**2. Environmental concept**

The preliminary climatic diagnosis highlighted the importance of shading and light colors as well as the possibility of natural ventilation as the main passive strategies to reduce heat gains in buildings and improve thermal comfort both indoors and outdoors. Analysis were based in a reference climatic year, with hourly data, encompassing readings from 2000 to 2004 of the meteorological station situated at the International Airport of Rio de Janeiro, situated within 2Km from the site of the Petrobras Research Centre. Air temperatures were high, more than 29oC for 10% of the year, and below 20oC, for 10% of the year as well, combined with high relative humidity rates, more than 70% in 66% of the year [4].

22 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

*Visualization Centre* (*Núcleo de Visualização e Colaboração*, NVC), (see figure 2) [1].

research centre had active cooling as a functional requirement: the two restaurants and the

**Figure 2.** CENPES site planning, including the 1st phase of the Research Center towards the south and the expansion with new buildings on the north part of the site facing the bay, as presented in the

The initial requirement for active cooling in all office spaces of the Petrobras research centre for all year round could be associated with the air-conditioning cultural of working spaces (artificial cooling is an unquestioned factor in commercial buildings in most Brazilian cities, being definitely a common practice in Rio de Janeiro), rather than a climatic driven need. Challenging the supremacy of air conditioning in the context of office spaces in Rio de Janeiro, the efficiency of natural ventilation and the introduction of the mixed-mode strategy were critically evaluated for the various typologies and conditions of working environments within the new buildings of the research centre, being ultimately recommended in some particular cases. Initially a simplified analysis of the local climate suggested the possibility of natural ventilation in a typical office space for approximately 30% of the working hours over the year, which justified a more detailed analysis of the mixed-mode strategy for the

The preliminary climatic diagnosis highlighted the importance of shading and light colors as well as the possibility of natural ventilation as the main passive strategies to reduce heat

winning proposal.

final design proposal [3].

**2. Environmental concept** 

In this context, the search for adequate building environmental strategies started at the concept stage, addressing thermal comfort in buildings and open spaces, daylighting, acoustics and the specific issue of cooling demand. A horizontal architectural composition of multiple buildings derived from the core objective of creating meeting areas in semi-outdoor spaces, With buildings connected by transitional spaces, site planning and architectural form were defined to respond to need of protection from solar orientation, versus the exposure to natural ventilation and views towards the bay. Double roofs and various shading devices, high-level openings and open circulation routes are some of the defining architectural features which are found in all key buildings of the expansion of the Petrobras Research Centre in Rio de Janeiro.

At the masterplanning scale, the main environmental strategy was to position the different functions of the programme in separate low-rise buildings, keeping people at the ground level, or close to it and in contact with the external environment. As buildings were interspersed by transitional spaces on a predominantly horizontal occupation of the site, a series of open and semi-opened areas of different environmental qualities, including sunny and shaded areas (or partially shaded), exposed to various wind directions, as well as different landscape projects were created between, around and within buildings [5].

The value of such transitional spaces to the overall design concept was primarily related to the possibility of comfortable outdoor spaces protected from the all year round inhibiting solar radiation of Rio de Janeiro, available for leisure, social interaction and working activities, in other words, introducing the outdoors experience in the daily routine of the occupants and visitors of the Petrobras Research Centre in the Guanabara bay. Furthermore, environmentally the transitional spaces also give the benefit of reducing the impact of solar gains in the thermal performance of buildings' internal spaces (being some of them artificially cooled). In summary, the main transition spaces of the complex are associated with the three main buildings: the terraces from the Central Building, the gardens between the wings of Laboratories and the central open atrium of the Convention Centre, which is the main access to the expansion of the Research Centre.

The building cluster formed by the main office building (the Central Building), the laboratories and the convention centre was conceived to be the core of the masterplan of the extension of the research centre (see figure 3) laboratories were allocated in parallel wings facing the north-south orientation, on the two sides of the main office building (which then looks at east and west towards the bay).

The emphasis given to the efficiency of space and functionality, specially with respects to the laboratories and their connections to the rest of the research centre, was a fundamental to the site planning of buildings both in the first phase as in the expansion of the Petrobras Research Centre, as it was the importance given to the transitional spaces in the overall environmental quality of the masterplan. Whilst in the first phase, the laboratories follow and radial displacement on the site, in the expansion project, parallel rows of laboratories oriented north-south are attached to the long linear main central building, as shown previously in figure 2.

