Badanie możliwości dodania balkonów do wewnątrz kwartałowej elewacji kamienic we Wrocławiu - wyzwania przestrzenne związane z przesłanianiem i doświetleniem wnętrza

Marta Smektała

doi:10.37190/arc230406

Streszczenie

Spodziewana intensyfikacja termomodernizacji wynikająca z wymogów Unii Europejskiej dotyczących ograniczenia emisji CO2 jest okazją do podjęcia refleksji nad potencjałem dostosowania lokali mieszkalnych w kamienicach do aktualnych potrzeb i oczekiwań użytkowników. Jednym z elementów architektonicznych wpływających pozytywnie na jakość przestrzeni mieszkalnej jest dostęp do dobrze zaprojektowanej prywatnej przestrzeni zewnętrznej takiej jak np. balkon. Kwartałowa zabudowa kamienic potencjalnie umożliwia dostawienie zewnętrznych balkonów do tylnych elewacji. Niemniej działania takie nie są podejmowane ze względu na liczne ograniczenia m.in. przestrzenne związane z nieregularną linią zabudowy wnętrz kwartałów. Celem badania jest wskazanie, na przykładzie Wrocławia, jakie warunki przestrzenne muszą być spełnione, aby umożliwić dostawienie balkonów do podwórkowej elewacji kamienic w ramach polskich przepisów prawa budowlanego. W artykule skupiono się na przepisach dotyczących przesłaniania i zacieniania budynków oraz na wpływie dostawienia balkonów na doświetlenie mieszkań światłem dziennym. Badania przeprowadzono na podstawie analizy warunków technicznych pod względem minimalnych odległości wynikających z zacieniania i przesłaniania budynków, analiz urbanistycznych systematyzujących typologię linii zabudowy elewacji kamienic wewnątrz kwartału oraz komputerowych symulacji pomiaru Daylight Factor i natężenia światła dziennego pokazujących wpływ dostawienia balkonu na zacienianie mieszkania. Rezultatem jest zestawienie typologii sytuacji w kwartałach kamienic, gdzie dobudowanie byłoby utrudnione lub niemożliwe, ze wskazaniem wymaganych minimalnych odległości, oraz przedstawienie wpływu dostawienia balkonu na doświetlenie mieszkania w zależności od kierunków świata i formy balkonu. Badania potwierdzają, że polskie warunki techniczne nie są wystarczającym narzędziem do zapewnienia odpowiedniego poziomu światła dziennego. Symulacje przeprowadzone na przykładach wykazały, że dodanie balkonu do południowej, zachodniej i wschodniej elewacji nie zaniża średniego poziomu natężenia światła poniżej poziomu 300 luksów, który jest uważany za minimalny. Ponadto balkon może niwelować poziom natężenia światła powyżej 3000 luksów, który może wywołać niechciany efekt olśnienia. Wymagana jest dalsza analiza biorąca pod uwagę polskie wymogi nasłonecznienia oraz badania mające na celu określenie odpowiedniego projektu balkonów, który wspomoże adaptację mieszkań do pór roku

Podgląd pełnego artykułu jest możliwy wyłącznie na większych ekranach.

2023

4(76)

Marta Smektała*

Exploring the potential for balcony addition to

tenements’ backyard elevation in Wrocław

– spatial challenges related to shade and indoor daylight illumination

Introduction

The operation of existing buildings constitutes 30% of

the global nal energy consumption and 26% of global

emissions [1]. As the European Union (EU) aims to

achieve the goals of The United Nations Framework Con-

vention on Climate Change’s Paris Agreement on limiting

global temperature increase all the EU buildings should

be renovated by 2050. This implies that the current mod-

ernization pace needs to increase from 1% to 3% per year

[2]. Residential buildings constitute 75% of the EU build-

ing stock and 36% of them are urban apartment blocks

[3]. The urban heat island amplies the eects of climate

change further increases the vulnerability of residential

buildings to overheating Urban sprawl, despite oering

individuals residents an escape from the urban heat is-

land, contributes to climate change, therefore is regarded

as a harmful development pattern. Improving the standard

of existing urban housing by oering a viable and attrac-

tive alternative to the new-built suburban homes could

help reverse this trend. For this reason, to address climate

change, the expected intensication of refurbishments

should address not only energy eciency challenge but

also living quality improvement. In contrast to demoli-

tion, preservation of existing buildings brings far-reach-

ing social, environmental, and economic benets [4].

Circa 22% of residential buildings in the EU were

constructed before 1946 [3]. Signicant part of these are

recognized as heritage buildings. Spatial, technical and

energy upgrade of heritage buildings stock poses specic

challenges, including the need to abide to conservator’s

guidelines. However, retaining the usability of a heritage

building is necessary for its preservation and avoiding ne-

glect and abandonment e.g. with dwellers’ moving to the

outskirts looking for better living quality [5].

An access to a private outdoor space such as garden, ter-

race, loggia or balcony is a multi-family house feature that

signicantly improves the living environment [6]. In post

war multi-family housing, characterised by uniform repeti-

tive façades and rectangular forms, balconies or loggias can

be added as an extra layer to elevations at thermal retrot-

ting stage [7]. Th

e Lacaton Vassal architectural practice

has managed to save a derelict social block of ats from

demolition and change the image of social apartments into

luxurious dwellings thanks to extending the elevations

with spacious, well-lit, in-built loggias. In the literature

the theme of balcony additions in housing focuses mostly

on exploring the technical challenges such as overall en-

ergy or acoustic performance of the envelope [7], thermal

bridges, indoor air quality, or daylight and visual comfort

[8]. Also their inuence on urban living quality such as

enhancing apartment’s usability and adaptability or acting

as a proxy for a private garden [9], particularly during the

global experience of Covid-19 pandemic lockdowns has

been studied. An impact of an access to private outdoor

space on human well-being has been established [10], as

well as the need to consider contextual features in balcony

design to make the most of usability potential of balcony

spaces [9].

