Disturbance of transparency in the architecture of contemporary glass façades. Part 1

Marcin Brzezicki

doi:10.37190/arc210109

Abstract

Over the last two decades, new trends have emerged in the design of translucent façades. Those trends result from the dynamic technological progress and achievements in material engineering. The trends that are associated with the use of envelopes that interfere with the transmission of light through the façade are particularly interesting. This is strongly related to the significant transformation that took place in the dialectic of the building, the transformation of the “façade” into an “envelope”. The paper presents the author’s original distinction between the two most characteristic main sub-trends, distinguished based on optical phenomena occurring within the façade. The proposed division includes two main groups of disturbances: homogenous and heterogeneous. The former is present where panes of glass are used to disperse/diffuse light evenly, while the latter in façades with strong – usually printed – ornamentation. The article systematizes the issues of transparency disturbance in contemporary architecture and presents the typology of light-transmitting façades, in which this phenomenon takes place. The author also presents a matrix of relations that systematizes the presented case studies. Only this type of matrix makes it possible to illustrate an issue in which more than one variable is present. An assignment of the case studies to the trends and the determination of trend models are also included in the paper. The first part of the paper presents the introduction, methodology and simplified typology, the second one presents case studies, discussion and conclusions.

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Full article

2021

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DOI: 10.37190/arc210109

Marcin Brzezicki*

Disturbance of transparency in the architecture

of contemporary glass façades. Part 1

* ORCID: 0000-0002-3901-144X. Faculty of Architecture, Wrocław

University of Science and Technology, e-mail: marcin.brzezicki@pwr.

edu.pl

Introduction

Architecture communicates with the viewer through the

façade. Façades, apart from their function of the cover and

illumination, are the hallmark of the building – they com-

municate its meaning and prestige. However, the complex-

ity of the relationship between the dierent architectural

“forms” and the “messages” makes contemporary archi-

tecture not easy to understand or value. Already 150 years

ago, Gottfried Semper claimed that buildings “should be

cloaked by a façade” [1], just like the gentleman is dressed

in a frock. Some 50 years later, the modernists postulated

“honesty” in design, which resulted in radical formal op-

erations involving the removal of all classical ornamen-

tation. The widespread introduction of skeletal structur-

al systems allowed for the use of the then-revolutionary

glass curtain walls, which were completely independent

of the building’s supporting structure. Smooth glass panes

representing the “new architecture”, apart from illuminat-

ing the interiors of buildings, also created mirror reec-

tions. This is because the use of glass makes it transparent

in certain lighting conditions, while – with the dierent

balance of internal and external illumination – the glass

surface becomes the mirror. Therefore the rst phase of

the formal development of the so-called “glass architec-

ture” was focused on studying the basic laws of optics. In

his garden, Mies van der Rohe […] photographed a model

of the famous glass skyscraper to assess the optical eects

that inuenced the appearance of the building [2, p. 82].

This basic optical eect of transforming the transparent

into the mirrored surface (with the increasing use of re-

ective coatings) has become the source of many critical

opinions concerning entirely glazed buildings. Those crit-

ical opinions are also currently formulated by renowned

authors, critics, and publicists. L. Alter, a journalist for the

inuential TreeHugger portal, writes that […] all-glass

buildings are an aesthetic, as well as a thermal crime [3].

In some buildings transparent façades have turned into

a large-scale version of the one-way-mirror, in others, the

reective coating makes the façade disappear and thus the

façade becomes a trap for people and animals.

The division of the building into “the structure” and

“the envelope”, was originally motivated by strictly en-

gineering reasons. Over time this division also gained

an important narrative function. In historical epochs, the

façade – apart from its load-bearing and covering func-

tions – played an important role in communicating the

meaning, the prestige of the client, and even the purpose

of the building. However, especially in the era of “inter-

national style” the spread of identical-looking glass cur-

tain walls caused this important narrative function of the

façade to be signicantly reduced, and in some cases, it

ceased to be performed at all. As a counteraction, new

buildings began to emerge for which the façade is much

more than just a simple physical climate barrier between

the internal and external environment. This new façade

gained an additional meaning: informational, communica-

tive, and also political [4]. In a sense, it returned to its

historical roots when the façade informed about the status

of the building and the client.

