Use of vegetation to increase building energy efficiency: application to a real case study

The research here presented deals with the relationship between vegetation and architecture, and how its presence can influence a building project and performance. In the last years, many ways of integrating green in building envelopes have already been experimented, for their potential of reducing thermal loads; the research investigates a specific solution, the vertical forest, which integrates trees and small bushes in specific permanent planters on balconies of high-rise buildings. The main scope is to understand if trees, treated as shadings, can really affect positively the building energy consumptions. Moreover, other aspects, such as trees mechanical stability, construction issues and maintenance are deepened. Through a particular case study, energy consumptions are analysed using dynamic simulations tools, developed with Grasshopper™ and EnergyPlus™ software, in which trees are considered as special external shadings, characterized by a variable permeability to solar radiation during the year. Results demonstrate that trees can contribute to reduce energy loads, depending on species and orientation, especially in association with traditional shading systems. Eventually, some guidelines on technological and construction aspects, as well as on trees species selection, are given, in order to assure the optimal vegetation life and to maximize its benefits on the building

Use of vegetation to increase building energy efficiency: application to a real case study

The research here presented deals with the relationship between vegetation and architecture, and how its presence can influence a building project and performance. In the last years, many ways of integrating green in building envelopes have already been experimented, for their potential of reducing thermal loads; the research investigates a specific solution, the vertical forest, which integrates trees and small bushes in specific permanent planters on balconies of high-rise buildings. The main scope is to understand if trees, treated as shadings, can really affect positively the building energy consumptions. Moreover, other aspects, such as trees mechanical stability, construction issues and maintenance are deepened. Through a particular case study, energy consumptions are analysed using dynamic simulations tools, developed with Grasshopper™ and EnergyPlus™ software, in which trees are considered as special external shadings, characterized by a variable permeability to solar radiation during the year. Results demonstrate that trees can contribute to reduce energy loads, depending on species and orientation, especially in association with traditional shading systems. Eventually, some guidelines on technological and construction aspects, as well as on trees species selection, are given, in order to assure the optimal vegetation life and to maximize its benefits on the building

Architectural integration of photovoltaics in high-rise office buildings: a case study in Milan

The paper illustrates the potential use of PV Glass as a solution for building purposes, as well as an electricity-generating opportunity with the aim of capturing the sunlight for electricity production, focusing on high-rise office towers. In this regard, the use of Building Integrated PhotoVoltaics (BIPV) in the building envelope is very varied and opens many strategies for designers and architects. The concept of BIPV refers to an architectural technology and to the capability of photovoltaic systems to be multifunctional and interact with the building, producing free energy from a renewable source. The PV glass panels consist of layers of heat-treated safety glass (laminated with polymeric interlayer foils), which include in the middle a certain number of PV cells (monocrystalline, polycrystalline or amorphous). The cells are linked together following electric schemes based on technology of various bus bars connection and plugs (current state of art with 3 or 5 bus bars). BIPV glass provides the same performance (thermal and sound insulation) as a conventional glass and it can be assembled in Double Glazing Unit (DGU) or Triple Glazing Unit (TGU). Furthermore, PV systems can also be used as small stand-alone power units. Thus, the BIPV could be inserted in tailored solutions of new glass façades or replacing old glazings into retrofitting of curtain walls of buildings, generating free clean electricity and reducing the carbon footprint. In case of high-rise office buildings, BIPV technology may come to significant values of installed electrical power, but it is necessary to develop a consistent design strategy to take into account the daily and seasonal sun path and its positive input on available glazing area. Also shading given by adjacent buildings and sloping or recessed façade areas need to be clearly investigated as potential and crucial critical issues for the BIPV efficiency. The paper presents a significant case study of a high-rise office building in Milan (Italy), highlighting the “pros” and “cons” of PV integration in the building curtain walls for this specific building typology

Green walls for advanced building envelopes: design optimization and analysis - A case study in Milan

