VERNACULAR PRINCIPALS AND CONTEMPORARY ASPIRATIONS: ANALYSIS OF MEDITERRANEAN CLIMATE RESIDENCES

Liz AZZI 1 Silvia PIARDI Dr. 2

Dip.INDACO, Polytechnic of Milan, Milan, Italy 1 liz.azzi@polimi.it, 2 silvia.piardi@polimi.it

Keywords: Mediterranean Europe residences, summer thermal comfort, passive cooling, free running buildings

Summary The research deals with summer thermal comfort in hot moderate climates; verifying criteria to adopt in the interior architecture project, responding to urgent demands on offering good summer comfort in a sustainable optic. Three contemporary residences were chosen from different geographic locations in southern Europe, in particular Mediterranean Europe. The case studies chosen were designed by famous European architects that designed in their local environment. The research tested the sensibility of their design to the climate and the performance of their buildings. The natural ventilation potential and the sun protection were the basic issues in summer: cooling passively and protecting the interior space from the sun and the heat. With the help of international standards and several simulation programs the performance of buildings was tested, presenting a critical point of view about their weaknesses and their strengths. After analyzing the performance of each case a part and comparing them between each others, some modifications were presented to the contemporary residence using traditional passive strategies that adapt to each specific case, so to know whether these principles really need to be followed or not in modern architecture. The study is based on the aesthetical and ethical quality of the interior space, exploring a field that has the extreme competences of an engineer and the design touch of an interior architect.

1. Introduction The region of Mediterranean Europe is the cradle of all big civilizations where the story of mankind has written all its exciting pages. It’s a geographic location that ranges from memory, environments, aiming to a wider and more complex vision that makes the Mediterranean a unique place. The Mediterranean climate is generally dry and temperate and the dominant problem is summer overheating, as a solution for this problem, guaranteeing passive cooling and acceptable thermal comfort is the main objective in this region. At this point we notice the recovery of bioclimatic architecture in the 1990’s. But there is still a big lack of knowledge until now on the behalf of architects of alternative solutions for saving energies in the interior space and providing a good comfort. There is still a gap between evaluating the quality of the space and improving the quality of its comfort. We may think of cars and factories as the most obvious enemies of the environment, but buildings consume more than half the energy used worldwide. With the strive to minimise energy consumption and associated harmful atmospheric emissions, designers strive to avoid the use of mechanical cooling by passive means. This involves minimising heat gains, well protecting the interiors from solar radiations, controlling the prevailing winds and discharging the heat that has accumulated within exposed fabric during the daytime by nocturnal ventilation. During this process it is important that designers have some basis for judging the quality of the summer thermal comfort of a naturally ventilated space, so that the passive design can be

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further be improved. This has recently become more pressing in temperate climates, especially in southern Europe, as climate data for building simulation reflects a trend towards warmer summertime weather.

2. Improving summer comfort to reduce the need of artificial cooling Modern air-conditioning systems are used globally to control the temperature, moisture content, circulation, and purity of air. We live in air conditioned homes, travel to our air conditioned work places in air conditioned cars, shop in air-conditioned stores and malls, and enjoy sports in air conditioned arenas. Unfortunately, these conveniences come at a great cost to the environment. And beyond the environmental implications, the human cost of over-conditioned spaces is well documented. In cases of Sick Building Syndrome, as it is commonly known, heavily air conditioned spaces can actually significantly reduce comfort and productivity. The research verifies if contemporary architects are sensitive to the occupants satisfaction and demands for a low impact building on the environment in free- running buildings. If the residences do not respond to the satisfaction of the occupants then some modification are proposed to improve the summer thermal comfort of the interior space taking into consideration passive methods, since strategies for naturally ventilating and illuminating buildings are becoming more widely accepted. The modifications presented revive forgotten traditional strategies for the interior space. We are living in an era where designers and architects are working on developing advanced techniques for providing natural air-conditioning in buildings in the hottest of climates.

2.1 Advantages The advantages of the adopted approach sensitize interior architects to the problematic, showing that it is not only a specialist job to verify the quality of the interior space and its thermal comfort, but interior architects could be sensitive as well. The research verified the usability of simulation programs normally used by engineers, physicist and building physics specialists to test the quality of the interior space. Architects could use these programs but with an understanding of the problematic, in order to be able to analyze the results of the simulations, or else it would just be some graphs and numbers without any meaning for designer, this research helps them understand in order to interpret. The results of the simulation define criteria and guidelines for the interior architecture project under the concept of good summer thermal comfort and a low impact on the environment, which is the future of planning and design.