Environmental Design in Contemporary Brazilian Architecture:

The Research Centre of the National Petroleum Company, CENPES, in Rio de Janeiro 25

from giving the opportunity of views towards the bay, the east orientation facilitated exposure to the prevailing wind from south-east (comparable to the sea breeze) at the terrace level, where semi-open spaces totally protected from the sun were design to encourage outdoors working activities, leisure and social interaction. On the opposite orientation, the west façade looks at the first buildings of the Research Centre, built on the

Architecturally, the shading of windows and semi-open spaces coupled with the use of light colors on the external facades (primarily white) were primary strategies in response to the local climatic conditions. As a result, a series of opened circulation areas inside and between buildings, shaded from the direct sun but exposed to wind, alongside internal environments of diffuse daylight and protected views of the surroundings qualify the architecture of the buildings placed at the core of the new masterplan: The Central Building, Laboratories and

However, it is important to notice that the environmental qualities and the related architectural solution of the double roofs in the main office building and the laboratories were modified with the design development. In the case of the Central Building, the original permeable structure gave place to a more robust and closed roof (see figures 4 and 5), whilst in the laboratories, the space dedicated to capture daylight was taken by systems in response to the need for highly specialized technical installations (see figures 6 and 7). Despite the major changes in the design, in both cases the second roofs kept the original role of extra solar protection. The consequent differences in performance will be explored in the

**Figure 4.** Conceptual sketch of the Central Building with the permeable screen roof filtering sun, light

In addition, the two utility buildings, Operational Support and Utilities Centre, follow the factory-like building typology, in which daylight and natural ventilation by stack effect are intrinsically related to the roof design and its orientation in relation to the sun and the winds

70s.

Conventional Centre.

forthcoming topics.

(see figure 8).

and air flow creating environmental diversity.

The north-south orientation to the laboratories was chosen given the relatively minor exposition to the direct solar radiation, therefore the most favorable conditions to achieve good daylight (specially from the south) and minimize solar gains, considering that daylight was a fundamental requirement to the laboratories, where cellular office cells were designed to be naturally ventilated.

The north-south orientation of the laboratories' wings was also important to allow the penetration of the predominant south-east wind into the open and semi-open areas of the complex through the patios – the semi-open spaces between two parallel laboratory wings, whilst creating appropriate conditions for the installation of photovoltaic cells on the exposed areas of the roof of laboratories.

**Figure 3.** Physical model of the new masterplan for the expansion of the Research Center. Source: Zanettini Arquitetura S.A.

In the case of the Central Building, the orthogonal position in relation to the wings of laboratories resulted in the east-west orientation, which brought the challenges of providing solar control on the facades whilst allow for views and daylight. On the other hand, apart from giving the opportunity of views towards the bay, the east orientation facilitated exposure to the prevailing wind from south-east (comparable to the sea breeze) at the terrace level, where semi-open spaces totally protected from the sun were design to encourage outdoors working activities, leisure and social interaction. On the opposite orientation, the west façade looks at the first buildings of the Research Centre, built on the 70s.

24 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

previously in figure 2.

to be naturally ventilated.

Zanettini Arquitetura S.A.

exposed areas of the roof of laboratories.

The emphasis given to the efficiency of space and functionality, specially with respects to the laboratories and their connections to the rest of the research centre, was a fundamental to the site planning of buildings both in the first phase as in the expansion of the Petrobras Research Centre, as it was the importance given to the transitional spaces in the overall environmental quality of the masterplan. Whilst in the first phase, the laboratories follow and radial displacement on the site, in the expansion project, parallel rows of laboratories oriented north-south are attached to the long linear main central building, as shown

The north-south orientation to the laboratories was chosen given the relatively minor exposition to the direct solar radiation, therefore the most favorable conditions to achieve good daylight (specially from the south) and minimize solar gains, considering that daylight was a fundamental requirement to the laboratories, where cellular office cells were designed

The north-south orientation of the laboratories' wings was also important to allow the penetration of the predominant south-east wind into the open and semi-open areas of the complex through the patios – the semi-open spaces between two parallel laboratory wings, whilst creating appropriate conditions for the installation of photovoltaic cells on the

**Figure 3.** Physical model of the new masterplan for the expansion of the Research Center. Source:

In the case of the Central Building, the orthogonal position in relation to the wings of laboratories resulted in the east-west orientation, which brought the challenges of providing solar control on the facades whilst allow for views and daylight. On the other hand, apart Architecturally, the shading of windows and semi-open spaces coupled with the use of light colors on the external facades (primarily white) were primary strategies in response to the local climatic conditions. As a result, a series of opened circulation areas inside and between buildings, shaded from the direct sun but exposed to wind, alongside internal environments of diffuse daylight and protected views of the surroundings qualify the architecture of the buildings placed at the core of the new masterplan: The Central Building, Laboratories and Conventional Centre.

However, it is important to notice that the environmental qualities and the related architectural solution of the double roofs in the main office building and the laboratories were modified with the design development. In the case of the Central Building, the original permeable structure gave place to a more robust and closed roof (see figures 4 and 5), whilst in the laboratories, the space dedicated to capture daylight was taken by systems in response to the need for highly specialized technical installations (see figures 6 and 7). Despite the major changes in the design, in both cases the second roofs kept the original role of extra solar protection. The consequent differences in performance will be explored in the forthcoming topics.