Modern glass façades – and especially the latest frame-

less systems – are characterized by high transparency (nota

bene it is even possible to buy panes without a greenish

tint, caused by the content of iron ions in the glass mass

– the product called clear glass). The most recent glass

surface modication makes the application of coatings on

glass cheap, easy, and available on a large scale. Many of

the coating technologies are created to meet the growing

78 Marcin Brzezicki

environmental requirements, i.e., to protect buildings

from overheating or to reduce the escape of heat. These

important technologies are developing dynamically, but

remain outside the scope of interest of the author of the

presen ted paper.

However, the designers of “transparent” architecture do

not always push the glass/façade to be more and more

transparent. Recent trends may be found, in which – along

with signicant formal transformations – the pane of glass

is losing its basic optical feature of light transmission. In

those façades, the transparency is deliberately disturbed,

and glass is no longer chosen solely because of its basic

function of light transmission, but also because of its other

optical properties. E. Diller and R. Scodio emphasize

this very aptly, writing that: […] glass is now understood

as a surface to look at, not only through. Transparent

glass is no longer invisible, rather, it is a display surface

[5, p. 355]. The clients and building users […] also show

a particular interest in surface design, in tactile proper-

ties, colour and texture [6, p. 7], at least as much as in the

real needs of users.

State of the art

The issues of the disturbance of transparency have

been the subject of many publications and scientic ar-

ticles. Due to the limited space, it is worth mentioning

those which – in the author’s opinion – are the most im-

portant for the subject of this article. In 1995, after the

exhibition organized in the MoMA in New York entitled

“Light Construction”, the exhibition catalogue was pub-

lished, followed by a joint publication including papers of

the authors that studied the issues of transparency in ar-

chitecture [7]. In 2004, in the series Detail Praxis, a book

entitled Translucent Materials was published, which cov-

ers the subject of light-diusing materials and perforated

metals [6]. It is mainly a technical review including the

presentation of details important for the development of

design practice. This study was published in a popular,

widely-readable series and – according to the author – has

signicantly increased the use of translucent materials in

architecture. The book titled In Detail: Japan – Architects,

Constructions, Ambiance [8] gives a special insight into

the use of translucent glass and other translucent materi-

als in Japan. Not only details are shown in the book but

also comments on trends in architectural transparency,

especially in the chapter titled “Toyo Ito, Blurring Archi-

tecture”. E. Blau’s books and papers are particularly im-

portant for the development of the theoretical foundation

and make a signicant critical contribution to the issue,

with an essay titled Tensions in Transparency… written

in 2008 [9] which particularly stands out. An important

summary of the issue is included in the book titled Trans-

lucent Building Skins: Material Innovations in Modern

and Contemporary Architecture from the year 2012 [10]

written by S. Murray. In 7 chapters the author presents

case-studies in which various light-transmitting materi-

als are used: diusing, ornamental, perforated. The nar-

ration focuses more on the reasons for their use than on

visual eects. This is – so far – the most comprehensive

monograph on the issues of the use of translucent glass/

façades in architecture.

Many books and papers were also written in the Polish

language. The general issue of the transparency of glass

façade was presented by W. Celadyn in his book entitled

Przegrody przeszklone w architekturze energooszczędnej

[Glazed envelopes in energy-ecient architecture] [11].

In chapter no. 7.3 titled “Glass vs. Aesthetics and Percep-

tion of Buildings” the author addresses the optical aspects

of perception of glass envelopes and forms the basis of

nomenclature in the Polish language. This book consti-

tutes a local reference for all subsequent scientic publi-

cations on the issue. Celadyn’s book has become a direct

inspiration for the presented research undertaken by the

author. In 2012, a book entitled Szkło we współczesnej

architekturze. Monograa [Glass in Modern Architecture.

