Measuring up to the criteria of sustainable construction The Holcim Costa Rica head office building in San José is a bold departure from the norm, and the site design has ecological merit far beyond that of most office building sites. Office building in Costa Rica Measuring up to the criteria of sustainable construction Office building in Costa Rica Awareness of sustainable construction Five target issues for sustainable construction Quantum change and transferability Ethical standards and social equity Ecological quality and energy conservation Economic performance and compatibility Contextual and aesthetic impact Universal principles of sustainable construction Technical report Program and objectives Site Architectural design Building statistics Performance Illuminance, temperature, humidity, air speed Optimizing the indoor climate Conclusions Holcim Foundation for Sustainable Construction Credits and addresses 2 6 8 12 16 22 26 31 33 34 35 39 41 42 44 49 52 54 Awareness of sustainable construction Most of us are familiar with the concept of sustainable development, or balanced social, economic and environmental progress. But what By Hans-Rudolf Schalcher, Head of the Technical is sustainable construction? Essentially, it is that part of sustainable Competence Center and member of the Management development which has to do with building. The construction industry Board of the Holcim Foundation is one of the world’s largest consumers of energy and materials, so it offers great potential for improving sustainability performance. The Holcim Foundation for Sustainable Construction was set up to help realize this potential, and is doing so in several ways. To achieve the greatest effect, we must all be aware of sustainable construction – exactly what it is and why it is important. That’s why we have created this publication. It explains the Holcim Foundation’s five target issues for sustainable construction and illustrates each point with the example of the head office building of Holcim Costa Rica. We didn’t pick this building because it’s a Holcim building – we picked it because it’s a recognized example of sustainable construction. The Mexican Society of Architects named this building one of the outstanding projects of 2005 and published it in their Ninth Report on Architecture in Mexico and Latin America1. It has been featured in many international publications, such as RE, and was published by the Spanish National Centre for Renewable Energy (CENER). In February 2005, 1 Novena Reseña the Spanish version of GEO magazine 2 singled out five pioneering de Arquitectura sustainable buildings on the planet and the Holcim Costa Rica office México, Latinoamérica. México D.F.: Enlace building was one of them. Arquitectura y Diseño. 2 GEO Especial. 2005. The building is significant because it is a prime example of sustainable Cinco ideas para construction and also has great visual impact. It has the power to draw construir un mundo más limpio y habitable. attention to sustainable construction. GEO Especial. No. 217. February 2005. 2 3 Holcim office building in San José, Costa Rica Measuring up to the criteria of sustainable construction By Bruno Stagno, President of Bruno Stagno Arquitecto y Asociados 4 5 Five target issues for sustainable construction Sustainable development and sustainable construction are complex subjects that are intertwined with other complex issues. To make sustainable construction easier to understand, evaluate, and apply, the Quantum change and transferability Holcim Foundation developed a five-point definition. These five so-called Ethical standards and social equity target issues serve as yardsticks to measure the degree to which a building Ecological quality and energy conservation contributes to sustainable development. Economic performance and compatibility Contextual and aesthetic impact Three of the target issues for sustainable construction are the same as the three goals of sustainable development: balanced environmental, social, and economic performance. One applies specifically to building: the creation and improvement of good buildings, neighborhoods, towns, and cities. And one recognizes the global urgency of sustainable construction: the need for significant advancements that can be applied on a broad scale. This publication explains these five target issues in detail and shows how each criteria is met by the Holcim Costa Rica office building. 6 7 Quantum change and transferability Shading is a simple and direct way to keep indoor climates cooler, Outstanding examples of sustainable construction should not only mark significant advancement, the innovative idea should be one that can be and it can be applied copied again and again, thus promising the greatest benefit at a global anywhere. The Holcim scale. Transferable ideas are those that are affordable, simple, and broadly Cost Rica office building has at least seven applicable. types of shading systems that reduce thermal gain through the roof and facades. 