3. Environmental quality and thermal comfort Thermal comfort is the most relevant comfort factor that is analyzed in this study; it is in direct contact with the climate, it is the response of the occupants to the local climate. It is the condition of mind which expresses satisfaction with the thermal environment. In order to analyze the performance of the building the local climate should be taken into consideration. We are unable to apply the same climatic results for all the examples, because each climatic data is different from the other. The occupants are expected to have positive sensations in the interior space; they should be able to feel comfortable, not too cold and not too hot, so the building should moderate the interior temperature according to the exterior temperature. Inspired by the work of Fanger, indoor thermal comfort standards were based on comfort zones that were defined. The ASHRAE 55 comfort envelope spans a temperature interval of ~2°C from 20% - 80% RH. A new generation of standards has prompt defining comfort envelopes for free running buildings based on indoor temperatures which vary as a function of different time periods of outdoor temperature. This standard describes the PMV and PPD indices and specifies acceptable conditions for thermal comfort. The PMV predicts the mean value of the votes of a large group of people on the ISO thermal sensation scale (+3=hot; +2=warm; +1=slightly warm; 0=neutral; −1=slightly cool; −2=cool; −3=cold). The PPD predicts the percentage of a large group of people likely to feel ‘too warm’ or ‘too cool’. This was defined as those voting +3, +2, −2, or −3 on the scale. The indices are exactly as described by Fanger. A draft rating index is provided in the standard as an equation involving air temperature, air velocity and turbulence intensity. It is applicable to mainly sedentary people wearing light clothing with a whole-body thermal sensation close to neutral. This includes optimum operative temperature; vertical air temperature gradient; mean air velocity; floor temperature; and relative humidity.

Guiding hypotheses The study is influenced by the desire to test and quantify the following hypotheses in relation to the climate, the performance of the building and the reaction of the occupants.

1. Test and verify the performance of the building in relation with the local climate 2. Verifying the usability of simulation software 3. Guidelines for interior architects

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4. Methodology Three non air-conditioned residences, each located in a different country in the Mediterranean region, were selected based on the desire to have reasonable diversity in terms of design concepts. For each domestic space a full description of each residence is presented, an analysis of the climate, and a simulation of each room was made to see the performance of the interior space in relation with the exterior temperature and the satisfaction of the occupants during the summer period. The simulation process was divided into 2 parts: 1- The climate and the performance of the building where the indoor temperature is in relation with the outside temperature. The climate simulation was performed with the help of several meteorological programs: Meteonorm, Clim pro and the Weather manager, where we were able to have the results of the outside temperature, the prevailing winds, the humidity, sun radiation during the summer period from the 1st of May till the 31st of August. 2- Once we have the climatic data we were able to insert them into the simulation programs to see the performance of the space and to predict the satisfaction of the occupants according to the results. The programs used were: Ecotect and Esp-r. The results shown below were taken from the Esp-r results.

4.1 Description A detailed investigation of each case study was presented in order to understand the context, the climate, the geographic location, the topography, the culture, the architect, the interior architecture, the type of furniture, the social context of the occupants.

4.1.1 Courtyard house, Matonsinhos – Portugal – Arch: Eduardo Souto de Moura, 1993/1999

The project was designed by Eduardo Souto de Moura, one of the disciples of the architects Siza and Tavora. His building is not a complacent answer to the topographic and morphological qualities that he encounters at a particular site but his interventions is a new formal field of force that rearranges the situation and imposes a new order upon it. The first case chosen was a courtyard house in the city of Matosinhos in the district of Porto in Portugal. Its climate shares many characteristics with the coastal south: temperate dry summers, and mild rainy winters. Summers are typically sunny with temperatures between 16°C and 27°C but can rise to as high as 40°C during occasional heat waves, which typically last between 5 and 10 days. During such heat waves, the humidity remains quite low. In contrast, occasional summer rainy periods usually last a few days and are characterized by frequent showers, wind, and cool temperatures around 22°C. The project is an introverted residence with heavy construction materials such as stone, it recalls the traditional Mediterranean architecture and in particular northern African courtyard houses with refreshing fountains in the middle.

4.1.2 Apartment, Sabadell – Spain - Arch: Rafael Moneo, 2001/ 2005

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Rafael Moneo is a Spanish architect who lives and works in Madrid, Spain. He was named the nineteenth Laureate of the Pritzker Architecture Prize in 1996. His architecture is a softened version of Nordic and Dutch traditions. The second case study is located in Sabadell, it’s 20km north-west of the city of Barcelona. Sabadell has a Mediterranean climate, with mild, dry winters and warm, humid summers. January and February are the coldest months, averaging temperatures of 10 °C. July and August are the hottest months, averaging temperatures of 25 °C. The case study chosen in Sabadell is a luxurious apartment in a residential building of six storey. The building is located in an urban context where its forms follow the axis of the plot; it’s surrounded on the four sides by streets. The northern façade is perforated by windows that do not follow the symmetry axis; meanwhile the southern façade is decorated by balconies with sliding wood protections. The apartment chosen has a double wall in the northern and eastern façade, with window openings in the north. Meanwhile on the southern façade we find a thin balcony with wooden moveable sun protections.