Monograph] [12] was published by E. Wala in which the

author in the chapter titled “Transparency, Semi-transpa-

rency, Translucency” discusses the issues of the glass en-

vel opes that diuse or interfere with the light transmission

in various ways. The issues of translucent glass in archi-

tecture are also addressed by M. Zielonko-Jung [13] and

J. Marchwiński [14].

The novelty of the presented approach

According to the author’s knowledge, issues of the dis-

turbance of transparency presented in this article have not

been addressed in this way yet. In the previous refer ences,

typological distinctions were made, but this was done

either according to the type of material (glass, lux, plastic,

perforated metal) – see F. Kaltenbach [6], or according to

the function of the element in the building – see Murray

[10]. The typology presented here is based on the visual

eects – regardless of the material type that is used. The

visual eect is dened as a characteristic conguration of

the images received by the observer, created as a result of

the interaction of the light-transmitting pane and the light

itself [15]. Additionally, due to the dierent degrees of in-

tensity of visual eects, a relational matrix was created to

systematize the case-studies, allowing to organize them

according to two criteria (features): haze intensity (simply

speaking the degree of light scattering) and intensity of

the pattern which is applied to the glazing. In this method,

the position of the case-study in the presen ted matrix is

determined in a “fuzzy” way [16], according to the degree

of the optical phenomena (haze and pattern) marked on

the X and Y-axis. Therefore, it is possible to determine

the hazing intensity in the range between zero (clear) and

100% (fully scattered), and pattern intensity between zero

(clear) and 100% (opaque).

Aim and the scope of the paper

The article aims to systematize the issues of the distur-

bance of transparency in contemporary architecture and to

present the typology of light-transmitting façades in which

this optical phenomenon takes place. The author distin-

guishes the two most distinctive sub-trends of the main

trend and illustrates them with case studies of light-trans-

Disturbance of transparency in the architecture of contemporary glass façades. Part 1 79

Fig. 1. The diagram of research techniques used: a) desk study, field research; b) building data collection; c) formulation of trend models;

d) description of distinctive features; e) comparative analysis (elaborated by M. Brzezicki)

Il. 1. Schemat pokazujący wykorzystane techniki badawcze: a) badania literaturowe, wizje lokalne; b) zbieranie danych o budynkach;

c) formułowanie modeli nurtów; d) opis cech wyróżniających; e) analiza porównawcza (oprac. M. Brzezicki)

mitting façades. All presented case studies are assigned

to the sub-trends based on the characteristic features of

façades, which allows for the trend’s model denition (see

chapter titled “Matrix approach” in the second part of the

paper). The author also uses the matrix approach to sys-

tematize case studies (for a detailed description see the

paragraph above).

Method

The research methods adopted in the presented paper

are typical for architectural research conducted ex-post

on the built environment, the aim of which is to broaden

the knowledge about architecture [17]. The author started

research with the desk study (scientic publications and

internet portals). Then a database containing case-studies

was created. Next, GPS location data of all case-studies

were collected. This stage was followed by the eld re-

search and study trips to photograph, measure, and record

the case studies included in the paper. As emphasized by

J. Sławińska and B. Widera it is important to establish the

knowledge about architecture not only based on the lite-

rature and references but also “on in situ visits and re-

search” [18]. The analytical part of the presented paper is

based on the photographic material that was collected by

the author. This way of gathering/acquiring the research

data has advantages and disadvantages. The disadvantage

is a limited territorial range resulting from physical possi-

bilities of relocation and budgetary limits. The advantage

is the experience that results from the personal, direct con-

tact of the researcher with the analysed case-study [15].

The author used the research method of logical argu-

mentation [17], analysed the collected case-studies of

façades, distinguished the characteristic features of the

trends, and then undertook the eort to describe them

briey in a model. The inductive method reasoning was

used – experiences and observations were synthesized to

come up with a general truth – in which detailed analy-

sis of individual case studies resulted in the process of

the trends classication and the establishment of their

models [17]. The collected photographic data were sub-

jected to comparative analysis, on the basis of which the

author drew the conclusions and created a simplied ty-

pology proposed in chapter titled “Simplied typology”.

