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Journal of Living Architecture
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Aesthetics for Green Roofs and Green Walls
Richard K. Sutton
Professor, University of Nebraska-Lincoln, Department of Agronomy and Horticulture and
The Program in Landscape Architecture, rsutton1@unl.edu
Abstract
Do green roofs and green walls have aesthetic benefits? Most green roof proponents would
say so. But what are they and how do they relate to green roof design in terms of species
selection, planting arrangement, viewable context, access, maintenance and other factors?
Aesthetics according to the Green Roof Design 101 Manual 2nd Ed (GRHC 2006) provides
“pleasure- and psycho-physiologically-oriented benefits” but, this narrow understanding
suggests that the aesthetic potential of green roofs is limited to what one might experience
looking upon any garden. We suggest other ways that need exploring to make aesthetics
more relevant and understandable to the practice of wall and roof greening.
We suggest other ways that need exploring to make aesthetics more relevant and
understandable to the practice of wall and roof greening.
Keywords: Aesthetics, Enjoyable beauty, Admirable beauty, Ecological beauty, Biodiversity
Introduction
Most green roof and green wall advocates tout improved urban aesthetics as a benefit, yet
other than a passing reference to stimulating an urban dweller, reducing stays in hospitals, or
lowering the amounts of pain medication for patients, few other reasons have been offered.
Ulrich’s (1984) widely referenced article indicated that patients in a monotonous hospital
environment had shorter stays and reduced pain medicine among other positive affective
responses with window views of nature. The implication has been that green roof and wall
views may have the same impact. Yet applying such affective or psycho-physiological
benefits to a green roof (e.g., Lee and Koshimitz 2006) really is no different than applying
them to a landscape garden. Such tenuous aesthetic support does not represent the totality of
aesthetic benefits accruing to green roofs and green walls. Nor does it delve more deeply
into understanding of aesthetics generally or environmental aesthetics in particular. We
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expand below on several ideas to help demonstrate that an aesthetic experience, (i.e., an
experience of beauty) can be deeper, more encompassing, and much more sustaining than
simply a hedonistic response to pleasure.
According to Webster’s 7th Collegiate Dictionary, aesthetics has these meanings:
1) a branch of philosophy that deals with the nature of the beautiful and judgments
concerning beauty
2) description and explanation of artistic phenomena and aesthetic experience by means
of social sciences such as psychology, sociology, ethnology, or history.
So philosophers and social scientists, not just critics and designers, help us judge and
understand beauty. Beauty covers a suite of human experiences, affects, emotions, and
thoughts and as we can gauge from the definitions; applied beauty fully integrates a process
of description, interpretation, and evaluation. Make no mistake: when one talks about
aesthetics and beauty, or ugliness, the discussion broadly involves value judgments.
At least two aspects occur during that evaluation. First, there must be something describable
that arouses a judgment; second, an evaluator offers judgment. Aesthetics allows us to judge
our feelings and value our responses on a scale from value to disvalue and judgment may not
always be positive. Examining the disvalues below can help illustrate a broad range of
concerns and interactions found in real situations. For example, below are some common
disvalues (from Berleant 1997):
Banal - acquiesces to conventional style, subject matter, or sentiment
Dull - no invention, poor technique, shallow imagination
Unfulfilled - something’s missing; a good idea poorly executed
Trite - ignores new possibilities
Inappropriate - not suitable to its context
Desensitizing - ignores a place’s sensory richness or our perceptual completeness
Deceptive - hiding faults; lacking truthfulness
Destructive - degrades context or demeans user”
Notice how some, but not all, of the listed disvalues involve only the feature being judged.
Some disvalues call to question the skill and intention of the designer, or focus not just on the
feature or creation, but its context. Others begin to describe harmful impacts on the evaluator.
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Three Categories of Beauty
Describing and detailing beauty has occupied humans since at least the Ancient Greeks.
Alder (1981) in his book, Six Great Ideas, proposes that beauty as studied by philosophers
and our response to it can be reduced and summarized into the simple categories of enjoyable
beauty and admirable beauty. Given the last several hundred years of philosophical study and
debate, those two concepts work well to understand and interpret the beauty arising from
human creations. But a problem occurs when nature specifically or the non-human
environment in general, becomes the focus of aesthetic inquiry because, it is beyond human
control or understanding.
