1,720,975 research outputs found
Indoor vertical greening for regulating building microclimate
No full textThe integration of vegetation in buildings can increase the environmental sustainability of urban
contexts as well as produce other relevant unquantifiable effects. Vegetation can be applied both on the
exterior side of the buildings’ envelope and inside, in different ways and layouts. Green façades are a
specific kind of vertical greening for buildings consisting of plants covering vertical walls of buildings. The
presence of vegetation on the envelope positively affects the building’s thermal and acoustic performance,
air quality, aesthetics, with relevant consequences in terms of energy and cost savings and human wellbeing. Until now, research has focused mainly on vertical greening systems applied to the exterior side of
the buildings, but indoor applications deserve attention as well. This is the reason behind the present
research: assessing the physical functioning of an indoor green façade. To this end, an experimental
prototype of an indoor greening system was designed and realized to be monitored, at the University of
Bari. The prototype consists of a sealed chamber, with evergreen plants, properly equipped with sensors for
collecting air, soil and plant parameters, needed for studying the system functioning. The database created
with the collected data enables investigations of the green façade behaviour and effects. A better
understanding of this green technology, allowing for informed design and knowledge of induced effects,
can promote the spread of indoor green façades
Heat transfer mechanisms in vertical green systems and energy balance equations
Full text linkThe use of vegetated vertical systems is a sustainable technology for improving the energy efficiency of buildings in cities in order to reduce the energy consumption for air conditioning in summer and to increase the thermal insulation in winter. increasing urban green infrastructure (ugi) in a city can contribute to improve urban climate in summer reducing buildings surface temperature and urban air especially in southern europe. the application of vertical green systems requires the knowledge of the energy performance of the applied greenery system. the choice of the green facades depends on the local climate, water availability, building shape. the presence of green facades affects the building microclimate all day, by reducing heat waves during the warm periods and heat losses from the building in the cold period. the heat and mass transfer between the external environment, the green facades and the building surface determine the building microclimate. solar radiation, long wave infrared radiation, convective heat transfer and evapotranspiration are the main mechanisms of heat transfer in a green façade. the paper describes the main parameters concerning heat flow in green facades that can be used in simulation models for predicting temperatures in buildings using the external weather conditions as model inputs. the input parameters are: external air temperature and relative humidity, solar radiation, wind velocity and direction, plants and building characteristics. the green facade was described by a schematic representation, four layers were defined: the green layer, the external surface of the building wall, the internal surface of the building wall, the air inside the building. the energy balance was defined for each layer and all the terms involved in the energy exchange between the layers were defined as a function of the plant, the weather conditions and the constructive characteristics of the wall
Convective heat transfer in green façade system
Full text linkGreen fac ̧ades are passive living technologies applied to buildings. They produce many
advantages for human wellbeing, building performance, and city environments. Knowledge
of the energy behaviour of green fac ̧ade systems is needed to inform their best
design and application, and to define their energy performances. Heat and mass exchanges
between the system and the surrounding environment must be determined. In
this paper, the schematisation of the green fac ̧ade system into layers and the energy
balance approach are proposed. This study focuses on the analysis of the convective heat
transfer occurring between the plant layer and the external air. It is difficult to realistically
describe this mechanism and many approaches in the literature were considered.
Six different formulae were evaluated. Mathematical modelling and empirical data were
both used. Once it was discovered that forced convection was the prevailing convective
type, selected formulae were applied to the data, which were collected from an experimental
green fac ̧ade at the University of Bari. Based on the energy balance of the plant
layer, a comparison between the calculated and measured values was carried out.
Qualitative and quantitative statistical methods were used to assess the goodness-of-fit
of the considered convective models. These analyses suggest the least and the most
suitable approaches for convective heat transfer evaluation. The empirical equation of
Morrison and Barfield and an adaptation to green fac ̧ades of Deardorff model showed the
best agreement. This study could be extended in order to write codes for building energy
simulation software
Evaluation of the cooling effect provided by a green façade as nature-based system for buildings
No full textA strategy to make cities greener involves the use of green infrastructures. In this context, green façades 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 façades 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 façade 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 façades
A nature-based system for improving Mediterranean buildings’ performance: contribution to energy saving by heat transfer reduction and influence of climatic parameters
Full text linkUrban environments can be turned greener and more sustainable by letting in vegetation. Applying green facades on buildings’ vertical surfaces is a viable option that brings various advantages. This study focuses on the energy benefit provided by an evergreen green facade in Mediterranean climate conditions. The results came from a long experimental campaign, heat fluxes evaluation, and statistical analyses. The thermal behaviour of the experimental green facade was analysed all year round, highlighting differences between warm and cold periods and the time of the day. The main advantage was assessed in terms of energy saving, defined as heat flux reduction through the wall covered with vegetation compared to an unvegetated wall. The study pointed out that energy saving was achieved throughout the year, but at different times of the day based on the season. A daytime energy saving was obtained in warm periods due to the shading effect and the plants’ evapotranspiration. A night-time benefit was reached in cold periods mainly thanks to the green layer’s thermal and wind barrier action. The results showed daily mean energy saving values equal to 11.47 W m-2 for a warm period and 3.23 W m-2 for a cold period. The statistical analysis highlighted that the energy saving was positively influenced by external air temperature, especially in the daytime. Overall, higher energy saving was provided by the green facade when higher external air temperature values were recorded. This research contributes to filling existing literature gaps on the yearly behaviour of green facades and on the energy benefits these provide. use only
Mapping and Disposal of Irrigation Pipes for a Sustainable Management of Agricultural Plastic Waste