The research method adopted consisted of the following

techniques: desk study (literature review and internet por-

tals) case study trips, eld study, documentation using the

photographic equipment. The individual stages of the re-

search procedure are shown in the diagram – see Figure 1.

Definition of the trend and criteria

The article aims to classify and characterize trends in

contemporary architecture to the extent specied above

by the author. Based on the analysis of the available ref-

erences on the subject it has been assumed that […] the

trend in architecture is a group/collection of buildings,

while its model is a set of characteristic features of the

trend [19, p. 55]. Case-studies with similar characteristics

have been grouped, and their distinctive features are used

to dene the trend model in the chapter titled “Matrix ap-

proach” in the second part of the paper.

In the comparative analysis carried out below the ba-

sic criteria were: (i) degree of the distortion of an image

that is visible for the observer after the light is transmitted

through the façade; (ii) the density of the pattern visible

on the pane of glass. Research techniques previously de-

veloped by the author were used to carry out the analysis of

the digitally recorded image of the façade and specication

of the regions that have been blurred or/and blocked [15].

Based on this, it was possible to estimate the type of trans-

lucent or patterned material, its optical parameters, and

the case-study location in the proposed relational matrix.

Case-study selection principle

While working on the database, the author observed

many trends in contemporary architectural transparency

and determined their change in time and space; some of

them were described in other publications by the author

[20], [21]. For the presentation in this paper, only those

case-studies were selected that manifested the formal fea-

tures of the disturbance of transparency in the most ex-

pressive way. Those case-studies became later the basis

80 Marcin Brzezicki

for the description of the trend’s model. As a consequence,

the paper includes case-studies that are widely known

(e.g., Kuursaal in San Sebastian) but also little-known

ones, that are signicant for the research (e.g., Hopital

Mermoz in Lyon). The paper includes case-studies build

not later than 25 years ago, in which the transparency of

the façade was deliberately modied as a formal proce-

dure used by the architect/designer. Featured case-studies

are located in Europe, the USA, and Japan and present

a possible large spectrum of techniques used in trans-

parency disturbance. The presented case studies were se-

lected from 382 case studies, that were visited within the

research project titled “New trends in the architecture of

transparent façades – formal experiments, technological

innovations” in the years 2015–2018, funded by National

Science Center, Poland.

Definitions

To clarify the terms used in the article, it is necessary to

briey characterize the issues at the interface of architec-

ture and optics. A standard pane of glass is described in the

paper by the term “transparent” and should be understood

as a at pane that allows the light to pass through without

any distortion, meaning that it is possible to observe the

objects located on the other side of the pane without any

blur. In optics, this type of optical device is described as

an “optical at”. The “atness” of its geometry is essential

here, as this type of device allows a parallel passage of

the rays of light, without any concentration or dispersion

(it does not act as a lens).

The term “translucent” has been used to describe panes

that scatter the rays of light. The term originates from the

Latin words “trans” and “lucere”, meaning “through” and

“light”. Scattering is the phenomenon of the interaction

of light with matter, that results in the random change of

the direction of the ray of light. In the case of translu-

cent panes, an observer can see the blurred contours of the

source of light and all objects located behind the pane.

In material science, two parameters of light scattering are

measured: narrow- and wide-angle scattering. Wide-angle

scattering [15] is called haze. Haze determines the num-

ber/percentage of rays of light that have deviated by more

than 2.5° from the original direction. In contrast, the pa-

rameter called clarity determines the number/percentage

of the rays that have deviated by less than 2.5° in a pro-

cess called narrow-angle scattering. Due to the scale of

optical phenomena observed in the presented case-studies

linguistic simplications are used. The terms: translucent,

milky, foggy, misty are used in the text interchangeably.

In optics, translucent light scattering materials allow

light to penetrate but prevent the formation of sharp im-

ages (in focus) [15]. Thus, translucent pane works like

a screen – when backlit, it reveals its light-permeable/

ornamental structure, when it is illuminated […] its opa-

city increases as the space behind the glass grows darker

[22, p. 151]. As the result, the pane seems indierent from

a solid wall. The use of such translucent glazing makes the

interior of the building either invisible or visible depend-

ing on lighting conditions, e.g., with strong direct sunlight.