8 9 Target issue for sustainable construction The significant achievement of the Although some aspects of the Holcim Costa Rica office building design apply specifically to the of sustainable construction, a quantum leap in comparison venting thermal gain is the way it at once answers the hot tropical climate, many essential to conventional procedures. Breakthroughs and makes much more full range of concerns. It uses many aspects can be advantageously trend-setting approaches, irrespective of scale, must be and then counteracting (efficient) passive design mechanisms and easily transferred around the transferable to a range of other applications. it with expensive, ener- instead of (wasteful) conventional world. The concepts employed cal air-conditioning systems, it was built at a relatively are affordable, easy to understand, systems. modest cost (USD 658/m 2), it is and practical to realize. In hot climates, pre- sense than allowing it gy-intensive mechani- a visually intriguing piece of architecture with symbolic power, it serves its purpose fully by providing attractive and functional spaces, it develops the environmental awareness of the occupants Quantum change and transferability Contributions to the disciplines of architecture, urban and landscape design, civil, urban and environmental engineering and other related fields pertaining to construction. Innovative concepts regarding design, integration of materials and products, structure, enclosure and building services. The project must demonstrate innovation at the forefront Outstanding approaches regarding construction technology and processes, operation and maintenance. Long-term monitoring to evaluate the fulfillment of the initial expectations and goals. (passive building – active people), the landscaping enriches the local ecosystem, and the design meets the client’s wish to incorporate a significant amount of cementitious materials. Considered individually, these are not amazing design feats, but considered together, the way the building looks and works is a radical departure from the norm. 10 11 Dissemination of knowledge (project documentation and communication, education and training). Ethical standards and social equity A bright, well designed building is a pleasure to work in every day. Especially in poor countries, sustainable construction means building to supply urgent and basic needs: shelter, water, schools, access to goods and services, And a true piece and medical care. In other countries, affordable housing is a main issue. In still of architecture is an others, the problem is wasteful and excessive consumption, which might be inspiration. financially affordable but is irresponsible. Leaving sufficient materials and resources for others, including future generations, is a moral duty. Sustainable construction means cities and buildings that respond to the emotional and psychological needs of people by providing stimulating environments, raising awareness of important values, inspiring the human spirit, and bonding societies, communities, and neighborhoods. Many sustainable construction projects are developed by teams using a collective approach through which stakeholders and users are included in the design process. Sustainable construction involves the highly-principled treatment of people during the design, construction, use, and recycling of buildings. 12 13 Like most of us, the employees of at work, the building offers the Holcim Costa Rica were used to employees a comfortable, attractive, working in standard air-conditioned and inspiring working environment buildings. Considering the climate that includes a variety of amenities in Costa Rica, one can well imagine such as a gym, cafeteria, many that some employees had reserva- toilets with showers, and beautiful tions when they heard they would places for relaxation. The design be getting a new non-air-condi- encourages social interaction – tioned building. The company held employees can often be seen meetings with the employees sitting and chatting in their free and support social equity at all stages of construction, they were getting a to discuss the design of their time or enjoying the breeze and from planning and building processes to long-term impact special office building, workplace and to explain that the shade on the decks. on the communal fabric. The project is to provide an The employees knew but still they were surprised to see how sustainable construction is a the sensitive design part of Holcim’s commitment to The building provides a stimulating sustainable development. environment in which to work, began to change the way they acted and Ethical standards and social equity The project must adhere to the highest ethical standards advanced response vis-à-vis ethical and social responsibility. inviting the occupants to participate thought. Target issue for sustainable construction The owner and the architect visually, mentally, and physically. followed strict ethical principles It transforms values, changes the and used transparent practices way people think and act, and during the design, bidding raises awareness that we can and (tendering), and construction should take care of the environment. phases of the project. All contractors This eye-catching building were required to meet high dramatically symbolizes Holcim standards of social responsibility, Costa Rica’s care for its employees especially concerning worker safety and the environment. It gives a and environmental protection. bold identity to the company and About 150 people were involved to its commitment to social in the construction work, and not responsibility. This example has a single accident was reported encouraged other companies to among the workers or engineers. adopt the same principles. Adherence to ethical standards in all phases of the project's life cycle. Contributions to the formation of socially viable environments and the values of communities. Participation of stakeholders (client, users, neighborhood, local authorities, non-governmental organizations and others). Quality of working conditions in the suppliers' workshop, on site and during operation (compensation, safety, basic needs, gender issues). Once the building was erected, the company held training sessions to teach employees how to adjust the systems in response to changing climatic conditions. Supporting the employer’s objective of happiness 14 15 