Vertical Greenery Systems (VGS) for energy savings in buildings
International Green Wall Conference
4-5th September 2014
Stoke-on-Trent, UK Julià Coma Dr. Gabriel Pérez Dr. Cristian Solé
Dr. Albert Castell Dr. Luisa F. Cabeza
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Contents
• Introduction
• Objectives
• Previous research
• Current research
• Further research
• Conclusions
• Acknowledgements
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• Vertical Greenery Systems contribute positively to the
improvement of the built environment: – Aesthetics – urban landscaping
– Support to biodiversity
– Noise reduction
– Energy savings – Heat island reduction
– Etc.
Introduction
Thuir. France
Pergola Building
Belén, Costa Rica
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Introduction
• The classification of VGS must be taken into account for energy savings purposes
Extensive systems Intensive systems
Traditional
Modular trellis
Wired Double-skin
Mesh
Green façades
Perimeter flowerpots
Panels Living walls
Geotextile felt
Pérez G. Façanes vegetades. Estudi del seu potencial com a sistema passiu d’estalvi d’energia, en clima mediterrani continental. PhD thesis. Universitat Politècnica de Catalunya, 2010
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• The main mechanisms of VGS as passive tool for energy
savings are four: – Shade effect: Interception of the solar radiation by the plants
– Cooling effect: Due to the transpiration from the plants
– Insulation effect: Air layer create in the foliage
– Wind barrier effect: Variation of the direct wind effect over the building façade by the plants and the support structure
• Shade effect seems to be the most influential
Introduction
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• Difficulties to measure the influence of VGS on building
thermal performance: – Differences between constructive systems
– Living organisms (species, growth, diseases, etc)
– Different climate conditions
– Difficulties to quantify the effects individually
Introduction
Sihlcity Greenwall, Zurich
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Objectives
• To study the use of VGS as passive tool for energy savings in Mediterranean continental climate
– To quantify the shadow effect
– To quantify the energy savings
• These studies are conducted in a large real scale installation that the research group GREA has in Puigverd de Lleida (Lleida, Spain). http://www.grea.udl.cat
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Previous research
• Previous actions
– Action 1: Shadow capacity of different climber species. 2009-2010
– Action 2: Thermal behavior of green facades in an existing experimental cubicle. 2010-2011
Radiació
solar
incident
paret
Radiació
solar
incident
exterior
Tª 3, HR 3
(z = 3m)
Tª 1, HR 1
Exterior
Tª 2, HR 2
(z = 1,5m)Tª 4, HR 4
Interior
Action 1 Action 2
Pérez G. et al. Green vertical systems for buildings as passive systems for energy savings. Applied Energy 2011;88:4854-4859
Pérez G. et al. Behaviour of green façades in Mediterranean Continental climate. Energy Conversion and Management 2011;52:1861-1867
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Previous research
• Action 1: Shadow capacity of different climber species. 2009-2010
– The ability to intercept solar radiation of vegetation, even at low foliage densities, is similar to that offered by artificial barriers such as awnings, slats, etc. according to the Spanish technical code for buildings (CTE).
LUXOMETER
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
9 h 10 h 11 h 12 h 13 h 14 h 15 h 16 h 17 h
Hora
Tra
nsm
isiv
ida
d lu
mín
ica
Viña virgen Madreselva
Clematide Hiedra
Artificial barrier shadow factor
Cantilever 0.16 – 0.82
Setback 0.17 – 0.82
Opaque awnings 0.02 – 0.43
Translucent awnings 0.22 – 0.63
Horizontal slats 0.26 – 0.49
Vertical slats 0.32 – 0.44
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Previous research
• Action 2: Thermal behaviour of green facades in an existing cubicle. 2010-2011
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Previous research
• Action 2: Thermal behaviour of green facades in an existing cubicle. 2010-2011
– The shadow effect is evident over the wall surface temperature, reaching 14 ºC less than in the reference cubicle with 50% of the surface covered
Shade capacity (14 ºC)
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Previous research
• Action 2: Thermal behaviour of green facades in an existing cubicle. 2010-2011
– Shadow effect influences over indoor temperature too. The reduction was about 1 ºC less in the facade cubicle under free floating conditions
Inside temperature reduction free floating (1ºC)
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Previous research
• Action 2: Thermal behaviour of green facades in an existing cubicle. 2010-2011
– Some energy savings was observed for the accumulated energy consumption under indoor controlled conditions (24 ºC)
0
2
4
6
8
10
12
07-07-11 08-07-11 09-07-11 10-07-11 11-07-11 12-07-11
En
erg
y [
kW
h]
Day
Green facade Reference
Accumulated energy consumption by the heat pumps.