Ornamental panes (called also obscure glass, gured

glass) from an optical perspective act as an assembly of

adjacent optical elements: ats, prisms, concave or con-

vex lenses that form the surface of the pane. The surface

of the ornamental glass can be compared to the rippled

water surface, which is “not at, but smooth

”

[15]. In the

typology proposed by the author ornamental panes are an

intermediate phase between smooth transparent panes and

translucent panes. The reason for this is because on a build-

ing scale ornamental panes with a very ne pattern are

perceived by observers as translucent – individual small

compound lenses are beyond the perception of an observer.

In the paper, the author also refers to panes decorated

with various types of patterns. It should be understood as

such optical systems, where transparent areas are adjacent

to areas that are not transparent because they have been

covered with various prints that do not let light through at

all or do it only partially.

In the paper, two terms are used: “façade” and “enve-

lope”, which need to be explained. By the “façade” the

author understands a climate barrier separating two envi-

ronments internal and external (e.g. glass curtain wall). The

term “envelope” is also used in the paper in the meaning of

“shell, casing, and cover”, usually meaning an additional,

external layer, mounted outside the actual façade, fre quent-

ly as an optical device to achieve additional visual eects.

Disturbance of transparency

Transparency as an optical property of material has

been questioned in architecture many times. As early as in

the 1950s in order to limit the overheating of extensively

glazed oce buildings glass coated with metal oxides was

used. This type of glass is often called reective. Reec-

tive panes were also used in the famous works of modern-

ist architecture and in high-tech (e.g., Willis-Faber oce

building, arch. N. Foster, 1978). Thus, from an optical per-

spective, reective glass was considered as a tool of quan-

titative modication – part of the incoming daylight was

reected, part transmitted, but – in general – the direction

of the penetrating ray of light did not change. Disturbance

of optical transparency – if visible at all – usually resulted

from assembly errors or from imperfections of the mate-

rial itself (defects of products or used material, e.g., glass

mass). Since the 1990s, however, a new trend has been

developing in which optical transparency is deliberately

questioned by architects using new types of glass. Those

new types of glass change the direction of the penetrating

ray of light by refraction in a dierent scale (on macro or

micro level). In contrary to quantitative modication, this

new trend could be distinguished as a qualitative modi-

cation – the amount of light transmitted does not change

fundamentally, but its quality changes – it is scattered or

refracted in dierent directions when penetrating through

a translucent or ornamental pane.

The new trend in contemporary architecture is associ-

ated with a deliberate departure from the most desirable

feature of glass, i.e. optical transparency – transmission of

both light and image. It seems that it stems from a depar-

ture from pure modernist ideals, when a transparent façade

Disturbance of transparency in the architecture of contemporary glass façades. Part 1 81

Fig. 2. OMA’s competition proposal

for the French National Library (1989)

(drawing M. Brzezicki based on R. Koolhaas’ own sketch; source: [26])

Il. 2. Koncepcja konkursowa pracowni OMA’s

na projekt Francuskiej Biblioteki Narodowej (1989)

(rys. M. Brzezicki na podstawie szkicu R. Koolhaasa; źródło: [26])

disturbance of transparency can also occur at the level of

the envelope, an additional element applied or laid over

the actual façade. This additional envelope usually has

optical parameters other than transparent pane. It is there-

fore possible that the transparent façade is covered with

a translucent envelope. However, the disturbance of the

transparency may also result from the fact that the path of

the ray of light becomes so complicated – and there are so

many obstacles on this path – that guessing what is hidden

on the other side of the pane is almost impossible. This

phenomenon occurs when the pane is covered with a dense

ornament, which entangles the observer’s gaze in its com-

plexity, not allowing for deeper penetration. This “voile”

can also take the physical form of a screen or a blind,

which is located in front of or behind the actual pane. In

this case, the “voile” eect might not be permanent – the

blinds can be retracted, the cover can be removed. More

and more often it happens automatically, without human

intervention, e.g., in the so-called adaptive façades [29].

