PLEA 2020 A CORUÑA Planning Post Carbon Cities
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PLEA 2020 A CORUÑA
Planning Post Carbon Cities
The environmental performance of temporary urban
interventions:
Technical assessment of regeneration initiatives in the city centre of São
Paulo, with focus on thermal and acoustic performance
RANNY L. X. N. MICHALSKI1, LUCÉLIA RODRIGUES2, JOANA C. S. GONÇALVES3, ROBERTA C. K.
MULFARTH,4, LEONARDO M. MONTEIRO5, RENATA TUBELO6, ALESSANDRA R. P. SHIMOMURA7,
CAROLINA O. BLEY8, MARIANA S. VITTI9, DANIEL F. BILESKY10, MAYSA M. GUIMARAES11
1,3,4,5,7,8,9,10,11
Faculty of Architecture and Urbanism, University of Sao Paulo, (FAUUSP, LABAUT), Sao Paulo, Brazil.
2,6
University of Nottingham, Faculty of Engineering, Department of Architecture, London, UK.
ABSTRACT: Temporary urbanism is an approach to reactivate urban spaces through short-term interventions in a
range of urban contexts. In central São Paulo, the Luz and Santa Ifigênia neighbourhoods, characterized by
deprivation of their physical environments and social structures, were the focus of this investigation. The Mungunzá
Container Theatre and the General Osório Square, located within these neighbourhoods, were selected as case-
studies. Whilst the thermal performance of the container theatre itself was the main interest, in the case of the
Square the fundamental issue was the environmental noise. The objective was to identify adequate strategies to
improve environmental conditions in these locations in order to enhance positive social impact, and, then, contribute
to the regeneration of these neighbourhoods. This research was based on fieldwork and analytical procedures of
thermal and acoustic performances. In the container theatre building, the adoption of external shading and wider
openings for ventilation reduced its indoor peak temperatures and delivered thermal comfort during the warmest
period of the year. In the Square, sound absorber road surface material and an acoustic shell were proposed to
reduce noise and promote better acoustic quality for outdoor performances.
KEYWORDS: Temporary urbanism, Thermal performance, Acoustic performance, Fieldwork, Analytical work.
1. INTRODUCTION central São Paulo. Given the predominant warm
Temporary urbanism is an approach to reactivate conditions of São Paulo’s humid subtropical climate,
urban spaces through temporary and short-time coupled with the magnitude of the problem of noise
interventions in a range of urban contexts [1]. Different pollution, the environmental studies focused on
from the conventional top–down master planning thermal and acoustic performances. The technical work
approach, temporary urbanism is flexible, innovative was based on fieldwork and analytical procedures,
and more engaging with the local population. It often leading to environmental-focused design proposals.
involves the erection of temporary buildings and/or
changes to the landscape and urban furniture. 2. CLIMATE
In the neighbourhoods of the city centre of São São Paulo (latitude 23.85° S; longitude 46.64° W;
Paulo, Brazil, as in many megacities in the world, spaces altitude 792 m) is located in a region of humid
between buildings and public squares are vastly used by subtropical climate (Cfa) [8], being characterized by
informal business and street markets, or are warm-humid summer days, with predominantly
abandoned and crime ridden [2]. Nevertheless, positive partially cloudy sky, and cool and drier winter days,
changes have recently been made on these spaces with predominantly sunny sky. Air temperatures are
through the adoption of temporary interventions, moderate in most of the year with an annual average
promoted by a series of governmental and non- temperature of approximately 19 °C [9]. Due to the
governmental institutions [3, 4, 5]. The provision of subtropical conditions, overcast sky occurs during 60%
cultural and social spaces for the population to gather of the year, and diffuse radiation can reach 50% or
safely have proved to be helpful means to increase more of the total global radiation on the horizontal plan
social cohesion and community capital in deprived in all seasons. January is the hottest month, followed by
urban areas [6, 7]. February, with an average of nearly 23 °C, absolute
In this context, the work presented in this paper minimum of 14 °C and absolute maximum of 34 °C.