The recent discourse about monument conservation agrees

that, in order to preserve buildings, their usability must be

enhanced [5]. For this reason additive elements on external

parts of the buildings adjusting building to current technical

requirements and dwellers’ needs are becoming increasing-

ly common. However, they need to meet the conservators’

guidelines to preserve the character of the monument [11].

DOI: 10.37190/arc230406

Published in open access. CC BY NC ND license

* ORCID: 0000-0001-8533-8550. Faculty of Architecture, Wro-

cław University of Science and Technology, Poland, e-mail: marta.

smektala@pwr.edu.pl

62 Marta Smektała

A balcony constitutes a signicant part of elevation,

shaping the street image [12]. Nevertheless, the role of

the balcony as an architectural element has been devel-

oping with time. In front façade tenements it was mostly

functioning as a view platform for the street, meeting at

the same time an aesthetical demand as a part of eleva-

tion. During the modernist movement balconies became

more quotidian architectural elements provided in social

residential buildings with a mission to raise the hygiene

of apartments with fresh air ventilation for a massive pop-

ulation. From the 1970s spacious balconies and terraces

started to appear in residential buildings serving for lei-

sure functions as well [13]. Although the balcony is an

old architectural element, and its advantages in residential

buildings has been noticed it is not enforced within con-

struction law. Through, in several European countries re-

gu lations or guidance about the minimum size is suggest-

ed, they still do not consider the users’ comfort, need for

privacy and more space for various functions happening

[9]. The specic position of balconies, as private spaces,

but visible from the public cause tensions about e.g. pres-

sure to subordinate to public norms or expectations, what

limits the balcony usage, and individual domestication,

which may trigger various emotions [14].

In European tenements built at the turn of the 19

and

centuries not all of the apartments were equipped

with a private outdoors such as balcony. Although extend-

ing an elevation with balconies in heritage tenements is

challenging due to unique elevation features such as or-

naments and preservation guidelines protecting the form

of the building, there are examples of practices of adding

them during the renovation in countries such as Germa-

ny, Denmark, Austria [15] (Figs. 1, 2). In Wrocław, where

21% of the housing stock and 75% of social housing are

located in tenements [16], this practice is still uncommon.

In Wrocław, adding a balcony onto a street façade would

be questionable, due to monument preservation require-

ments, the limited space for addition and unfavourable spa-

tial context in terms of usability. Nevertheless, Wrocław’s

tenements quarters have spacious courtyards [17], which

constitute an untapped potential for adding balconies to

backyard elevations. However, irregular building line of

tenements’ backyard elevations (Figs. 3, 4), proves chal-

lenging for any extensions due to a need to individually

assess the risk of obscuration and overshadowing of any

apartments below balcony level. The current research

state about balcony addition is focused on technical as-

pects (improving energy eciency by in-built balconies’

extension [7], [8]) and social impact (enhancing the dwell-

ing standard by adding access to private outdoor space [6]

or evoking social expectations about proper usage and

realizing lack of privacy sense after providing extension

with balconies [18]). Although studies suggest that balco-

ny addition during retrotting enhances dwelling quality,

Fig. 1. An example of add-on

balconies to the backyard

elevation of tenement houses

situated in quarters,

Karl Liebknecht Street,

Chemnitz, Germany

(photo and plan by M. Smektała)

Il. 1. Przykład balkonów

opartych na zewnętrznej

konstrukcji dostawianych do

podwórkowych elewacji

kamienic w zabudowie zwartej,

Karl Liebknecht Straße,

Chemnitz, Niemcy

(fot. i plan M. Smektała)

Fig. 2. An example of add-on

cantilevered balconies to the

elevation of pre-war tenement

houses situated in quarters,

Nørrebro district in Copenhagen,

Danemark (photo by N. Nielsen,

source: Altaners Sociale Liv,

plan by M. Smektała)

Il. 2. Przykład balkonów

na wsporniku dostawianych do

elewacji przedwojennych kamienic

w zabudowie zwartej w dzielnicy

Nørrebro w Kopenhadze, Dania

(fot. N. Nielsen, źródło: Altaners

Sociale Liv, plan: M. Smektała)

 Exploringthepotentialforbalconyadditiontotenements’backyardelevationinWrocław 63

disregarding the spatial challenges may negatively impact

on apartments’ indoor daylight, balcony functionality or

feeling of privacy limiting the balcony usage [9]. The aim

of this research is to dene spatial conditions for balco-

ny additions to Wrocław tenements’ backyard elevation

based on Polish legal requirements regarding the obscu-

ration and overshading the adjacent buildings. Also the

impact of balcony addition on indoor daylight in adjacent

apartment is explored. The study addresses the following

research questions:

– What are the spatial conditions in Wrocław tene-

ments’ courtyards that would allow adding balconies to

backyard elevations within the context of Polish building

regulations?

– How would balcony addition impact indoor daylight

of an apartment?

