Design process of the environment low-impact demonstrative project: Interpretation Center Cañadón del Duraznillo, Argentine Patagonia

This paper presents the design process of the Cañadón del Duraznillo Interpretation Center, located in the San Jorge Gulf in the Argentine Patagonia. This project was commissioned as a result of the creation of the Cañadón del Duraznillo Nature Reserve on the Atlantic coast of the Province of Santa Cruz, Argentina with the aim of preserving the biodiversity of the sea-coastal environment associated with the Patagonian Steppe. The Interpretation Center program includes a multi-use space meant for exhibitions, conferences and film projections; an administrative office, a house for a park ranger and a room for guest researchers. From the first morphological sketches to the selection of materials and working details, this design process was guided by simulations and studies of the environmental conditions specific to this particular case, as well as by guidelines and general recommendations appropriate for this climate and geographical location gathered from previous design experience and specialized literature. The studies performed included simulations of direct sunlight, solar radiation, wind, natural daylight and thermal characteristics of the building skin. The aim of this paper is to present a specific case of energy efficient and environmental low-impact architecture and to examine the methodological productivity of architectural design assisted by bio-climatic studies in the lab.


Processo de desenho do projeto demonstrativo de baixo impacto ambiental: Centro de Interpretacion Cañadón del Duraznillo, Patagonia Argentina 1. Methodology: Research Through Design
The modality of Research Through Design (RTD) requires the incorporation of analytical and experimental stages simultaneous and complementary to the design process.Whereas all design process necessary entail a certain degree of 'research', in this case the analytical side acquires a special relevancy and must be systematically applied and recorded.This allows, among other things, that the resulting project can be to a large extent rationally explained.On the other hand, given that the final result of the research is primarily a design project -unlike in other forms of scientific research -the research methods applied are always mediated by the intrinsic characteristics of the design process, including a high level of subjectivity in matters such as esthetic preferences of the designers-researchers.
In the case of the project here introduced, the systematic-research side, which complemented the design process, was guided by a quest to explore the environmental conditions of the location and the possible architectural responses that could be adopted in order to achieve bioclimatic comfort, high levels of energy efficiency and minimize the impact on the site.With this purpose, the research began by analyzing the climate at the site, reviewing specialized bibliography (e.g. de Schiller et al., 2003;Givoni, 1992) and developing the main design strategies.Along with the development of the design project, several simulations were performed for each proposal assessed.The aim of these tests was to contribute with additional elements to assist the decision process inherent to the design practice.The studies included Wind, Solar Radiation, Natural Daylight and Thermal Characteristics of the Built Envelope simulations.The following section introduces the analysis of the climate along with the characteristics of the project and main ideas behind it.Bellow, a selection of the results of the studies and simulations is presented.

