Green Facades Research Articles

Resilient and Environmentally Efficient Residential Buildings - Assessment Method and Interim Outcomes

Historically, the fire-safety orders restricted the use of majority of the nature-based low impact materials in town buildings. Houses therefore became rigid and resilient. Today, we need to return to those materials, but the tradition and public opinion are preventing changes in building habits. This paper describes the work done within a research project, which aims to define a resilient and low impact residential building. The main goal of the research is a development of an assessment method that evaluates the building’s ability to withstand or easily overcome most important threats which may occur in the Central European area. The research team’s objective was to identify the risks, define the crisis scenarios and to provide an exemplary solution that will ensure the necessary resilience of a model building. The method includes environmental criteria with benchmarks set up to fulfil the requirements of the Paris Agreement. This leads the building design towards the low-impact materials and technologies and towards resilience at the same time. The research team developed an assessment method including 20 criteria. A set of buildings has been evaluated and favourable technical solutions have been developed. Based on the results, a design of a model building was carried out. New equipment and technologies were implemented: removable green facade, natural ventilation with solar chimneys, or a hybrid control system managing renewable sources in the building. The next step should be a test of the technology or the overall design in real conditions. The project outcomes show the possibility of reaching a sufficiently solid and robust design of a low-rise apartment building while following a sustainable design approach at the same time.

Leveraging Urban Planning and Building Design to Reduce Ambient Combustion Ultra-Fine Particles Exposure

Of all modern human settlements today, cities have the most potential to accommodate population growth in a sustainable and healthy manner. Water supply, sanitation, and mass-transit can be efficiently managed in well-functioning dense cities, where the compact urban tissue promotes healthy active transportation opportunities such as walking, biking or jogging. Unfortunately, most American cities today are burdened with increased traffic pollution, leading to ambient combustion ultra-fine particles (UFP) exposure, a significant public health problem.The growing body of evidence-based research in urban planning and building strategies can help to mitigate traffic-related UFP exposure for people living near highways. For environmental scientists and policy-makers to incorporate these strategies in future urban and building developments, they need to leverage the key tools and strategies of architectural practice that address outdoor and indoor air quality in cities.This poster illustrates regulations, strategies and tools used in urban planning and architectural practices in America, with the goal to facilitate the collaboration between environmental scientists and designers towards devising, implementing and evaluating tactics to reduce UPF exposure in cities. The poster describes how evidence-based UFP mitigation tactics can be integrated: (i) at the urban planning level (i.e. landscaped buffers, vegetated and wall barriers or decked highways) with different regulations such as land use, performance or sustainable zoning. (ii) at the building level (i.e. facade sealing, MERV and HEPA filtration, or green facades and roofs) with building codes for indoor air quality. Finally, the poster also explores the most widespread voluntary sustainable building standards (i.e. LEED, WELL, Fitwel or Passive House), and how they compare to evidence-based UFP mitigation strategies at the building scale.

Energy savings of block-scale facade greening for different urban forms

Many studies investigated the energy savings of buildings with green facades for different facade orientations and structures, whereas few studies have analyzed the influence of the urban form. This study evaluates the summer cooling energy savings of full-scale facade greening at blocks with different urban forms, using an integrated simulation with ENVI-met and EnergyPlus. Six idealized urban blocks (IUBs), each with two green-facade scenarios and one baseline bare-facade scenario, are established. The hourly output cooling loads of the bare- and green-facade scenarios are used to estimate the daily energy-saving rate (DER) and daily energy savings per m2 of green facades (DES). The results show that the block-scale facade greening provides a DER of 3.2–11% and a DES of 123–347 Wh/m2, representing a summer cooling energy reduction of 11–31 kWh for every m2 of the green facade. Among the six IUBs, the high-rise high-density site (HH) has the lowest DER and DES, and the mid-rise low-density site (ML) has the highest. A higher greening ratio (65%) results in a cumulative effect and a higher DER and DES than in the buildings with a lower greening ratio (35%). Shading provided by plants and substrates is the primary reason for the DES, whereas cooling and humidifying have relatively small influences, and a trade-off effect between the two is observed. The findings of this research can shed light on green-facade practices and building energy conservation in humid subtropical cities.

