• Energy Research

Agrochemicals, based on iron, sulphur and chlorine, generate by products that lead to a degradation of greenhouse films together with a decrease in their mechanical and physical properties. The degradation due to agrochemicals depends on their active principles, method and frequency of application, and greenhouse ventilation. The aim of the research was to evaluate how agrochemical contamination and solar radiation influence the radiometric properties of ethylene-vinyl acetate copolymer greenhouse films by means of laboratory and field tests. The films, manufactured on purpose with the addition of different light stabiliser systems, were exposed to natural outdoor weathering at the experimental farm of the University of Bari (Italy; 41° 05’ N) in the period from 2006 to 2008. Each film was tested for two low tunnels: one low tunnel was sprayed from inside with the agrochemicals containing iron, chlorine and sulphur while the other one was not sprayed and served as control. Radiometric laboratory tests were carried out on the new films and on samples taken at the end of the trials. The experimental tests showed that both the natural weathering together with the agrochemicals did not modify significantly the radiometric properties of the films in the solar and in the photosynthetically active radiation wavelength range. Within six months of experimental field tests the variations in these radiometric characteristics were at most 10%. Significant variations, up to 70% of the initial value, were recorded for the stabilised films in the long-wave infrared radiation wavelength range.

Abstract A strategy to make cities greener involves the use of green infrastructures. In this context, green facades applied to vertical envelope of buildings are one of the most promising technologies. Their contribution is particularly significant as passive cooling systems for buildings. Green facades allow to decrease air and surfaces temperatures mainly by canopy evapotranspiration and shading. Such processes are strongly influenced by environmental conditions and canopy characteristics. Aim of this research was to model and evaluate evapotranspirative and shading effects. Data recorded on an experimental prototype of building equipped with green facade were used for model development and assessment. Canopy characteristics, as leaf area index in vertical greening, were defined. Evapotranspiration was both measured with a load cell and evaluated through the green layer energy balance. The goodness-of-fit of the models was assessed by statistical indices. The models using Penman-Monteith and Deardorff formula, in summer, recorded average values of root mean square error equal to 12.48 W m−2 and to 14.61 W m−2, respectively. Plant coefficients useful for the application in vertical greening of the standardized evapotranspiration reference equation were defined. These were equal to 1.3 and 2.0 for Rhyncospermum Jasminoides in summer and spring, respectively. The daily overall cooling effect in summer, due to evapotranspiration and shading, was equal, on average, to 16.2 MJ m−2 of wall surface. Shading contributed about twice as much as the evapotranspiration. The findings of this research can be a useful contribution to writing routines of building energy models expressly developed for green facades.

Abstract. Research was conducted to evaluate how solar radiation, agrochemical contamination, and different light stabilizer systems influence the mechanical properties of ethylene-vinyl acetate copolymer (EVA/C) based films suitable for crop protection. Three independent outdoor trials were performed at the experimental field of the University of Bari (Italy) in 2006, 2007, and 2008. During each trial each film type was installed in the field as new covering of two low tunnels: one of the tunnels was periodically sprayed inside with agrochemicals containing sulfur, chlorine and iron, while the other one, not sprayed, was used as control. Besides, artificial photoaging tests were carried out on the films in laboratory. The research showed that the different light stabilizer systems influenced the mechanical behavior of the films in the presence of the progressively absorbed agrochemicals. An improved resistance to the agrochemicals was recorded for the EVA/C films stabilized with aminoether type hindered amine light stabilizer (NOR-HALS) and ultra violet filter.

Research on the application of innovative biodegradable materials for substrate mulching in greenhouse floricultural cultivation was carried out in Southern Italy. A transparent biodegradable film and a transparent biodegradable spray coating were compared with a commercial transparent low density polyethylene film. The biodegradable film was a starch based extruded material, the sprayed coating was created from a polysaccharide solution. The materials were used to mulch the peat and perlite growing media contained in trays during snapdragon cultivation in order to increase the substrate temperature and hasten early growth. The climate variables inside and outside the greenhouse and the growing medium temperature under the mulching materials were recorded. Biometrical data, such as mean blooming time, plant height and spike length, were collected. The laboratory radiometric tests showed that the biodegradable mulching materials had a lower solar transmissivity in comparison to the low density polyethylene film. The capacity to reduce the long wave infrared thermal losses was higher for the biodegradable mulches: the long wave infrared transmissivity coefficient was 53.9% for the low density polyethylene film, 12.1% for the biodegradable film and 8.2% for the spray coating. The increase of the growing medium temperature allowed the harvest of the snapdragon grown in the mulched trays 7 days before that of the flowers grown in the un-mulched trays. At the end of the crop cycle the disposal of the biodegradable mulching materials was carried out fragmenting and mixing them with plant residue and the growing medium. The residue biodegraded in almost 1 month for the spray coating and in about 12 months for the biodegradable film.

The use of plastic materials in agriculture causes the serious drawback of huge quantities of waste. The introduction of biodegradable materials, which can be disposed directly into the soil, can be one possible solution to this problem. Biodegradable materials are actually innovative materials; therefore, their physical properties must be evaluated in relation to their functionality during the use in field. In the present research results of experimental tests carried out on biodegradable films used in strawberries protected cultivation are presented. The decay of some relevant physical parameters of biodegradable films during the cultivation period was monitored by laboratory tests (SEM analysis, mechanical tensile tests and infrared reflectance spectroscopy). Infrared spectroscopy clearly indicated that the mechanical degradation starts from the starch component of the material. Tensile tests showed that the value of elongation at break of biodegradable materials decreased in some cases by 300% after 10 days of field application

An innovative biodegradable coating that can be sprayed was developed and tested as suitable alternative to low density polyethylene (LDPE) films for soil mulching in horticulture. A mulch was created by spraying onto the soil a sodium alginate water-based solution that, at the end of the cultivation cycle, could be tilled into the soil to be biodegraded. The mechanical and radiometric properties, the functionality of the spray coating, and its biodegradation were assessed by means of laboratory measurements and cultivation field tests. In the field, during the cultivation of strawberries, the spray coating was compared with a LDPE mulching film and a straw mulch. The mechanical properties of the coating degraded when exposed in the field, but the coating kept its mulching effect for 6 months. The radiometric properties varied without regular trends, but the coating maintained its capacity to suppress weeds. The biodegradation tests showed that the spray coating samples biodegraded by 65% after 6 months into the soil.

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.