investigated the environmental performance of Relative humidity varies between 31% and 100%.
temporary design interventions for two nearby sites in Maximum global solar radiation on the horizontal plan
is 1,068 W/m2, being 578 W/m2 diffuse. July is the abandoned site, supported by two light-weight
coolest month, followed by August, with an average of structures, one made of industrial containers and
16 °C, absolute minimum of 8 °C and absolute another being a geodesic dome made of polycarbonate
maximum of 27 °C. Relative humidity varies between triangular structures and enclosed by a plastic layer.
26% and 100%. Maximum global radiation is 719 W/m2, The second case, General Osório Square, is a top-
being the diffuse accountable for 435 W/m2, more than down approach initiative, implemented by the local city
half of the total [9]. authorities, where a previously underused square was
Regarding acoustic conditions, noise pollution is one treated to accommodate different kinds of leisure
of the biggest environmental problems in urban centres activities, including the provision of movable outdoor
considered a public health issue, affecting health and furniture, such as beach chairs, tables and umbrellas, to
quality of life [10]. The main sources of noise in central be placed on a wooden deck used for short
areas of the cities are those related to transport. In performances surrounded by wide pavements. Despite
order to tackle this issue, in São Paulo, a recent their different approaches, both projects aimed to
municipal law established the development of the first increase the permanence of residents on their
city noise map, to be finished in 2023 [11]. The noise locations, by proposing cultural and social activities.
map allows the diagnosis of the actual noise conditions
and, therefore, it can inform potential interventions for
improvement, as it already happens in Europe [10, 12].
Performance wise, the Brazilian standard ABNT NBR
10151 sets acoustic criteria for environments outside
buildings [13]. The standard describes procedures for
acoustic measurement and evaluation, and establishes
limits for sound pressure levels for different outdoor
environments, as a function of land use, occupation,
and time of the day the exposure occurs.
Figure 1: Locations and views: General Osório Square and
3. CASE-STUDY INTERVENTIONS Cultural Complex Mungunzá.
In central São Paulo, the neighbourhoods of Luz and
4. METHOD
Santa Ifigênia are characterized by a high level of
This research was based on fieldwork and analytical
deprivation of their physical environments, with a
work focusing on thermal and acoustic performances.
significant number of degraded and vacant buildings
In situ measurements recorded outdoor conditions in
alongside with underused public spaces mainly
both case-study areas as well as inside the structures of
occupied by homeless and drug-addicts. On the other
the Container Theatre in August 2018. The
hand, they are also the location of important cultural
measurements were cross-compared to time-lapse
facilities and listed buildings. In addition to that, the
observations in order to understand how people
area encompassed by the two neighbourhoods is one of
interact with the built environment on specific climatic
the main pool of jobs in the city and is well connected
conditions, helping to inform about suitable temporary
by public transportation modes to the edges of the city,
uses and potential improvements on the existing ones.
where most of the poor population lives [14].
Given the nature of its physical and social problems, 4.1. Thermal analysis
the area has been the focus of small-scale urban With regard to the thermal analysis, in the Cultural
interventions as well as temporary urbanism initiatives Complex Mungunzá, measurements of dry-bulb
[2, 3, 15]. In this context, the Cultural Complex temperature (DBT), wet-bulb globe temperature
Mungunzá Container Theatre, here called Cultural (WGBT) and relative humidity (RH) were continuously
Complex Mungunzá (Compania de Artes Teatro taken in four locations: inside the container building
Mungunzá) [3] and the Open City Centre Square Largo (the theatre), the geodesic structure, outdoors under a
General Osório, here called General Osório Square tree and under the sun, from 11:45 am to 3:45 pm, with
(Centro Aberto Largo General Osório, CALGO) [2] were readings each 15 minutes. In the General Osório Square,
selected as case-studies. Figure 1 shows their locations spot measurements were taken in the middle of the
and pictures. They were selected because a degree of day, between 12 am and 1 pm.