Climate
According to the Norm IRAM 11.603, the site location corresponds to the Bioclimatic Zone V meteorological station with complete records, located in Puerto Deseado (Latitude: 47º44´S -Longitude: 65º55´W -Altitude: 80m).
The medium temperature oscillates between approximately 15ºC in January and 3ºC in June and July.The maximum values are typically recorded in January, with 21.5ºC being the average maximum, and 34.6ºC the absolute maximum.The minimum values, in June and July, reach an average minimum of 0.6ºC and -10ºC of absolute minimum (Figure 1).
According to the recorded data, and following the 'Degree Day' (DD) indicator, the energy demand on site is fairly elevated: 2551 DD, with 7 months of cold days, cold nights during the whole year, 5 months in which the thermal amplitude is higher than 10ºC, and 5 months with daytime heat.
The relative humidity, with average values between 57% and 79% (Figure 2), in this case does not represent a variable that could significantly affect the bioclimatic comfort zone.The humidity levels registered do not require specific ventilation strategies.The rainfall is low, thus it is difficult to grow vegetation without artificial irrigation.This characteristic of the climate limits the range of resources available to achieve protection from the strong Patagonian winds.
Figure 1 Temperature Figure 2 Relative Humidity The predominant wind comes from the West, with an annual frequency of 33% and a variation between 28% in summer and 40% in winter.The annual average speed is 28 km/hour, with a variation of the average value between 30 km/hour in summer and 24 km/hour in winter.The secondary wind comes from the South West with an annual frequency of 27% (28% in winter and 26% in summer) and average speeds similar to those of the West wind.In total, the sum of the winds from West and South West comprise a 60% of the records (Figure 3).
http://www.fec.unicamp.br/~parcpesqui 35 Apart from the studies and simulations above mentioned, another determining factor that conditioned the design process and selection of the materiality of the project was related with the availability of economic and technical resources.One of the preliminary stipulations was the determination of using a construction system of preassembled panels that could reduce the works on site to approximately a week.This decision was not only based on economic reasonsgiven the remoteness of the place, the transport of workers and materials typical in traditional constructions becomes an important item in the budget in this casebut also it was based on the aim of minimizing the construction works on site, and thus reduce the waste produced, energy use and disturbance of the tranquility of the site.
The preassembled panel system adopted, with balloon frame structure and exterior waved tin cladding, was selected based on the supply availability provided by local firms.The selection of this system is also consistent with thermal insulation requirements and the construction http://www.fec.unicamp.br/~parcpesqui 36 tradition of the Patagonian Atlantic Coast.In order to provide the mass with thermal inertia necessary to store heat in indoor spaces, a stone wall -the only masonry work on siteand a gabion wall were strategically located in the building.The orientation of the plan, disposition of the program and design of the envelop, respond to the solar geometry with the aim of maximizing the hours of solar gain, achieve adequate levels of daylight according to the use of each space and minimize that thermal loss.The compact morphology of the building was adopted as an answer to the cold climate.The program was set so the main spaces would face the (southern hemisphere) northern sun and that the thermal losses in the southern façade were minimal (Figure 4).The conservatory space works as an independent access to the park ranger house and as a source of heat generation, which is transferred to the bedrooms and dining room through a stone wall with high thermal inertia.During summer months, the eaves of the roof provide solar protection to the glazed surface avoiding the effects of overheat (Figures 5 and 6).On the other hand, in summer warm days, the design of the openings allows the conservatory space to function wide open as a semi-covered chamber.
http://www.fec.unicamp.br/~parcpesqui 37 The form and technical characteristics of the project also respond to the local wind conditions, with the aim of ensuring that the accesses to the building are well sheltered and avoid cold air infiltrations.Thus, the entrances to the building, through chambers, confer protection to the strong winds from the west and southwest (Figure 7).The roof of the sanitary volume, with solar flat collectors on the top, has an angle similar to the latitude of the site, 47ºS, to reach the highest annual average solar radiation gain.Besides, the slope of the main roof achieves http://www.fec.unicamp.br/~parcpesqui 38 the highest height on the north elevation -the one most exposed to solar radiationand the lowest height on the southern side (Figure 8).

Wind
The main objective of the wind studies was to verify the design decisions taken in relation with the shelter of the access to the building and potential use of outdoor spaces.With this aim, simulations of speed variation and detection of still zones were performed in the Wind Tunnel.
The speed values were registered with a hot-wire anemometer in 8 points selected (Table 1 and Figure 9) for both predominant wind directions (W and SW).As a result of these studies and a theoretical analysis of the model, the 'wind shadows' were estimated (Evans andde Schiller, 1994 [1988], p. 94) and the diagrams drawn (Figures 10 and 11)  http://www.fec.unicamp.br/~parcpesqui 40

Solar Radiation
The solar radiation studies were performed with the aim of determining the thermal gain obtained during the cold months, and to verify the solar protection in the summer, especially in the conservatory space.Figure 12 presents the elevations exposed to solar radiation, with their respective glazed areas highlighted.The elevation with the highest proportion of glazed area is that of the North, with a 19.1%.This is the elevation that receives less direct solar radiation in summer and more in winter (Table 2).The West face is the one with less glazed area (1,71m2), so thermal gains in the afternoons are avoided during summertime.Although the East and West elevations receive the same amount of radiation, in the case of the East face it was possible to increase its proportion of glazed area, given that this side collaborates with the early warming up of the building, without being able of overheating the indoor air.
http://www.fec.unicamp.br/~parcpesqui 41  When outdoor temperature is low the conservatory captures more direct radiation, with a maximum performance in winter.The indirect solar radiation, diffuse and reflected, works inversely: it is higher in summer and lower in winter.For this reason, the lower openings in the conservatory, a sash window and a door, can be opened.During the days with maximum temperatures in summer the conservatory can function as a semi-covered ventilated space (Figure 14).The adopted model achieves a good daylight distribution; more than 90% of the plan receives a Daylight Factor higher than 2%.The Norm IRAM AADL 20.03 considers 'acceptable' the DF values higher than 2%, represented in Figure 15 within the spectrum of light green to red colors.

