1,720,995 research outputs found
Walls comparative evaluation for the thermal performance improvement of low-rise residential buildings in warm Mediterranean climate
No full textBuildings built in warm climates are affected by severe overheating problems in summer, which negatively affects people's comfort and health. For these reasons, many users are forced to install cooling systems, leading to an increase in costs, consumption and a meaning impact on the environment. This study gives a valid method to monitor the overheating problems in buildings located in Mediterranean climates, without the use of cooling systems, but just with an accurate design of the envelope. The main challenge is to demonstrate that the hourly monitoring of the internal operative temperature (TOP), in accordance with the UNI EN ISO 52016, is able of defining univocally the performances of the building, taking into consideration the characteristics of the envelope. The optimization of this parameter permits to reach high level of internal comfort in a building, ensuring the designer to identify the best choice of building materials that compose the envelope. The TOP trends, for a whole year, are tested on a single-residential building model located in a warm Mediterranean climate, considering different configurations of the external walls. The results put in evidence that the best solutions are characterized by the presence of the double layer of tuff, with a very massive layer in the internal side and resistive layer outside. At the end, this study demonstrates that once optimized the envelope, it is easier to reach good values of internal operative temperature with the only use of a mechanical ventilation system
Hypothesis of thermal and mechanical energy storage with unconventional methods
No full textThere is not a real “storage market” and the range of technical solutions for electrical storage appears to be underdeveloped. The use of electrochemical batteries seems to be the easiest and cheapest way, but some problems related to disposal, average life span and storage capacity, still put a brake on their diffusion. The micro CAES-TES (Compressed Air Energy Storage – Thermal Energy Storage) systems with small renewable energy plants for cogeneration and trigeneration represent an important development perspective thank to the reuse of the heat generated at the stage of air compression (for heating) and air expansion (for cooling). This improves the complexity of the entire system because of the heat exchange and thermal storage units must match the capacities and performances of the air compression/expansion units. The paper presents a new mathematical model for micro CAES-TES systems, implemented in Matlab software environment. The novelty is the use of air compressed energy storage in small and residential applications, a trigeneration due to reuse of heat from air compression and expansion stage, only renewable energy used. By keeping the initial investment low, the analysis is extended to the optimal system configuration and identifies key parameters that have a dominant influence on improving system efficiency and provides useful guidance for CAES-TES system design. The results show that, for an air storage volume of 4 m3, the optimal configuration is with a compression ratio of 15 splitted in two stages, charging time 5 h, mechanical storage efficiency 48%, compression air flow rate 3.73 kg/hour. The proposed system has a possible future development overall if combined with new possible scenarios of direct use of compressed air in the residential sector
A new device hypothesis for water extraction from air and basic air condition system in developing countries
Full text linkThis work proposes a new device for air treatment with dehumidification and water recovery/storage, with possible mitigation of indoor environmental conditions. The system is based on Peltier cells coupled with a horizontal earth‐to‐air heat exchanger, it is proposed as an easy‐to-implement alternative to the heat pumps and air handling units currently used on the market, in terms of cost, ease of installation, and maintenance. The process provides the water collection from the cooling of warm‐humid air through a process that leads to condensation and water vapor separation. The airflow generated by a fan splits into two dual flows that lap the two surfaces of the Peltier cells, one flow laps the cold surfaces undergoing sensible, latent cooling with dehumidification; the other flow laps the hot surfaces and heats up. The airflow undergoes thermal pre‐treatment through the underground horizontal geothermal pipe that precedes the Peltier cells. In the water storage tank, which also works as a mixing chamber, the two air streams are mixed to regulate the outlet temperature. The system can be stand‐alone if equipped with a photovoltaic panel and a micro wind turbine, able to be used in places where electricity is absent. The system, with different configurations, is modeled in the African city Kigali, in Rwanda
Modeling of light pipes for the optimal disposition in buildings