There is not enough room here to fully trace how interest rises and falls in aesthetics as
applied to the environment. If the reader wishes more depth, Carlson (2012) has completed
such review. In brief, Carlson’s explication of environmental aesthetics goes beyond what
Adler called enjoyable beauty and admirable beauty. Carlson describes and discusses the
recent interest in environmental beauty as paralleling concern regarding the deterioration of
our environment starting in the last part of the 20th Century. Aestheticians (e.g. Hepburn
1966) working on the characteristics of the environment or nature relationships showed
interest in our everyday environments and our interaction and response to natural elements
and ecological processes. According to Carlson, cognitive views of environmental aesthetics
use knowledge of nature while non-cognitive views rely on some other aspect such as
nature’s engagement of humans (Berleant 1997). Most recently, Carlson notes that some
scholars of environmental aesthetics (e.g. Nassauer 1997) and ecological-based beauty are
attempting to include multiple viewpoints.
Below we describe Adler’s simple, but useful and accurate explanations of enjoyable beauty
and admirable beauty, because those concepts fit and are widely espoused by many who
envision the aesthetics of green roofs and walls. We then bring forward a wider and more
useful concept of ecological beauty.
1. ENJOYABLE BEAUTY
St. Thomas Aquinas (1274) stated adroitly that beauty is, "that which being perceived,
pleases." Such an idea of beauty, while it may be true, is, unfortunately, strongly subjective.
It is one’s opinion and no one else can confirm or deny that personal response. Its basis
cannot be accessed; so therefore, it is not really open to dialog or persuasion. Much of the
subjectivity of enjoyable beauty (Adler 1981) may be the result of cultural learning not
shared by others. “Beauty is in the eye of the beholder” as a shallow and self-contained
approach, tends to separate one from what catalyzed the aesthetic experience in the first place.
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Finally, its focus on immediate gratification also fails to deal with a wider older, and more
complex context for the experience.
2. ADMIRABLE BEAUTY
Turning to what brought on the experience provides no more complete an explanation to an
aesthetic experience either, since it focuses solely upon the stimulus’ physical and admirable
properties. This object-oriented approach, favored by art critics and many designers, may
also be culturally learned and should acknowledge the intention of the artist. According to
Kant (1792), contemplation or interpretation of an aesthetic experience must be a
disinterested act. And just as enjoyable beauty requires separation of a subject and object, so
does admirable beauty (Adler 1981). Often based solely on formal, visual elements such as
color, texture, and form, and the design principles of variety, unity and proportion, this
approach can become superficial and focus narrowly on pleasure derived from shallow
surfaces. This pleasure or affect often ignores the surrounding context in favor of a designed
object.
Explaining an aesthetic experience based upon admirable beauty brings several problems.
First, not all critics agree that some object may be worthy of admiration or use widely
different criteria to judge it. Cold, calculated criticism fails to account for human emotions
and may be often biased in favor of only the sense of sight. Trapped in a static field, objects
often belie and deny their changing context.
These arguments all seem fairly obvious when dealing with a solely human-created
phenomena like a sculpture, painting or even a building, but things become more
complicated when natural phenomena (like plant growth on a green roof or wall) come into
play. When an ecological system, however much it was designed and initiated by a human,
takes on a life of its own, we need a different more encompassing approach to beauty.
3. ECOLOGICAL BEAUTY
Ecological beauty arises from the subject (individual user), object (landscape) and their
higher order connection (Individual-landscape-context) (Gobster 1999). In this approach,
subject, object and context become unified. Focusing on interaction frames ecological beauty
hierarchically much like nature herself. Beauty and its perception emerge from these
underlying properties and interactions. An ecological approach to beauty thus extends
beyond mere surface properties and embraces unseen forms and processes, deeply and
holistically engaging our personal experience. This deep experience simultaneously draws
upon our knowledge and teaches us about our general environment. Over time, experience
bonds us to a specific place. Unlike enjoyable or admirable beauty, ecological beauty makes
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no attempt to control the subject with esoteric cultural knowledge or the object with precise
description. Those who desire perfection in aesthetic experience will be disappointed with
ecological beauty because humans will never have enough knowledge to perfectly describe
or specify all natural features, contexts, and processes.