The use of the Analytic Hierarchy Process in Determination of the Design Solution for Vertical Gardening

The researches cover the methodological basis for formation of vertical gardening (landscaping) of building facades in the concept of landscape architecture, ecology of vertical gardening, green construction technologies and measures aimed at the improvement of the energy efficiency of buildings. The ‘Tree of Objectives’ is substantiated, which determines contemporary fields of development of green facades. For the first time, a methodology for choosing variants of the project design and technology solution of vertical gardening is proposed. In the work, multi-factor landscape ecological analysis is used; the analytical method of system analysis – the Analytic Hierarchy Process – is discussed. The author of the method is Thomas L. Saaty (USA), who represents the structure of a practical decision as a hierarchy, with further decomposition of the problem into more simple elements, and further, in the processing of the sequence of judgments of a decision maker on the basis of comparing elements to each other two at a time. In result, the intensity of interaction between elements in the hierarchy is described, and then, the judgments are expressed numerically. The method includes the procedures of synthesis of multiple judgments, of obtaining priority ranking of criteria, and finding alternative solutions. The proposed method for evaluation of a group of factors is universally applicable and can be easily used in practice, and also is the basis for preliminary selection of urban environment factors for creation of a comfort environment in the course of realization of landscape ecological properties of vertical gardening. The use of the system analysis method allows solving the analytical problem of choosing a design solution for vertical gardening system.

Modeling of hygrothermal behavior for green facade's concrete wall exposed to nordic climate using artificial intelligence and global sensitivity analysis

Green facades are one of the most promising natural-based solutions for buildings. Notwithstanding, in regions with variating weather such as the northern hemisphere, these can be counterproductive for the structures due to humidity retention. For these reasons, this work presents the development of an Artificial Neural Network (ANN) model to estimate the hygrothermal behavior inside a concrete wall protected by a second foliage skin. The database used for model formation was obtained through measurements made in an Accelerated Weathering Laboratory (AWL) to emulate the Nordic climatic conditions for a typical year. The ANN-hygrothermal model was trained in function of the parameters: environment relative humidity, ambient temperature, microclimate's relative humidity, microclimate's temperature, and the separation distance between the vegetation and the wall. The statistical results of the model demonstrated successful adaptability and great generalization capacity for both internal temperature (R2 = 99.98% for training and R2 = 99.95% for testing) and internal humidity (R2 = 99.16% for training and R2 = 99.17% for testing). Additionally, a sensitivity analysis was implemented, showing that the most influential variable in the estimation of both hygrothermal parameters is the ambient temperature and that the separation distance has a significant impact on the humidity produced inside the wall. Finally, the presented computational approach can be implemented in non-invasive monitoring systems or as a complementary tool in studies of concrete degradation due to humidity.

The impact of green facades and vegetative cover on the temperature and relative humidity within model buildings

Vertical greening solutions such as direct greening are gaining popularity due to their relatively low cost and minimal ground footprint. However, concerns about increases in relative humidity (RH) can reduce implementation.The impact of several widely-used plant species (Hedera helix, Parthenocissus tricuspidata and Pileostegia viburnoides) on the internal/external temperature and RH on the south-facing wall of replicated experimental model ‘buildings’ was studied during summer and winter. All plant species reduced the air temperature internally/externally during the summer daytimes by at least 1 °C compared to bare ‘buildings’. Hedera produced the greatest cooling effect internally and externally, by 7.2 °C and 5.7 °C respectively. All plant species reduced daily variation in external RH and external/internal temperature during summer; Hedera reduced variation most and Pileostegia least. During night-time in both seasons, the temperature behind Hedera foliage typically remained higher, which could reduce the risk of freeze-thaw damage in winter.The RH was not significantly elevated by vegetation except during warm afternoons in summer and winter. During warm afternoons, the external RH was significantly higher only behind the Hedera foliage compared to the bare ‘buildings’, 11% and 3.7%, summer and winter respectively. However, inside all vegetated ‘buildings’ the RH was at least 11% higher compared to the bare ‘buildings’ during summer. Yet, in winter the internal RH was 5.7% lower in the Hedera-covered compared to the bare ‘buildings’. Current building standards would prevent the transfer of external RH in this range internally, as the walls include protective layers such as damp-proof membranes.