**Figure 4.** Conceptual sketch of the Central Building with the permeable screen roof filtering sun, light and air flow creating environmental diversity.

In addition, the two utility buildings, Operational Support and Utilities Centre, follow the factory-like building typology, in which daylight and natural ventilation by stack effect are intrinsically related to the roof design and its orientation in relation to the sun and the winds (see figure 8).

Environmental Design in Contemporary Brazilian Architecture:

The Research Centre of the National Petroleum Company, CENPES, in Rio de Janeiro 27

**Figure 8.** Design concept of the typical naturally ventilated factory- type building for services and

spaces and transition spaces between outdoors and indoors. Given the warm-humid characteristics of the local climate, the transitional spaces followed the principle of protection against the impact of solar radiation, but exposed to wind. In this respect, as shown in figure 9, ssimulations of air flow around and between the buildings has shown lower velocities particularly near the eastern edge of the laboratory buildings, but better conditions in centre of the patios as well as in the central void of the conventional centre.

**Figure 9.** Simulation of air flow around and between the buildings of the new masterplan. Data about air speed was one of the fundamental variables to the prediction of thermal comfort in the open spaces

utilities.

of the masterplan.

**Figure 5.** The final design of the Central Building with the insulated metal sandwich roof offering a higher protection against the sun and the rain.

**Figure 6.** Conceptual sketch of the Laboratories showing the original concept of the double roof shading skylights.

**Figure 7.** The final design of the Laboratories with the space between the two roofs taken by the technical systems.

## **3. Thermal comfort in open spaces**

Considering the attractive scenery of the Guanabara Bay, in Rio de Janeiro, and the intention to promote an environment for encounters and enjoyment in outdoor spaces, the architectural premises brought a horizontal composition, with buildings connected by open

Environmental Design in Contemporary Brazilian Architecture: The Research Centre of the National Petroleum Company, CENPES, in Rio de Janeiro 27

26 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

**Figure 5.** The final design of the Central Building with the insulated metal sandwich roof offering a

**Figure 6.** Conceptual sketch of the Laboratories showing the original concept of the double roof

**Figure 7.** The final design of the Laboratories with the space between the two roofs taken by the

Considering the attractive scenery of the Guanabara Bay, in Rio de Janeiro, and the intention to promote an environment for encounters and enjoyment in outdoor spaces, the architectural premises brought a horizontal composition, with buildings connected by open

higher protection against the sun and the rain.

shading skylights.

technical systems.

**3. Thermal comfort in open spaces** 

**Figure 8.** Design concept of the typical naturally ventilated factory- type building for services and utilities.

spaces and transition spaces between outdoors and indoors. Given the warm-humid characteristics of the local climate, the transitional spaces followed the principle of protection against the impact of solar radiation, but exposed to wind. In this respect, as shown in figure 9, ssimulations of air flow around and between the buildings has shown lower velocities particularly near the eastern edge of the laboratory buildings, but better conditions in centre of the patios as well as in the central void of the conventional centre.

**Figure 9.** Simulation of air flow around and between the buildings of the new masterplan. Data about air speed was one of the fundamental variables to the prediction of thermal comfort in the open spaces of the masterplan.

The predictions of thermal comfort in outdoor spaces were established using the Outdoor Neutral Temperature (Tne), presented by Aroztegui [6], which considers as reference the concept of Neutral Temperature (Tn) introduced by Humphreys [7], who defined Neutral Temperature (tn) as the room temperature considered thermally neutral to a given population, observing the local conditions. The author presents a linear ratio between mean monthly temperature (tmm) and Neutral Temperature (tn), valid indoors in situations with low air speeds and mean radiant temperature close to air temperature.

$$\text{Tn} = 17.6 + 0.31 \bullet \text{tmm} \tag{1}$$

Environmental Design in Contemporary Brazilian Architecture:

The Research Centre of the National Petroleum Company, CENPES, in Rio de Janeiro 29

TE\* = to + w • Im • LR • (pa – 0.5 • psTE\*) (3)

to = hr • trm + hc • tbs / (hr + hc) (4)

plus latent heat exchange from a person at the actual environment, and it can be calculated

Where: to = operative temperature [ºC]; w = skin wetness [dimensionless]; Im = index of clothing permeability [dimensionless]; LR = Lewis relation; pa = vapour pressure [kPa];

The Operative Temperature (to) is the uniform temperature of an imaginary black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual non uniform environment. It is numerically the average of bulb temperature (tbs) and mean radiant temperature (trm), weighted by their respective heat transfer coefficients (hc and hr). ASHRAE defines the equation for the Operative

Where: trm = mean radiant temperature [ºC]; tbs = dry bulb temperature [ºC]; hr = radiant

