Applied Energy 88 (2011) 4854–4859

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Applied Energy

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Green vertical systems for buildings as passive systems for energy savings

Gabriel Pérez a, Lídia Rincón a, Anna Vila a, Josep M. González b, Luisa F. Cabeza a,⇑a GREA Innovació Concurrent, Edifici CREA, Universitat de Lleida, Pere de Cabrera s/n, 25001 Lleida, Spainb Dept. Construccions Arquitectòniques I, Universitat Politècnica de Catalunya, Avinguda Diagonal 649, 3a planta, 08028 Barcelona, Spain

a r t i c l e i n f o

Article history:Received 5 November 2010Received in revised form 20 May 2011Accepted 18 June 2011Available online 16 July 2011

Keywords:Green systemsPassive systemsEnergy savingsBuilding

0306-2619/$ - see front matter � 2011 Elsevier Ltd. Adoi:10.1016/j.apenergy.2011.06.032

⇑ Corresponding author. Tel.: +34 973 003576; fax:E-mail address: lcabeza@diei.udl.cat (L.F. Cabeza).

a b s t r a c t

This paper presents a classification of green vertical systems for buildings. The aim of this classification isto facilitate the identification and differentiation between systems. This classification is also essential tocompare future research results relating to their operation. In addition, the mechanisms by which greenfacades can be used as passive energy savings systems are reviewed: shadow produced by the vegetation,insulation provided by vegetation and substrate, evaporative cooling by evapotranspiration, and the bar-rier effect to the wind. Finally, the paper describes the first results about the behaviour of a double-skingreen facade or green curtain in Dry Mediterranean Continental conditions. It is verified that a microcli-mate between the wall of the building and the green curtain is created, and it is characterized by slightlylower temperatures and higher relative humidity. This means that the green screen acts as a wind barrierand confirms the evapotranspiration effect of the plants.

� 2011 Elsevier Ltd. All rights reserved.

1. Introduction

In recent years the mechanisms that influence the use of greenroofs as passive system for energy savings in buildings have beenstudied. However, there are very few studies on the use of greenfacades with this purpose. In addition, while building systems ofgreen roofs are quite normalized, in the case of green facades thereare too many differences between systems. This hinders the com-parison of previous experimental results. Therefore it is necessaryto establish a classification of green facades to distinguish differenttypes and to compare in the future their behaviour as passive sys-tem for energy savings.

On the other hand, since plants are living organisms and theirdevelopment depends on the weather, the final results may greatlydiffer from one climating area to another, spoiling the expectationsof energy savings that had been planned according to theoreticalcalculations for a given system. So it is essential to know thebehaviour of the different plant species in local weather conditionsfor the efficient operation of green facades.

Most of the published work on this topic originates fromGerman studies, thus there is a great need for more research intoall aspects of this technology and its applications in other partsof the world [1].

Given the extreme climatic conditions in the area of Lleida(continental part of the region of Catalonia, Spain), it is even morenecessary to have more knowledge about the development of thesespecies in this local weather conditions. Lleida has a climate

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classified as Dry Mediterranean Continental, characterized by itsgreat seasonal variations. It has low rainfall, divided in two seasons,spring and autumn. It also has a thermometric regime with largedifferences between a long winter (between the spring and the lastfrost may take more than 160 days) and a very hot summer. Theaverage annual rainfall falls between 350 and 550 mm, and themean annual temperatures oscillates between 12 and 14 �C, withthermal amplitudes of 17–20 �C. A special mention must be madeto the fog, typical of the region in the months of November, Decem-ber and January that can give a period of up to 55 days in theabsence of sunlight. This is a very similar climate to that of the areaof Madrid, although it has annual rainfall and fewer days of fog peryear (Table 1).

This paper is divided in three parts. First it proposes a classifica-tion of green vertical systems. This classification considers bothtraditional systems and newly developed systems. Second, it sum-marizes an overview of the mechanisms in order to use the greenvertical systems as a passive system for energy savings. Finally, itdescribes one of the started actions in order to collect data aboutthe real behaviour of green verticals systems of buildings as pas-sive system for energy savings. Specifically it is a double-skin greenfacade or green curtain in a real building in Dry MediterraneanContinental conditions.