The paper is structured as follows: First, the methods of

studies are introduced such as: desktop study of relevant

documents, eldwork observation, urban plan analysis

with feasibility study, and daylight simulations. Second-

ly, the results are presented. In the beginning the techni-

cal requirements regarding balcony addition preventing

building from obscuring and shading are presented briey

and juxtaposed with Daylight Factor (DF) and illumi-

nance measurement. Next, the typologies of irregularities

and guidance for minimum required distance between the

buildings, and the result of computer simulations present-

ing the impact of balconies on indoor daylight. Later, the

discussion, with focus on issues missing in Polish regula-

tions and importance of the idea of adding a balcony with

the need of individual proceeding of each case. Finally,

the conclusion consists of research question responses

about potentiality of this idea with balcony impact on

indoor daylight, recommendation deriving from the study

about assisting the design decisions with daylight simula-

tion, and further research suggestions of a role of balcony

addition in indoor daylight control.

Technical and legal capabilities

of balcony assembly

Regarding balcony form three typologies can be dis-

tinguished: a recessed balcony (loggia), cantilevered and

semi-recessed (Fig. 5) [19]. Providing a recessed and semi-

recessed balcony typology to an existing building is com-

plex since it requires the removal of an external wall, and

dedicating part of oorage for outdoor space. The cantile-

vered balconies added to existing buildings are commonly

used for example in Copenhagen (Fig. 2). However, this

method is challenging for three reasons. The rst is the

structural capacity of the existing wall which not in all cas-

es can hold additional hanging elements. Secondly, the can-

tilevered balcony hanging structurally to the exiting wall

may contribute to thermal bridges. Thirdly, cantilevering

elements may destroy ornaments in elevation. However,

this research considers backyard elevations, which usually

have technical character and are deprived of ornaments.

The exemplary balconies from Chemnitz, presented in

Figure 1 are based on the external structure with separated,

independent fundaments. Such a solution avoids the prob-

lems mentioned above and gives exibility in terms of the

balcony size and its potential disassembly. On the other

hand, these balconies have a bigger visual impact on ele-

vation in comparison to the light cantilevered ones, which

may be troublesome in the case of heritage buildings. Ad-

ditionally, balconies on external structures give rise to an-

other problem. The tenements’ plot border at the courtyard

side is usually aligned with the backyard elevation. Thus,

in such a solution, the additional external structure needs

to be situated outside of the tenement’s plot. Most of the

tenements’ courtyards belong to the municipality adminis-

tratively (Fig. 6). For this reason, adding a balcony would

require additional collaboration with authorities, in the

form of for example, signing agreements about leases for

using external area.

Monument preservation requirements

regarding balcony addition

Many tenements are heritage buildings protected by

Ustawazdnia23lipca2003r.oochroniezabytkówiopie

ce nad zabytkami [The Monument Protection Act] [21].

In Poland, there are two types of protection: the rst one,

registering the monument in the national monuments list

governed by the Voivodeship Monument Conservaton Of-

cer, and the second one, is the register of architectural

monuments, managed by the municipality or voivodeship,

depending on the monument’s rank. The Monument regi-

ster entry contains the denition of

the buildings’ value

and protected elements. However, the protection guidance

does not constitute an ultimate decision but rather should

function as a starting point of negotiations between an

owner and a conservator [22]. Thus, the guidance shapes

the overall approach to protection, neverthe

less, more de-

tailed decisions are determined during the modernization

process. Therefore, adding a balcony requires consent

from the relevant monument conservator and consultancy

regarding its shape. As appropriate, the balcony form var-

ies depending on monument’s characteristics, building’s

materials, context, and local conservation practice. For

instance, Copenhagen authorities decided on cantilevered

balconies, which have a lighter visual impact on brick

elevation outlook. In the case of Chemnitz, where inner

courtyard elevations are insulated, the external structures

are more useful.

Methodology

The study is based on three research methods. The rst

is a desktop study of the relevant regulations dening spa-

tial requirements preventing a building from overshad-

owing adjacent buildings along with articles referring to

indoor daylight analysis, focused in identication of dif-

ferent typologies of irregular building lines of tenements’

backyards elevations, where adding a balcony could be

challenging due to overshadowing prevention regulations.

The third one is computer simulation, aiming to calculate

Daylight Factor and illuminance of tenements’ apartments

rooms with varied scenarios in terms of balcony sizes and

balustrades.

64 Marta Smektała

Desktop study

The relevant Polish legal requirements for building’s ob -

scuration, insolation and shading are dened within Tech-

nical conditions for buildings and their location [23].

These requirements also dene the spatial conditions for

new additions to existing buildings. Also, the relevant legal

articles about indoor daylight measurement methods ques-

tioning the eciency of Polish insolation requirements

were reviewed. These articles served as an inspiration to

introduce alternative daylight measurements, which full

the Polish requirements and assist in investigating how the

balcony addition may impact indoor daylight.

Urban analysis

An urban analysis were prepared based on Wrocław

geoportal urban plans, marking the irregularities in in-

ner-courtyard building line of quarters containing the ten-

ements from the turn of the 19

and 20

and 1

half of

the 20

centuries from Nadodrze, Ołbin and Przedmieście

Oławskie district (Fig. 7). The irregularities were grouped

in order to nd the similar patterns. Later the analysis

was fullled with eldwork observation of 39 quarters

from Ołbin and Nadodrze districts visited in June–August

2022. Photographic survey and notes with schematic plan

drawings were made with marks indicating the elevations

with windows and without and building entrances from

the inner courtyard. Based on these analyses, main irreg-

ularities’ typologies were distinguished. Next, the typol-

ogies were used as a foundation for screening analysis.