Aldo Leopold (1949) in his classic book, A Sand County Almanac, developed the well-
known valuation system called the “Land Ethic” and in the same book also sketched out
another valuation system he called the “Conservation Esthetic”(sic). Callicot (1983) recounts
the differences and similarities in Leopold’s valuation systems. The Conservation Esthetic
Table 1. Three Categories of Beauty
Enjoyable
Admirable
Ecological
Subjective
Cultural model (learned)
All about one’s experience
Sensory-based pleasure
Objective
Art model
Product of intentional creative act
Requires disinterested interpretation
Object/Subject interact
Biological/Cognitive model
Interactive; hierarchical
Pleasure requires active interpretation/
knowledge
Separation of viewer from object
Opinion not open to discussion
Internalized
Separation of viewer from context
Judged in isolation of its context
Superficial, shallow-surfaced
Object/Subject/Context unified
Evidence-based; emergent properties
Based on formal characteristics
Deeply engages one’s experience
Descriptive
Normative
Primarily visual
Multi-modal, uses all senses and
movement
Teaches and bonds us with place
Criticism
Criticism
Criticism
Shallow and self-contained
Does not deal with context
Critics disagree, or use the same criteria
How to access and apply human
emotion?
Too often only visually-based
Static; denies change
Never will have enough knowledge
Can’t control context or viewer
recognizes the more common, directly visible and less scenic (i.e., non-superficial); it
emphasizes benefits such as psychic and spiritual rewards. Unlike the Land Ethic, the
Conservation Esthetic is non-consumptive and applies to private not just public places; it
does not focus on obligations and responsibilities but offers spiritual rewards. The major
connection between the two, interactive relationships, derives from ecology, albeit for the
Conservation Esthetic it is more conceptual; it includes ideas of diversity, complexity,
species rarity, nativity, their interactions and so on. Another key feature of the Conservation
Esthetic encourages individuals over time to cultivate sensibilities and acquire knowledge
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about specific environments. In short, it evokes learning and ecological awareness that may
take a lifetime to acquire.
Leopold’s Conservation Esthetic embraces many of the aspects described earlier for
ecological beauty such as interaction between subject and object with the subject capturing
information that is beyond a “pretty” surface. As well, it allows a deep and knowledgeable
experience to bond us with place over time. As alluded to earlier, ecological science’s raison
d’être seeks to unlock and explain how the ecological world works. However with regards to
an ecological aesthetic, ecological science becomes propelled by lack of knowledge
dampened neither by control of viewer nor by context. The essence of ecological beauty
means that we will always be engaged and learning about it.
Ecological Aesthetic Guidelines Applied to Green Roofs and
Walls
1. MAKE GREEN ROOFS AND WALLS CONSPICUOUS
Over twenty years ago, landscape architect, Robert Thayer (1989) examined the nascent
sustainable landscape. To him, it “symbolize[d] resource preservation through visual, spatial
and sensory means to produce a positive affective response.” Sustainable landscape features
like green roofs and green walls also exemplify Thayer’s idea that, "visibility and
imageability of the sustainable landscape is critical to its experiential impact and the rate at
which it will be adopted and emulated in common use" (p. 108). This means that for an
ecological aesthetic to become understood and appreciated by the public, it must be seen and
experienced (Figure 1). Accordingly, "conspicuous experiential quality" (Figures 2 and 3)
will help speed the diffusion of change in aesthetic expectations (Thayer 1989).
2. ALLOW HUMAN PARTICIPATION TO AID ECOLOGICAL KNOWING
We must be able to interact with a design’s natural elements and draw out information that
conveys content as well as form (Figure 4). Arnold Berleant (1997) has offered new insight
to this participatory aesthetics that he calls “aesthetics of engagement.” It jibes with Gregory
Bateson’s (1979), statement about aesthetics as “be[ing] responsive to the pattern which
connects.” The design process allows for input from the client and potentially the user. An
ecological aesthetic would capture such activity as a chance to educate and thus participate
more fully in the design intent and implementation.