Full text linkA light pipe is an excellent solution to transport and distribute daylight into environments without or with little lighting, guaranteeing comfort inside the rooms. As stated in the literature, the evaluation of the performances of light pipes presents numerous complexities, making the work very dicult for technicians and designers. This study is aimed to present a methodology that is able to identify the potential of light pipes using indices such as daylight autonomy (DA), continuous daylight autonomy (DAc), and useful daylight illuminance (UDI). This paper presents an analysis of daylight obtained by several configurations of simple models of light pipes installed into a 5 5 m plant area room. All simulations are carried out in a DAYSIM environment, which allows calculating the annual availability of daylight based on a RADIANCE raytracer backward. Several daylight conditions were analyzed for dierent light pipe configurations, considering dierent pipe lengths and a variable number of light pipes. The light pipes are tested also in the horizontal position, for dierent orientations. The results of all the combinations were compared with the performances of a window with dimensions equal to 1/8 of the internal surface, which was in accordance with the minimum value to be guaranteed by the Italian Regulation (D.M. 5 July 1975 n. 190) for dierent orientations. The results indicated a dierence in daylight distribution, showing a strong correlation between the percentage levels of DA and DAc with the length and number of pipes, during dierent periods of the year. The simulated model is strongly influenced by the aspect ratio (R = diameter/length). The results show that the illuminance levels decrease drastically, increasing the length
CO2 emission changes in two Italian regions: progress toward 2050 climate neutrality under the Covenant of Mayors
No full textIn 2008, the European Commission established the Covenant of Mayors (CoM), a voluntary initiative to involve and support local authorities in pursuing the European Union's climate change mitigation and adaptation goals. This study proposes a methodology to evaluate the effectiveness of Sustainable Energy Action Plans (SEAPs) and Sustainable Energy and Climate Action Plans (SECAPs) in terms of reducing carbon dioxide emissions in the regions of Apulia and Sicily. The CO2 emissions are analyzed at the provincial level, before and after the approval of the plans by the municipal council, using homogeneous consumption data from national sources, rather than from data declared by the CoM signatories themselves. The methodology adopted combines the analysis of variance and compound annual growth rate (CAGR) of emissions, both total and per capita, with an assessment of the level of involvement of municipalities and the population in CoM plans. Through Pearson's coefficient, the correlation between the spread of plans and emissions at the provincial level was also assessed. The main results show that Apulia and Sicily, with a share of approved plans of 45.5% and 87.7%, respectively, experienced a reduction in total emissions of 12.1% and 21.2%, and per capita of 9.3% and 18.7%, in the period after municipalities submitted their SEAPs or SECAPs. A greater effectiveness of the plans is denoted in Sicilian provinces than in Apulian ones. These findings underscore the importance of emissions monitoring by signatory local governments, particularly through a uniform methodology, as well as monitoring at the provincial and regional levels, implemented by the Covenant Territorial Coordinators (CTCs), to assess the implementation of the action plans and ensure that regional and national emission reduction targets are met
Scenarios for urban resilience—perspective on climate change resilience at the end of the 21st century of a photovoltaic-powered mixed-use energy community in two European capitals
No full textCities are particularly susceptible to extreme and sudden catastrophic events, such as climate change, pandemics, and wars, that change people's lives. No city is completely safe from unforeseen risks; resilience indicates the ability of cities to be prepared for disasters and sudden events, allowing people to adapt and live without being exposed to too much stress. Resilience shows that the threat is not entirely negative; it can be a great opportunity to generate change and open new possibilities related to development and innovation. In this perspective, cities can emerge as driving forces for adaptation to change in which resilience becomes a central and crucial factor for sustainable development. One of the recurring questions today is how to make cities energy independent. This work analyzes the change in electricity supply from photovoltaic (PV) systems as a consequence of climate change in a hypothetical mixed energy community located in two European cities characterized by different climates, Rome and Berlin. The analysis was extended to possible climate change scenarios by including possible future climate effects due to mitigation policies, scenarios selected from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Specifically, the Representative Concentration Pathways (RCP) 4.5 and RCP 8.5 scenarios were included, that is, the stabilization scenario and the high emissions scenario. The hourly electrical power values of the PV system are calculated in TRNSYS software, considering the years 2020 and 2100. A comparison of the different scenarios shows that Berlin RCP 8.5 suffers a greater impact than Rome RCP 8.5 in 2100. Even though the RCP 8.5 scenario is a worst-case scenario, comparing 2020 and 2100 shows that there are greater differences in Berlin than in Rome. Berlin shows a high level of excess energy, but this is not always a good thing because it does not always pay to overload the grid, especially during peak hours