2. Typologies of green verticals systems of buildings. Proposalfor classification

Traditional green facades are considered those made by climbingplants that develop directly in the building wall without any sub-jection system. This practice of landscaping has been typically

Table 1Normal climatic values for Lleida/Station 2. Period: 1971–2000 – Altitude (m): 192 – Latitude: 41�3703300N – Longitude: 00�3504200E State Meteorological Agency. Spanish Ministryof Environment http://www.aemet.es/es/portada.

Month T TM Tm R H DR DN DT DF DH DD I

January 5.3 9.6 1.0 26 81 4 1 0 12 13 5 116February 7.9 13.7 2.2 14 70 3 0 0 5 8 7 167March 10.8 17.5 4.2 27 61 4 0 0 3 3 8 226April 13.2 19.8 6.5 37 58 5 0 1 1 0 6 248May 17.3 24.0 10.5 49 58 6 0 3 1 0 5 279June 21.4 28.5 14.4 34 54 4 0 3 0 0 9 313July 24.7 32.2 17.2 12 51 2 0 2 0 0 14 348August 24.5 31.6 17.4 21 56 3 0 4 0 0 12 313September 20.7 27.3 14.1 39 63 4 0 2 1 0 8 250October 15.3 21.2 9.4 39 71 4 0 1 4 0 6 200November 9.3 14.2 4.4 28 79 4 0 0 11 5 5 137December 6.0 9.8 2.1 28 83 4 0 0 14 10 5 96Year 14.7 20.8 8.6 369 66 46 1 18 53 37 91 2685

T – Monthly/annual temperature average (�C).TM – Monthly/yearly maximum daily temperatures average (�C).Tm – Monthly/annual minimum daily temperatures average (�C).R – Monthly/annual precipitation average (mm).H – Relative humidity average (%).DR – Monthly/annual days of precipitation greater than or equal to 1 mm average.DN – Monthly/annual snow days average.DT – Monthly/annual storm days average.DF – Monthly/annual fog days average.DH – Monthly/annual frost days average.DD – Monthly/annual clear days average.I – Monthly/annual sunshine hours average.

G. Pérez et al. / Applied Energy 88 (2011) 4854–4859 4855

associated with damage to the facade materials, animal attraction,and high maintenance costs. However, recently, different buildingsystems are being developed. These new systems allow greeningthe facades of buildings, which have evolved technically and con-ceptually with respect to the traditional ones.

We can encompass all the systems available on the market un-der the common name of green vertical systems of buildings (Table 2).

A first division is the differentiation between green facades andliving walls.

Green facades are facade systems in which climbing plants orhanging port shrubs are developed using special support struc-tures, mainly in a directed way, to cover the desired area. Theplants can be planted directly in the ground at the base of thestructure, or in pots at different heights of the facade.

Green facades can subsequently be divided into three differentsystems. Traditional green facades, where climber plants use the fa-cade material as a support; double-skin green facade or green cur-tain, with the aim of creating a double-skin or green curtainseparated from the wall; and perimeter flowerpots, when as a partof the composition of the facade hanging port shrubs are plantedaround the building to constitute a green curtain.

In the case of double skin green facades, the systems used aremodular trellises, wired, and mesh structures. Modular trellises are

Table 2Classification of green vertical systems for buildings.

Extensive systems Intensive systems

Greenfacades

Traditional greenfacadesDouble-skin greenfacade or green curtain

ModulartrellisWiredMesh

Perimeterflowerpots

Living walls PanelsGeotextile felt

very light trellis metal modules mounted on the building wall oron independent structures, which become the support for climbingplants. Application examples of commercial systems are the GreenScreen system [2], and the G-SKY Green Wall Container [3]. Thewired structures use a system of steel cables, anchorages, separa-tors, and other items which constitute a light structure that servesas support for climbing plants. Application examples of commer-cial systems are the Façade Scape system I-SYS Stainless Cablesand Rods by Carl Stahl Décorcable [4], and the Jakob inox line[5]. The mesh structure is a very light structure that provides sup-port for the climbers, made with steel mesh anchored to the build-ing wall or to the building structure. One application example ofcommercial systems is the FacadeScape system X-Tend StainlessSteel Flexible Mesh Fabric by Carl Stahl Décorcable [4].

Living walls are made of panels and/or geotextile felts, sometimespre-cultivate, which are fixed to a vertical support or on the wallstructure. The panels and geotextile felts provide support to thevegetation formed by upholstering plants, ferns, small shrubs,and perennial flower, among others.

