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Solar 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.

Zero Energy Buildings (ZEBs) are expected to play a significant role in reducing energy consumption and combating climate change. Despite this awareness, there is a lack of approaches and indicators at the regulatory level to quantify the long-term potential of strategies applied to buildings today. This study concerns the dynamic thermal modeling over the years, until 2080, of a multi-residential building located in Lecce, a city in southeastern Italy, characterized by a Mediterranean hot summer climate. Over time, Italian legislation has brought increasingly stringent limits on the design of the building envelope. Although with different regulatory limits, in the different climates across Italy, a growing trend towards a more insulated envelope, characterized by very low transmittances, has been observed over the years. This study shows how, in hot climates, buildings constructed within the legal limits will suffer from overheating over the years, necessarily leading to a disproportionate, and more extensive, use of cooling systems throughout the year. This study proposes a critical analysis of the long-term effectiveness of national strategies applied to the building envelope to date to achieve the ZEB goal, emphasizing that long-term predictive analyses become relevant in current building design and should be considered in regulations.

The European Energy Performance of Buildings Directive (EPBD) recast proposes, a comparative methodology to calculate cost-optimal levels of minimum energy performance requirements for buildings. This paper presents a method able to select the best retrofit action for lighting system, selectively analysing the daylight conditions and applying the cost-optimal methodology for different scenarios proposed for two existing educational buildings located in Italy. With the aim to improve both energy efficient and visual comfort conditions, the retrofit scenarios include lighting solutions with different combinations. They consider the replacement of lamps with more efficient lighting sources and the application of lighting control.

This paper investigates the performance of a 960 kWP photovoltaic (PV) system, located in southern Italy. Monitoring data over a 43 months period are used to evaluate the monthly average of energy yields, losses and efficiency. The performance ratio and the capacity factor were 84.4% and 15.6%, respectively. The yearly average module efficiency was 15.3% and the system efficiency was 14.9%, whereas the capture and system losses were 0.6 h/day and 0.1 h/day respectively. The degradation rate of the PV system, after continuous outdoor exposure, has been estimated at about 1.48%/year by applying the Classical Seasonal Decomposition (CSD) method. A comparison in terms of degradation rate is made with other PV plants installed in different climates to address the need of standard methods to determine this crucial parameter. The actual performance of the studied PV system is compared with the expected outcomes by using two widely used PV simulation tools, SAM and PVsyst. A detailed difference analysis is carried out to evaluate the accuracy of the SAM and PVsyst models. Results show that the yearly average energy injected into the grid was under-estimated by 3.0% by SAM and by 3.3% by PVsyst, but overall PVsyst outperforms the SAM tool. Results provide reliable data on the plant and demonstrate its good performance compared to other plants located in the same climate. The results can be used to improve the prediction of the performance of future PV of systems in the Mediterranean climate, and also provide a useful dataset for comparative studies.

Geothermal energy has a huge potential in building applications. This paper proposes the use of an Air-Source Heat Pump (ASHP) system coupled with a Horizontal Earth-To-Air Heat Exchanger (EAHX) to reduce energy consumption in buildings. The novelty is to geothermally pre-heat or pre-cool the air source of the ASHP through the EAHX, reducing the electric power needed, keeping constant heating/cooling capacity. The behaviour of ASHP-EAHX system has been investigated by a numerical model implemented in TRNSYS. A total of 54 combinations have been obtained and tested varying ground thermal properties, burial depth, air flow rate and pipe length. The model has been validated with a real case showing a good agreement between simulated and monitored data. The study is focused on the city of Turin (North of Italy), compared with Brindisi (South of Italy), and extremely cold and hot climates like Tromso (Norway) and Bechar (Algeria), respectively. The ASHP-EAXH performance has been investigated, by the comparison with the traditional ASHP, using different coefficients, such as the Coefficient of Performance (COP), the Energy Efficiency Ratio (EER), the Seasonal Coefficient of Performance (SCOP), and the Seasonal Energy Efficiency Ratio (SEER). The paper reveals how the ASHP-EAHX system show higher performance compared to the traditional ASHP, in all seasons. The overall merit is, for cold extremely climate, the reduction of the shutdown periods, when the outside temperature is below the limit operating temperature, and to allow the extension of the use of the heat pump to locations, where it is currently not convenient for the average outside temperature lower than the limit operating temperature of the heat pump.

Buildings 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.

The development of hybrid renewable systems is an economically competitive solution to reach energy decarbonization and reduction of greenhouse gasses. Based on the literature, energy, economic and environmental indicators were rarely simultaneously employed in the optimization of a hybrid renewable system. In addition, there is no procedures or a set of indicators to be applied uniformly in all applications for the shared analysis. The paper presents a novel energy-economic-environmental multi-criteria decision-making in the optimization of a hybrid renewable system, based on a new set of dimensionless indicators, proposed as a standard for future applications. The procedure compares the entire PV-wind-battery system configuration with the PV-wind, PV-battery and wind-battery system sub-configurations. A width parametric and multi-optimization analysis permit the identification of the most proper nominal powers of each system component. The procedure proposed was applied in a Mediterranean residential building, demonstrating that some system configurations allow complying simultaneously with at least two of the three energy objectives proposed, the cost-optimal level and the maximum reduction of emissions, for specific values of the load. The solar source was the most suitable both from energy, environmental and economic point of view, while the use of the wind source leads to a greater system operating time in the nominal power conditions. The study pointed out and quantified that, for specific loads, PV, wind and battery powers, the development of specific incentives for wind systems and of battery systems with a higher lifespan can help to make the hybrid systems more economically competitive.