Political transparency and correctness. Ecological quality and energy conservation Modern architecture can blend magnificently with nature. A fundamental principle of sustainable development is to keep our planet in condition to indefinitely support future generations. This is an enormous If we are to build challenge because our global ecosystem is in a state of stress and overuse. sustainably, it must. Finite sources of energy and materials are being depleted, and much of our environment is being polluted or spoiled. The construction industry plays a great role here as a large consumer of materials and energy. At the building scale, sustainable construction aims to provide longlasting, healthful, and useful buildings while conserving finite resources of materials and energy by using durable, recyclable, and renewable materials, through energy-efficient design, and by using environmentally neutral energy sources (wind, sun, geothermal, etc.) and mechanisms (shading, simple evaporation cooling, etc.). At the urban and regional scales, sustainable construction involves planning that preserves environmental quality, conserves energy through efficient design, reduces waste and consumption through sensible design, and reduces pollution by establishing efficient transportation networks. At all scales, sustainable construction aims to support ecosystems through design with nature (establishing and improving habitats for wildlife, supporting biodiversity, replenishing groundwater instead of channelling rainwater into storm sewers, etc.). 16 17 The building design The design concept of the Holcim energy resources we consume. This Costa Rica office building can be design principle can significantly takes advantage of summed up as “passive building, contribute to sustainability. In this many renewable active people.” Departing from building only the auditorium has available on the site conventional building practice, mechanical air conditioning; the including sunlight, the idea is that the occupants rest of the building is naturally air should actively control their indoor conditioned by cross ventilation, environment by operating the which works because of the breeze passive building systems. They and the courtyard garden. resources and assets shade, vegetation, sea breeze, and water. should develop an awareness of heat transmission and airflow, and The courtyard garden, designed they should operate the windows, as a jardín de climatización, is vents, and shading devices to situated to catch the prevailing maintain comfortable temperatures wind. The air circulates, keeping and humidity. In conventional the courtyard fresh and humidified. buildings, with automatically con- In the dry season, jets in the trolled mechanical air conditioning garden spray mist for ten seconds systems, people are passive. every ten minutes to moisten the climbing plants that cover the Renewable or unlimited resources rocks, and these in turn humidify in the tropics where the Holcim the air. Umbrella-shaped almond Costa Rica office building is situated trees shade the courtyard to retain include sunlight, shade, vegetation, the moisture. The pergolas that wind, and a breeze from the Pacific screen the western sun and coast 55 kilometers to the west. carefully placed trees provide The more we use these and other shade and cool the area around simple, natural, and efficient the building, improving the air mechanisms to achieve indoor quality, enhancing the appearance, comfort, the less non-renewable and filtering dust. These plant 18 19 Target issue for sustainable construction materials are growing and their the limited and energy-intensive Ecological quality and energy The project must exhibit a sensible use and management beneficial effects will improve communal drinking water. conservation of natural resources throughout its life cycle, including over time. High-quality modern building materials operation and maintenance. Long-term environmental The landscape design incorporates concerns, whether pertaining to flows of material or The use of durable and low-main- several ecological principles to energy, should be an integral part of the built entity. tenance materials is another benefit the environment. Many hallmark of sustainable construction. existing trees were conserved, The Holcim Costa Rica office and many native species of new building uses concrete, stone, glass, trees were planted to better and concrete are wood for the floors and window support wildlife. The landscape energy-intensive to blinds, and fiber-cement panels for design includes 174 tree species durable, making the siding. The materials are not and 1,100 new coffee bushes. The ecological sense in painted; the surfaces are left to age coffee and fruit trees were planted naturally and develop the beautiful for use by the company. The number patina of durable natural materials. and diversity of animals thriving on such as metal, glass, produce but highly the long term. Energy and material efficiency in construction, operation and maintenance. High ratio of renewable energy to fossil energy in construction, operation and maintenance. Land use efficiency. Low environmental impacts over the project's life cycle. the site have increased – especially Expansive glass walls make artificial indigenous birds, insects, and other lighting unnecessary during the small animals. This has improved day. The ceilings are painted white the quality of life for all species, to reflect the light. Louvers diffuse including humans, who enjoy this the light and control solar gain. pleasant setting. Rainwater is collected in a tank. Earth movement during construction This water is used for the fountains was limited, and all materials and channels at the entrance, the were reused (even rocks that had courtyard humidification system, been excavated when the factory and plants. This ‘free’ water source was built several years earlier not only saves money, it conserves were used in the courtyard garden). 