temporary urbanism approach was undertaken on both The equipment used for the external continuous
cases. The first case, the Mungunzá Container Theatre, monitoring consisted of data loggers Hobo Onset
is a result of a bottom-up approach, dedicated to U23001 with weather shield. Internally, data loggers
cultural and theatre related activities. It was built on an Hobo Onset U12 were adopted. In addition, grey globes
to measure mean radiant temperatures were adopted In addition to the measurements and simulations
in both indoors and outdoors. The spot measurements analysis of potential uses, an acoustic shell for musical
were taken with thermo-hygrometer Hanna. performance was proposed to be installed in General
For the assessment of outdoors thermal comfort, Osório Square, in order to adequately direct sound to
the index of Predicted Thermal Sensation, developed by the audience, located in the middle of the square.
Monteiro to the climate of São Paulo [16] was adopted.
In the sequence, thermal analytical studies addressed 5. FINDINGS: CULTURAL COMPLEX MUNGUNZÁ
the performance of the container structure with focus 5.1. Measurements
on the intensity of its occupation and the risk of The measured data (Fig. 2) revealed comfortable
overheating during the warmest period of the year. For conditions both indoors and outdoors during the time
this purpose, indoor peak summer temperatures were of the fieldwork, being consistent with a typical winter
calculated using the Centre Scientifique et Technique du day for the city of São Paulo, with a clear sky and
Bâtiment (CSTB) method [17]. perceivable air movement, as per the adaptive comfort
4.2. Acoustic analysis criteria [18]. The highest air and globe temperatures
The acoustic assessment consisted of sound were found within the geodesic structure, followed by
pressure level evaluation, computational simulations the container building (unoccupied during the
and an intervention design proposal to improve the measurements). The lowest temperatures were found
quality of the outdoor spaces. Sound pressure levels outdoors, under the tree (Fig. 2). The geodesic dome
were measured in different points in order to had its poorer thermal performance associated to the
characterise acoustic conditions in the selected high thermal transmittance of its plastic skin that
locations. Results were also compared with the values combined to higher levels of global radiation
established by the Brazilian Standard ABNT NBR 10151 significantly impacted on the amount of heat that
[13]. For the measurements, a sound level meter Larson passed through the structure. Whilst in the indoor
Davis model SLM 831 and a sound level meter measurements air temperatures were higher than (but
calibrator Larson Davis model 200 CAL were used. very close to) the radiant ones (with the exception of
The A-weighted equivalent continuous sound one measurement in the geodesic) because of lack of
pressure level (LAeq), maximum and minimum A- internal thermal mass, outside it was the opposite:
weighted sound pressure levels (LAmax and LAmin) and radiant temperatures were higher than the air ones due
statistical levels (LAN), where N is the percent to the effect of the sky diffuse radiation.
exceedance level, were measured. LA90 is the A- The peak temperature inside the container reached
weighted sound pressure level that is exceeded for 90% 24.5 °C at 11h45 and 24 °C in the geodesic structure at
of the time interval considered and it is an indicator of 2 pm, 6 °C higher than under the tree, where the
the residual noise. On the other hand, LA10 is the A- maximum temperature registered was 18 °C.
