs in a hot climate. Regarding the building envelope, the outcomes suggest the low insulation of dispersing structures and local solar shading of windows as recommended measures.

Research on nearly zero-energy buildings has addressed mainly the aspects of energy saving or technical and economic optimization, while some studies have been conducted on comfort and indoor air quality. However, the potential problems that may arise in low-energy buildings during the operational phase, and especially the risk of fungal growth, which can deteriorate the indoor environment and pose a health risk to the occupants, are yet to be extensively investigated. The present work intends to analyze previous research on microbial contamination in zero-energy buildings in order to identify the possible risks that may lead to fungal formation and the possible strategies to prevent the proliferation of molds. The methodology is based on a systematic literature review and subsequent critical analysis to outline perspectives on this topic. The main results indicate that high envelope insulation and inadequate ventilation are the leading causes of fungal growth in energy-efficient buildings. The need for more detailed regulation in this area is also highlighted. The study’s outcomes underline the need for more attention to be paid to the design and management of zero-energy buildings, aiming to achieve the reduction in energy demands while ensuring the occupants’ well-being.

Buildings energy efficiency has a key role in achieving the objectives set in the energy-environment field. In energy renovation, the performance goal is generally defined based on design assessments, supported by simulation tools. However, due to the uncertainty relating to input variables, the actual performance of the building may be different from the expected value. The uncertainty of the input parameters depends on several factors, including insufficient knowledge in the design phase, the actual quality of construction and plant systems, the unpredictability of external climatic conditions, the modes of use of the building by users. To adequately describe the energy behaviour of the building, it is necessary to define a range of variation within which the real performance value occurs. This range is estimated through the Uncertainty and Sensitivity Analysis (UA/SA), which considers the simulation output as “probabilistic” rather than “deterministic”. In this study, the UA/SA was applied to plan renovation interventions on an energy-intensive public residential building located in the Mediterranean area. The sensitivity analysis has shown that the main parameters affecting the annual energy demand are the efficiency of the cooling system, the set-point temperature and the photovoltaic efficiency. When risk mitigation actions are neglected, the most frequent result is within the range 17,780–19,573 kWh in terms of annual primary energy demand, and the chance to meet the design target is only 22%. Conversely, when appropriate risk mitigation measures are considered for the mentioned parameters, the possibilities to meet the set goal increase to 82%, and the annual primary energy need reduces down to 5489–6446 kWh. Therefore, the UA/SA is a reliable tool to support legislators in meeting the objectives set by the energy policies promoting the attainment of the planned results.

Abstract The paper deals with the investigation of the heating energy consumptions of a sample of residential buildings located in South Italy. A survey for the collection of data concerning energy performance certificates, characteristics of the building envelopes, air-conditioning plants and real consumptions, was carried out. A statistical analysis aimed at the identification of the main parameters affecting the energy requirements was developed using SPSS software. A multiple regression analysis was applied to obtain a forecasting tool that can be used to identify suitable action strategies for the retrofitting of buildings in the considered area.

This study tackles the analysis of fixed external solar shading systems. The geometry of a building and of the shading system has been parametrically defined and a genetic optimization analysis has been carried out to identify an architectural solution that would allow the increase of energy savings, through a suitable window-to-wall ratio and an accurate design of the shading device. A multi-objective analysis has been performed with the aim of minimizing the energy consumption for space heating, cooling and artificial lighting, while ensuring the visual comfort of the occupants. The main goal of the study is to explore the influence of climatic context on the optimal design of shading devices. The analysis has been performed for three different latitudes across Europe. In all analyzed cases, a reduction of the annual energy consumption could be achieved, up to 42% if the optimal shading configuration is used. Moreover, the possibility of integrating the shading system with photovoltaic (PV) panels has been considered and the electricity production has been estimated.