20 21 Robust products and technologies. Economic performance and compatibility The investment in shading will pay off every day throughout Through efficiency of design, construction, maintenance, operation, reuse, and recycling, sustainable construction seeks feasible projects that provide the life of the building long-term economic benefits for owners, users, and communities. Such by greatly reducing benefits can take many forms besides profits or lower costs, for example: the cost of air conditioning. strengthening the economic base of a region, boosting the local economy, giving residents more control over their housing costs, or even giving people a financial base. Innovative deployment of financial resources, durability, adaptability, lifecycle cost planning, ‘free’ low-tech natural resources, and other attributes can work together to make sustainable construction not only financially feasible but the preferred choice and a sound long-term investment in the future. 22 23 Target issue for sustainable construction The construction cost of the construction is conventional: Economic performance and The project must prove to be economically feasible and Holcim Costa Rica office building no technological miracles, compatibility innovative as to the deployment of financial resources. weather-resistant came in at just under USD 2.6 million no sophisticated materials, no Funding must promote an economy of means and be materials keeps main- (a relatively modest cost of USD spectacular architectonic feats. compatible with the demands and constraints encountered The use of durable tenance costs low. 658/m ), slightly over the original 2 throughout the construction’s life span. budget, but in line with the changes By making efficient use of free that arose during the project. This energy sources (wind, daylight), figure does not includes the site and simple low-tech mechanisms work and landscaping, access (shading, humidification with roads, parking area, and the cost rainwater), the building is of furnishings. economical to operate, requiring Innovative models for financing. Financial resources over the project's life cycle and their regional impact. Flexibility with regard to future changes (user, ownership, laws and regulations). Robustness to economic conditions (interest rates, taxes, inflation). much less electricity than a The building was designed to comparable conventional building incorporate Holcim products for with mechanical air conditioning two reasons: to save costs and and artificial lighting. The to express the identity of the rainwater collection system also company. Holcim products used saves money. And by using durable include prefabricated foundations, weather-resistant materials, columns, beams and floors, maintenance costs are kept low. standard and special posts, cement and concrete, and various aggregates. Through its comfortable and unique working environment, the The design and the construction building promotes a high level methods and processes were of productivity of employees, adapted to the capabilities of local sustainably enhancing the construction contractors and the economic performance of both the construction industry in Costa Rica. company and the employees. Except for the tensile structures and the wind diapason, the 24 25 Economy of resources deployed in construction. Contextual and aesthetic impact The building is a pleasure for the eye from many angles. Design quality is the aspect that clearly distinguishes sustainable construction from other forms of sustainable development. Visual expression and fitness of form are two essential qualities of all good architecture and planning, and these are also central to sustainable construction. This applies at all scales: land use planning, urban planning, and architectural design. Land use planning should preserve natural areas and the inherent qualities of the landscape. Besides providing an efficient and functional infrastructure, urban planning should create spaces and places of cultural significance and social value. Urban redevelopment projects and large public projects should heal and upgrade neighborhoods and city quarters. And architectural projects should not only meet the owner’s requirements (program), but match the physical context (site and neighborhood) and improve the local surroundings. 26 27 Target issue for sustainable construction The Holcim Costa Rica office elements they boldly proclaim building perfectly suits its tropical the passive energy concept of the quality as to the manner in which it addresses its cultural elements, the contrast context, expresses corporate building and in concert they make and physical context. With space and form of utmost of light tensile fabrics responsibility and the products of the building a pleasure to look at. significance, the construction must have a lasting aesthetic The rhythm of the and massive concrete pillars, the interplay Holcim, offers durable, functional, of sky and shade – pleasant, flexible spaces, fits The architecture is at one with the sculpture, but it’s all into its industrial setting while landscape design. Trees and plants there to create a good improving the site as a natural are not just ornamental, but part habitat, and is visually attractive of the overall design, planted for from many perspectives. shade and treating the indoor air. one could think it’s working environment. Contextual and aesthetic