Field measurement on the model of green facade systems and its effect to building indoor thermal comfort

Green facade systems are part of urban green technologies and can be applied in the building facade to improve building thermal performance. Three experimental studies were conducted in tropical country to explore the effect of green facade systems to building thermal comfort. In this study, three types of green facade systems with different leaves coverage area were attached on the facade of scaled building model. Field measurements were conducted in three days during December. Psychrometric and effective temperature chart were used to calculate the effective temperature. Generally, greater temperature differences from bare wall model were more visible than green facade with greater leaves coverage area from 1.9 °C to 9.9 °C. The result of the analysis also revealed that the model with green facade had less frequency distribution of high temperatures and never exceeded 26 °C. However, the average of relative humidity inside the building increased up to 72.5% due to evapotranspiration and effected indoor thermal comfort. In addition, the results showed that the trend of Te on the model with greater leaves coverage area was higher by 1.14 °C compared to bare wall model. While, the frequency distribution of high Te exceeded from 25.1 °C occured up to 48%. Finally, even though green facade can decrease temperature on the building, yet it also increases relative humidity and possibility creates uncomfortable indoor thermal comfort.

Reducing the Carbon Footprint of the Bucharest University of Economic Studies through Green Facades in an Economically Efficient Manner

This paper focuses on the current environmental issues, more specifically the amount of greenhouse gases humanity is being confronted with at the moment. The research was carried out on a niche of the topic, namely on the carbon footprint of public buildings. The concept of a sustainable university is new and insufficiently explored, and as part of the environmental metabolism, it influences anthropic sustainability in a directly proportional manner. This indicator’s monitoring systems reveal how vulnerable humanity is in front of the latency of an unprecedented and inevitable environmental catastrophe. The ecological effects may be mitigated by the academic community through green urban design. The ecological performance can be expressed in an economically efficient manner, which can, at the same time, create a precious channel of communication within the entire academic community though volunteering for sustainability. Moreover, this research has identified several solutions for optimizing the carbon footprint, which do not hinder the necessary economic development. Within the current context, when most economic activities are leading to ecological collapse, sustainability should be reprioritized with the help of the academic society, through the examples offered by applied research. The premises of this research were represented by bibliometric analyses and the results obtained have proven its importance, as well as the importance of certain scenarios involving solutions for improving the metabolism of nature.

EXPERIMENTAL INVESTIGATION OF HYGROTHERMAL BEHAVIOR OF DIRECT GREEN FACADES UNDER SEMI-ARID CLIMATE

This paper aims to investigate the hygrothermal behavior of direct green facades and assess their efficiency under semi-arid climate. For that purpose, a comparative study was conducted in three buildings; two buildings with direct green facades (covered with deciduous climbing plants) and one with a bare facade. Air and surface temperature, relative humidity and wind speed were collected in situ and several factors were taken into consideration as thickness and density of plant cover. The analysis of measurement data revealed that direct green facades contribute to improve the outdoor and indoor thermal environment of buildings due to the effect of shading and evapotranspiration. Moreover, the different types of green facades illustrated their different heat impact on the thermal environment of buildings depending on the density and thickness of the plant layer and the covering ratio.