As follows, the average tenements’ height was assumed

as 22 m on the basis of Wrocław geoportal information

and average rst storey window sill height as 1.5 m from

eldwork data. These assumptions helped to dene the

average screening building height as 20.5 m. Next, the

feasibility study of required space for balcony addition in

relation to obscuring regulations was conducted.

Computer simulations

For daylight computer simulations a simplied model

of 6-storey (22 m height) tenement house was prepared

based on review of tenements’ oor and section plans

found on an internet database with archived buildings

photographs from Wrocław. Two rooms (5.8 m × 2.2 m

and 5.8 m × 3.5 m), which represent a typical indoor

space arrangement situated at backyard elevation were

modelled at each storey with height of 3.2 m and 2.5 m

at the last storey. The openings for windows equal 1 m ×

2.1 m and for balcony doors 1 m × 2.7 m. Each opening

is glazed with a triple glazed panel with U-value = 0.84,

Fig. 3. Examples of Wrocław

tenements quarters’ interiors

with an irregular building line:

a) corners with adjacent

buildings create an air shaft

(E. Stein, Nowowiejska

Street’s corner)

b) outbuildings’ which create

inner courtyard urban interior

within all the quarter tenements’

common courtyard (Barlickiego,

Kluczborska, Nowowiejska,

Żeromskiego Streets’ quarter)

(photos and plans by

M. Smektała)

Il. 3. Przykłady wrocławskich

wnętrz kwartałów kamienic

z nieregularną linią zabudowy:

a) narożnikowe i sąsiadujące

kamienice tworzą wąskie studnie

(narożnik ul. E. Stein

i Nowowiejskiej),

b) dobudowania, które tworzą

małe wnętrza urbanistyczne

na podwórku wspólnym

dla wszystkich kamienic

w kwartale (ul. Barlickiego,

Kluczborska, Nowowiejska,

Żeromskiego)

(fot. i plany M. Smektała)

 Exploringthepotentialforbalconyadditiontotenements’backyardelevationinWrocław 65

Fig. 4. Examples of Wrocław

tenements quarters’ interiors

with an irregular building line:

a) protruding elevations, which

create irregular building line

in the courtyard,

(Jedności Narodowej,

Kluczborska, Żeromskiego,

Oleśnicka Streets’ quarter)

b) additional buildings within

the courtyard situated in a close

distance from inner-courtyard

elevations, limited open space

directly in front of the building

(św. Maciej square and Henryka

Pobożnego, Henryka Probusa

Streets’ quarter) (photos and

plans by M. Smektała)

Il. 4. Przykłady wrocławskich

wnętrz kwartałów kamienic

z nieregularną linią zabudowy:

a) wystające części elewacji,

które tworzą nieregularną linię

zabudowy wewnątrz kwartału

(ul. Jedności Narodowej,

Kluczborska, Żeromskiego,

Oleśnicka),

b) dodatkowe zabudowania

na podwórku zlokalizowane

w bliskiej odległości od wewnątrz

kwartałowej elewacji;

ograniczenie otwartej przestrzeni

bezpośrednio przed budynkiem

(kwartał przy pl. św. Macieja

i ul. Henryka Pobożnego,

Henryka Probusa)

(fot. i plany M. Smektała)

which meet current energy eciency requirements for

new houses and assumed transmittance TVIS = 0.713 with

0.1 m frames and divided lites from 0.06 to 0.1 m. This

assumption about the openings serves to investigate how

the daylight would function after thermal modernization.

The internal walls are spread with white paint with 83%

reectance and external walls with beige plaster of 78%

reectance. 3 balcony sizes were modelled (6 m × 1.5 m,

6 m × 2 m, 6 m × 2.5 m) with 3 options for balustrades

(clear glass with TVIS = 0.88; opaque with 78% reec-

tance and with low transmittance glass TVIS = 0.158) and

with option for screens placed from both sides of balcony

1.5 m wide. The simulations were conducted in Rhino ar-

chitectural modelling software with Climate Studio plug

for simulative analysis. The sensors were located every

0.3 m and 0.85 m above the oor surface (working plane)

at the lowest storey, as the worst case scenario for day-

lighting. First, the Daylight Factor simulation was con-

ducted for a tenement without balconies and with added

balconies with dierent sizes and balustrades. Next, the

illuminance simulation with option “Custom” considering

Wrocław localization and dierent rooms’ orientations

(North, West, East, South) presenting the average daylight

illuminance in lux was conducted to full the information

from Daylight Factor. The simulation served for indica-

tion of add-on balconies’ impact on indoor daylighting.

Results

Desktop study

Polish technical regulations for building location

and required sun exposure

According to the Polish building law, no part of a build-

ing should breach the space within the 60 degrees angle

placed on a horizontal plane with the apex situated in the

middle of the window axis starting from the internal wall

plane (Fig. 8). The length of the arms of the angle depends

on screening building height, which is counted from the

bottom edge of the lowest situated windows on the ele-

vation to the highest edge of the screening building. Nev-

ertheless, in the inner city build-up area, it is allowed to

66 Marta Smektała

room’s oor area (200 lx). The DF presents the lowest

possible daylight intensity in reality. Providing simulation

with this method allows to indicate how balcony addition

diminishes indoor daylight. However, it disregards the

room’s solar orientation and building’s localization [24].