impact The project must convey a high standard of architectural impact on its surrounding environment. The courtyard is an integral part The solid concrete building masses of the building’s climate control are interspersed with light shafts system, and the indoor climate that regulate solar radiation, complies with ISO comfort reduce the thermal mass of a standards. The building proclaims building, and provide cross that we must recapture a balanced ventilation. The tensile structures relationship between architecture shade the roofs and windows and nature. Improvement of existing contextual conditions responding to the natural and human-made contexts. Interdependencies of landscape, infrastructure, urban fabric and architecture. Cautious restoration and alteration of the built environment. Programming strategies (use, flexibility, multiplicity of functions, change). Architectural quality and its aesthetic impact (space, form, light, ambiance). and contrast beautifully with the heavy concrete masses below. Fiber-cement exterior louvers shade windows at critical times of day. Wooden interior blinds are adjustable to control and direct ventilation. Horizontal parasols shade the upper floor windows all year round. All these architectural elements not only contribute to indoor comfort – as visual 28 29 Universal principles of sustainable construction Of course the Holcim Costa Rica office building is just one example of sustainable construction. Other examples can be found around the world, and each is unique – a product of its creator, function, climate, budget, site, local materials, local culture, and other factors. Although the specifics may differ, the principles of sustainable construction apply universally, regardless of climate, culture, or economic situation. The idea is to achieve lasting environmental, social, and economic benefits through the construction of well designed buildings and cities. Applying this idea once can make an remarkable building; applying it worldwide would be a giant step toward global sustainability. 30 Bruno Stagno, architect of the Holcim Costa Rica office building 31 Holcim office building in San José, Costa Rica Technical report The owner’s list of requirements for the Holcim Costa Rica office building included the program (list of rooms and floor areas to be provided), the wish for an environmentally and socially responsible design, and the request to include Holcim products in the construction. The owner, Holcim (Costa Rica) S.A., is a company that produces cement, aggregates, concrete, and prefabricated concrete elements for buildings. A modest but adequate construction budget was set for the project. By Marco V. Gutierrez, Ph. D. 32 33 Site Architectural design The site is in San Antonio de Belén, Alajuela province, in the western part The office building, designed in 2003 and built in 2004, is conceived to of the central valley of Costa Rica. The parcel of land is in an industrial provide a comfortable indoor environment using passive means instead of park at 10°N, 84°E, on a hill with superb views and considerable wind mechanical means such as air conditioning. The floor area of 3,896 m 2 is exposure, at an elevation of 800 meters. The local climate is hot, tropical, divided among four two-story wings, strategically situated around a climate- and strongly seasonal with a well-defined dry season. Temperatures are regulating courtyard (jardin de climatización). The building allows much high year-round; the average temperature on the site is 22°C. Humidity light and air to enter and incorporates shading devices to control glare fluctuates strongly; average humidity is 78%. Illuminance is high year- and limit heat gain. The landscaping includes 174 trees, 1,100 coffee round. Strong trade winds from the northeast (~ 20 km/h with gusts up plants, and bushes of various size and species that augments the sparse to 74 km/h) blow across the site from mid-December to March. Lighter vegetation originally on the site. Most of these species are endemic, selected southwest winds (~ 10 km/h) blow from September to December. Average to attract and support local fauna. Plants are also part of the indoor annual rainfall is 1.9 m; most rain falls from mid-May to mid-December. design, moderating the indoor climate, adding shade where needed, and Costa Rica is not in a normal hurricane path, but hurricanes in the region filtering dust. Of the four wings, the entrance wing is exposed to the do produce heavy rainfall that can be damaging. greatest winds. It is partially shielded by a perforated wall of polished concrete, the so-called wind diapason. Location San Antonio de Belén, San José, Holcim materials were used for the concrete masts, the wind diapason Costa Rica (with special aggregates, mix, and finish), the concrete walls (with a special smooth texture), the polished, random-cut concrete floors, and Climate Tropical the large boulders in the central courtyard garden. Terrain Flat hilltop During the design phase the indoor climate of the north and south wings Site size 24,384 m (192m x 127m) (those with the most occupants) was studied using a simulation program 2 called ‘Comfort.’ The climate data used was obtained from the nearest meteorological station, located 8 kilometers north of the site. The studies Setting Suburban industrial park Number of parking spaces 117 provided information that was used to optimize the construction without changing the architectural design. The biggest improvement gained thereby was the reduction of thermal gain through the roof. To optimize the insulating performance of the roof, an assembly of ventilation, insulation, 34 35 and shading layers was designed. Tensile structures shade the roof and the facades. Massive concrete walls insulate the east and west facades of the two wings. Without further scientific support, but based on the empirical knowledge of the geography and local climate, the drawings were finished and construction carried out. Once the building was completed and occupied, it was necessary to reduce glare in certain rooms. This was done by tinting the glass. In some densely occupied rooms ceiling fans were installed to improve comfort. The central courtyard was landscaped using boulders that were left from the construction of the client’s nearby industrial plant. F A E B D C The Holcim Costa Rica A North wing office building is B Entrance wing approached from the C South wing east, across a plaza D Administration wing with an array of E Jardin de climatizatión climatic fountains and F Fountains and channels channels. The building comprises four wings surrounding the jardin de climatización. 36 37 Building statistics The courtyard was planted with grass, ivy, and beach almond trees Year of construction 2004 Building type Office Building volume 15,214 m3 in four wings Maximum number of occupants 162 Gross usable floor area 3,896 m2 Number of finished floors 2 Number of basements – Construction system Reinforced concrete slabs, walls (T. catappa), which have a broad canopy, providing shade to reduce moisture loss. The microclimate of the courtyard can be further humidified and cooled with a misting system, which is activated every ten minutes for ten seconds, from 6 am to 6 pm on working days during the dry season. Plants are watered every morning and evening. Response to the environment – especially solar radiation in the tropical climate of Costa Rica – was a prime consideration during the desing phase. and post-and-beam frame; extensive shading systems for roof and facades Construction cost (building only) USD 2,564,800 or USD 658/m2 gross floor area Construction cost of typical USD 580/m2 gross floor area* office buildings in Costa Rica Annual operating cost USD 9.24/m2 (cooling, lighting, mech. systems, etc.) Annual operating cost of typical USD 27.60/m2* * Source: Claudio Soto/National office buildings in Costa Rica Company of Power and Electricity (CNFL) 38 39 Performance The performance of bioclimatic buildings (those designed in harmony with nature) must be assessed. Is the design effective? Is the indoor climate as planned? Does it meet ISO comfort standards? To answer these questions, the indoor environment of the Holcim Costa Rica office building was measured during the rainy season of 2004 (August 30 to September 15) and the early dry windy season of 2005 (February 1 to March 15). Most measurements were taken on the second floor, where most of the daily activity occurs from 8 am to 7 pm. 40 41 Measuring illuminance, temperature, humidity, and air speed Illuminance was measured in lumens per m 2 using a Hobos system (model Air movement inside the building and wind speed outside the building H08-004-02) set up in the southern wing. One sensor monitored average were measured during times of maximum winds (October 2004 and light conditions in the building and a second sensor was directed toward February 2005). Two pairs of anemometers (MetOne, model 014A) were set the north-facing windows to read during the late afternoon and sunset up, one on the upper floor of the administration wing (west wing), and the hours, times when illuminance could become excessive. other on the ground floor at the east end of the building. In each case, one anemometer was positioned inside and the other outside the building. Air temperature and relative humidity were monitored at six locations in The data was recorded by a data logger (Campbell Scientific model CR10X) the building using the same Hobos system. In the north wing, sensors programmed to record average and maximum wind speeds at ten-minute were positioned in the middle of the room and inside an office. In the intervals during 24-hour cycles. south wing, two sensors were placed in the middle of the hall and one in the stairway between the ground floor and upper floor. Another sensor was positioned in a shaded corridor on the southern side of the courtyard. All sensors were programmed to record average values at ten-minute intervals during 24-hour cycles. Readings taken in the stairway were not used in calculations of average values for the building. Several shading devi- Shading and ventila- ces protect the north tion instead of mecha- wing against the low nical air conditioning late-afternoon sun, provide a comfortable including three metal indoor climate. Three trellises (right) that shading mechanisms will soon be covered are visible here: a with vines. fabric canopy, vertical sun-blocks, and horizontal louvers. 42 43 Optimizing the indoor climate Illuminance inside the building was measured to be within the comfort near 24°C to 25°C during both seasons. Compared with mean and maximum range, typically below 1,500 lumens per m (Figures 1A, 2A). In offices and temperatures observed outdoors (22°C and 28.5°C, respectively), the building halls with north- or south-facing windows illuminance was found to be provided a comfortable climate, with indoor temperatures close to the excessive all day, and especially during early morning and late afternoon. average recorded outdoors, but with far lower maximum temperatures. The To correct this problem additional louvers and screens were installed. stairway between the ground floor and upper floor is an exceptional situation. Temperatures measured at five locations in the building show the diurnal This volume is wrapped in glass, which creates a greenhouse effect through- pattern typical of tropical climates, with