Performance of foliage ornamentals in hydroponic nutrient solutions

Vertical garden is one of the approach of green building envelope with green facades and green living walls creates a richer ecosystem, enhances biodiversity, improves mental health, alleviates environmental externalization generated by urban areas (Pollution, runoff and heat island effect etc). However, the limitations of vertical gardening system are the choice of plants and the module of growing. Numerous exotic and native ornamentals are suggested for vertical systems based on the requirements. Selection of plants grown under indoor environments with limited space is narrowing down the choice of ornamental flora. On the other hand hydroponics is an alternative sustainable production system under conditions in which resources are limited. Hydroponics is a very young science which has commercial basis during recent days. However, even in relative short period of time it has been adapted in many situations from outdoor to indoor for growing various crops. Hence, an experiment was conducted with Hoagland & Arnon solution (1938), Cooper’s solution (1979), Saparamadu’s solution (2010) and Mattson and Peters solution (2014) and a control with Irrigation water to study the rooting behavior of five plants viz., Devil’s ivy (Epipremunm aureum), Wandering jew (Zebrina pendula), Arrowhead plant (Syngonium podophyllum), Philodendron (Philodendron erubescens), Boat lily (Tradescantia spathacea) under passive hydroponic vertical garden module. The pH was monitored for acidity and basicity range and EC were monitored for salt concentration in all the nutrient solution periodically. Observation on root parameters viz., Number of roots plant -1, Root length (cm) and Root weight (g plant-1) were observed at 30, 60 and 90 days after planting. Results of the experiment revealed that number of roots, root length and root weight exerted maximum values in those plants grown under T3 (Cooper’s solution). Minimum rooting with lowest weight was recorded in T4 (Saparamadu solution) in all the stages of observation in devil’s ivy. Whereas in other four ornamentals viz., Wandering jew (Zebrina pendula), Arrowhead plant (Syngonium podophyllum), Philodendron (Philodendron erubescens) and Boat lily (Tradescantia spathacea) recorded lowest root parameters in T1 (Irrigation water) under 30 days of observation and at 60 and 90 days minimum number of roots, root length and root weight was recorded under T4 (Saparamadu solution).

ART-COMPOSITIONAL LANDSCAPING AS MEANS OF EXPRESSION IN THE SPACE OF THE CITY

In the article the peculiarities of psychophysiological influence of plants on the central nervous system of a person are substantiated. The theme is supplemented with information about ornamental plants, as a factor of artistic and aesthetic organization of space, sanitary and hygienic and medical and biological functions, contributing to the rest of the person from physical and nervous loads. Criteria and features of plant selection, creation of phyto-compositions in urban environment design, as well as the use of plants in the formation of object-space environment were formed. One component of phytodesign is the cultivation of different plants on vertical surfaces with the help of different designs for the decoration of fences, facades of buildings. This system allows the cultivation of plants with various constructions in the vertical direction, regardless of the plant germination plane. Its purpose is to create a favorable urban environment, to form new directions in urban design, to take on the function of a small architectural form, or to create a new recreational space for recreation and events. Vertical landscaping includes green walls or vertical facades, eco-graffiti, vertical flower beds, green roofs and terraces, kinetic elements of urban landscaping, vertical green infrastructure, vertical farms. The concept of vertical phytodesign is becoming more popular every year, and we can already trace this to the example of elements appearing on the streets of cities. Today, vertical gardening can serve not only as a complement to the architectural environment, as an element of its design, but as a unique independent unit, capable of creating new shapes or forming new spaces.

Certain aspects of formation of green facades for high-rise development

“Green architecture” gains more and more popularity worldwide. In many ways, this relates to the need for improving environmental quality of urban area. Often, enviromentalization is used for creating green spaces on buildings, including vertical or with significant inclination. This article is dedicated to studying the questions of the structure of greening of vertical surfaces of the buildings (green facades) for medium and high-rise buildings. The research is aimed at determination of technical characteristics of designing green facades. The subject of this article is building structures of various designation (architectural, load-bearing and enclosing) that serve for the formation of greening. The author examines their potential in the formation of objects of "green architecture". The key research method is the analysis of normative and scientific framework for the design of vertical greening. The existing experience in designing green facades is explored. The scientific novelty of this work consists in systematization of the applied design concepts and engineering solutions. As a result of the study, the two types of structures are determined: supporting and maintaining. The author reviews structural systems characteristic to each type, outlines the assortment of greenery, engineering and technical solutions for maintaining plants, as well as forming capacities of the types of design solutions of green facades.