For this reason the DF calculation can be completed with

average illuminance calculation expressed in lux. Accord-

ing to John Mardaljevic the most “desirable or at least tol-

erable” illuminance ranges from 300 to around 3000 lx,

and signicantly reduces the electric lighting usage [25],

[26]. Since the daylight illuminance divers in rooms of

dierent solar orientation, in case of north elevation the

balcony addition may cause daylight underexposure (be-

low 300 lx) or prevent from unwelcome glare eect at

south orientation (over 3000 lx). Lack of considering de-

scribed above daylight measurement methods in Polish

regulations may cause the design to be inecient and in-

hibit a more exible approach to architectural solutions.

Urban analysis

The irregularities types in building line of tenements’ back-

yard elevation. Spacious courtyards of Wrocław tenements

provide a lot of potential possibilities for balcony addition.

However, the irregular courtyard building line, especially

in the corner wells, causes that there are spots in tenements’

courtyards, where balconies cannot be added straight for-

wardly, due to lack of space and causing a risk of ob scu ra tion

and overshadowing the neighbouring buildings. Based on

urban plan analysis and eldwork observation 4 types

of ir re-

gularities, where balcony addition is limited were distin-

guished: corners creating air shaft, out buildings creating

inner courtyard urban interior, protruding elevations creat-

ing irregular building line in the courtyard and facing

build ing in a close distance (Table 1).

The minimum space required for balcony addition.

For typologies described in previous paragraph the fea-

sibility studies were conducted regarding the requirements

about obscuring buildings to investigate the potentiality of

be shortened by half. Apart from it, placing an obscuring

object at a distance of not less than 10 m from the window

of the obscured room, such as a mast, chimney, tower or

other building, without limiting its height, but with an ob-

scuring width of not more than 3 m, measured parallel to

the plane of the window is allowed [23] (Fig. 8).

Another rule requires direct insolation of at least one

room in the dwelling for at least 3 h between 7 a.m. to

5 p.m. at the day of March and September equinox and the

ratio of the plane passing the daylight within the window

frame to oor area should be at least 1:8. However, the in-

solation time for dwellings situated in the inner city build-

up area is only 1.5 h and in case of one room apartments

the rule is not required [23].

Daylight Factor and illuminance calculation

– missing themes in Polish regulations

The Polish regulations for indoor daylight consider the

insolation only geometrically, disregarding other inu-

encing factors’ such as the window’s glass transmittance,

protruding elements shading the window. Apart from it,

the regulations do not consider the fact that most of the

room’s daylight comes from reection. The rules were de-

ned when the low U-value factor of buildings’ openings

was not required and most of the windows were single

glazed. Currently used triple or double glazed windows

limit signicantly the daylight transmittance. European

countries regarding daylight regulation use the ratio of

glazed area to oor area with duration of sunlight in rooms

as in Poland or Slovakia or Daylight Factor. DF is de-

scribed as a percent share of indoor to outdoor daylight,

calculated with sky overcast (10 000 lx) on the 22

March

at 0.85 m height from the oor surface.

where:

Ei – indoor light intensity at point of a working plane [lx],

Ee – outdoor light intensity at horizontal plane from

the entire hemisphere.

According to Danish building requirements, the apart-

ments’ rooms intended for living and kitchens the DF

should be equal or more than 2% at more than half of the

 =





· 100%,

Fig. 5. Balcony’s typologies (drawings by M. Smektała)

Il. 5. Typy balkonów (rys. M. Smektała)

Fig. 6. Map presenting the types of plots’ ownership in Wrocław.

The interiors of the quarters marked in yellow, orange and beige

belong to Wrocław municipality

(source: Wrocław Spatial Information System, [20])

Il. 6. Mapa własności gruntów we Wrocławiu.

Wnętrza kwartałów oznaczone kolorem żółtym,

pomarańczowym i beżowym należą do gminy Wrocław

(źródło: System Informacji Przestrzennej Wrocławia, [20])

 Exploringthepotentialforbalconyadditiontotenements’backyardelevationinWrocław 67

Fig. 7. An extract of urban analysis based on plans available to SIP

– Wrocław Spatial Information System (source: [20])

Il. 7. Fragment analiz urbanistycznych na podstawie planów

dostępnych

w Systemie Informacji Przestrzennej Wrocławia (źródło: [20])

Fig. 8. Scheme explaining the regulation

of building obscuration

(drawing by M. Smektała)

Il. 8. Schemat wyjaśniający przepis

dotyczący przesłaniania budynku

(rys. M. Smektała)

Typology name Typology’s schemes

Typology’s examples from urban plan

[geoportal Wrocław]

Corners creating

air shaft

Outbuildings elevations

creating inner courtyard

urban interior

Protruding elevations

creating irregular

building line

in the courtyard

Facing building

in a close distance

Table 1. A schedule of irregular building line in tenements’ courtayrds

(elaborated by M. Smektała)

Tabela 1. Zestawienie typologii nieregularnej linii zabudowy wewnątrz kwartałów kamienic

(oprac. M. Smektała)

68 Marta Smektała

Table 2. A schedule presenting minimal distances between the buildings to add balconies, depending on irregularity’s typology

(elaborated by M. Smektała)

Tabela 2. Zestawienie minimalnych odległości między budynkami do spełnienia w przypadku dodania balkonów

w zależności od typologii nieregularności (oprac. M. Smektała)

Typology name Scheme without balconies Scheme with balconies

Minimimun required distance

between the elevations (A)

Corners creating

air shaft

Adjacent

buildings’ walls

without windows

(prevalent case)

There are many variables influencing

the distance e.g. windows’ positions,

if there are protruding elevations from

both (2, 3, 4) or one side (1), if adjacent

building walls of protruding building

have windows (1, 2) or do not (3, 4).