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Figure 1. While some green roofs like the Barney’s New York retail store in Chicago may
have limited access, viewers in nearby buildings still can experience its planted surface from
a distance.
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Figure 2. Thoughtful space design within the Vancouver Convention Centre captures green
roof views and integrates user experience of outdoors and indoors. (Photo courtesy
Vancouver Convention Centre.)
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Figure 3. On axis with a main exit from the baggage collection area of the Vancouver
International Airport, this green wall’s bold, living textures intrigue users and its vertical
plane confronts our experience of what a wall should be.
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Figure 4. Native grasses and forbs on the Pioneers Park Nature Center green roof in Lincoln,
Nebraska, reflect its visual context and support the center’s mission of teaching the public
about the local prairie ecosystem.
The result of response and participation, Thayer (1989) claims is, “People who are able to
comprehend how and why a sustainable landscape functions will respond differently to that
landscape than those who are uninformed… environmental knowing heightens landscape
experience.” This cumulative, educated effect comes from “. . . creating new associations
between place and perception and displacing the old normative meanings of landscape
context” (Figure 5). Complexity and diversity in content take time, training, and experience
to discern. In using ecological beauty, we add the ecologist’s knowledge with the artist’s
intent, thus raising our level of participation and interaction with the environment and
ultimately improving our sense of connectedness.
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Figure 5. Honey harvested from hives supported by the flowering plants on Chicago’s City
Hall green roof lets one vicariously experience of the roof.
3. CARE COMMUNICATES AND CONNECTS KNOWLEDGE, INTENT, AND
COMMITMENT
Peter Harries-Jones (2005) notes Gregory Bateson’s ecological aesthetic examined
“epistemological propositions that arose from and were expressive of forms of
nature…patterns of recurrence; the perceptual abilities of all organisms engendered through
their capacity for anticipatory response; a way in which the evident interconnectedness of
nature is not simply a phenomena of physical interaction but is mediated through
communication (p.65).” (Figure 6) Nassauer (1997) says that seeing and understanding
connectedness is critical for humans; making connections makes us human. For example, to
Nassauer, common landscapes communicate the owner’s knowledge and may apply an
aesthetic of care seen as intention and involvement. Naturalized landscapes “without a clear
human intention seem unoccupied and invite human presence whatever its intention.”
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Figure 6. Guided tours and interpretative signage on the Eco-Phillips extensive green roof in
Minneapolis, Minnesota help communicate knowledge about the resident plants and the
concept of sustainability intended by its low maintenance design.
Intelligent care (Nassauer 1997) of landscapes calls on human understanding of ecological
parts, relationships and systems as best we can understand them. It also requires that we be
modest and humble when deciphering natural systems. Such an attitude applied to green
roofs and green walls forces the designer to treat each one as an experimental creation
(Sutton 2013a). Learning how these synthesized communities work as assemblages should
be embedded in their design program from intent to ideation to care. When one realizes
plantings on a green roof have begun to self-organize, disperse, and reproduce this
knowledge should lead to a joyous reaction.
Nassauer’s (1997) concept of vivid care, occurs when we “suppl[y] the visual framework of
human presence” and intent with requisite knowledge about what constitutes ecological
health (Figure 7). Nassauer talks about vivid care for natural and agricultural landscapes
including lawn care, so the analogy with green roofs and walls may not be obvious. Green
roofs and walls in one way can hardly be mistaken as natural, yet once planted and like any
living or inter-connected thing, they assume a life of their own (Figure 8). They may not
conform to an initial pattern and may seek their own dynamic pattern. Green roof and green
wall designers already apply some specific standards of care such as stopping substrate
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erosion, removing weeds, having vigorous plants and covering sufficient area. Sustainable
maintenance of green roofs and walls also fits this analogy offered by Nassauer, “Landscapes
are more like children than art. They require tending more than making.”
Figure 7. On the Ducks Unlimited Canada, Oak Hammock Marsh Interpretive Centre green
roof, fire as a natural process vividly controls thatch build-up that threatens to smother the
roof’s native plant layer. (Photo Credit: Tye Gregg, Ducks Unlimited Canada.)