How green facades affect the perception of urban ambiences: Comparing Slovenia and the Netherlands

How green facades affect the perception of urban ambiences: Comparing Slovenia and the Netherlands

Moisture Safety of Green Facades

In Nordic climate, climbers covering facades are conventionally removed, although there is no evidence of the actual impact of the climbers on the moisture performance of facades. Such information is needed to support building design and nature-based solutions for climate change adaptation. This study aimed to find evidence on the performance of green facades from the physical and life-cycle engineering perspectives of buildings by testing double-skin green facades in laboratory and field conditions. First a mature thicket creeper was grown on a steel mesh over 100 days, and it was exposed to rain and dry periods by accelerated weathering equipment in a laboratory. Then the leafless creeper was exposed to rain cycles on a rooftop in natural conditions. The results indicated the high protective capacities of the climber during the leaf season, but even during the winter season (without leaves) protective performance was measured in laboratory and natural conditions. In conclusion, double-skin green facades provide effective protection from wind-driven rain while the distance between the green structure and the load-bearing wall impacts the relative humidity levels, and the drying process of the load-bearing wall. Thus, moisture safety can be improved with a double-skin structure with ventilation and access for maintenance.

Cooling effects of block-scale facade greening and their relationship with urban form

Green facades in cities have great potential for facilitating climate change adaptation and mitigation due to their well-documented energy and cooling effects. Many studies have reported that a green facade can noticeably reduce the building surface temperature and cooling loads in summer. However, little is known about the extent to which large-scale facade greening cools the ambient air or the relationship between the cooling effects and urban form. This research employed the ENVI-met model to evaluate the summer cooling effects of block-scale facade greening and their relationship with urban form in Nanjing City in China. Six idealized urban blocks (IUBs) representing typical urban forms in Nanjing combined with five hypothetical facade-greening ratios generated 30 scenarios for simulation. The results revealed a distinct spatial pattern of cooling effects in each IUB. The cooling intensity decreases with increasing elevation, and it is strongest in ground spaces on the downwind side. The maximum cooling intensity is 0.96 °C and observed in the high-rise high-density site (HH). Among the six IUBs, the low-rise high-density block (LH) appears to be optimal for facade greening since it ranks in the top 1–3 for the four cooling-effect indicators. The threshold values were evaluated to further estimate the minimum greening ratios required to achieve corresponding energy-saving targets in each IUB. The findings can provide insights into the cool air dispersion process in urban canyons that have varying geometries. Furthermore, the results can inform vertical greening practices for the determination of appropriate sites and coverage ratios.

How internal heat loads of buildings affect the effectiveness of vertical greenery systems? An experimental study

Nature-based solutions applied to the building skin, such as green roofs and vertical greenery systems, are standing out as the most promising by contributing with thermal improvements at building scale. From previous research done by GREiA research group at the University of Lleida (Spain), energy savings up to 58% were obtained by implementing vertical greenery systems on external building walls for cooling purposes. However, since there exist other passive and active energy saving technologies in the literature review that were limited their cooling and heating capacity after implementing internal heat loads, new experimental tests for two different vertical greenery systems simulating the heat loads in both, summer and winter were conducted in this research. Additionally, these experiments also improve the scarce and controversial literature for winter conditions. The results demonstrated that considering internal loads in experimental investigations is crucial for the results of the effectiveness of the green walls and green facades. The energy savings of VGS were reduced between 22.5% and 26.7% because of the internal loads for cooling purposes, and increased about 3.6% and 3.1% for heating.