strong diurnal fluctuations out the day. Temperatures here reached almost 32°C, uncomfortably hot. (10°C or more), but stable average conditions throughout the year (Figures The temperature here is expected to drop substantially once the shading 1B, 2B). Minimum daily temperatures were typically observed at pre-dawn plants and trees grow. Mean and maximum air temperatures predicted hours (5 am to 6 am), and varied from 18°C to 20°C during both rainy and using the Comfort model were 24.9°C and 24.4°C during the dry season dry seasons. Maximum daily temperatures were observed during the early and 26.6°C and 25.9°C during the rainy season, respectively. In comparison afternoon (12 noon to 2 pm) and varied from 26°C to 28°C during both with actual values measured in the building, the model underestimated seasons. Average temperatures during working hours (8 am to 7 pm) were maximum air temperature during the rainy season (see table page 47). Rainy season Rainy season 2 Figure 1: Diurnal patterns (in days) of illuminance, air temperature and relative humidity inside the Holcim building during rainy and dry seasons • Illuminance (lum m-2) x 10-2 • Temperature (°C) • Humidity (%) • Days Dry season A 100 80 60 40 20 0 B 32 28 24 20 16 C A A 100 80 60 40 20 0 B 32 28 24 20 16 C B C 80 100 60 80 40 60 20 Figure 2: A Diurnal patterns (in hours) of illuminance, air temperature and relative humidity inside the Holcim building during rainy and dry seasons. • Illuminance B (lum m-2) x 10-2 • Temperature (°C) • Humidity (%) • Days C 40 2 44 Dry season 4 6 8 10 12 14 2 4 6 8 10 12 14 0 4 8 12 16 20 24 0 4 8 12 16 20 24 45 Relative humidity also showed typical tropical patterns (Figures 1C, 2C), During the second half of the rainy season (September to mid-November), characterized by strong diurnal and seasonal fluctuations. During the winds blew predominantly from the southwest and showed a clear diurnal rainy season, average air humidity was close to 73% (table page 49). pattern. Wind speed was very low at night and increased to maximum Humidity inside the building reached the highest levels at night (~ 90%) values of 3 to 4 meters per second (mps) during the day. In contrast, air and progressively declined as air temperature increased during the movement measured indoors reached much lower maximum values close daytime, reaching the lowest values around midday and early afternoon to 0.6 mps, although gusts close to 3 mps were observed, which caused (~ 50%). In contrast, average air humidity during the dry season was only slight discomfort in some offices. During the dry season, trade winds 53%. Indeed, maximum humidity during the dry season was typically blowing from the northeast prevailed, with average values of 4 to 6 mps below 80%, reaching lowest values close to 40% at midday and remaining measured outdoors (Figure 3). These winds peaked at speeds greater than low during the early afternoon. Humidity remained low (below 70%) 10 mps. Inside the building, average air movement was usually lower than during most of the working hours, causing a slightly uncomfortable climate 0.5 mps, although gusts close to 2 mps were recorded. for the occupants. In response, the misting system was installed in the courtyard to increase the humidity, cool the air, and improve indoor comfort. Dry season 2005 Figure 3: Wind speed measured Outdoor wind speed outside the building and Controlled amounts of air, heat, humidity, and 14 light enter the offices 12 in the south wing, creating a comfortable 10 indoor environment 8 that consumes very air movement measured inside the building during the dry windy season. • Wind speed (mps) • Days – average – maximum 6 little energy. 4 2 0 Indoor air movement 3 2 1 0 2 46 4 6 8 10 12 14 16 47 Conclusions Excessive air movement caused several problems. Papers were blown Measured by ISO comfort standards, the Holcim Costa Rica office building about and dust was spread, particularly during the early dry season. provides a comfortable indoor climate during working hours (see table The excessive air movement made cooler weather chillier and made hot below). The indoor climate is comfortable but slightly hot during the dry dry weather worse by contributing to dehydration and overheating. Air season, and comfortable but slightly humid during the rainy season. movement was an asset during hot and humid weather because natural ventilation speeds evaporation, thereby improving comfort. Ceiling fans Environmental variable Dry season Rainy season Indoor environmental were installed in some rooms (Figure 4). Mean temperature (oC) 24.19 ± 0.11 24.80 ± 0.28 and comfort conditions in the Holcim Costa (actual conditions, indoors) Rica office building during the dry and rainy seasons. Mean temperature ( C) o 24.90 24.40 (‘Comfort’ model, indoors) Relative humidity (%) 53.07 ± 1.13 72.90 ± 1.45 26.04 ± 0.33 27.47 ± 0.87 26.60 25.90 Comfort conditions Comfortable, Comfortable, (ISO norms) slightly hot slightly humid (actual conditions, indoors) Figure 4: How fan operation during working hours February 1 and 2, 2005 Maximum temperature (oC) 30 (actual conditions, indoors) affects air temperature inside the building on 28 during the dry season Maximum temperature off • Temperature (ºC) • Time of day 26 – office with fan – office courtyard – office without fan 24 off (‘Comfort’ model) 22 20 Even in a highly seasonal tropical climate, a comfortable indoor climate 18 12 48 can be achieved in buildings with ecological and economical passive cooling 16 20 00 04 08 12 16 20 24 and humidification systems instead of expensive and energy-intensive 49 The misting-cooling system in the courtyard is activated for ten seconds every ten minutes during the dry