The paper illustrates the potential use of green walls for advanced building envelopes. In the last years, several technological systems have been developed for green building envelopes. They can be categorised into two groups, according to their system and growing methods: green façades and living walls. Green façades are created by growing climbing plants up and across the façade itself, either from plants grown in garden beds at its base, or by container planting installed at different levels; they can be direct (i.e. self-clinging climbers, deciduous or evergreen, which adhere to the building exterior by means of adventitious roots) or indirect, where plants are kept away from the walls by continuous supporters and substructures. Living wall systems differ from green façades in the fact that they incorporate multiple ‘containerised’ plantings to create a vegetation cover rather than being reliant on fewer numbers of plants that climb and spread. Once decided to include vegetation into the building project, several questions may be asked. The first one is about structural stability and safety, as envelopes have to be designed to withstand very high dead loads. Another crucial safety aspect is the fire performance: vegetation could be considered a fire propagation medium ‘par excellence’, and the façade must be designed to assure that, in case of fire, its propagation is reduced as much as possible. Moreover, plants sustentation should be carefully considered, since they have to receive light and water to naturally live and grow; natural light supply depends on surroundings and building shape; water supply could be more problematic, because a system of water irrigation and disposal must be designed and integrated in the building envelope. If not properly designed, these aspects can lead to cumbersome and noisy drainpipes and to maintenance issues related to difficulties in inspections and replacement of the drainage components in case of damage Therefore, a very important aspect is maintenance, and maintenance schedule as well: plants need to be cut to keep them healthy, and excessive or abnormal grow has to be avoided. Maintenance system is a sensitive issue, and the designer should think about it since the beginning. This paper presents and details a case study of an office building in Milan with an indirect green façade: vine plants are located in special planters across the façade, and they are free to grow and develop along metal wires included in the curtain wall. Eventually, technical aspects are analysed and some guidelines on technological and construction aspects are given, in order to assure the optimal vegetation life

Innovative building envelopes with fibre-reinforced composite materials and BIPVs integrated technology: state of art and possible applications

The building envelope has a dominant impact on a building’s energy balance, and it plays an essential role towards the nearly Zero Energy Buildings (nZEB) target. Global energy demand is continuously growing, with the building sector consuming one third of the total energy supply in developed countries and one-fourth in developing ones. The research aims to integrate new innovative sustainable materials (fibre-reinforced composite material) and renewable energy sources (PV) into certified building envelope system technologies. Façade systems represent generally the building skin, aiming to satisfy a growing complexity of functional demands such as the stringent green energy requirements given by most of the building codes and to ensure the weather resistance (i.e. energy-efficiency, wind load, air tightness and water penetration). Maintenance aspects and durability of the curtain walling kit are mainly also involved in accordance with the long-term performance of the individual components and materials as well as product assembly and environment. Based on scientific approach and integrated design, the use of new technologies improves the overall performance of the building envelope, including solutions and integrations with photovoltaic systems as part of a holistic “green” strategy. The state of art and the following discussion provide a wide overview of the main variables involved in FRP pultruded profiles production, installation and use. This in order to define tools, technical rules and testing methods suitable to assess the performances of the possible design solutions under specific requirements and boundary conditions. The building envelope system that integrates BIPVs with an innovative fibre-reinforced composite material – used such as frame, subframe or specific component - allows also to significantly reduce the thermal bridges, via its low values of thermal transmittance in comparison with the common construction materials used nowadays, contributing to the improvement of the energy efficiency of buildings. The environmental impact assessment will be considered as well, since the use of re-usable or recyclable building materials will be even more important in the next future (transition to a circular economy)

Double skin façades: externally and naturally ventilated small and big cavities: a case study in Milan

Double-skin façades aim to improve the thermal, acoustic and daylight performances of the building envelope, contributing substantially to the indoor comfort and reducing solar heat gains in summer. To evaluate the performances of a double-skin façade, various analytical and CFD modelling methods (Computational Fluid Dynamics) are used to assist designers and key-role makers in defining architectural and technical characteristics. Double skin façade systems are basically divided in natural and mechanically ventilated ones. Technical solutions for a natural ventilated double skin system range among single vertical channel, dual channels or single ventilated façade unit. These different configurations may significantly modify the thermal, acoustic and daylight response of a building. Coupling a double-skin façade to a natural ventilation system is also challenging for the correct design of width and height of the cavity between the two skins. Furthermore, outer skins have also a specific architectural function, considering irregular or non-planar glass panes or cladding panels, that characterize today rounded, twisted façade free forms. The paper presents the case study of a double skin façade of an office building in Milan, highlighting technical advantages and disadvantages of natural ventilation in relation with depth and height of the interspace cavity