The optical phenomena taking place in the translucent

façades have already been described. The author of the ar-

ticle proposes his original simplied typology, according

to which – depending on what optical phenomena occur

in the façade or the envelope – the disturbance of trans-

parency can be classied as homo- and heterogeneous

disturbance:

Homogenous disturbance

The rst group is homogeneous disturbance in which

the whole surface of the pane is the source of the same

optical distortion. A good example of this phenomenon is

allowed not only for illumination the interior, but also al-

lowed users to “be seen” and “become visible” [23, p. 36].

The use of coatings that interfere with light is strongly

connected with a signicant transformation taking place

in the dialectic of the building, with the transformation of

the modernist curtain wall – a mullion and transom skele-

tal system lled with transparent glass – into an envelope,

more metaphorical membrane. This new envelope allows

for the perception of the distorted image of the building

by the observers located outside and the distorted image

of the surrounding environment by those located inside.

While the façade – in the sense of the modernist curtain

wall – is something very literal and specic but never-

theless closely related to the building, the new envelope

gains its independence. In the literal, technical sense, as

an element forming an additional layer of façade, in for-

mal sense, as an element introducing additional quality

into the façade space.

As early as in 1966, R. Venturi observed the division of

the building into the volume and facade/envelope [24]. In

2011 in the text titled Building Envelope as Surface S. Lee

and S. Holzheu write: […] here the medium is the actual,

physical and material presence of the façades themselves,

while the content consists of visual eects, messages, signs

and other elements that are supercial to the façades [25,

p. 125]. From their perspective – in the Venturian view

– the façade is […] a communicative device that is ex-

pected to signify, symbolize and convey certain narratives,

messages and information [25, p. 125]. After the book

Complexity and Contradiction was published, the trend of

the envelope independence went even further than Venturi

himself had expected. However, gradual erosion of trans-

parency has been observed in architecture progressing only

after 1989, from the time the R. Koolhaas proposal of the

French National Library was revealed – see Figure 2 [26].

In the proposed design one cuboidal block made of trans-

lucent glass enveloped small functional elements that were

contained inside. Only a few oval-shaped, clear openings

allowed for illumination and an unobstructed view into and

out of the interior; the remaining envelope served more as

a “cover than a fenestration” [15]. This specic relation of

“closeness and inaccessibility” was noted by French phi-

losopher J. Starobinsky as early as 1961 [27] and in 1995

T. Riley described a very similar mechanism of […] shift-

ing the objects meaning from its form [meaning the spatial

form – M.B. note] to its surface [7, p. 29], thus strength-

ening the role of the façade itself, regardless of the volume

to which it was attached. H. Muschamp concludes well:

building skin is used not to reveal but to veil [28, p. 1].

Simplified typology

The disturbance of transparency can be manifested in

many dierent ways. It can take place within the space

of the façade when the transparent pane is replaced by

a translucent pane and the light penetrating through the

façade is scattered to a degree that depends on the opti-

cal parameters of the pane (e.g., the shoji eect – a matte

screen made of rice paper mounted in bamboo frames

which is present in the Japanese building tradition). The

82 Marcin Brzezicki

face scattering the central group of scattered rays is vis i-

bly stronger and the contours of objects on the other side

of the pane are visible. What is more, the closer they are

to the surface of the pane, the more recognizable the out-

line will be. In contrast, the scattering in the mass of the

material results in an image devoid of contours of objects

that are located on the other side of the pane and the pane

itself radiates/illuminates an even brightness. What may

seem an insignicant dierence at rst glance, has signi-

cant consequences for the perception of the entire build-

ing. Etched panes can transmit the colour, while in the

case of mass-scattering this transmission is either equal to

zero or is strongly limited. Surface-scattering allows for

the better integration of the object with the environment

as the blurred boundary of the building body “melts” with

the colour “taken” from the surrounding.