July 2011. Set-point 24 ºC
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Current research
• Current research
– As the previous results were positive, a new green facade have been
built, covering the east, south and west walls
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• Current research
– Deciduous vegetation (Boston Ivy, Parthenocissus Tricuspidata) was planted in June 2012 and was growing during summer 2012 and spring 2013
Current research
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Current research
• Data from summer 2013 show the shade effect, with a set point of 24 ºC
15
20
25
30
35
40
45
50
10-7 0:00 10-7 6:00 10-7 12:00 10-7 18:00 11-7 0:00
Tem
pe
ratu
re (
ºC)
PeriodSouth internal wall green facade South internal reference roofOutside temperature South external wall green facadeSouth external wall reference roof
Green facade; South internal wall
Outside
Reference; South external wall
Reference; South internal wall
Green facade; South external wall
15
20
25
30
35
40
45
50
10-7 0:00 10-7 6:00 10-7 12:00 10-7 18:00 11-7 0:00
Tem
pe
ratu
re (
ºC)
PeriodSouth internal wall green facade South internal reference roofOutside temperature South external wall green facadeSouth external wall reference roof
Green facade; South internal wall
Outside
Reference; South external wall
Reference; South internal wall
Green facade; South external wall
7ºC
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Current research
• And interesting energy savings (set point 24 ºC), up to 50%
0
2
4
6
8
10
12
14
16
2-7 3-7 4-7 5-7 6-7 7-7 8-7 9-7 10-7 11-7
Reference roof Energy green facade
Acc
um
ula
ted
ele
ctri
cal
en
erg
y co
nsu
mp
tio
n [
kwh
]
Reference cubicle Green façade cubicle
0
2
4
6
8
10
12
14
16
2-7 3-7 4-7 5-7 6-7 7-7 8-7 9-7 10-7 11-7
Reference roof Energy green facade
Acc
um
ula
ted
ele
ctri
cal
en
erg
y co
nsu
mp
tio
n [
kwh
]
Reference cubicle Green façade cubicle
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Current research
• In 2014 a Green Wall was built (BuresInnova S.A.) on another identical cubicle
– Well adapted perennial bushes Helichrysum stoechas and Rosmarinus officinalis
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Current research
• Data from summer 2014 with a set point of 24 ºC. The shade effect was confirmed for the Green Wall too
10
15
20
25
30
35
40
45
50
15-7 0:00 15-7 6:00 15-7 12:00 15-7 18:00 16-7 0:00
Tem
pe
ratu
re [
ºC]
PeriodGreen Wall; South internal wall Green Facade; South internal wallReference; South internal wall Outside temperatureGreen Wall; South external wall Green Facade; South external wallReference; South external wall
12 ºC 17 ºC
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Current research
• Data from summer 2014. Energy savings of more than 50 %
0
1
2
3
4
5
6
7
9-7 10-7 11-7 12-7 13-7 14-7 15-7 16-7
Period
Acc
um
ula
ted
ele
ctri
cal e
ne
rgy
con
sum
pti
on
[kw
h]
Green Wall Green Facade Reference
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Further research
• In 2013 a review of the scientific literature available to date regarding to the use of VGS as passive tool for energy savings was conducted
• Some of the most important conclusions which will guide future research are:
– The number of species used for Green Facades is very limited, mostly climbing plants, having two predominant species:
• Ivy (Hereda helix) Perennial
• Boston Ivy (Parthenocissus tricuspidata) Deciduous
• Chinese Wisteria (Wisteria sinensis) Deciduous
– For Green Walls the number of species used is higher, mostly herbaceous and bushes, but this can result in different thermal behaviours in the same Green Wall
Pérez G. et al. Vertical Greenery Systems (VGS) for energy saving in buildings: a review. Renewable and Sustainable Energy Reviews (2014), pp. 139-165
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Further research
– Most of the studies found are located in Europe (mainly Green Façades) and Asia (mainly Green Walls).
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Further research
– A lack of studies in areas of the world that receive more radiation, in which these systems consequently could be more effective, have been observed
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Further research
– The most interesting parameters to consider for energy savings purpose design of VGS are:
Traditional Green Facades
Double-skin Green Facades
Green Walls
Purpose/period
Heating/Cooling/Both
x x x
Species used x x x
Facade orientation x x x
Foliage thickness
(or coverage %)
x x x
Air gap thickness x x
Substrate thickness and composition
x
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Conclusions
• Shade effect
– Vertical Greenery Systems (VGS) show a great shade effect with
reductions in outside wall surface temperatures ranging from
7 ºC to 12 ºC, for Green Facades, and up to 17 ºC for Green
Walls, for the studied constructive systems
• Energy savings
– This shade effect implies great energy savings around 50 %, in
summer periods, for the studied constructive system, under
Mediterranean Continental climate
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Conclusions
• Further research
– To study the contribution of the different effects on energy savings
– To study the suitable plant species for energy savings purpose
– To develop these systems in areas of the world that receive more
radiation
– To focus the research/design on the parameters/variables that
regulate the thermal behavior of these systems:
• Purpose/period (heating/cooling) – Species – Orientation – Foliage
thickness - Air gap – Substrate thickness and composition
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Acknowledgements
• To the European Union's Seventh Framework Programme (FP7/2007-2013)
under grant agreement n° PIRSES-GA-2013-610692 (INNOSTORAGE)
• To the Spanish government (ENE2011-28269-C03-01, ENE2011-28269-C03-02,
ENE2011-28269-C03-03 and ULLE10-4E-1305)
• To the Catalan Government for the quality accreditation given to their research
group (2014 SGR 123)
• To Department of Vegetal Production, University of Almería (Almería), the
company Buresinnova S.A (Barcelona) and with the City Hall of Puigverd de
Lleida
• Julià Coma wants to thank the Departament d'Universitats, Recerca i Societat de
la Informació de la Generalitat de Catalunya for her research fellowship
• To all co-authors of this work
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Thank you for your attention