4.1.3 Apartment- Ancona, Italy, Arch: Cino Zucchi, 2000/ 2003

The architect, Cino Zucchi is one of Europe's most admired and innovative architects, he’s been nominated for numerous prizes, including the European Union Prize for Contemporary Architecture, and the Italian Architecture Gold Medal. He received the Piranesi Award for Architecture in 2001. The third case is localed in Ancona, a seaport city in the Marche, a region of central Italy. Ancona is situated on the Adriatic Sea and is the center of the province of Ancona and the capital of the region; it is the busy administrative capital of the Marche and the largest city in the region. The climate is mild with moderate winters with hot summer recording the hottest months in July and August and an average precipitation all year long. The case study chosen for the study is an apartment located in a residential building of three stories with an axis north south; it’s a brick construction with a double facade facing the exterior. On the eastern side symmetric bay windows of 1m x 2m decorate the elevation; meanwhile on the west we find a grid of balconies creating an effect of metallic bird cages, where each apartment has access to its own balcony.

5. Case study results

5.1 Temperature In order to evaluate thermal stimuli perceived by occupants, it is useful to compute precisely the number of hours for which they have been exposed to the different ranges of temperature. Such data allow clear quantification of thermal conditions inside a building. The cumulative graph was able to graphically represent in ordinate the proportion of time below a given temperature in abscise.

5.1.1 µ : Average temperature The average interior temperature µ in the traditional houses is in the limit of comfort between 23°C and 26ºC as well as in Ancona, meanwhile in Porto and Barcelona the temperature is under the comfort zone. The average exterior temperature in all of the locations of the case studies chosen is below 23ºC (the comfort temperature).

5.1.2 θ90: Temperature

The standard deviation is the most common measure of statistical dispersion, measuring how widely spread the values in a data set are. If the data points are close to the mean, then the standard deviation is small. Conversely, if many data points are far from the mean, then the standard deviation is large. If all the data values are equal, then the standard deviation is zero. So we can consider three as a good standard deviation for the interior temperature of a building. The Barcelona residence has the best result with 3.22, the building is well moderating the temperature, but we should not neglect the standard deviation of the exterior temperature as well, since we can only understand the performance of the building according to its own local climate.

Table 1. Summary of the temperatures

T.INT ºC

Average T.int µ

Standard deviation σ

5.2 PMV The best result for the satisfaction of the occupants according to the PMV goes to the apartment designed by Rafael Moneo in Barcelona. The case studies chosen do not represent all contemporary architecture in the Mediterranean region. We should not neglect the fact that not all contemporary domestic spaces have bad performances, but our study showed that there are still architect that are sensitive to the demands of the occupants of their buildings.

Table 4. PMV percentage

BARCELONA ANCONA PORTO

Discomfort Cold -3 0.0% 0.0% 0.0%

Cool -2 0.0% 0.3% 0.0%

Comfort zone Slightly cool -1 1.1% 1.2% 1.4%

Neutral 0 6.9% 5.2% 6.7%

Slightly warm 1 9.9% 9.8% 7.4%

Discomfort warm 2 1.4% 3.1% 3.0%

hot 3 0.0% 0.3% 0.4%

6. Modifications After the analysis of each case apart and the comparison with the rest of the cases, some rooms in each case had a very bad thermal performance and the occupants were dissatisfied. Some modifications were proposed for the rooms that weren’t well functioning in order to improve the quality of the thermal comfort according to traditional methods studied earlier in vernacular residences. The modifications proposed in the contemporary residences were inspired by passive and traditional principals; each modification was adapted to each case. The purpose was so to know whether these principals really need to be followed or not in modern architecture.

6.1 Courtyard house in Matosinhos, Porto, Portugal, arch: Eduardo Souto de Moura. After a first observation of the Souto de Moura’s courtyard house in Porto, we have the impression that it’s a good building with vernacular design elements that remind us traditional residences: heavy construction, introverted architecture, the interior courts, and the presence of water. But after simulating we notice that the house is not well functioning of the thermal point of view, the inside temperature is always hotter than the outside. The spaces that presented the worse performance were room 2 and room 3. The 2 rooms have a very high interior temperature; the only openings to the outside are the big bay windows facing south.

