• Energy Research

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.

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.

Abstract The renovation of existing buildings represents a major challenge towards the transition to sustainable cities, as these edifices were built according to principles far from the current standards, especially in those urban areas where the poor quality of structures often determines social conditions of hardship and unlivable spaces. For refurbishment planning, suitable tools are required for the choice of more recommended interventions. For this purpose, the cost-optimal analysis represents a reliable way to promote the energy requalification of the existing building stock, identifying the best compromise between the energy demand reduction and the cost of the intervention. In this paper, a cost-optimal analysis was conducted on a reference building (RB) representative of a typical Italian social housing building, widespread in disadvantaged areas, strongly energy-inefficient and requiring urgent renovation. The influence of different energy efficient measures (EEMs) was considered by locating the RB in two different climatic zones, to evaluate how weather data also influence the obtained results. The economic analysis was carried out as a financial projection rather than a macroeconomic evaluation, in order to increase the stakeholder awareness for targeted routes addressed to the achievement of social and environmental advantages, while respecting a sustainable economic frame.

Abstract The paper presents a review of the literature on the use of the questionnaire as a tool for collecting energy data in residential buildings. Numerous studies used the questionnaire to gather necessary information for different purposes. However, even using the same tool, the procedures differ in terms of distribution and compilation, contact with the interviewees and type of proposed questions. One hundred thirty-seven studies were considered in the review, including both scientific articles and surveys reports. The available works were analysed and classified according to the geographical origin, period, sample size, sample structure, data collection methods, response rate, data processing, and objectives of the investigation. In the 80% of the selected studies, the questionnaire is used as unique tool for data collection, albeit cases in which the questionnaire is coupled with other survey techniques, such as field measurements and time use surveys, have also been recorded. The in-person interview is the most common completion option in the sample and it is also the method that produces the highest response rate (77.6%). Generally, the collected data are subjected to statistical processing (over 80% of the cases). Regarding the objective of the surveys, the questionnaire is mainly employed for investigations on energy consumption and occupants’ behaviour, but also other purposes were identified. Overall, the revised sample and the experiences reported are largely varied and heterogeneous. The lack of a homogeneous methodology appears in the use of an extremely diversified terminology. Therefore, the codification of a reference method and the standardisation of the nomenclature would be desirable. It would be useful to define general guidelines to be followed when designing surveys by using questionnaires. The review provides some suggestions and guidance on the use of questionnaire, highlighting strengths and weaknesses, and represents a source of information for future researches focused on the energy performance of buildings.

Cost-optimal analysis was pointed out in the 2010/31 European Directive as a tool to evaluate the achievable building energy performance levels as a function of the corresponding costs. These analyses can be carried out by a financial projection for private investors and a macroeconomic approach to establish the minimal energy performance levels. Consequently, the financial projection provides different results that could stimulate private investors toward other cost-optimal solutions that do not match the minimal energy performance levels. For this purpose, both the projections were analyzed in the BEopt environment, developed by NREL, on a multistory building located in two contrasting climatic zones of the Mediterranean area, one cold and the other warm, highlighting the differences. The cost-optimal solutions were identified by a parametric study involving measures that affect thermal losses and solar gains, whereas the air-conditioning plant was left unchanged in order to include a fraction of renewable energy in the coverage of the building demands. Results showed that both the projections produced the same cost-optimal solutions, however, the latter matches the building designed to fulfill the minimal energy performance levels only in the cold climate. Conversely, noticeable deviations were detected in the warm location, therefore minimal energy performance levels should be revised, with preference for less insulated opaque surfaces and better performing glazing systems. Moreover, the macroeconomic scenario returns a more limited distance between the minimal energy performance levels and the cost-optimal solutions, therefore, it is far from the real economic frame sustained by private investors.