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Figure 8. The initial decorative planting forms reminiscent of paisley layout on the Chicago
City Hall green faded as plants reproduced in new locations and coalesced into a more
random, but dynamic, and more self-organized but complex natural patterns.
4. ALLOW FOR CHANGE AND INCREASED BIODIVERSITY
Concerning itself with biological variety and a hierarchy of species, ecosystems and the
genes within (GRHC 2006), biodiversity fits easily within an ecological aesthetic and
produces ecological beauty for green walls and roofs.
Dunnett (2010) concludes that biodiversity designed onto accessible green roofs has been
guided by neither aesthetics nor studies of people’s preferences. He argues that nativity of
individual species, ecotypes or communities and substrates in support of green roof plantings
is at best misplaced. Though acknowledging biodiversity for its own sake cannot be sustained
by a public unaware of esoteric and largely scientific concepts of ecology, Dunnett fails to
probe more deeply into educating people about what they see planted on green roofs and how
it interacts and how gardeners seeking maximized color effects.
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As suggested above, green roofs and walls that grow, change, and become more self-
organizing may on their surface look disheveled, rough and unpolished. Harries-Jones (2005)
notes an, “Ecological aesthetic … registers a relation between the parts and the whole in a
manner very different from an observer pretending to be outside the setting engaged in an
exercise of eco-management” (pp. 67-68). On the other hand, Nassauer (1995) points out “A
neat, orderly landscape [or green roof] seldom enhances ecological function”; they “require
control and domination.” Horticultural green roofs and walls maintained with an eco-
management mindset often lack biodiversity, ecological structure, and require excessive,
costly outside inputs such as water, fertilizer, and labor (Sutton 2013b) (Figure 9).
Figure 9. A clipped, watered, and fertilized plant assemblage on this green roof requires
constant attention to maintain the static forms and blocks of color.
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5. DESIGN DIFFERENTLY
Nassauer (1995) identifies the nexus of design and an ecological aesthetic as “translating …
ecological patterns into cultural language.” To do this Koh (1988) suggests revising long-
held design principles by remaking unity into inclusive unity, seeing balance as dynamic
balance, and adding complementarity (Pattee 1967) as a third principle. Inclusive unity
brings together the participant and the environment; dynamic balance acknowledges an
ecological and biological system that self-organizes and permutes over time and is always
changing; complementarity revises the dualistic view from “either-or” to a qualitative, “both-
and” approach thus gives a designer other ways to communicate knowing. Suzi Gablik as
quoted in Harries-Jones (2005) might agree saying, “the sub-text of all art [and design]
should therefore be restoring the balance, attunement to nature, together with the idea that all
things are linked together in the cyclical processes of nature.” (Figure 10)
Figure 10. Blocks of native grasses at the Sandhills Publishing, Inc. green roof in Lincoln,
Nebraska, suggest the fuzzy natural boundaries of the nearby fields found in local
agricultural landscapes rather than a hardened, precise geometry.
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Summary
Aesthetics deals with the sensory experiences that make us value part of the material world
and is non-trivial because it taps our senses and links us to the world around us. A green roof
or green wall designer must certainly acknowledge all technical requirements such as site
analysis, membrane selection, user access, load bearing, media composition, and plant
hardiness, moisture requirements, managing sustenance etc. However, when embracing
ecological beauty, he or she must have goals to conspicuously engage the user as partner and
participant, to communicate the client’s intentions, to educate the user about the place’s
unique ecology, to allow for dynamics of growth, change and self-organization and to design
differently moving beyond the static, visual, and shallow in the creation. Doing so will
reduce or eliminate the disvalues brought by the banal, dull, unfulfilled and trite in
assembling green roof and wall plantings.
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Literature Cited
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1 (1) 23p. http://livingarchitecturemonitor.com/index.php/journal/research
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Acknowledgements
We wish to thank Dr. Paul Gobster for input into this article and to thank the Vancouver
Convention Centre and Ducks Unlimited Canada for allowing reprint of their photographs.
This article was given as a paper at the Atmospheres 5: Ecology and Design conference at the
University of Manitoba February 7-9, 2013. Research was funded in part by a UN-Lincoln,
Department of Agronomy and Horticulture Fleming Horticulture Research Grant.