In this work the calculation of TE\* adopted the proposed equations by Szokolay [10], according to which the new effective temperature is given by lines in the psychometric chart, crossing the curve of relative humidity of 50% for the given temperature [11]. These lines inclination equal to 0.023 • (TE\*-14), if TE\*<30, and 0.028 • (TE\*-14), if TE\*>30. Knowing the operative temperature and absolute humidity of a specific location, the new

In this process, the New Effective Temperature is the mean temperature of all the hours from the previews thirty days. Assuming a tolerance range of ± 2.5°C to the outdoor neutral temperature, at least 90% of the users would be satisfied with the thermal environment conditions. Assuming a tolerance range of ± 3.5°C the satisfaction percentage drops down to 80%. In this research, the more restrictive range was applied, working with a satisfaction

Three typologies for outdoor environments were studied configuring nine possible different environmental conditions, as shown in table 1 [11], in order to quantify the impact of different degrees of exposure to sun and wind in the overall thermal comfort in open spaces.

The key outdoor environments studied in this analysis were: the open central atrium of the convention centre, the patios of semi-enclosed gardens between the laboratories and the

 rv r\*v rv\* r\*v\* r r\* v v\* cold 7,6% 14,5% 0,1% 0,1% 0,0% 0,0% 28,8% 0,4% 0,0% comfort 57,0% 75,4% 42,4% 54,1% 0,3% 1,1% 68,8% 78,3% 1,7% hot 35,4% 10,1% 57,5% 45,8% 99,8% 98,9% 2,4% 13,2% 98,3%

exchange coefficient [W/m2 ºC]; hc = convective exchange coefficient [W/m2 ºC].

effective temperature was calculated through iterative process.

**Table 1.** Comparative results of the considered configurations

psTE\* = saturation pressure of the new effective temperature [kPa].

by the following equation.

Temperature as follows [9]:

index superior to 90% of all users.

Where: tn = Neutral Temperature [ºC]; tmm = mean monthly temperature [ºC]

It is important to notice that the equation for the calculation of the Neutral Temperature is valid for the value range 18.5 ºC - 30.5 ºC, considering individuals in sedentary activity and wearing light clothing. For different human activities, the following corrections can be applied: light work (M=210W), -2.0ºC; moderate work (M=300W), -4.5ºC; heavy work (M=400W), -7.0ºC.

Aroztegui [6] proposed the Outdoor Neutral Temperature based on the same variables of the Neutral Temperature for internal spaces previously defined by Humphreys, to which variables related to sun irradiance and wind speed were incorporated. With respect to sun irradiation, the direct component should not be the only factor, but also diffuse irradiance and surrounding reflections. Regarding wind, the author highlights the need for simplifications, as variables associated with wind are difficult to value, as it is affected in space and time by random accidents at pedestrian level. Looking at other references, Givoni's Index of Thermal Stress (ITS) [8], is based on an empirical equation for indoor neutral temperature, that takes also into account variables that are characteristics of outdoor.

To establish the sweat rate in sedentary activity, considering mean conditions for the individual and the surrounding characteristics (with relative humidity ranging from 35% to 65%), the following equation for outdoor neutral temperature was established:

$$\text{time} = 3.6 + 0.31 \text{ tmm} + \{100 + 0.1 \text{ Rdn} \left[1 - 0.52 \left(\text{v} \, 0.2 - 0.88\right)\right] / 11.6 \text{ v} \, 0.3 \tag{2}$$

Where: tne = Outdoor Neutral Temperature [ºC]; tmm = mean monthly temperature [ºC]; Rdn = normal direct solar irradiance [W/m2]; v = wind speed [m/s].

Outdoor neutral temperature is estimated for a mean monthly temperature, corrected to a 50% relative humidity situation. Therefore, in the context of this work, the formulation of the new effective temperature was used to correct the mean monthly temperature values to an equivalent value of a 50% relative humidity situation. This means that, instead of using only the air mean monthly temperature value, this value was considered in terms of the New Effective Temperature, which considers the air temperature and also air humidity, providing equivalent temperature values, having as reference a 50% relative humidity situation.

According to ASRHAE [9], the New Effective Temperature (TE\*) is the operative temperature of an enclosure at 50% relative humidity that would cause the same sensible plus latent heat exchange from a person at the actual environment, and it can be calculated by the following equation.

28 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

low air speeds and mean radiant temperature close to air temperature.

(M=400W), -7.0ºC.

Where: tn = Neutral Temperature [ºC]; tmm = mean monthly temperature [ºC]

65%), the following equation for outdoor neutral temperature was established:

Rdn = normal direct solar irradiance [W/m2]; v = wind speed [m/s].

tne = 3.6 + 0.31 tmm + {100 + 0.1 Rdn [1 – 0.52 (v 0.2 – 0.88)]} / 11.6 v 0.3 (2)

Where: tne = Outdoor Neutral Temperature [ºC]; tmm = mean monthly temperature [ºC];

Outdoor neutral temperature is estimated for a mean monthly temperature, corrected to a 50% relative humidity situation. Therefore, in the context of this work, the formulation of the new effective temperature was used to correct the mean monthly temperature values to an equivalent value of a 50% relative humidity situation. This means that, instead of using only the air mean monthly temperature value, this value was considered in terms of the New Effective Temperature, which considers the air temperature and also air humidity, providing

According to ASRHAE [9], the New Effective Temperature (TE\*) is the operative temperature of an enclosure at 50% relative humidity that would cause the same sensible

equivalent temperature values, having as reference a 50% relative humidity situation.