season. The courtyard air flows into the building, providing humidity and cooling. mechanical air-conditioning systems. Occupants of bioclimatic buildings must actively operate the building’s mechanisms (e.g. windows, louvers, and blinds) to regulate the indoor climate and maintain comfort. Optimal control of these devices requires an understanding of some simple principles of physics, awareness of one’s environment, and an active attitude instead of a passive one. Landscape design plays an important role in bioclimatic buildings, functioning to make the indoor climate more comfortable. Plants and trees can create shade, reduce thermal gain, reduce the air temperature, and moderate humidity. Trees can serve as windbreaks; in groups and in green corridors they can greatly reduce wind problems year round. Besides creating habitats and supporting biodiversity, plant materials beautify buildings and views from indoors. Intelligent use of plant materials is one of the many skills architects must learn in order to design sustainable buildings in harmony with nature. 50 51 Holcim Foundation The Holcim Foundation for the An international competition for A series of symposiums for academia Implementation funding for research Sustainable Construction promotes future-oriented and tangible and practitioners to encourage projects and building initiatives to innovative approaches to sustainable sustainable construction projects. discourse on the future of the built accelerate progress and promote environment. The Holcim Forum sustainable construction. construction. The objective of the Holcim Foundation is to encourage The Holcim Awards recognize supports sustainable construction sustainable responses to the any contribution to sustainable in the scientific field, among The Holcim Foundations provides technological, environmental, construction – irrespective of scale – experts in the construction sector, USD 1 million per three-year cycle socio-economic and cultural issues in architecture, landscape and business and society. to support the implementation affecting building and construction, urban design, civil and mechanical regionally as well as globally – engineering and related disciplines. of research in sustainable conIn addition to renowned specialists struction, and the implementation from around the world, promising of building projects. Projects including Holcim Awards, Holcim Prize money of USD 2 million per international students from leading nominated for implementation Forum, and Holcim Projects. three-year competition cycle en- technical universities are invited, funding are evaluated according to courages and inspires achievements to represent the next generation the target issues for sustainable that go beyond convention, explore and to share their visions. construction, and must be endorsed through a range of initiatives, by a local Holcim Group company. new ways and means, and draw attention to and identify excellence. The first Holcim Forum was held at the Swiss Federal Institute of The Holcim Foundation acts as The Awards competition is conducted Technology (ETH) in Zurich, an enabler for both research in partnership with five of the Switzerland, in September 2004 projects and building initiatives so world’s leading technical universities* under the theme “Basic Needs.” that, whatever their origin, exciting are the Swiss Federal Institute of Technology who evaluate entries according The second Holcim Forum will be and important new ideas can be (ETH Zurich), Switzerland; Massachusetts Institute to the target issues for sustainable held at Tongji University in Shanghai, more widely implemented and Shanghai, China; Universidad Iberoamericano construction, and lead the China, under the theme tested by a broader audience of (UIA), Mexico City, Mexico; and University of the independent competition juries. “Urban_Trans_Formation.” specialists. www.holcimawards.org www.holcimforum.org www.holcimprojects.org * The partner universities of the Holcim Foundation of Technology (MIT), Boston, USA; Tongji University, Witwatersrand, Johannesburg, South Africa. The University of São Paulo (USP), Brazil, is an associated university of the Holcim Foundation. 52 53 Holcim Costa Rica office building Architects Bruno Stagno Arquitecto y Asociados Structural engineer Juan Carlos Sotela Tensile structures FTL Design Engineering Studio Holcim Foundation Mechanical engineer Juan Luis Flores for Sustainable Construction Electrical engineer Claudio Soto Hagenholzstrasse 85 Landscape architect Jimena Ugarte CH-8050 Zurich/Switzerland General contractor RAE Ingenieros S.A. Phone +41 58 858 82 92 Bioclimatic survey Marco V. Gutierrez and Carlos Vega G. Fax +41 58 858 82 99 info@holcimfoundation.org Sources Gutiérrez, M.V., Soto, D and Alpízar, M. 1997. Forty years of meteorological This publication can be downloaded observations at Fabio Baudrit as PDF at www.holcimfoundation.org Experiment Station, Costa Rica. Boltec 30:1-14 “Harnessing Comfort Through Climate. Performance of the Holcim Building. A Case Study in Costa Rica” by Bruno Stagno and Marco V. Gutierrez Editor: Edward Schwarz, Holcim Foundation, Zurich Consulting editor: Daniel Wentz, Addresses Institute for Tropical Architecture P.O. Box 680-1007 San José, Costa Rica Architect, WentzWords, Magden Layout: Schadegg Grafik, Gockhausen stagno@racsa.co.cr Printed in Switzerland on FSC paper www.brunostagno.info by Zürichsee Druckereien AG, Stäfa www.arquitecturatropical.org University of Costa Rica Fabio Baudrit Experiment Station Stäubli Verlag AG, Zurich ISBN 978-3-7266-0075-4 P.O. Box 183-4050 ©2006 Holcim Foundation Alajuela, Costa Rica for Sustainable Construction, surdo26@racsa.co.cr Switzerland