The safest assumption is maintaining

distance between the elevations of

screening building height (h = 20.5 m)

+ balcony depth. However, if one of the

protruding elevations is situated in this

minimum required distance of

screening building height (4),

the second one can be in a closer

distance, but it cannot breach the space

of the plane of 60 degrees angle with

apex situated in the corner and one of

the angles’ arms places along the

elevation (1, 4, marked with dotted

lines). If both adjacent buildings have

protruding elevations situated in

a closer distance than screening

building height (2, 3, marked with

dotted lines), then the both adjacent

buildings cannot breach the space

of an angle 60 degree

Corners creating

air shaft

Adjacent

buildings’ walls

with windows

Outbuildings

creating inner

courtyard

urban interior

A = screening building height

(h = 20.5 m) + the sum of 2 balconies’

depths if balcony perimeters

the elevation

 Exploringthepotentialforbalconyadditiontotenements’backyardelevationinWrocław 69

Table 2 cont. A schedule presenting minimal distances between the buildings to add balconies, depending on irregularity’s typology

(elaborated by M. Smektała)

Tabela 2 cd. Zestawienie minimalnych odległości między budynkami do spełnienia w przypadku dodania balkonów

w zależności od typologii nieregularności (oprac. M. Smektała)

Protruding eleva-

tion creating irreg-

ular building line

in the courtyard

In cases were A < screening building

height (h = 20.5 m),

the ratio A + balcony depth to B

should be more than 2

(A + balcony depth)/B≥2

Facing building in

a close distance

A = screening building height

(h = 20.5 m) × (√3)/2 + balcony depth

A = 17.75 m + balcony depth

adding balcony in these precarious spots. The Table 2 pre-

sents the results of the study, indicating the minimal distan-

ces for buildings situated in these irregular spots outlining

an overall space requirement. The guidance is simplied

since there are many variables inuencing the distance such

as: windows’ positions, if there are windows in adjacent

buildings. Especially in cases of the corners creating an air

shaft, it is dicult to propose a straightforward assumption,

and in reality each case requires an individual proceeding.

The guideline was considering the full screening build-

ing height as a minimum distance instead of half of this

height, as it is allowed for inner-city areas. Thus in reality

the distance can be twice smaller, however this assumption

was refused because of underexposure of rooms. Many te-

nements’ courtyard corners create very narrow air shafts,

which without adding balconies, do not meet current re qui-

rements about the building localization. Nevertheless, apart

from courtyards’ corners, there are many spots in Wrocław

tenements courtyards, which have a distance of screening

height (in this study assumed as 20.5 m plus balcony depth),

where balconies can be easily added.

Daylight simulations

The Daylight Factor

Besides the feasibility studies, the daylight simulation

analysis was conducted to investigate how the balcony may

potentially shade the interior of the tenement. The Table 3

presents the simulation results for 3 balcony sizes (6 m ×

1.5 m, 6 m × 2 m, 6 m × 2.5 m) with dierent balustrade

types: clear glass, reecting glass with law transmittance

and opaque panel, and with option of adding screens at both

sides of opaque and reecting glass balustrades. First of all,

the Daylight Factor simulation for a current state without

a balcony with triple glazed windows, presents a signi-

cant daylight dierence between the rooms. In the smaller

room the proportions of windows’ opening to oor area

equal approx. 1:6.25, whereas in the bigger 1:5. In this case

almost half of a bigger room has DF ≥ 2%, which is in

accordance with Danish indoor daylight requirements for

living spaces, whereas the smaller room has approximately

1/3 oor area with DF ≥ 2%. Added balconies consequent-

ly diminishes this area. It is especially noticed in bigger

rooms, where the area above 2% DF shrinks from 1/2 to

1/3 or 1/4 of the room surface. Balcony depth and screens

impact more signicantly the daylight than balustrade ma-

terials. However, high ceilings and windows cause that the

daylight still reaches the back wall of the rooms (Table 4).

Illuminance

Since the DF does not consider the building localiza-

tion and solar orientation, the illuminance simulation was

conducted. The simulation presenting the average lux

levels on the areas allows to indicate the underexposed

(below 300 lx) and overlit (above 3000 lx) spaces. In this

simulation only one case of a balcony with screens and

balustrades of high reective glass was considered since

the most inuencing daylight elements are the sizes of

balconies. This balustrade type presents the average day-

light impact regarding the balcony materiality. The Table

4 demonstrates the simulation results for rooms exposed

to North, South, West, East solar orientation with 3 balco-

ny sizes and current state without a balcony. The average

illuminance varies signicantly depending on the solar

70 Marta Smektała

Table 3. Schedule with Daylight Factor simulation results (elaborated by M. Smektała in Climate Studio software)

Tabela 3. Zestawienie wyników symulacji Daylight Factor (oprac. M. Smektała przy wykorzystaniu Climate Studio software)