The predictions of thermal comfort in outdoor spaces were established using the Outdoor Neutral Temperature (Tne), presented by Aroztegui [6], which considers as reference the concept of Neutral Temperature (Tn) introduced by Humphreys [7], who defined Neutral Temperature (tn) as the room temperature considered thermally neutral to a given population, observing the local conditions. The author presents a linear ratio between mean monthly temperature (tmm) and Neutral Temperature (tn), valid indoors in situations with

It is important to notice that the equation for the calculation of the Neutral Temperature is valid for the value range 18.5 ºC - 30.5 ºC, considering individuals in sedentary activity and wearing light clothing. For different human activities, the following corrections can be applied: light work (M=210W), -2.0ºC; moderate work (M=300W), -4.5ºC; heavy work

Aroztegui [6] proposed the Outdoor Neutral Temperature based on the same variables of the Neutral Temperature for internal spaces previously defined by Humphreys, to which variables related to sun irradiance and wind speed were incorporated. With respect to sun irradiation, the direct component should not be the only factor, but also diffuse irradiance and surrounding reflections. Regarding wind, the author highlights the need for simplifications, as variables associated with wind are difficult to value, as it is affected in space and time by random accidents at pedestrian level. Looking at other references, Givoni's Index of Thermal Stress (ITS) [8], is based on an empirical equation for indoor neutral temperature, that takes also into account variables that are characteristics of outdoor. To establish the sweat rate in sedentary activity, considering mean conditions for the individual and the surrounding characteristics (with relative humidity ranging from 35% to

Tn = 17.6 + 0.31 • tmm (1)

$$\text{TE}^\* = \text{to} + \text{w} \bullet \text{Im } \bullet \text{ LR } \bullet \text{ (pa } -0.5 \text{ } \bullet \text{ psTE\*)} \tag{3}$$

Where: to = operative temperature [ºC]; w = skin wetness [dimensionless]; Im = index of clothing permeability [dimensionless]; LR = Lewis relation; pa = vapour pressure [kPa]; psTE\* = saturation pressure of the new effective temperature [kPa].

The Operative Temperature (to) is the uniform temperature of an imaginary black enclosure in which an occupant would exchange the same amount of heat by radiation plus convection as in the actual non uniform environment. It is numerically the average of bulb temperature (tbs) and mean radiant temperature (trm), weighted by their respective heat transfer coefficients (hc and hr). ASHRAE defines the equation for the Operative Temperature as follows [9]:

$$\text{to} = \text{hr} \bullet \text{trm} + \text{hc} \bullet \text{ts} / \text{(hr} + \text{hc)} \tag{4}$$

Where: trm = mean radiant temperature [ºC]; tbs = dry bulb temperature [ºC]; hr = radiant exchange coefficient [W/m2 ºC]; hc = convective exchange coefficient [W/m2 ºC].

In this work the calculation of TE\* adopted the proposed equations by Szokolay [10], according to which the new effective temperature is given by lines in the psychometric chart, crossing the curve of relative humidity of 50% for the given temperature [11]. These lines inclination equal to 0.023 • (TE\*-14), if TE\*<30, and 0.028 • (TE\*-14), if TE\*>30. Knowing the operative temperature and absolute humidity of a specific location, the new effective temperature was calculated through iterative process.

In this process, the New Effective Temperature is the mean temperature of all the hours from the previews thirty days. Assuming a tolerance range of ± 2.5°C to the outdoor neutral temperature, at least 90% of the users would be satisfied with the thermal environment conditions. Assuming a tolerance range of ± 3.5°C the satisfaction percentage drops down to 80%. In this research, the more restrictive range was applied, working with a satisfaction index superior to 90% of all users.

Three typologies for outdoor environments were studied configuring nine possible different environmental conditions, as shown in table 1 [11], in order to quantify the impact of different degrees of exposure to sun and wind in the overall thermal comfort in open spaces.


**Table 1.** Comparative results of the considered configurations

The key outdoor environments studied in this analysis were: the open central atrium of the convention centre, the patios of semi-enclosed gardens between the laboratories and the

terraces at the rooftop of the main office building, at 10 meters high, (see figures10 to 12) being these three areas for mid and long-term permanence, also being some of the major circulation routes between buildings1.

