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Light-emitting diodes (LED) are a promising light source for the cultivation of edible vegetables in greenhouses. The spectral radiation of the light sources has an impact on plants physiological parameters, as well as on morphological features. In this study the growth of spinach plants has been carried out in experimental boxes under two white LED treatments having different correlate color temperature (CCT): the cold lighting (CL) corresponded to 6500 K, while the warm lighting (WL) to 3000 K. The work was aimed to investigate the influence of the two light spectra on plant development and comparing the results. Results showed that the different lighting treatments impact differently on plant development and on growth parameters. [ABSTRACT FROM AUTHOR]

This paper analyzes the impact of a change in the thermal insulating material on both the energy and environmental performance of a building, evaluated through two different green building assessment methods: Leadership in Energy and Environmental Design (LEED) and Istituto per l'innovazione e Trasparenza degli Appalti e la Compatibilità Ambientale (ITACA). LEED is one of the most qualified rating systems at an international level; it assesses building sustainability thanks to a point-based system where credits are divided into six different categories. One of these is fully related to building materials. The ITACA procedure derives from the international evaluation system Sustainable Building Tool (SBTool), modified according to the Italian context. In the region of Umbria, ITACA certification is composed of 20 technical sheets, which are classified into five macro-areas. The analysis was developed on a residential building located in the central Italy. It was built taking into account the principles of sustainability as far as both structural and technical solutions are concerned. In order to evaluate the influence of thermal insulating material, different configurations of the envelope were considered, replacing the original material (glass wool) with a synthetic one (expanded polystyrene, EPS) and two natural materials (wood fiber and kenaf). The study aims to highlight how the materials characteristics can affect building energy and environmental performance and to point out the different approaches of the analyzed protocols. [ABSTRACT FROM AUTHOR]

• Identification of solution sets to reduce construction costs in nearly zero energy houses. • 15% maximum reduction of energy related construction cost in Continental Italy. • 26% maximum reduction of energy related construction cost in Mediterranean Italy. • Net present values up to 163 €/m2 after 50 years building lifetime. Concerning Nearly Zero Energy Buildings, it is important to guarantee energy efficiency, thermal comfort and indoor environmental quality, while keeping construction and operational costs low. In this framework, this paper explores the efficacy of applying different scenarios, for reducing construction costs of new nearly zero energy multi-family houses in a life cycle perspective. Conversely to the standard cost-optimal approach, a real Italian case study building was chosen. Alternative and unconventional combinations of solutions for envelope and technical systems were adopted. Calculations were performed in two Italian cities (Rome and Turin). Three types of analysis were developed thermal comfort, energy performance and financial calculation. Results of the thermal analysis show that the installation of active cooling to prevent summer overheating can be avoided by applying low-cost passive strategies. All the proposed low-cost scenarios (4 alternative scenarios in Rome and 5 in Turin) reached the highest grade of energy performance, with a reduction of the non-renewable primary energy consumption up to 46% compared to the base case in Rome and 18% in Turin. From the economic perspective, all the scenarios in the two climate zones allow both reductions in the construction costs, up to 26% in Rome and 15% in Turin, and a Net Present Value after 50 years up to 163 €/m2 in Rome and 158 €/m2 in Turin. [ABSTRACT FROM AUTHOR]

Climatic conditions strongly affect the energy performance of buildings, and due to the synergy between global climate change and the Urban Heat Island (UHI) effect, the climatic conditions inside and outside the city are highly different. However, weather data collected at airports are commonly used for building energy simulations and these data do not take into account real temperature distribution in cities. Many studies in the literature address the topic but mostly considering only a couple of urban and non-urban stations. In this paper, the urban climate in Rome, Italy, is analysed after monitoring of the air temperature and relative humidity in four selected neighbourhoods and one reference station from October 2014 until September 2017. Rome is characterised by a composite urban pattern and high variability of building types, of which the four selected areas are representative. The heating degree days decrease up to 18% and cooling degree days increase up to 157% in the urban area with respect to the rural reference and the area most affected by the UHI is the city centre. The UHI is more intense in summer than in winter (average increase between 0.7 °C and 1 °C); while the diurnal and nocturnal UHI depends on the season and the neighbourhood. Then, the energy performance of a representative apartment block and a typical office building was computed using the measured data. Regarding the predicted energy performance, comparing the four urban sites and the reference site, the UHI causes a reduction of heating consumption up to 21% in residential building and 18% in the office building. An increase of cooling consumption up to 74% is instead computed for the residential building and up to 53% for the office building. [ABSTRACT FROM AUTHOR]

• Quantitative assessment of the heat waves in different city zones. • Quantification of the heat waves impact on building energy performance. • Influence of heat waves on the indoor operative temperature. • Impact of the synergic effect of heat waves and urban heat island. Global and local climate change increases the occurrence and the magnitude of extreme phenomena, as urban heat island and heat waves. These phenomena seriously affect the quality of life in several aspects: society, health, environment; they also heavily affect the building sector, increasing the energy use for cooling and deteriorating the indoor thermal environment. This paper utilizes data from a continuous urban microclimatic monitoring over three years to quantify the impact of heat waves on the thermal quality of two reference residential buildings in the city of Rome, Italy. The synergic effect of heat waves with the urban heat island is also analysed. The observation period includes summers of 2015, 2016 and 2017. The buildings' response is analysed through numerical thermal analyses in transient regime, taking into account several variants: thermal insulation, mechanical cooling system and thermal free-floating conditions, with different night ventilation strategies. Results show that daily average temperature and urban heat island intensity increase by up to 4.3 °C and 1.5 °C respectively during the heat waves with respect to the rest of the summer. The building cooling energy use rises up 87% during heat wave periods, while average operative temperature in free-running buildings increments by up to 3.5 °C. Results also show the impressive combined impact of heat wave and heat island: triplication of cooling energy use in the worst case and increase of the average operative temperature above 5 °C. [ABSTRACT FROM AUTHOR]

• The annual net energy saving of switching cool roofs is assessed via dynamic models. • Thermochromic cool roofs provide savings up to 19% compared to conventional roofs. • Thermochromic cool roofs provide savings up to 8% compared to cool roofs. • Limited switching magnitude comes with limited energy savings or even penalties. Cool materials are a well established solution to mitigate urban overheating. Notwithstanding, their net energy and cost impact might turn negative in year-round assessments, owing to space heating penalties. Thermochromic materials, that are able to switch from a prevalent absorbing to a prevalent reflective behaviour, may overcome this problem. Several studies at the material level show advantages and limits of the technology, however no marketable solution exists yet. This study aims at quantifying the energy saving potential of switching cool roofs to optimize the thermal response of residential buildings in the Mediterranean Basin. The task is performed by simulation in transient regime, drawing on different material modelling approaches. The analysis is carried out in three cities: Barcelona, Palermo and Cairo, representative of different areas of the Basin. Several scenarios are considered, different in terms of building insulation, transition temperature and switching magnitude. Thermochromic materials exhibit potential annual energy savings up to 8.5% and 19% with respect to cool and conventional roofs, respectively, when the solar reflectance switches from 0.15 to 0.75. Smaller annual energy savings are achieved as the switching magnitude is decreased. Due to several factors, thermochromic cool roof can also lead to annual energy penalties compared to static roofs. Further modelling and experimental efforts are needed to better predict the response of the material during the transition phase and refine the optimization process. [ABSTRACT FROM AUTHOR]