Current state without

balcony, window open-

ings equal 1 m × 2.1 m

Legend:

border of 2% Daylight Factor area

Materials\Size

door openings equal

1 m × 2.6 m

1.5 m × 6 m

2.0 m × 6 m 2.5 m × 6 m

Opaque balustrade

Opaque balustrade with

screens

Balustrade with

reflective glass

Balustrade with

reflective glass

and screens

Clear glass balustrade

 Exploringthepotentialforbalconyadditiontotenements’backyardelevationinWrocław 71

Legend

South West East North

Current state without balcony

1.5 m × 6 m, balustrade

with reflective glass

and screens

2.0 m × 6 m, balustrade

with reflective glass

and screens

2.5 m × 6 m, balustrade

with reflective glass

and screens

Table 4. Schedule with illuminance simulation results (elaborated by M. Smektała in Climate Studio software)

Tabela 4. Zestawienie wyników symulacji natężenia światła (oprac. M. Smektała przy wykorzystaniu Climate Studio software)

orientation. The smaller room at the North ele va tion

even without a balcony is underexposed on the half of

the working plane area, whereas adding a balcony makes

1/4 of the smaller and 1/2 of a big room underexposed

(black area on the graphs). There are also underexposed

areas in a small room without a balcony on the West and

East elevation, which reveals that the ratio window open-

ing to oor area 1:8 is insucient. In other cases balcony

can be added without a fear of overshadowing the interior.

What’s more, it may limit the glare eect (pink area on

the graphs) (Table 4).

Discussion

The aim of building codes is to ensure the safety, func-

tionality, and sustainability of constructed buildings. The

requirements regarding insolation and building obscuration

are part of the rules which preserve dwellers’ right for living

72 Marta Smektała

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References

in a healthy house with proper ventilation and lighting. The

impact of an access to a private outdoors space such as bal-

cony, loggia, terrace, private garden on dwellers’ wellbeing

and housing condition has been proved scientically [9],

[10]. Nevertheless, equipping an apartment with a balcony

is not required within building regulations [23]. The need

of adding a balcony to existing housing buildings is recog-

nized and practised during retrotting modernization in par-

ticular countries such as Germany, Denmark, Austria [15].

However, regarding the heritage housing there is a fear that

balcony addition is not compatible with historical urban

tissue, or may destroy façade ornaments. Besides, the bal-

cony may deteriorate the living condition by lowering the

interior daylight [27]. Polish building codes for buildings

in the inner-city build-up area allows twice shorter distance

between the buildings, and insolation time than in other ar-

eas [23]. Many historical houses facing the backyard were

built disregarding the need for proper daylight. Low tech-

nical requirements and strict preservation guidelines may

cause tenements to be doomed to poor daylight conditions

[24], [28]. The study reveals that there are many tenements’

backyards ele vations, where balconies can be straightfor-

wardly added. Nevertheless, the courtyard inner-corners

remain questionable to this idea and require individual pro-

ceeding whether the balcony addition is possible and what

measures should be taken to upgrade these apartments.

The daylight simulation may contribute to guidelines,

considering the factors, which lack in Polish requirements.

The study reveals that Polish regulations about insolation,

shading and obscuring the buildings do not suciently

preserve the indoor from overshadowing [27]. The rooms

exposed to North elevation and the smaller rooms exposed

to West and East are underexposed, even without adding

a balcony. However, in such a case widening a window

opening could improve the indoor daylight. In other cases

the balcony addition may prevent the indoor from over-

heating and glare eect. Thus, the balcony can enhance

the housing adaptability to changing seasons [7], [9]. Nev-

ertheless, the illuminance analysis shows only an average

amount, which uctuates during the seasons. Thus, it is

worthy to reect on how the balcony design and elevation

in tenements can respond to dierent demands depending

on seasons. The feasibility study and simulation conrms

that it is dicult to provide unambiguous rules in chal-

lenging spatial situations such as tenements’ courtyards’

inner corners. Such places require an individual approach.

Conclusions

This study examined the spatial possibility for adding

bal cony to tenements’ backyard elevation considering

Po lish requirements about obscuration of the buildings

and balcony addition impact on indoor daylight. The

spacious tenements’ courtyards in Wrocław have an un-

tapped potential for such an intervention. Nevertheless,

there are spots, which require an insightful look, since

irregular building lines complicates the balcony addi-

tion. The guidelines presented above indicate simplied

patterns for minimum distance requirements depending

on irregularity typology. Many inner-quarter elevations

have enough space for balcony extension. However, there

are spots in the tenements courtyards, especially in their

corner’s parts where adjacent buildings are in too close

distance and do not meet current daylight requirements.

The daylight simulation has revealed that regarding the

south, west and east elevation, the balcony addition does

not reduces the illuminance below recommendable lev-

el of 300 lux. Additionally, it can limit the glare eect

in areas above 3000 lux, and consequently overheating.

Rooms with North orientation are underexposed without

balcony addition. In this case widening the window open-

ings could be considered to improve the indoor daylight.

The Polish requirements about building obscuration,

shadowing and insolation are not ecient in indoor day-

light preservation. For this reason, it is recommended to

assist the design with daylight simulation indicating the

underexposed and overlit spaces. The irregularity of in-

ner-courtyards building line, dierent solar exposure,

cause that adding a balcony requires an individual ap-

proach, and simulation analysis may assist the design.

The importance of possessing an access to private

space was a starting point for discussion of providing bal-

cony extensions to inner-courtyard elevations. However,

the study reveals that the balconies can play a role of an

adaptive element to climate seasons, preventing overheat-

ing and glare. Nonetheless, to explore this potential of

adaptability further research needs to be conducted about

Polish insolation requirements and providing proper bal-

conies design features regarding factors inuencing in-

door daylight in dierent seasons.