weighted sound pressure level that is exceeded for 10% Comparatively, the nearest weather station (located in
of the time interval and it is an indicator of events. a park area) had a measured air temperature value
For the advanced analytical studies on urban noise, slightly lower by less than 0.5 °C (Fig. 2). Exposed to the
the software CadnaA was used. The software sun, air temperature varied between 19 °C and 21 °C
acoustically models the outdoor environment based on for most of the time, whereas the globe temperature
the following inputs: contour lines, buildings, roads and reached 24 °C at 2 pm (Fig. 3). The results in the
noise sources, ground and surfaces absorption, number container and in the geodesic structure showed the
of different types of vehicles per hour and speed limits potential risk of thermal discomfort in the warmest
of the roads. Then, based on these assumptions, it is periods of the year, when external temperatures can
possible to calculate and predict the environmental reach as high as 34 °C and solar radiation can represent
noise of the place. The purpose of the analytical more than the double of a typical winter day (as the day
simulations was to identify effective solutions to of the fieldwork) [9]. Although only the results of
improve the acoustic outdoor environment of the case temperatures are shown here, it is worth mentioning
studies, in order to create appropriate and health that relative humidity varied throughout the
conditions to the development of outdoor measurement points during the day, from 75% in the
social/communal activities. Following the analysis of morning to 35% in the afternoon. Nevertheless, despite
the base-case acoustic urban environment, alternative the typical dry conditions, the findings of relative
scenarios for the road surfaces, insertion of landscape humidity did not indicate any risk for comfort or health
and other strategies were compared. in any of the four measurement points.
The Physiological Equivalent Temperatures (PET)
were calculated taking into account the hourly
predicted thermal sensation for the position under the and 52 dB. Considering the statistical levels, LA10 was
sun and the respective comfort temperatures for the 64 dB and LA90 was 56 dB. Recorded sounds were
month of August. The results indicated the oudoor locksmiths in the surroundings, children playing
thermal conditions in the slightly cold band for most of outdoors on the site´s external area and the adjacent
the time (Fig. 4). Adding to the measurements, the road traffic. In this particular case, traffic was not
time-lapse image series showed air movement of leaves identified as a problematic noise source in the
of trees, whilst people were seating under the sun. It is surroundings of the cultural complex.
important to consider that this was a typical winter day,
with mild temperatures near 20 °C. 5.2. Design Optimisation
Alternative design scenarios were tested to reduce
the solar gains and increase heat losses through the
metal and glazed envelope of the container building. A
set of opportunities to improve its thermal
performance were also identified. The climate-
responsive design strategies examined were: 1. the
increase of ventilation, 2. additon of brise-soleil on east
and west glazed facades, 3. additon of brise-soleil on
east and west facades combined with the increase of
ventilation, and, 4. increase of internal thermal mass in
Figure 2: Measurements of DBT and WGBT in three locations the ceiling (Fig. 5). Despite the unprotected glazed
at Cultural Complex Mungunzá: container theatre, geodesic facades and the minimum aperture for ventilation, the
dome, shaded outdoors (under the tree), compared to the current light reflective colour of the external cladding
closest weather station in São Paulo, on August 10th 2018,
(specially in the roof) proved to be benefitial to the
from 11:45 am to 3:45 pm.
thermal performance of the base-case. Maximum
indoor temperatures for each of the strategies and
their potential thermal comfort conditions were
calculated using the CSTB method [17].
Figure 3: Cultural Complex Mungunzá, summary of
measurements of temperatures, RH and LAeq recordings in the
outdoor position, exposed to the sun on August 10th.
Figure 4: Calculated outdoor thermal comfort zone for the
month of August with the predicted thermal sensation for the Figure 5: Analytical studies of the building of the container
case-study area and air temperature under the sun [16]. theatre, showing the range of design interventions tested to
improve thermal performance.
Looking at noise conditions on site, the measured A-
weighted equivalent continuous sound pressure level The findings showed that the increase of the area of
(LAeq) was 63 dB, lower than the 65 dB daytime limit ventilation and adoption of shading (strategy number 3)
established by ABNT NBR 10151 (2019) [13]. According would be able to reduce summer peak temperature
to the standard, for outdoors, in mixed-use area with from 28.4 oC (base case) to 26.6 oC, increasing the
predominance of cultural activities, leisure and tourism, indoor thermal comfort conditions. The introduction of
a 65 dB limit is allowed for LAeq for the daytime period, internal thermal mass reduces the peak temperature to
and a 55 dB limit is allowed for the night period. 26.3 oC, a small improvement compared to the
Maximum and minimum sound pressure levels were 87
combined effect of shading and ventilation. However, 6.2. Design Optimisation
introducing the ventilation alone already results in Acoustic computational simulations were
comfortable conditions for 90% of the occupants. The undertaken to examine different scenarios with the aim
thermal performance of the container in a typical of reducing urban noise levels and, thus, improving
autumn day is very similar to the summer one. As a user’s outdoor comfort. The alternative scenarios
result, more than 90% of the users would feel examined were: 1. vehicles prohibited at adjacent
comfortable in both summer and winter periods. In the streets, 2. road’s speed limit reduced to 10 km/h, 3.