Panels of varying sizes and types, with holes in which the sub-strate and plants are located, are fixed to the wall. Applicationexamples of commercial systems are the G–SKY Green Wall Panels[3], the ELT Easy Green Living Wall Panel – Elevated LandscapeTechnologies [6], the Parabienta ‘‘green wall’’ [7], the Paramentovegetal vertical – Intemper [8], and the Green Wall System – MarieClarke [9].

The geotextile felt systems use geotextile felt as support for theplants or mosses, anchored directly to the wall. Application exam-ples of commercial systems are the Mur végétaux – Patrick Blanc[10], and the BRYOTEC Technology – MCK Environment – BRYOTEC[11].

This classification considers the different construction systems,the different types of plant used, as well as future maintenancenecessary. As vegetated roofs, green vertical systems can be differ-entiated as extensive and intensive systems. Extensive systems areeasy to build and it have minimum future maintenance, and inten-sive systems have more complex implantation and require a highlevel of subsequent maintenance.

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3. Overview of green vertical systems as passive systems forenergy savings

In order to use green vertical systems as passive energy savingssystems four fundamental mechanisms should be considered:interception of solar radiation due to the shadow produced bythe vegetation, thermal insulation provided by the vegetationand substrate, evaporative cooling that occurs by evapotranspira-tion from the plants and the substrate, and by blocking the wind.

3.1. Shadow produced by the vegetation

The first studies on the use of plants for solar control go back tothe 80s. Different uses of plants were chosen to study how theycontrol solar radiation, reduce the cooling load and improve the in-door and outdoor thermal environment with remarkable results[12].

Akbari et al. [13] showed that shade trees in two monitoredhouses yielded seasonal cooling energy savings of 30%, correspond-ing to an average daily savings of 3.6 and 4.8 kW h/d. Peak demandsavings for the same houses were 0.6 and 0.8 kW (about 27% sav-ings in one house and 42% in the other) [13].

Others previous experiences with trees show that the solar radi-ation incident on the area shaded by trees (100 W/m2) is signifi-cantly inferior to that area without shade (600 W/m2) [14].

The temperatures of the different layers of a double-skin facadeare generally lower if plants are used instead of blinds in the inte-rior space. For the same solar radiation, the increase of tempera-ture is two times lower than when plants are used respect toblinds. In addition, the plants surface temperature never exceeds35 �C, while in blinds it can exceed 55 �C. The installation of plantsinside a double skin facade reduces energy consumption air condi-tioning system by up to 20%. The magnitude of this effect dependson the density of the foliage (number of layers of leaves) [15].

In the ‘‘Bioshader’’ experiment, carried out at the University ofBrighton (United Kingdom) [16,17], a double-skin green facadewas placed at an office room window, and was compared withanother office without plants. Indoor temperatures reductions of3.5–5.6 �C, were measured. Solar transmittance of the foliage wasalso measured, ranging from 0.43 with one layer of leaves, up to0.14 with five layers of leaves. This corresponds to a reduction ofsolar radiation crossing the plants of 37% with one layer of leaves,up to 86% with five layers of leaves.

In experimenting with traditional green facades Köhler (2007 &2008) found that the magnitude of this shadow effect depends onthe density of the foliage. Ivy is the species that provides the max-imum cooling effect, comparable to the shade of trees. Differencesup to 3 �C in indoor temperature in winter were found [1,15].

Recently news studies shows that climbers can provide a cool-ing potential on the building surface, which is very important dur-ing the hot periods of the year, especially in warm climates. Hence,the peak temperatures that appear are essentially lower, in addi-tion to the decrease of heat flow losses [18,19]. Similar studieswere carrying out for tropical climate [20,21].

3.2. Insulation provided by vegetation and substrate

Green walls can produce changes in ambient conditions (tem-perature and humidity) of the space between the green screenand the building wall. This layer of air can produce an interestinginsulation effect. The renewal of the air in this space, the densityof the foliage and the design of the openings of the facade shouldbe considered. For the living walls, the insulating capacity can de-pend of the substrate thickness.

A dynamic computer model, simulating the thermal effects ofdeciduous and evergreen vegetation cover on exterior walls, wasformulated by Holm (1989). The thermal improvement of the in-door environment was found to be most pronounced in low-massbuildings in hot-arid climates where the best results were obtainedwith equator-facing walls of high radiation absorptance in winter,but covered by vegetation during summer, while all other outsidewalls were covered with evergreens. This design (which can be ret-rofitted on existing and poorly orientated buildings) can obviatethe need for artificial heating or cooling in the given climates [22].