Thermal Characteristics of the Envelope
The control of heat loss is a fundamental design factor in cold climates, as it is the case of this site in the Atlantic Patagonia.The incorporation of good levels of thermal insulation allows a http://www.fec.unicamp.br/~parcpesqui 43 reduction of heat demand, avoids the risk of superficial condensation and provides comfortable thermal conditions for users.In order to reduce thermal loss from heated spaces is necessary to consider the following factors: To achieve a low thermal transmittance of walls, roofs and windows, in order to reduce the heat flow from indoor spaces to outdoor.
To reduce the total exterior area of the envelope through the adoption of a compact building form.
To locate the spaces with lower heat demand, such as the entrance hall and restrooms, as a buffer zone, protecting the heated spaces.
To control the ventilation rate, with double doors in the accesses, oriented to be sheltered from predominant winds.
With the aim of verifying the thermal insulation of the building, the levels of thermal transmittance of the design envelope were compared to those recommended by norms IRAM 11.605 for walls and roofs and IRAM 11.601 for windows.The parameters of the norms IRAM 11.900, with regard to the certification of energy efficiency, and IRAM 11.625 and 11.630 for superficial and interstitial condensation risk, were also examined.
The thermal transmittance of walls and roofs are Level B 'good', significantly lower to the minimum allowed for this category and closer to the Level A 'optimal' (Figure 16).The heat loss in the roof during winter is 29% higher than a roof Level A, but also 50% lower than a roof that achieves the minimum requirements of one Level B. Heat loss in walls is 18% http://www.fec.unicamp.br/~parcpesqui 44 higher than a wall Level A, but 56% lower than a wall labeled Level B with minimum requirements.
In order to assess the thermal behavior of the building, establish the conditions in which no heat is required and determine the overheating risk, a number of simulations of indoor temperature in winter, equinoxes and summer were performed for the bedroom and dining room spaces.The charts in Figure 17 indicate the time variation of outdoor and indoor temperature during a period of 24 hours.The simulations use meteorological data of temperature in a typical, or warmer than the average, day, with data of the medium intensity of solar radiation.
The results show that a stable indoor temperature is kept with limited variations, despite the light construction and the variable solar gains.The thermal insulation levels are enough to keep a temperature raise of 4ºC in summers, 8ºC in October and 5ºC in winter.This difference is the result of the variation of the incidence of solar rays, with a solar penetration more favorable in October-November and March-April.In winter, when the intensity of the sun is lower and sunny days are fewer, there is a reduction in the advantage that can be taken from this renewable energy for heat.

Conclusions
The building form effectively protects the accesses from the predominant winds, especially those of the west, and does not provoke wind accelerations in any of the points studied in the

Figure 3
Figure 3 Predominant wind direction and speed

Figure 4
Figure 4 Orientation, morphology and disposition of the program according to the solar geometry

Figure 5
Figure 5 Solar gain an protection in the conservatory space

Figure 7 Figure 8
Figure 7 Access to the building and predominant winds

Figure 9
Figure 9 Location of the measured points

Figure 12
Figure 12 East, West and North elevations with their glazed surfaces highlighted

Figure 13
Figure13presents the Total Incoming Radiation values on the elevations examined.The North façade is the one that performs best from a thermal point of view.The levels of direct solar radiation penetration during winter are 3 times higher than those during summer.Direct solar gain will collaborate with the thermal conditioning of the building, decreasing the energy demand.The East elevation will help warming up the building catching the first solar rays of the day.The West façade, for only having 1.7m2 of windows, does not constitute a potential problem in summer.The disposition of windows and the eaves of the roof allow a similar amount of solar radiation penetration throughout the year.The cold climate of the site requires solar protection only during summer.The openings were design to provide shade and reduce the penetration of solar radiation only for this season.The practicable windows allow the access of breeze that could refresh the indoor spaces, especially in the exhibition space, were the opening facing East, North and West allow a fine circulation of air.

Figure 13
Figure 13 Total radiation gain by elevation Figure 14 through the conservatory space

Figure 16
Figure 16 Comparison of the thermal transmittance values included in Norm IRAM 11.605, levels A, B and C, and thermal transmittance according to the design in the roof (left) and walls (right)

Figure 17
Figure17Indoor and outdoor temperature simulations in a day in January (left), October (center) and July (right)

Table 1
Points studied and speeds recorded for W and SW orientations at the Wind Tunnel http://www.fec.unicamp.br/~parcpesqui 39

Table 2
Direct solar radiation according to orientations and seasons