Glass pane optically composed of smaller or larger

groups of convex and concave lenses constitutes the so-

called compound lens. From the optical perspective, this

type of pane does not scatter the light at all, only the di-

rection of the ray of light is changed by refraction. Light

transmission is less homogeneous and the specic pattern

is superimposed on the image visible through the pane,

which reects the arrangement of smaller convex and

concave lenses in the pane. The inuence of such a pane

on the visible image depends on the size of lenses vs. the

size of the building and the building-observer distance.

In large-size glass elements, optical refraction will visi-

bly distort the image of the building behind the glazing

and this distortion will be visible to the observer. On the

contrary, ornamental glass the surface of which consists

of many small lenses will produce similar optical results

as an evenly light-scattering pane. Although the optical

mechanism is dierent, typologically, compound lenses

(ornamental glass) can be classied as belonging to the

homogenous disturbance group.

Heterogeneous disturbance

The second group is a heterogeneous disturbance in

which some areas of the pane change the path of the ray

of light, while others do not. This type of disturbance is

therefore not uniformly distributed over the whole sur-

face of the pane but is present only in selected regions.

It is usually observed in the case of screen-printed panes

with the pattern or when selective acid etching is applied

to the regions of the pane. A heterogeneous disturbance

is very sensitive on the scale in the sense that the scale

of the pattern determines the nal optical eect visible

to the observer. The distance from which the building

is observed is decisive. Small patterns (e.g., small dots,

squares, dashes) that are too small to be recognized by the

observer from a distance are perceived as a homogeneous

disturbance, while large, easily recognizable patterns are

perceived literally – as patterns. The large, easily distin-

guishable ornament on transparent glass usually entan-

gles an observer’s eye with its complexity, not allowing

for deeper penetration. In this way, the pattern – print of

frit – gains independence, becomes more important than

the light-transmitting surface on which it is placed. These

Fig. 3. Diagrams showing three main types of light scattering:

scattering on the surface of the material (T

scattering in the mass of the material (T

and refraction when passing through complex lenses,

e.g. an ornamental pane (T

), which, due to the scale of the pattern,

is perceived as passing through a translucent sheet of glass.

The light sources S

, S

and S

are identical

(elaborated by M. Brzezicki)

Il. 3. Schematy przedstawiające trzy główne rodzaje rozpraszania światła:

rozpraszanie na powierzchni materiału (T

rozpraszanie w masie materiału (T

)

oraz załamanie przy przejściu przez złożone soczewki,

np. szybę ornamentową (T

), która ze względu na skalę wzoru

odbierana jest jako przejście przez przeświecalną taflę.

Źródła światła S

, S

i S

są identyczne (oprac. M. Brzezicki)

a light-scattering pane that makes objects located behind

optically blurred. Homogeneous distortion usually occurs

when translucent, etched, or sandblasted glass (or acrylic)

panes are used. The mechanism of the optical phenome-

non is simple and well known: one ray of light falling on

the surface of a pane is “scattered” into many randomly

oriented rays. This change of the ray’s direction results

from the microstructure of the pane’s surface. Similar

optical eects can be achieved with materials that scat-

ter light not only on the surface (as in the case of etched

glass), but in its entire mass of the material like in the milk

glass, polycarbonate, or even solid stone (e.g., alabaster).

Detailed optical experiments prove that there is a signif-

icant dierence: light is more evenly scattered in the mass

of the material (mass-scattering) vs. when the scattering

process takes place only on the surface (surface-scatter-

ing). Figure 3 shows the dierence. In the case of the sur-

Disturbance of transparency in the architecture of contemporary glass façades. Part 1 83

patterns are often applied to an additional envelope laid

over the proper glass façade of the building. In optical

terms, they resemble classic decorative jacquard curtains

and behave similarly. Observed from the outside, they

form a barrier, viewed from the inside, usually with the

pattern backlit, allow for a limited view of what is happen-

ing outside like a one-way mirror.

Summary of part 1

An envelope “rich in ornamentation” and a “tempting

veil” are two dierent design strategies in the disturbance

of transparency, leading to dierent visual phenomena.