The heat flux distribution on a west-facing wall of a two-storybuilding covered with thick ivy was measured experimentally toinvestigate the cooling effect of the ivy. The green wall reducedthe peak-cooling load transferred through the west-facing wallby 28% on a clear summer day [23].

The presence of trees acts as a barrier and blocks the thermalradiation emitted by the surface of the build facade. Thus, accord-ing to Papadakis et al (2001) the ratio of heat flow between thearea without shade and shaded area ranges between 2 and 4 [14].

The heat transfer through a concrete wall is significantly lowerif it is externally coated with a layer of vegetation. Hoyano (1988)reported that a living wall can reduce the energy transfer into abuilding wall by 0.24 kW h/m2 [3,12].

The insulation effect of ivy covering a traditional facade hadbeen measured by Köhler (2007). Cooling in summer as well insu-lation of about 5 �C in extreme winter are measurable effects [24].

According to Köhler (2008), in studies on traditional facades animprovement in heat loss up to 25% in a northern facade was mea-sured, although this improvement depended on the insulation lev-els of the building [1].

3.3. Evaporative cooling by evapotranspiration

The evapotranspiration process of plants requires energy. Thisphysical process generates the so-called ‘‘evaporative cooling’’,which represents 2450 J for every gram of water evaporated. Thisevaporative cooling of the leaves depends on the type of plantand exposure. Also climatic conditions influence. Dry environ-ments or the effect of wind can increase evapotranspiration ofplants. In the case of living walls evaporative cooling from the sub-strate will be important. In this case the substrate moisture is animportant factor.

In previous experiences with trees, the cooling effect due toevapotranspiration of plants (trees) resulted in a decrease in tem-peratures around the building. Papadakis et al (2001) reported thatthe water evaporated by trees can increase absolute humidity by1–2 kg of water per m3 of dry air [14].

A project at the Institute of Physics, Humboldt University ofBerlin – Adlershof, combined the management of rain water andenergy savings through the use of green facades and the condition-ing with technical media [1,25]. The shades created by plants andthe cooling effect influenced energy consumption of the building,becoming a true passive air conditioning system. In the measuresat Berlin – Adlershof, a planter box of about 1 m2 and 40 cm depthof growing medium by full artificial rain water saturation with twoWisteria climbers could have yearly evapotranspiration of about2000 l.

Moreover, in the ‘‘Bioshader’’ experiment, described before, itwas shown that the humidity level of the office with the greenfacade was constantly higher than the office without this mecha-nism, between 5% and 14% higher from July to October, demonstrat-ing that the use of vegetation provides a lot of extra humidity to theindoor environment [16,17].

An experimental approach carried out by Cheng (2010) assessedthe effect of vegetation on the thermal performance of a verticalgreening system, which comprised of turf-based vertical planting

G. Pérez et al. / Applied Energy 88 (2011) 4854–4859 4857

modules. It shows that the vegetated cladding reduced interiortemperatures and delayed the solar heat transfer, which conse-quently reduced power consumption in air conditioning. The cool-ing effect was closely associated with the area covered by livingplants and with the moisture in the growth medium [26].

According to Wong (2009, 2010) since insulation applied to theexterior of buildings is much more effective than interior insula-tion, especially during the summer months, vertical greenery sys-tems would have the two fold effect of reducing incoming solarenergy into the interior through shading and reducing heat flowinto the building through evaporative cooling, both increasing en-ergy savings [20,21].

Fig. 1. Green facade in Golmés, 2008.

ETER

A 265.19

265.75

NORTHWEST

3.4. Variation of the effect of the wind on the building by its blockage

Green vertical systems of buildings act as wind barrier and con-sequently block the effect of wind on the facades of the building.This effect depends on the density and penetrability of the foliage,as well as the orientation of the facade and the direction and veloc-ity of the wind.

A computer simulation was used by McPherson et al. (1988) totest the effects of irradiance and wind reduction due to vegetationon the energy performance of similar residences in four US citiesrepresenting four different climates. They showed that planting de-signs for cold climates should reduce winter winds and provide so-lar access to south and east walls. This guideline also applies fortemperate climates, however it is also important to avoid blockingsummer winds. In hot climates, high-branching shade trees andlow ground covers should be used to promote both shade and wind[27].

