• Energy Research

Green façades are effective passive systems for buildings, but the research about their winter effects is still few. This study investigated the influence of a green façade during winter nights in a Mediterranean area. The effects on microclimate and heat transfer were evaluated based on experimental data. These data were used to calculate radiative and convective heat transfer by formulae available in literature. The behaviours of the covered wall and a bare wall were compared. Vegetation allowed to keep the air velocity near the wall below 0.9 m s−1. The covered wall external surface and the nearby air recorded a warming of up to 3.4°C and 3.3°C, respectively. The walls lost radiative and convective energy, but for the covered wall these losses were 60% and 38% lower, respectively. Acting as a thermal and wind barrier, the green façade reduced overall heat losses by 57% improving building envelope performance.

Green façades are effective passive systems for buildings, but the research about their winter effects is still few. This study investigated the influence of a green façade during winter nights in a Mediterranean area. The effects on microclimate and heat transfer were evaluated based on experimental data. These data were used to calculate radiative and convective heat transfer by formulae available in literature. The behaviours of the covered wall and a bare wall were compared. Vegetation allowed to keep the air velocity near the wall below 0.9 m s−1. The covered wall external surface and the nearby air recorded a warming of up to 3.4°C and 3.3°C, respectively. The walls lost radiative and convective energy, but for the covered wall these losses were 60% and 38% lower, respectively. Acting as a thermal and wind barrier, the green façade reduced overall heat losses by 57% improving building envelope performance.

Energy consumption in greenhouse heating could reach up to 90% of the total energy requirement depending on the type of greenhouse, environmental control equipment and location of the greenhouse. The use of climate conditioning technologies that exploit renewable energy and the application of passive systems to improve the energy efficiency and the sustainability of the greenhouse sector are recommended. During winter 2020-2021, an experimental test was carried out at the University of Bari in a Mediterranean greenhouse heated by a polygeneration system, composed of a solar system and an air-water heat pump. Three localized heating systems were tested to transfer thermal energy close to plants of Roman lettuce. Heating pipes were placed inside the cultivation substrate in the underground pipe system and on the cultivation substrate in the laid pipe system. The third system consists of metal plates heated by steel tubes and placed in the aerial area of plants. A weather climatic station and a sensor system interfaced with a data logger for continuous data acquisition and storage were used. The plate system was the best for air temperature rising, as it allowed an increase of 3.6% compared to the set-up without any localised heating system. The underground pipe system was the best for the soil heating, as it achieved a temperature increase of 92%. Localized soil heating systems contributed significantly to an earlier harvest by almost 2 weeks.

Energy consumption in greenhouse heating could reach up to 90% of the total energy requirement depending on the type of greenhouse, environmental control equipment and location of the greenhouse. The use of climate conditioning technologies that exploit renewable energy and the application of passive systems to improve the energy efficiency and the sustainability of the greenhouse sector are recommended. During winter 2020-2021, an experimental test was carried out at the University of Bari in a Mediterranean greenhouse heated by a polygeneration system, composed of a solar system and an air-water heat pump. Three localized heating systems were tested to transfer thermal energy close to plants of Roman lettuce. Heating pipes were placed inside the cultivation substrate in the underground pipe system and on the cultivation substrate in the laid pipe system. The third system consists of metal plates heated by steel tubes and placed in the aerial area of plants. A weather climatic station and a sensor system interfaced with a data logger for continuous data acquisition and storage were used. The plate system was the best for air temperature rising, as it allowed an increase of 3.6% compared to the set-up without any localised heating system. The underground pipe system was the best for the soil heating, as it achieved a temperature increase of 92%. Localized soil heating systems contributed significantly to an earlier harvest by almost 2 weeks.

Passive systems, such as high solar reflective roofing materials, protective facades, vegetative green walls and roofs, can be used in order to control solar heat gain in buildings. These sustainable technologies can reduce the temperature of the external surface of the building envelope, so reducing the energy consumption for cooling in summer. The radiometric properties of metallic roofing materials and their effects on the surface temperature were evaluated. Nine smooth metallic materials used for livestock buildings were tested; 4 were made of aluminium and the other 5 of steel and they were characterised by different colours. Solar reflectivity and long wave infrared emissivity were evaluated by means of laboratory tests; the influence of the radiometric properties on the surface temperature was evaluated in the field by using an experimental structure in Summer. The solar reflectivity coefficient ranged from 7.1% for the brown aluminium to 40.1% for the red steel; significant differences of the temperatures were recorded when the solar radiation hitting the metallic surface was higher than 600 W m −2 . A difference of 13.4% of the solar reflectivity coefficient resulted in a difference of the surface temperature of up to 8 °C. Variation of the slope from 15° to 40° resulted in an increase of the surface temperature of more than 8 °C. The value of the convection coefficient was calculated by means of the data measured in the field, and the mean value was equal to 12.2 W m −2 K −1 .

Passive systems, such as high solar reflective roofing materials, protective facades, vegetative green walls and roofs, can be used in order to control solar heat gain in buildings. These sustainable technologies can reduce the temperature of the external surface of the building envelope, so reducing the energy consumption for cooling in summer. The radiometric properties of metallic roofing materials and their effects on the surface temperature were evaluated. Nine smooth metallic materials used for livestock buildings were tested; 4 were made of aluminium and the other 5 of steel and they were characterised by different colours. Solar reflectivity and long wave infrared emissivity were evaluated by means of laboratory tests; the influence of the radiometric properties on the surface temperature was evaluated in the field by using an experimental structure in Summer. The solar reflectivity coefficient ranged from 7.1% for the brown aluminium to 40.1% for the red steel; significant differences of the temperatures were recorded when the solar radiation hitting the metallic surface was higher than 600 W m −2 . A difference of 13.4% of the solar reflectivity coefficient resulted in a difference of the surface temperature of up to 8 °C. Variation of the slope from 15° to 40° resulted in an increase of the surface temperature of more than 8 °C. The value of the convection coefficient was calculated by means of the data measured in the field, and the mean value was equal to 12.2 W m −2 K −1 .

Urban agriculture (UA) initiatives have been increasing in recent years as a nature-based solution for achieving many of the 2030 UN Sustainable Development Goals. However, climate change is expected to have effects on rainfall patterns, which are likely to impact urban food production. The main aim of this paper is to evaluate how issues related to water sources for UA have been addressed in the scientific literature from two different socioeconomic and environmental realities, Brazil and Italy. The method involved a systematic literature review, considering the PRISMA guidelines. The Web of Science database and papers' reference lists were used for retrieving original articles, published in 2000-2020 interval, indexed on scientific databases, and containing data on the typology and quality of water sources used in UA studies. After applying the eligibility criteria, 191 papers were selected - Brazil (108) and Italy (83). The last five years have seen an intensification of studies into issues involving water. Tap water has been identified as an important source of irrigation water for UA, if not the main one. No studies were found that addressed the impact of UA on public water supply systems. The findings point towards more sustainable practices involving the reuse of water and adaptive practices towards water security. We identified that innovative production systems like container farming, aquaponics and indoor agriculture, as well as cultivation of fruit trees, wild edible plants and varieties with low water requirements can represent water-saving options.