Environmental Design in Contemporary Brazilian Architecture:

The Research Centre of the National Petroleum Company, CENPES, in Rio de Janeiro 31

**Figure 12.** View of the terraces at the roof top of the Central Building, from the west to the east terrace.

Regarding the patios between the laboratories, considering total exposure to direct solar irradiation when the wind speed is lower, the predicted comfort conditions are identified only for 13% of the time. This percentage increases to 23% when 90% of incident solar irradiance is blocked by tree shading. On the other hand, when the wind speed is higher, the hours in thermal comfort raise to 67.5% of the time in the spots with direct solar irradiance, increasing to 98% of the time when the sun is blocked by the trees, as shown in tables 3 and

Considering the terraces at the rooftop of the main office building (the Central Building), the insulated sandwich metal roof, specified in the final design, provides a high percentage of time in comfort conditions (77%), against the metallic screen solution (64%), proposed in the

Month cold comfort hot January 0,0% 74,7% 25,3% February 0,0% 82,3% 17,7% March 0,0% 93,4% 6,6% April 0,0% 91,5% 8,5% May 0,0% 90,5% 9,5% June 0,0% 100,0% 0,0% July 0,0% 91,8% 8,2% August 0,0% 96,3% 3,7% September 0,0% 83,6% 16,4% October 0,0% 82,2% 17,8% November 0,0% 72,7% 27,3% December 0,0% 83,5% 16,5% Year 0,0% 86,9% 13,1%

**Table 2.** Thermal comfort at the open central area of the convention centre (shading)

4 (see figure 11).

**Figure 10.** View of the open atrium of the Convention Centre.

**Figure 11.** The gardens between the two laboratory wings. Images of the still "immature" landscape.

Technical studies proved that in the central atrium of the convention centre, when exposed to the sun, one will be in comfort condition approximately for half of the time. When shaded, this figure goes up to nearly 85% of the time, showing a major improvement of outdoors thermal comfort, as seen in table 2 (see figure 10). Aiming for even better results, more and wider apertures between the multiuse rooms, which connect the central atrium to the immediate surroundings of the building, would increase the air flow in the open centre.

<sup>1</sup> All the analytical assessments were done considering the period of occupancy set by Petrobras (from 7am to 6pm), during weekdays of the whole year.

circulation routes between buildings1.

**Figure 10.** View of the open atrium of the Convention Centre.

during weekdays of the whole year.

terraces at the rooftop of the main office building, at 10 meters high, (see figures10 to 12) being these three areas for mid and long-term permanence, also being some of the major

**Figure 11.** The gardens between the two laboratory wings. Images of the still "immature" landscape.

Technical studies proved that in the central atrium of the convention centre, when exposed to the sun, one will be in comfort condition approximately for half of the time. When shaded, this figure goes up to nearly 85% of the time, showing a major improvement of outdoors thermal comfort, as seen in table 2 (see figure 10). Aiming for even better results, more and wider apertures between the multiuse rooms, which connect the central atrium to the immediate surroundings of the building, would increase the air flow in the open centre.

1 All the analytical assessments were done considering the period of occupancy set by Petrobras (from 7am to 6pm),

**Figure 12.** View of the terraces at the roof top of the Central Building, from the west to the east terrace.

Regarding the patios between the laboratories, considering total exposure to direct solar irradiation when the wind speed is lower, the predicted comfort conditions are identified only for 13% of the time. This percentage increases to 23% when 90% of incident solar irradiance is blocked by tree shading. On the other hand, when the wind speed is higher, the hours in thermal comfort raise to 67.5% of the time in the spots with direct solar irradiance, increasing to 98% of the time when the sun is blocked by the trees, as shown in tables 3 and 4 (see figure 11).

Considering the terraces at the rooftop of the main office building (the Central Building), the insulated sandwich metal roof, specified in the final design, provides a high percentage of time in comfort conditions (77%), against the metallic screen solution (64%), proposed in the


**Table 2.** Thermal comfort at the open central area of the convention centre (shading)


Environmental Design in Contemporary Brazilian Architecture:

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metal screen with local shading devices are associated with feeling "cold" for 15% of the time, due to slightly high wind speeds, and feeling "hot" for 10%. In the case of the insulated sandwich metal roof, the total hours of discomfort are practically due to feeling "hot". Despite the fact that the sandwich metal roof provides less time in discomfort, it has a distribution curve of thermal conditions tending to a more extreme part of the "hot" zone, i. e. its values are closer to the limit of hot discomfort. On the other hand, the metal screen solution with shading devices presents values closer to better comfort situations, i.e. they are

Month cold comfort hot January 1,6% 71,9% 26,5% February 1,4% 66,8% 31,8% March 0,0% 78,9% 21,1% April 0,0% 77,3% 22,7% May 0,0% 67,1% 32,9% June 0,0% 85,0% 15,0% July 0,0% 65,8% 34,2% August 0,0% 76,4% 23,6% September 0,9% 89,1% 10,0% October 1,6% 79,4% 19,0% November 0,4% 84,3% 15,3% December 0,9% 83,1% 16,0% Year 0,6% 77,1% 22,3%