Translated by

MartaSmektała

 Exploringthepotentialforbalconyadditiontotenements’backyardelevationinWrocław 73

Abstract

Exploring the potential for balcony addition

to tenements’ backyard elevation in Wrocław

– spatial challenges related to shade and indoor daylight illumination

The expected intensication of thermal modernizations due to the European Union requirements related to the reduction of CO

emissions is

a chance to reect on potentiality of adaptation apartments in tenements to the current users’ needs and expectations. One of the elements improving

living quality is a properly designed access to private outdoor space such as balconies. Urban typology potentially allows extending tenements’

backyard elevations with balconies. Nevertheless, these actions are not taken due to numerous limitations, i.a. because of an irregular elevations’

building line inside the quarters. The research aims to indicate the spatial conditions that would allow adding balconies to backyard elevations within

the context of Polish technical regulations. The article focuses on regulations regarding obscuring and overshadowing the building and the impact

of balconies’ additions on apartments’ indoor daylight. The research was conducted based on following methods: the desktop study of relevant reg-

ulations about minimal distances regarding obscuring and overshadowing the buildings, urban analysis presenting the typologies of inner-quarter

elevation building line and daylight simulations of Daylight Factor and illuminance unveiling the balcony addition’s impact on interior daylight were

conducted to reply these questions. The results are schedules of situations in tenements’ courtyards, where an addition would be dicult or impossi-

ble indicating minimal distances requirements and of balconies’ impact on indoor daylight depending on their forms and solar orientations. The study

demonstrates that the Polish requirements are insucient tool for indoor daylight preservation. The simulations conducted on the cases demonstrate

that adding a balcony to the South, West and East elevations the illuminance does not lower the interior daylight below 300 lux, what is considered

as a minimum level. What’s more, balcony may reduce daylight illuminance, where it exceeds 3000 lux and may cause an unwelcome glare eect.

However, further research is necessary to investigate the Polish insolation regulations and proper add-on balcony design as an element enhancing

apartment adaptability to dierent climate seasons.

Key words: balcon, indoor daylight, heritage housing adaptation

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74 Marta Smektała

Streszczenie

Badanie możliwości dodania balkonów do wewnątrz kwartałowej elewacji kamienic we Wrocławiu

– wyzwania przestrzenne związane z przesłanianiem i doświetleniem wnętrza

Spodziewana intensykacja termomodernizacji wynikająca z wymogów Unii Europejskiej dotyczących ograniczenia emisji CO

jest okazją do

podjęcia reeksji nad potencjałem dostosowania lokali mieszkalnych w kamienicach do aktualnych potrzeb i oczekiwań użytkowników. Jednym

z elementów architektonicznych wpływających pozytywnie na jakość przestrzeni mieszkalnej jest dostęp do dobrze zaprojektowanej prywatnej prze-

strzeni zewnętrznej takiej jak np. balkon. Kwartałowa zabudowa kamienic potencjalnie umożliwia dostawienie zewnętrznych balkonów do tylnych

elewacji. Niemniej działania takie nie są podejmowane ze względu na liczne ograniczenia m.in. przestrzenne związane z nieregularną linią zabudo-

wy wnętrz kwartałów. Celem badania jest wskazanie, na przykładzie Wrocławia, jakie warunki przestrzenne muszą być spełnione, aby umożliwić

dostawienie balkonów do podwórkowej elewacji kamienic w ramach polskich przepisów prawa budowlanego. W artykule skupiono się na przepi-

sach dotyczących przesłaniania i zacieniania budynków oraz na wpływie dostawienia balkonów na doświetlenie mieszkań światłem dziennym. Ba-

dania przeprowadzono na podstawie analizy warunków technicznych pod względem minimalnych odległości wynikających z zacieniania i przesła-

niania budynków, analiz urbanistycznych systematyzujących typologię linii zabudowy elewacji kamienic wewnątrz kwartału oraz komputerowych

symulacji pomiaru Daylight Factor i natężenia światła dziennego pokazujących wpływ dostawienia balkonu na zacienianie mieszkania. Rezultatem

jest zestawienie typologii sytuacji w kwartałach kamienic, gdzie dobudowanie byłoby utrudnione lub niemożliwe, ze wskazaniem wymaganych

minimalnych odległości, oraz przedstawienie wpływu dostawienia balkonu na doświetlenie mieszkania w zależności od kierunków świata i formy

balkonu. Badania potwierdzają, że polskie warunki techniczne nie są wystarczającym narzędziem do zapewnienia odpowiedniego poziomu światła

dziennego. Symulacje przeprowadzone na przykładach wykazały, że dodanie balkonu do południowej, zachodniej i wschodniej elewacji nie zaniża

średniego poziomu natężenia światła poniżej poziomu 300 luksów, który jest uważany za minimalny. Ponadto balkon może niwelować poziom natę-

żenia światła powyżej 3000 luksów, który może wywołać niechciany efekt olśnienia. Wymagana jest dalsza analiza biorąca pod uwagę polskie wy-

mogi nasłonecznienia oraz badania mające na celu określenie odpowiedniego projektu balkonów, który wspomoże adaptację mieszkań do pór roku.

Słowa kluczowe: balkon, światło dzienne, adaptacja zabytkowej architektury