No full textPlastic materials are largely used in agricultural activities. Plastic products are commonly employed as covering in greenhouses and tunnels, for soil mulching, silage, pots, and containers and for irrigation and drainage pipes. The use of plastic products provides several benefits for agricultural production. However, the downside is represented by the large amount of generated agricultural plastic waste (APW). There is a need of a conscious and sustainable management of APW from an environmental and economic point of view. APW should be considered as a resource, in the optic of a circular economy. To this end, the definition of a rigorous approach for agricultural plastic detection, mapping, collection, and disposal is required. In this study, the attention was focused on the irrigation pipes. An agricultural area, characterized by a variety of crops, in Apulia region (Southern Italy) was considered as case study. The paper proposes a territorial analysis, performed using a Geographical Information System (G.I.S), for mapping areas of use of irrigation pipes and of waste production from these. As a result, a georeferenced database and the quantification of the potential waste were obtained. This allows identifying critical areas for plastic waste production due to irrigation pipes and can be used as tool for planning a proper collection and disposal strategy
Energy analysis of a green façade in summer: an experimental test in Mediterranean climate conditions
No full textEnergy performance of a double-skin green façade in Mediterranean climate was investigated. Experimental data were collected at a green façade prototype realized at the University of Bari. The green façade thermal behaviour was assessed under different summertime weather scenarios. To point out the plants influence, a comparison was carried out between microclimatic conditions and energy transfer at the covered wall, behind the vegetation, and at an un-vegetated wall. Experimental data concerning the walls surface, the air gap in the green façade and the external air were used to perform statistical analyses and to evaluate the heat fluxes. At daytime, the green façade provided a reduction of the wall surface temperature up to 9.9 °C, while air relative humidity behind the vegetation rose up to 18.7%. Surface and air warming were found at night-time. A time-shift was detected between the maximum surface temperature of the covered and of the bare wall. The analysis of the energy flux through the two walls highlighted a sensible reduction in the covered wall, equal to 62% during daytime. Solar and LWIR radiative and convective fluxes were generally lower in the covered wall. Latent heat due to evapotranspiration was evaluated, as well. Net radiation was found to be the most influencing parameter for latent heat transfer. A simplified relationship was proposed to quantify latent heat due to evapotranspiration. The formula based on the net radiation, as input parameter, was found to be the most suitable. The findings of this research contribute to the knowledge of the effects provided by green façades in terms of cooling and heating, influence on the proximity microclimatic conditions and overall energy transfer
Heat transfer reduction in building envelope with green façade system: A year-round balance in Mediterranean climate conditions
Full text linkThis study focuses on the thermal behaviour of a building prototype equipped with an evergreen green façade. The results of a two-year experimental campaign carried out under Mediterranean climate conditions are presented. Heat fluxes in the green covered wall and in the bare wall were analysed. Their comparison allowed finding out the energy saving, in terms of heat flux reduction through the wall, obtained through the use of the green façade. The energy benefit was evaluated throughout the year, differences between warm and cold periods and between times of day were pointed out. In the warm periods, energy saving was recorded mainly at daytime, while in the cold periods at night-time. The evergreen green façade allowed remarkable energy saving in wintertime as well. The monthly mean energy saving resulted equal to 8.19 MJ m−2. The maximum benefit was achieved in July, 17.24 MJ m−2, while the minimum in January, 2.33 MJ m−2. The green façade provided an annual energy saving equal to 28.5 % compared to the un-vegetated wall
Effect of Leaf Area Index on Green Facade Thermal Performance in Buildings
Full text linkGreen facades applied on a building’s envelope allow achieving the building’s passive thermal control and energy consumption reduction. These are complex systems and many site-and plant-specific parameters influence their energy behavior. The leaf area index (LAI) is a relevant plant characteristic to consider. Solar shading and latent heat loss of plant evapotranspiration are the two main cooling mechanisms. The aim of this study was to assess the cooling effect provided by an evergreen south oriented green facade in summer in a Mediterranean area and to investigate what happens when LAI changes. Experimental data were used to calculate the cooling effect provided by the facade. Simulations with different LAI values were performed to determine the related cooling effect. The canopy solar transmissivity decreased by 54% for every LAI unit increase. LAI significantly influenced the green facade cooling performance. As LAI increased, solar shading and latent heat increased; this was relevant until an upper limit value of 6. An exponential equation to calculate the mean extinction coefficient (km), and a polynomial relationship, with very good agreement, were proposed to calculate shading and latent heat as function of LAI. The findings of this research can effectively contribute to fill still existing gaps on green facades’ energy performance and to the energy simulation of buildings equipped with them
Wintertime thermal performance of green façades in a mediterranean climate
Full text linkThe increasing environmental issues have afforded opportunities for a widespread application of green systems in urban areas. Greening the building with green roofs and vertical green systems can be a design and retrofitting strategy to improve building energy performance in summer and in winter. Research efforts have been mainly concentrated on their energy saving function during warm periods. Green façades have a great application potential thanks to the space available in urban environment. The effect of green façades on building energy performance has been studied mainly for warm periods. In order to evaluate the effect during cold periods, an experiment was conducted in Bari, Italy, for two years. Pandorea jasminoides variegated and Rhyncospermum jasminoides were tested as evergreen climbing plants on walls; a third wall was used as control. The night-time temperature of the covered wall was higher than the uncovered wall temperature by up to 3.5°C, thanks to the presence of plants. The thermal barrier function performed by the vegetation layer was analysed. The influence of outdoor air temperature, relative humidity and wind velocity on the façades thermal effect during night-time was investigated. The experimental test demonstrated that both Pandorea jasminoides variegated and Rhyncospermum jasminoides are suitable for green façades in the Mediterranean climatic area during winter. The use of the green façades allowed increasing the thermal performance of the walls during night-time. They also reduced the surface temperature changes throughout the day
- …