typical winter day, the external fixed horizontal shading surface of the road changed to an asphalt with greater
over glazed areas coupled with the selective use of sound absorption, 4. circulation of heavy vehicles
ventilation reduce peak temperatures from 24 oC to prohibited on the studied area, 5. road’s speed limit
21.9 oC, keeping the internal space comfortable. reduced to 10 km/h and road’s surface changed to an
asphalt with higher sound absorption. Simulation
6. FINDINGS: GENERAL OSÓRIO SQUARE results pointed out to the significant contribution of
6.1. Measurements reducing speed limits and changing the sound
In the General Osório Square, outdoor thermal absorption of the roads. Figure 7 shows the base case
conditions were within the neutrality zone, showing and the best alternative (number 5).
temperatures around 19 oC in the middle of the day,
when the square is often used by local workers and
residents (Fig. 6). Despite that, the time-lapse revealed
people with different preferences, both under the
shadow and exposed to the sun in a variety of activities
such as talking, eating, resting, or just waiting. This is
result from the environmental diversity provided by the
landscape coupled with the availability of urban
furniture and other public amenities, such as portable
Figure 7: Simulations of urban noise in the area of the case-
deck-chairs and umbrellas. Thermal conditions were studies. On the left, base case. On the right, alternative 5. The
not a problem to the square occupancy. darker the colour (closer to purple), higher the noise levels.
On the other hand, measurement results indicated
the urban noise as an issue in the location, LAeq value After testing the alternatives, the other potential
was measured at 66 dB, and a LAmax at 89 dB. LAmin was temporary initiative proposed at General Osório Square
54 dB, L A10 was 69 dB, and L A90 was 59 dB. was an acoustic shell to be placed on the existing stage
of the square. The idea was to create a new urban
equipment within the square that could have the same
cultural ethos of the surroundings – a new equipment
for artistic performances, where plays and music
performances could be presented. The starting point
considered an acoustic shell that could be easily
assembled and disassembled and stored within the
municipality container, located at the square and
currently used to store the movable beach chairs used
during the day. The form intention was to create a
structure for musical performances which was able to
Figure 6: General Osório Square, summary of outdoor take the sound up to the middle of the square and to
measurements on August 10th, including temperatures, RH
reduce the interference of the streets´ noise. Figure 8
and LAeq recordings.
shows the proposal: a planar acoustic system with its
For outdoors artistic performances in the General geometry allowing the reflected sound generated at the
Osório Square, 66 dB is a high sound pressure level, deck to reach up the middle of the square.
compromising some activities such as listening to music
and understanding speech. Therefore, the need of
acoustic structures to qualify short-term music
performances was identified. However, prior to the
design of such structures, analytical studies on how to
improve local urban noise were developed. Figure 8: Final proposal - Section.
7. FINAL CONSIDERATIONS and the University of Birmingham for supporting this
The local remarkable social-economic complexity research. Thanks to the Secretary of Urban
and a series of cultural initiatives found in the area of Development of São Paulo City for the information
Luz and Santa Ifigênia neighbourhoods provide a provided. Thanks to Cultural Complex Mungunzá for the
potential for a programme of successful temporary access to fieldwork. The authors would also like to
structures, such as what can be observed in the Cultural thank the technician from FAUUSP, Ranieri Higa, for his
Complex Mungunzá or in the General Osório Square. support with the fieldwork.
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