Climate change and building performance: pervasive role of climate change on residential building behavior in different climates
No full textOngoing climate change is posing new challenges in all fields. The building sector is strongly being affected. Comfort conditions inside buildings can be damaged, even in currently high-performing buildings. Temperatures are expected to rise globally. This study aims to provide an overview of building interior conditions under climate change in four very different climates. The locations under analysis are Miami, Damascus, Izmir, and Yakutsk, falling within the locations defined by the international Köppen-Geiger climate classification as tropical, arid, temperate, and continental. A small residential apartment was chosen as a case study and modeled in Termolog Epix 12. The results are plotted in terms of internal operative temperature in the free-floating regime, on an hourly and yearly basis, for the years 2020, 2050, and 2080. This application concentrates on the building envelope as it asserts that a building with an optimal envelope will need significantly less demand for air-conditioning systems. Moving from 2020 to 2080, maximum indoor operative temperatures increase by 5.8°C in Izmir, 3.7°C in Yakutsk, 3.2°C in Damascus, and 2.3°C in Miami; while minimum operative temperatures increase by 5.4°C in Yakutsk, and by 2.4°C in Miami, 2.2°C in Izmir, and 2.1°C in Damascus. From 2020 to 2080, annual indoor comfort hours decrease by 18% in Miami, increase by only 1.8% and 1.4% in Damascus and Izmir, and remain nearly unchanged in Yakutsk
Solar greenhouses: Climates, glass selection, and plant well-being
No full textSolar greenhouses are currently the most energy-intensive agricultural sector. In literature, there is no worldwide mapping of solar greenhouse performance under different climate scenarios. This study analyzes the performance of a Venlo solar greenhouse for 48 localities around the world. Solar greenhouses are mainly made of a transparent envelope and the effect of the direct and diffuse component of solar radiation impacts the internal plant well-being. This study aims to identify the best solution of a transparent envelope on locations with different latitudes and evenly distributed around the globe. The simulations are carried out using TRNsys, considering different thermal phenomena three-dimensional shortwave and longwave radiative exchange, airflow exchanges, presence of lamps with their exact 3D position, ground, plant evapotranspiration, and convective heat transfer coefficients. A total of 336 simulations are performed in the free-floating regime. A new index for the identification of the best glass solutions based on annual average deviation is defined. For all climates, the best glass solutions work better in winter than in summer. The optimal choice of the glass must be combined with effective scheduling of openings for natural ventilation to avoid internal overheating phenomena
Worldwide dynamic predictive analysis of building performance under long-term climate change conditions
No full textAround the world, expected climate changes can affect indoor comfort conditions in buildings. Analysing the climate in which buildings are located is the first step towards high-efficiency design, and today it is no longer possible to ignore impending climate change. This study has provided a worldwide picture of how comfort conditions inside a building can change as external climatic conditions change. For the first time, a building is tested worldwide over a long-term period, and not just in a specific climate or a small group of climates. Several cities homogeneously distributed around the world were selected, covering all climates of the Köppen-Geiger classification. A hypothetical building was implemented with the Termolog Epix 11 software in order to monitor the operative temperature (TOP) in free-floating mode on an hourly basis and test its temperature variations in the short, medium and long term. The percentage values of the hours when the TOP is in a comfort or discomfort conditions were compared for all configurations. The results showed that the comfort conditions vary with the climate. Climate zone A displayed for most subclimates high TOP values. Climate zone B showed an irregular trend, from 2020 to 2080 the hours when TOPs fall below 20 °C decreased in most locations. Climate zone C included areas where TOPs are mostly in the comfort range. Some sub-climates in zone D show very cold climates, with an average of about 15–20% of the annual hours in the comfort zone in 2020, then increasing slightly by a few percentage points in 2080
Experimental analysis of the rising damp by the comparison between different geometrical configurations: mono and multi-blocks of carparo and pietra leccese
Full text linkThe rising damp is the principal cause of the deterioration of the masonry in the existing constructions. Since carparo and pietra leccese are the most used materials in southern Italy, this study aims to underline the trend of the rising damp for the two building materials considering mono and multi- block configurations. All analyzes were developed with and without the influence of the Domodry® system
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