One way of increasing energy efficiency of a building is blockingthe wind. In winter, cold wind plays a crucial role in reducing thetemperature inside the buildings. Even in airtight buildings, thewind reduces the effectiveness of regular insulation. Dinsdaleet al. [28] showed that protecting the building of the cold windwith vegetation (green roofs and green walls), reduces the heatingdemand by 25% [27].

Previous studies with vertical ‘‘hedges’’ of shrubs and treesfound out that the energy consumption in winter increases be-cause of the shadow produced on the building, but substantialreductions in energy consumption are finally obtained due to theeffect of change in the climate in the space between the wall ofthe building and the green facade and the wind speed reduction[29].

On the other hand, when considering the use of vegetation as amodifier of the effect of wind on buildings, one must be careful notto obstruct the ventilation in summer and not to favour the circu-lation of air in winter [30].

C CA

RR

265.68

266.16 267.90

SW1

SW2

SW3

SW4

SW5

NE1

NE2

SE1

SE2

SE3

NORTHEASTFACADE

SOUTHWESTFACADE

SOUTHEASTFACADE

FACADE

OUTSIDE

Fig. 2. Location of measurement points in the green facade of the theatre Lo Casalde Golmés.

4. Methodology

In order to obtain information on the operation of green verticalsystems several actions has been initiated by the authors. One ofthese actions refers to green facades, specifically a double-skingreen facade or green curtain. This typology is characterized by itseasiness to assemble and disassemble, its easiness to be integratedinto a building, and because the requirement of maintenance.

In May 2007 the rehabilitation of a building in Golmés (Lleida,Spain), to be used as social activities local, was finished. A greenfacade with a structure of steel and deployè sheet steel (modulartrellises), in the northwest, southwest and southeast facades wasincluded in the project (Fig. 1). The structure is located parallelto the facades, at 0.8 m in the northwest and southwest, and at1.5 m in the southeast facade (due to the presence of safetyladders).

The species planted on all three fronts is Wisteria sinensis, adeciduous climbing plant which is characterized by its rapidgrowth and great development, well adapted to the conditions ofthe Dry Mediterranean Continental climate.

Although there was no possibility of automating the data acqui-sition, manual measurements were performed, because it was agood opportunity to see the real behaviour of a vegetated façadein such a building and climate.

Different parameters to evaluate this green facade were mea-sured from April 2009 to September 2009. The parameters thatwere monitored were intermediate and exterior illuminance(Lux), with a TESTO 545 light metre, intermediate and exterior

4858 G. Pérez et al. / Applied Energy 88 (2011) 4854–4859

environmental temperature (�C) and intermediate and exteriorenvironmental relative humidity (%), with a TESTO 625 digitalthermo-hygrometer, surface temperature of the built facade (�C),with a TESTO 845 infrared thermometer, and finally, the windspeed outside (estimate based on the Beaufort scale).

The collection of data was done weekly and the measurementswere always taken at about 14:00 h in different points located inthe intermediate space between the structure and the facade,and also the exterior (Fig. 2). This distribution compared thebehaviour of the green facade in different orientations with theexterior conditions.

It was considered appropriate to take the data always at thesame hour of the day. In terms of quantity of surface facade andbetter plants development, the best facade was the south-west fa-cade. For this reason the data was acquired at 14:00 h.

5. Discussion and results

This paper presents the results obtained during the spring andsummer (the period with leaves). During these months the foliageof the green facade became more consolidated covering 62% of thesurface of the facade.

Fig. 3 shows the illuminance in the intermediate space betweenthe building wall and the vegetated facade, as well as the outsideilluminance. These values measure the ability to produce shadeof the green facade. The differences between outside illuminanceand intermediate illuminance range from 15.000 lux in April, to80.000 lux in August. These results are similar to those obtainedfor trees and for the ‘‘bioshader’’ experiment.

Fig. 4 presents the values of the shadow factor, which expressesthe ratio between the intermediate space illuminance and the out-

0100002000030000400005000060000700008000090000

100000

April May June July August SeptemberMonths

Illum

inan

ce (l

ux)

SW facade SE facade NW facade All facades Outside

Fig. 3. Illuminance measured at Golmés green facade, in 2009.

0.37

0.17

0.04

0.08 0.10

0.03

0.08

0.07 0.07

0.08

0.21

0.27

0.27

0.04 0.03 0.04

0.040.06

0.05 0.070.08

0.090.13

0.30

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

April May June July August September

Shad

ow fa

ctor

MonthsSW facade SE facade NW facade All facades

Fig. 4. Calculated shadow factor for Golmés green facade, in 2009.

side illuminance. This value varies from 0 to 1, indicating theamount of radiation that passes through the light screen plant(solar transmittance in ‘‘bioshader’’ [16]). Values in south-westfacade range from 0.03 in June to 0.37 in April.