Month cold comfort hot January 7,1% 64,8% 28,1% February 9,5% 58,2% 32,3% March 9,9% 55,8% 34,3% April 10,0% 54,7% 35,3% May 10,0% 64,9% 25,1% June 12,3% 66,4% 21,3% July 5,6% 68,8% 25,6% August 7,4% 59,9% 32,7% September 17,7% 61,8% 20,5% October 19,0% 60,1% 20,9% November 14,5% 67,4% 18,1% December 10,4% 64,5% 25,1% Year 11,1% 62,3% 26,6%

**Table 6.** Thermal comfort at the rooftop area of the central building (metal screen)

located in the central part of the comfort zone.

**Table 5.** Thermal comfort at the rooftop area of the central building

(insulated sandwich metal roof)

**Table 3.** Thermal comfort at the open areas between the laboratories (low mean wind speed and shading)


**Table 4.** Thermal comfort at the open areas between the laboratories (high mean wind speed and shading)

conceptual stage, as shown in tables 5 and 6. However, it should be noticed that the thermal performance of the metal screen roof, coupled with local shading strategies (such as small trees, green wired structures, umbrellas, etc), results in a percentage of hours in comfort in the terraces which is verified to be very close to the predicted results for the case of the sandwich metal roof (75%), as seen in table 7 (see figure 12).

Interestingly enough, although the percentage of hours in comfort is fairly close in both cases (insulated sandwich metal roof versus screen roof), the conditions related to discomfort show a significantly different performance. The discomfort in the case of the metal screen with local shading devices are associated with feeling "cold" for 15% of the time, due to slightly high wind speeds, and feeling "hot" for 10%. In the case of the insulated sandwich metal roof, the total hours of discomfort are practically due to feeling "hot". Despite the fact that the sandwich metal roof provides less time in discomfort, it has a distribution curve of thermal conditions tending to a more extreme part of the "hot" zone, i. e. its values are closer to the limit of hot discomfort. On the other hand, the metal screen solution with shading devices presents values closer to better comfort situations, i.e. they are located in the central part of the comfort zone.


(insulated sandwich metal roof)

32 Energy Efficiency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities

shading)

shading)

January 0,0% 7,5% 92,5% February 0,0% 13,6% 86,4% March 0,0% 21,5% 78,5% April 0,0% 21,1% 78,9% May 0,0% 22,5% 77,5% June 0,0% 46,6% 53,4% July 0,0% 28,1% 71,9% August 0,0% 39,7% 60,3% September 0,0% 22,7% 77,3% October 0,0% 18,6% 81,4% November 0,0% 17,4% 82,6% December 0,0% 19,5% 80,5% Year 0,0% 23,2% 76,8% **Table 3.** Thermal comfort at the open areas between the laboratories (low mean wind speed and

Month cold comfort hot January 0,0% 100,0% 0,0% February 0,0% 100,0% 0,0% March 0,4% 99,6% 0,0% April 0,6% 99,4% 0,0% May 1,3% 98,7% 0,0% June 5,9% 94,1% 0,0% July 3,0% 97,0% 0,0% August 7,9% 92,1% 0,0% September 0,5% 99,5% 0,0% October 0,0% 100,0% 0,0% November 0,0% 100,0% 0,0% December 0,0% 100,0% 0,0% Year 1,8% 98,2% 0,0% **Table 4.** Thermal comfort at the open areas between the laboratories (high mean wind speed and

conceptual stage, as shown in tables 5 and 6. However, it should be noticed that the thermal performance of the metal screen roof, coupled with local shading strategies (such as small trees, green wired structures, umbrellas, etc), results in a percentage of hours in comfort in the terraces which is verified to be very close to the predicted results for the case of the

Interestingly enough, although the percentage of hours in comfort is fairly close in both cases (insulated sandwich metal roof versus screen roof), the conditions related to discomfort show a significantly different performance. The discomfort in the case of the

sandwich metal roof (75%), as seen in table 7 (see figure 12).

**Table 5.** Thermal comfort at the rooftop area of the central building


**Table 6.** Thermal comfort at the rooftop area of the central building (metal screen)


Environmental Design in Contemporary Brazilian Architecture:

The Research Centre of the National Petroleum Company, CENPES, in Rio de Janeiro 35

the rain led to the adoption of the sandwich metal roof (see figures 7 and 8). Technical assessment led to a final solution composed by metallic screen at the edges of the roof (shading the windows), sandwich metal panels in the main part of the roof, with strips of green glass along the roof surfaces and a central opening for air exhaustion placed along the

Besides the results about the thermal comfort conditions in open spaces of the three buildings at the core of the expansion of the Research Centre, the study of insolation and wind speed in such areas have also informed the landscape design as a whole. Regarding the creation of shadows, the areas less shaded by buildings (or permanently exposed to the sun) have received a higher protection by the landscape than those already shaded, in order to create favourable conditions to thermal comfort in open spaces between and around buildings, taking into consideration the routes of people as well as the adequate conditions