The energy of the green: green facades and vertical farm as dynamic envelope for resilient building

The paper shares the results of a design submitted to a competition launched by the University of Wageningen, focusing on the retrofitting action of one of the existing towers of the former Bijlmerbajes prison complex in Amsterdam. The effort of an interdisciplinary team was oriented to demonstrating that it is possible to imagine the architectonic environment as a living organism, being part of the new food production chain, sponsoring zero kilometer products and increasing buildings’ sustainable comfort while reducing their energy consumptions. Promoting a healthy lifestyle, an awareness of how to environmentally friendly behave and keeping the ecological footprint as low as possible were the main goals we wanted to achieve with our retrofitting and regenerative proposal of the GreenTower.

Convective heat transfer in green façade system

Green facades 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 facade 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 facade 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 facade 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 facades of Deardorff model showed the best agreement. This study could be extended in order to write codes for building energy simulation software.

Thermal behavior of a vertical green facade and its impact on the indoor and outdoor thermal environment

Vertical green facades (VGFs) are one of the most promising technologies for reducing building energy consumption and mitigating the urban heat island phenomenon. Many studies have investigated the cooling effects of VGFs; however, research on the thermal behavior of VGFs and the impacts on indoor and outdoor thermal environments are scarce, which limits the understanding and application of VGFs. Therefore, field measurements were conducted in the subtropical city of Guangzhou, China, during hot days. First, the thermal balance of the vegetation canopy was investigated. In particular, the net photosynthesis and transpiration of foliage were measured to estimate the thermal effect of plant physiological activities. Moreover, the operative temperature (OT) and wet bulb globe temperature (WBGT) were measured to assess the comprehensive effects of the VGF on the indoor and outdoor thermal environments, respectively. The results indicated that transpiration could consume approximately 50% of solar radiation absorbed by the vegetation canopy. Furthermore, the thermal effect ratio of net photosynthesis to transpiration was less than 5.5%, suggesting that omission of the thermal effect of the net photosynthesis of climbing plants in thermal balance calculations could result in an error lower than 2.9%; such a low error may be acceptable for most engineering applications of VGFs. The VGF caused a decline in room air temperature and mean radiation temperature, resulting in a peak OT reduction of 3.6 °C. Moreover, the peak WBGT in the outdoor environment could be reduced by up to 2.7 °C due to the shading effect and transpiration cooling of the VGF. These findings help advance our understanding of the thermal transfer process of VGFs and extend the application of VGFs from a single cooling purpose to comprehensive improvement of the thermal environment.

Green Facades and Living Walls—A Review Establishing the Classification of Construction Types and Mapping the Benefits

The green facades and living walls of vertical greenery systems (VGS) are gaining increasing importance as sustainable building design elements because they can improve the environmental impact of a building. The field could benefit from a comprehensive mapping out of VGS types, an improved classification and nomenclature system, and from linking the benefits to a specific construction type. Therefore, this research reviews existing VGS construction types and links associated benefits to them, clearly differentiating empirical from descriptive supporting data. The study adopted a scoping research review used for mapping a specific research field. A systematic literature review based on keywords identified 13 VGS construction types—four types of green facades, nine types of living walls, and ten benefits. Thermal performance, as a benefit of VGS, is the most broadly empirically explored benefit. Yet, further qualitative studies, including human perception of thermal comfort are needed. Improvements in air quality, reduction of noise, positive effects on hydrology, and visual benefits need much further empirical testing, as the current supporting data is mostly descriptive and based on the similarities with green roofs. The educational benefits of VGS has no supporting empirical evidence, while the social benefits have only been empirically evaluated through one identified study. Future progress of the field depends on the adoption of a clear VGS nomenclature system and further qualitative and quantitative empirical testing of VGS benefits, which should be clearly linked to a specific VGS construction type so that cross-comparison of studies is enabled.