Figure 1. Bad performance of BR2 and BR3 Three modifications were proposed to improve the indoor thermal comfort

1. Protect from summer sun: Tree shading: Since we are not able to increase the dimension of the sun protection we could plant a tree in the courtyard in order to cool the air during summer, meanwhile during winter it would loose its leaves and the sun could penetrate to heat the interior. The shading from trees depends on the species, pruning and maturity of the plant. The transmission can be as low as 20% during summer and as high as 70% in the winter.

2. Evaporative cooling: Using fountains, pools and plants for evaporative cooling. The use of this courtyard is to prevent cooled air from blowing away, so creating a small fountain in the middle of the courtyard permits the evaporative cooling to function and refresh the surrounding rooms.

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3. Stack effect: Increasing the height of the roof of 1m creating the stack effect. It is also referred to as the "chimney effect", and it helps drive natural ventilation and infiltration. During the heating season, the warmer indoor air rises up through the building and escapes at the top through the ventilation openings. The rising warm air reduces the pressure in the base of the building, forcing cold air to infiltrate through the openings. During the cooling season, the stack effect is reversed, but is typically weaker due to lower temperature differences.

Figure 2. Solutions for improving the quality of room

6.2 Apartment in Sabadell, Barcelona, Spain, arch: Rafael Moneo. At a first glance the apartment does not show any particularity towards sensitive design to the environment. But the more we observe the more we discover: The northern and the eastern façades are protected by a heavy insulation; meanwhile the southern façade has a big bay window with an access to the balcony, with moveable wooden sun protections. These moveable shading devices respond better to the dynamic nature of weather than do static devices, since we need shade during the overheated periods and sun during the under heated periods, a shading device must be in phase with the thermal conditions. The spaces with the worse performances were the living (oriented south) and room 1 and 2, so the modifications should be in relation with these spaces.

Figure 3. Solutions for the bad performing rooms

1. Cross ventilation: Cross ventilation is effective because air flows from strong positive pressure to strong negative pressure areas located opposite walls. Since the prevailing winds are north and south and the openings are located towards the prevailing winds, we just have to adjust the openings facing each others; the ventilation on windows on adjacent walls is good or bad depending on the pressure distribution.

2. Space modification: The master bedroom’s dressing room place has been modified in order to make an access between the living and the night zone, permitting a cross ventilation between the two zones. Meanwhile a big closet on the entire eastern wall in the master bedroom has been placed in this way, the two zones benefit from a cross ventilation of the prevailing southern and northern winds.

6.3 Apartment in Ancona, Italy, arch: Cino Zucchi This case study is a standard apartment that has no particularity or any sensitive design towards the environment. The exterior walls have a double wall made of bricks, well insulated. Meanwhile the north western façade shows no sun protection, for this reason the living is the space that has the worse performance and the hottest temperature compared to the rest of the apartment. The hall and room 1 show bad performance as well. The modifications that should be made should take into consideration improving these three spaces in the apartment.

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1. Sun protection: The afternoon is the hottest period of the day during summer, since it stores the heat of all day and the living is the space that is basically occupied in the late afternoon. For this reason the occupants show a lot of discomfort in this space. Moveable sun protection is the best option for shading and protection from sun radiations, they could be wooden panels fixed on a rail and move horizontally, adjustable vertically as well and have different openings.

Another option could be deciduous plants most of which in phase with the thermal year because they gain and lose their leaves in response to temperature changes. Other advantages of deciduous plants include low cost, aesthetically pleasing quality, ability to reduce glare, visual privacy, and ability to cool the air by evaporation from the leaves.

Figure 4. Moveable sun protection

2. Cross ventilation: In order to create a cross ventilation, we should understand the direction of the prevailing winds and try to create openings in the same direction. In room 2 it is preferable to change the position of the door and put it in the same axis of the window. Eliminate the kitchen walls and the second bathroom in order to create an open space, allowing winds to circulate freely. The bathroom could be relocated in the hall facing the other bathroom. In that way the previous kitchen window that was divided in two would be one big window allowing better ventilation.

3. Increasing the openings in the prevailing winds direction: Since we have a prevailing wind blowing from the north and the living’s interior temperature is very high during summer, we could propose to create another opening in the northern wall of the façade, since we only have one small opening in that wall. The ventilation is possible in the asymmetric placement of windows because the relative pressure is greater at the center than at the sides of the windward wall.

Figure 5. Modification of the interior space, improving natural ventilation

7. Conclusion The software used for this study help the designers predict the thermacl conditions before the construction process and on a long distance: This means being able to proceed in the design process modifying the solutions to adapt best to the climatic process. A better knowledge of traditional practices united with the capacity of using simulation programs should be an important issue in the sustainable education of architects and designers.

References Fanger, P O 1970 : Thermal comfort : Danish Technical Press ISO 7730 Second Edition 1994, Moderate thermal environments determination of the PMV and the PPD indices and specification of the conditions for thermal comfort.

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