These values are comparable to that provided by artificial obsta-cles used for the purpose of providing shade to the building, beingthe extreme values for the south facades of 0.16–0.98 for cantile-ver, from 0.23 to 0.83 for setback, from 0.39 to 0.61 in the caseof opaque awnings, and 0.42–0.81 for translucent awnings. In thecase of the slats, the values range from 0.26 to 0.54 for horizontaland from 0.30 to 0.56 for vertical slats [31].

The increase of illuminance in the months of May and June onthe south east facade is due to the position of the sun at the timewhen the measurement were taken, because the sunlight camethrough the top of the green facade.

Fig. 5 shows the measured wall surface temperature of thebuilding. In all orientations, the sunny area values were muchhigher than the values in the areas with shade. The surface temper-ature in sunny areas was on average 5.5 �C higher than in shadedareas. This difference was higher in August and September, reach-ing maximum values of 17.62 �C on the North West side inSeptember.

Fig. 6 summarizes the values of the ambient temperature. Nosignificant differences were measured between outside and theintermediate space, showing slightly lower temperatures in theintermediate space in the hottest months (May, June, July, andAugust).

Finally Fig. 7 shows the results for the ambient relative humid-ity. Ambient relative humidity in the intermediate space was high-er than outside humidity during the months with highest density

0

5

10

15

20

25

30

35

40

45

50

April May June July August SeptemberMonths

Bui

ldin

g W

all S

urfa

ce

Te

mpe

ratu

re (º

C)

No shadow SW facade SE facade NW facade All facades

Fig. 5. Building wall surface temperature measured at Golmés green facade, in2009.

19

21

23

25

27

29

31

33

35

April May June July August SeptemberMonths

Am

bien

t Tem

pera

ture

(ºC

)

SW facade SE facade NW facade All facades Outside

Fig. 6. Environment temperature measured at Golmés green facade, in 2009.

3032343638404244464850

April May June July August SeptemberMonths

Am

bien

t Rel

ativ

e

Hum

idity

(%)

SW facade SE facade NW facade All facades Outside

Fig. 7. Environment relative humidity measured at Golmés green facade, in 2009.

G. Pérez et al. / Applied Energy 88 (2011) 4854–4859 4859

of foliage, June and July. In July maximum daily differences up to7% were measured.

6. Conclusions

There are different types of green verticals systems of buildingsclearly distinguished, each with different construction systems.Therefore, it is necessary to differentiate them and study individu-ally their suitability as passive systems in the energy efficiency ofbuildings.

In this paper, a classification of green vertical systems to clarifyconcepts and to be able to compare results in the future was estab-lished as shows Table 2. A first division is the differentiation be-tween green facades and living walls. Green facades cansubsequently be divided into three different systems: traditionalgreen facades; double-skin green facade or green curtain; and perim-eter flowerpots. Living walls can be made with panels and/or geotex-tile felts.

Green vertical systems of buildings follow basically four funda-mental mechanisms when are used as passive system for energysavings. These mechanisms are the interception of solar radiationby the effect of the shadow produced by the vegetation, the ther-mal insulation provided by vegetation and substrate, the evapora-tive cooling that occurs by evapotranspiration from the plants andthe substrate, and finally, through the variation of the effect of thewind on the building.

A double-skin green facade or green curtain, made with modu-lar trellises and wisteria (a deciduous plant), in Dry ContinentalMediterranean climate was monitored during 2008–2009. In theresults for the seasons of spring and summer, the following find-ings could be pointed out:

� Both values of illuminance and shade factor, as well as thebuilding wall surface temperatures, confirm the great capacityof the green screen to intercept the radiation.� The measurements of the ambient temperature and humidity

confirm that the green facade creates a microclimate in theintermediate space, characterized by lower temperature andhigher humidity. This fact verifies that the green facade actsas wind barrier and shows the effect of evapotranspiration ofplants.

Acknowledgements

The work was partially funded by the Spanish Government(Project ENE2008-06687-C02-01/CON) and the European Union(COST Action COST TU0802), in collaboration with the Cityhall ofGolmés and Fundación Mapfre. The authors would like to thankthe Catalan Government for the quality accreditation given to theirresearch group (2009 SGR 534).

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