Katia Perini

Vertical greening systems, a process tree for green façades and living walls

This study shows that greening the building envelope with vertical greening systems such as climbing plants or living wall systems provides ecological and environmental benefits. Contemporary architecture in fact is increasingly focusing on vertical greening systems as a means to restore the environmental integrity of urban areas, biodiversity and sustainability. Applying green façades, which is an established feature of contemporary urban design, can offer multiple environmental benefits on both new and existing buildings and can be a sustainable approach in terms of energy saving considering materials used, nutrients and water needed and efficient preservation of edifices. To provide a full perspective and a viable case study on vertical greening systems a process tree is developed throughout this research. Elaborating the process tree has proved to be a useful methodology to analyse main parameters as climate and building characteristics, avoid damages and maintenance problems caused by inappropriate design, and compare different elements such as technologies, materials, durability, dimensions, and plant species employed.

Life cycle assessment (LCA) of green façades and living wall systems

Abstract: Greening the building envelope using vegetated (green) facades is a good example of a new construction practice. Plants and partly growing building materials, in the case of living wall systems (LWS), have a number of functions that are beneficial for the built environment. However, the development of LWS is so rapid that various different materials and characteristics are available at the moment. The latter positively or negatively influence the environmental burden as discussed in this chapter. Greening the building envelope can be a sustainable option for new and retrofitted constructions, by using materials with a relatively high influence on the environmental profile, although not all benefits are yet quantifiable. The present study identifies new scientific directions to reduce the environmental costs of green constructions.

DESIGNING GREEN FAÇADES AND LIVING WALL SYSTEMS FOR SUSTAINABLE CONSTRUCTIONS

The integration of vegetation in urban areas is a constantly evolving research fi eld. However, green envelopes (especially the most innovative vertical greening systems) are not yet fully accepted as an environmental quality restoration and energy-saving method for the built environment, due to the lack of data needed to quantify their effects and to evaluate the real sustainability (environmental and economic) of these. The many systems available on the market allow combining nature and built space to improve the environmental quality in urban areas; green facades, living wall systems offer more surfaces with vegetation and, at the same time, contribute to the improvement of the thermal performance of buildings. From a functional point of view, vertical greening systems often demand a complex design, which must consider a major number of variables. In the case of vertical greened surfaces, there are numbers of systems to green facades with or without windows, starting from a simple disposition of climbing plants at the base of the facade. Vertical greening systems’ characteristics and materials involved can either positively or negatively infl uence theirs performances, with respect to the improvement of the building envelope effi ciency and microclimate conditions (cooling potential and the insulation properties), and the environmental burden produced during their life span (installation, maintenance, disposal, etc.). This paper analyses characteristics, advantages and critical aspects of four common vertical greening systems, with special attention to micro-scale benefi ts (the benefi ts most related to the systems peculiarities) and to environmental sustainability.

Green Streets to Enhance Outdoor Comfort

Abstract This chapter describes the positive effects and improvements of green streets on outdoor thermal comfort, considering the relevant influence on human well-being and urban heat island phenomenon in cities. The most influencing characteristics of plant species, which determine outdoor comfort, are described, e.g., foliage shape and dimension, leaf area density, and seasonal cycle. In order to investigate effective factors determining thermal comfort, an analysis of parameters, i.e., wind speed, air temperature, relative humidity, and mean radiant temperature, is provided. Simulation results of summer performances of greenery in urban canyons show different performances depending on the relation between trees and the built environment during day and night.

Green Streets for Pollutants Reduction

Abstract In this chapter, the mitigation effect of greening solutions on air pollution within urban canyons is reviewed. First, a glance at the specific scientific literature is made and the different outcomes by authors about the effectiveness of greening solutions on air quality improvements are stressed. The main parameters to consider, the most promising strategies and the most suitable plant species characteristics, are discussed. Considering the important role played by numerical simulation in this field, the main issues that have to be taken into account in implementing a computational fluid dynamics model of the problem are listed and commented. Finally, with reference to evergreen hedges and a row of trees, some preliminary results obtained by means of a simple numerical model applied to CO 2 are presented and discussed.

Vertical Greening Systems for Pollutants Reduction

Abstract Applying vertical greening systems (VGS) on both new and existing buildings can offer multiple environmental benefits, including air pollutants’ mitigation and air quality improvement. The direct effects of VGS on air quality are mainly related to the absorption of fine dust particles and the uptake of gaseous pollutants. Indirect effects, e.g., cooling capacity and related reduction of energy demand and gas emissions connected, can be relevant as well. VGS can therefore reduce adverse health impacts from long term exposure to air pollutants at the same time improving the local urban environment. Selecting the most suitable plant species is of key importance, especially considering particulate matter collecting capacity. Attention should be also paid in low allergenicity, low cost of maintenance, and climatic suitability.

Urban Sustainable Development in the Mediterranean Area: The Case of Sestri Ponente, Genoa

In November 2014 a green facade was built in the Sestri Ponente district in Genoa, Italy, on an office building owned by the Istituto Nazionale di Previdenza Sociale (National Institute of Social Insurance). This area, which is characterized by a relatively high population density, faces important environmental issues related to, for example, air pollution, stormwater management, and the urban heat island effect. The Department of Sciences for Architecture at the University of Genoa (Italy) is conducting monitoring activity to evaluate the effectiveness of the green facade with regard to summer cooling, winter heating – in collaboration with Research on the Energy System – air quality improvement, and economic and environmental sustainability. Starting from this first pilot project a question arises: what would be the effect of vegetation at the district scale? This article discusses the potentialities for urban sustainable development of the integration of green infrastructure. Simulations carried out with ENVI-Met software demonstrate the potentialities of different amounts of vegetation for urban heat island mitigation. In addition, the possible stormwater runoff reduction was calculated. Such calculations are based on urban design projects developed for the area to evaluate the possible improvement to environmental quality owing to the integration of green infrastructure.

Is Greening the Building Envelope a Sustainable Design Practice

Nowadays, the number of products and also of architectural projects, qualified as “sustainable”, is ever more growing. Following this trend, architectural design may exploit the use of (eco) materials and components to promote a project as sustainable even without considering its impact on the environment; This can be defined as architectural greenwash. This paper considers the case of green envelopes with the aim to evaluate if these can be defined as sustainable design practice. Green envelopes provide environmental advantages together with the suggestion to a green aesthetics par excellence. In fact, the integration of vegetation in urban fabric plays an important role in improving ecological and environmental conditions of (and in) cities, although systems can have a high environmental burden. This paper aims to answer the question: Is greening the building envelope a sustainable design practice? To do so, the paper provides a literature review which includes the main research developed regarding environmental burden, benefits and LCA (life cycle assessment) calculations of green envelopes.