Furthermore, the location of the different *restingas* implanted in the open gardens between the laboratories, extending until sea shore of the site, was reviewed based on the diagnosis of air movement around the buildings. The *restinga* of sand, initially proposed for the southern garden, the most exposed to wind, was replanted to the northern garden, thus avoiding sand grains displacements to other open spaces. In the same token, the analysis of insolation and daylight availability in the terraces of the Central were important for the choice of species that would best adapt to the specific conditions of daylight and heat

The analytical studies of thermal comfort in open and semi-open spaces of the Research Centre verified the possibility of satisfactory comfort scenarios, especially due to the wellplanned design of shading and access to air movement in such areas, in the warm-humid

In response to the design brief, daylighting should be prioritized and maximized in all interior spaces where there is no functional restrictions, in order to provide visual comfort with energy efficiency [1]. Given the specific warm-humid climate of Rio de Janeiro and the major impact of solar irradiation on buildings thermal performance, coupled with the typical partially cloudy and bright local sky conditions, the major challenge of taking maximum benefit of daylight was related to the need for solar protection and avoidance of glare. For this purpose, the building form, together with roof's and facades' components were designed and sized with precision to shade the direct sun, whilst capturing and

redirecting daylight to the deeper parts of the interior spaces (see figures 13 and 14).

The design and assessment processes of daylighting focused on the three main building typologies of the research centre, where buildings' orientation and form had a significant impact on the daylighting performance: the linear north and south rows of laboratories, the

entire length of the roof, In order to improve daylight and ventilation on the terraces.

for short and long permanence.

tropical climate of Rio de Janeiro.

exposure.

**4. Daylighting** 

(metal screen with local shading)

**Table 7.** Thermal comfort at the rooftop area of the central building

Without barriers in the rooftop area, and since the wind speed at 10m is higher than at the ground, the wind speed in rooftop areas is more significant. Nevertheless, the cold discomfort periods caused by the wind could be reduced by adopting local wind breaks in the more affected areas of the rooftop. Moreover, given the hot-humid climatic conditions throughout the year in Rio de Janeiro, theoretical discomfort for "cold" can be challenged by real-life practice and be simply solved considering occupants adaption through clothing.

At first sight, comparing the insulated sandwich metal roof solution and the metal screen one, without other designing strategies, both present similar thermal comfort performance. But the metal screen solution has a higher potential to increase thermal comfort conditions, since local shading devices and wind brakes (if required) proved to increase comfort hours significantly. On the other hand, in the case of the insulated sandwich metal roof, in which almost all the situations of discomfort are hot ones, local solutions are not possible, since all solar irradiance is already blocked and it is difficult to induce, yet locally, an increment in the air speed.

Due to the possibilities of local solutions, the choice of metal screen provides a great diversity of environmental conditions, with different local figures of thermal radiation and air speed, which affect the thermal comfort sensation in open spaces. Providing environmental diversity, with areas of thermal sensation varying between slightly hotter to slightly colder, it is known that people can satisfy their comfort needs by choosing wherever they want to be, increasing even more the percentage of thermal comfort satisfaction. Nevertheless, in real practice, the possibility of creating a semi-open space protected from the rain led to the adoption of the sandwich metal roof (see figures 7 and 8). Technical assessment led to a final solution composed by metallic screen at the edges of the roof (shading the windows), sandwich metal panels in the main part of the roof, with strips of green glass along the roof surfaces and a central opening for air exhaustion placed along the entire length of the roof, In order to improve daylight and ventilation on the terraces.

Besides the results about the thermal comfort conditions in open spaces of the three buildings at the core of the expansion of the Research Centre, the study of insolation and wind speed in such areas have also informed the landscape design as a whole. Regarding the creation of shadows, the areas less shaded by buildings (or permanently exposed to the sun) have received a higher protection by the landscape than those already shaded, in order to create favourable conditions to thermal comfort in open spaces between and around buildings, taking into consideration the routes of people as well as the adequate conditions for short and long permanence.

Furthermore, the location of the different *restingas* implanted in the open gardens between the laboratories, extending until sea shore of the site, was reviewed based on the diagnosis of air movement around the buildings. The *restinga* of sand, initially proposed for the southern garden, the most exposed to wind, was replanted to the northern garden, thus avoiding sand grains displacements to other open spaces. In the same token, the analysis of insolation and daylight availability in the terraces of the Central were important for the choice of species that would best adapt to the specific conditions of daylight and heat exposure.

The analytical studies of thermal comfort in open and semi-open spaces of the Research Centre verified the possibility of satisfactory comfort scenarios, especially due to the wellplanned design of shading and access to air movement in such areas, in the warm-humid tropical climate of Rio de Janeiro.