Nowadays, reducing energy consumption and obtaining thermal comfort are significant for making educational buildings more climate resilient, more sustainable, and more comfortable. To achieve these goals, a sustainable passive method is that of applying green walls and roofs that provide extra thermal insulation, evaporative cooling, a shadowing effect, and the blockage of wind on buildings. Therefore, the objective of this study is to evaluate the impact of green wall and roof applications on energy consumption and thermal comfort in an educational building. For this purpose, a university building in the Csb climate zone is selected and monitored during one year, as a case study. Then, the case building is modelled in a well-calibrated dynamic building energy simulation tool and twenty-one different plant species, which are mostly used for green walls and roofs, are applied to the envelope of the building in order to determine a reduction in energy consumption and an increase in thermal comfort. The Hedera canariensis gomera (an ivy species) plant is used for green walls due to its aesthetic appeal, versatility, and functional benefits while twenty-one different plants including Ophiopogon japonicus (Mando-Grass), Phyllanthus bourgeoisii (Waterfall Plant), and Phoenix roebelenii (Phoenix Palm) are simulated for the green roof applications. The results show that deploying Hedera canariensis gomera to the walls and Phyllanthus bourgeoisii to the roof could simultaneously reduce the energy consumption by 9.31% and increase thermal comfort by 23.55% in the case building. The authors acknowledge that this study is solely based on simulations due to the high cost of all scenarios, and there are inherent differences between simulated and real-world conditions. Therefore, the future work will be analysing scenarios in real life. Considering the limited studies on the effect of different plant species on energy performance and comfort, this study also contributes to sustainable building design strategies.

In recent years, residential buildings have seen a notable increase in energy consumption. To address this, it is crucial for researchers to invest in renewable energy technologies, aiming to develop highly sustainable and nearly-zero energy buildings. Many countries are started to commit to this goal, seeking to phase out fossil fuels due to their harmful environmental effects. Wind energy stands out as a promising renewable resource, especially in areas with strong wind patterns. This study focuses on a case in Karaburun, Izmir province, Türkiye, where annual wind speeds range from 6 to 8 m/s and evaluates the performance of two types of small-scale Vertical Axis Wind Turbines (VAWTs) in reducing energy consumption in a three-story residential building, along with associated costs. Utilizing advanced simulation tools like ANSYS Fluent and DesignBuilder Software, the study examines Ice-Wind VAWTs and Savonius VAWTs. The findings reveal that installing 15 Ice-Wind VAWTs on the building's roof can reduce energy consumption by approximately 22.5%, with each turbine costing about $2000 and a payback period of around 14.57 years. Conversely, using 15 Savonius VAWTs can reduce energy consumption by 36%, with each turbine costing about $2300 and a payback period of around 8.93 years. These results indicate that the Savonius turbine offers a faster return on investment compared to the Ice-Wind turbine under the specified conditions. Overall, this study highlights the significant benefits and cost implications of integrating renewable energy solutions like VAWTs into residential buildings.

Residential energy consumptions are determined by the interaction of many factors. Apart from physical characteristics such as climate, heating type, age, and size of the house, occupants’ behavior and socio-economic aspects are critical. Furthermore, the relative impact of the occupants’ characteristics and behavior seems to differ in various investigations confirming the importance of contextual analysis. In this study, different procedures for obtaining occupancy profiles are described and applied with reference to a residential building stock located in Mediterranean climatic conditions (Italy). The heating and domestic hot water (DHW) energy consumptions and indoor comfort conditions of a representative building were determined by introducing different occupant scenarios in dynamic simulations. The occupancy profiles were built by means of data collected at the University of Calabria using surveys, interviews, bills, and statistical elaborations. Considering different modes of use of the dwelling (Regulations, Current-use, and Statistical), in the simulation process, all the inputs of occupancy, ventilation, lighting, DHW, and heating operation were modified. The Regulations occupancy profile produces an underestimation of heating energy consumption. Additionally, primary energy for DHW is strongly affected by the family composition. The effect of the occupants’ preferences on the energy performance of the building was investigated: mainly energy consumptions and internal comfort conditions vary with the set point temperature and the duration of ventilation. The analysis provides reference procedures for obtaining occupancy profiles. Furthermore, the simulation results demonstrate the significant dependence of heating and DWH primary energy consumption on the characteristics and preferences of occupants in the Mediterranean climate.