Façade performances assessment and essential on-site and off-site laboratory testing

The paper illustrates characteristics and performances of curtain walling kits intended to be used as part of the building envelope. Façade systems represent generally the building skin, aiming to satisfy a growing complexity of functional demands such as the stringent green energy requirements given by most of the building codes and to ensure weather resistance (e.g. wind load, air tightness and water penetration). Curtain walling determines the comfort level of the occupancy but also safety in use, heat retention and solar control, included acoustic and fire requirements, building and seismic movements, with or without failure analysis (test/assessments/calculation methods). The authors discuss about the common well known standards (ISO, EN, voluntary guideline and technical notes) used in carrying out off-site (laboratory) and on-site performance tests and procedures. The manufacturer should establish protocols and method statements to meet performances set by the European product standards for a common market (CPR) but also to achieve parameters and requirements set specifically project by project. Today curtain walling performances are assessed by rigorous tests performed directly by the manufacturer or by an independent third party (i.e. under harmonised AVCP system - Assessment and Verification of Constancy of Performance). The FPC (Factory Production Control) shall address the standards to ensure that the declared characteristics are maintained during the production and, later, with the installation on site

Recycled Glass Mixtures as Cast Glass Components for Structural Applications, Towards Sustainability

The problem of sustainability represents one of the most important issues that the world has to face nowadays, not only in terms of energy consumption and of the consequent CO2 emissions, but also in terms of material waste streams that end in landfill. 38 million tons of glass waste are produced every year in the European Union and new targets have been set for 2020 towards a more sustainable management of such wastes. Nowadays, only the container glass industry has reached a considerable recycling rate, while for all the other sectors we are still witnessing downgrading processes. Looking at the world of construction, glass has been more and more employed as a structural material thanks to its high transparency and compression strength. Although the use of glass can be attractive under multiple aspects and its production is continuously increasing, once employed as a construction element, it is rarely reused or recycled due to the high-quality requirement demanded to the industry of production. Nevertheless, besides its main applications as a 2-dimensional element, the new technology of cast glass has been recognised as a potential mean of glass recycling. Here, glass is designed and used under the form of repetitive 3-dimensional units assembled in a whole geometrical shape. In fact, thanks to its higher load-bearing capacity under monolithic shapes, this glass can admit less restrictions and potentially incorporate different types of waste. For this reason, the aim of this experimental work is to find a possible combination between glass families, specifically soda-lime, borosilicate and lead-crystal glass, to be recycled as cast glass components. Each type of glass was powdered or grinded under the form of cullet and different mixtures were prepared to be melted at temperatures of 970°C, 1120°C and 1200°C through the kiln-cast tecnique. Finally, an experimental splitting test was performed to define a force trend and a fracture behaviour for each sample. Some preliminary results have been achieved drawing the guidelines for a further investigation. Soda-lime-silica glass and lead-crystal glass mixture revealed to be the most compliant glass recipe with the required physical and mechanical properties, when reheated at 1120°C. The decrease in the melting temperature of the compound and the higher transparency given by the addition of lead glass revealed the potential benefit, in terms of sustainability, for future projects

Fire Safety Façade Design and Modelling

Nowadays, the construction industry is characterised by high-rise, multifunctional, and complex buildings with innovative façade systems. Unlike a simple prescriptive approach in accordance with standards and codes, a performance-based design allows us to: define safety levels and goals, evaluate heat transfer to the structure and the structure’s response based on fire behaviour, model different fire scenarios using Computational Fluid Dynamics (CFD) software, and personalise the design of any specific project in order to reach the required level of safety. Through a significant case study, the Libeskind Tower in Milan’s City Life district, this paper describes the Fire Safety Engineering (FSE) performance-based design approach. The analysis demonstrates consistent results between the CFD fire modelling output and the laboratory test on a full-scale façade mock-up. Moreover, a Finite Element Analysis (FEA) performed on a section of the façade mullion, identifies and highlights the façade system’s critical issues in different fire scenarios