The rst part of the paper addresses the issues of methodo-

logy, denitions and proposed the simplied typology of

light-disturbing envelopes in contemporary architecture.

Matrix approach, case studies and the characteristics of

sub-trends based on conducted analyses are presented by

the author in the next part of the presented paper in the

next issue of an journal. The following part will also in-

clude the discussion and conclusions.

Translated by

Marcin Brzezicki

Fig. 4. A diagram illustrating

optical phenomena in sub-trends

defined by simplified typology:

a) homogenous disturbance;

b) heterogeneous disturbance

(elaborated by M. Brzezicki)

Il. 4. Schemat ilustrujący

zjawiska optyczne występujące

w pod-nurtach:

a) zniekształcenie jednorodne;

b) zniekształcenie niejednorodne

(oprac. M. Brzezicki)

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Abstract

Disturbance of transparency in the architecture of contemporary glass façades. Part 1

Over the last two decades, new trends have emerged in the design of translucent façades. Those trends result from the dynamic technological pro-

gress and achievements in material engineering. The trends that are associated with the use of envelopes that interfere with the transmission of light

through the façade are particularly interesting. This is strongly related to the signicant transformation that took place in the dialectic of the building,

the transformation of the “façade” into an “envelope”. The paper presents the author’s original distinction between the two most characteristic main

sub-trends, distinguished based on optical phenomena occurring within the façade. The proposed division includes two main groups of disturbances:

homogenous and heterogeneous. The former is present where panes of glass are used to disperse/diuse light evenly, while the latter in façades with

strong – usually printed – ornamentation. The article systematizes the issues of transparency disturbance in contemporary architecture and presents

the typology of light-transmitting façades, in which this phenomenon takes place. The author also presents a matrix of relations that systematizes the

presented case studies. Only this type of matrix makes it possible to illustrate an issue in which more than one variable is present. An assignment of

the case studies to the trends and the determination of trend models are also included in the paper. The rst part of the paper presents the introduction,

methodology and simplied typology, the second one presents case studies, discussion and conclusions.

Key words: transparency, theory of architecture, façade glazing, printing on glass, coatings on glass

Streszczenie

Zakłócenie przezroczystości w architekturze współczesnych szklanych fasad. Część 1

W ciągu ostatnich dwóch dekad pojawiły się nowe nurty w projektowaniu przezroczystych fasad. Są one wynikiem dynamicznego postępu tech-

nologicznego i osiągnięć w dziedzinie materiałoznawstwa. Szczególnie manifestują się te nurty, które związane są z zastosowaniem powłok zakłó-

cających przenikanie światła przez fasadę. Wiąże się to silnie z istotną przemianą, która dokonuje się w dialektyce budynku, z przemianą fasady

(ang. façade) w obudowę/powłokę (ang. envelope). W artykule przedstawiono dokonane przez autora rozróżnienie zjawisk optycznych, które zacho-

dzą w obrębie fasady. Proponowany podział obejmuje dwie główne grupy: jednorodne i niejednorodne zniekształcenia przezroczystości. Te pierwsze

występują tam, gdzie zastosowano tae równomiernie rozpraszające światło, te drugie natomiast w fasadach o silnej – zazwyczaj nadrukowanej

– ornamentacji. Artykuł systematyzuje zagadnienia zniekształcenia przezroczystości w architekturze współczesnej i przedstawia typologię tych fasad

przepuszczających światło, w których występuje to zjawisko. W artykule przedstawiono też macierz relacyjną, która systematyzuje opisywane studia

przypadków. Jedynie ten typ macierzy pozwala na pokazanie zagadnienia, w którym obecna jest więcej niż jedna zmienna. W tekście dokonano

również przypisania studiów przypadków do nurtów, a także charakterystyki samych nurtów – stworzenia ich modeli. Pierwsza część tekstu zawiera

wstęp, opis metodologii oraz uproszczoną typologię, a w drugiej znajdą się studia przypadków, dyskusja oraz wnioski.

Słowa kluczowe: przezroczystość, teoria architektury, szklana fasada, nadruk na szkle, powłoki na szkle