The following projects showcase three examples based on comparable design principles: Nasma School and Shams Library, both in Lebanon, and the Forum in Marvin Hall at the University of Kansas.
Although the three examples may appear different at first glance, they share many similarities. In each project the local climate was first analyzed to understand the potential support offered by nature: sun, wind, and earth. In all cases, the architectural design integrates the most rewarding passive measures, daylight autonomy, and air quality without compromising thermal comfort, while at the same time minimizing the energy required for active measures. All three buildings take advantage of natural ventilation using the physical phenomenon of the stack effect, driven by thermal buoyancy. The first two low-tech buildings in Lebanon operate by pre-tempering the air in the ground. This low-cost passive measure can be implemented economically by choosing suitable building materials that are easily obtainable locally. The first building, the temporary refugee school, uses no mechanical systems at all; while the second example, which has higher occupancy levels, uses fans to supplement ventilation. In comparison, the Forum at Marvin Hall exploits the same physical principles, but takes a somewhat more high-tech approach. The building mechanically adapts to outside conditions. Its double skin facade creates a buffer zone that utilizes seasonal temperature differences and allows ventilation that is, for the most part, natural. All three buildings were designed and realized by young architects and engineers during their training, providing the students with a unique interdisciplinary learning opportunity. This gave them useful experience for their subsequent professional life. But above all the project imbued them with a sense of responsibility and offered them an opportunity to shape their future in a positive way.
Nasma – a breeze of hope
Millions of Syrians have been displaced by the ongoing civil war; alone 1.2 million are registered as refugees in Lebanon. Not only are these refugees traumatized, as they have lost their homes and the basis of their existence but educational opportunities for the younger generation are also lacking. A recent UNHCR educational assessment indicated that 80 per cent of Syrian refugee children do not attend school. The makeshift schools provided face many difficulties. The seasonal temperature extremes frequently lead to cancelation of classes. Conventional heating and cooling appliances are often inefficient, costly, and difficult to obtain. The cramped, dark spaces in the simple buildings rarely have good ventilation and the poor acoustics make it even more difficult for the pupils to learn. Najjar Najjar Architects, Transsolar Academy, and the Lebanese youth-oriented NGO, SAWA, collaborated to investigate a low-cost solution – a pilot project applying climate-responsive strategies to the design of a model refugee school. The temporary structure has a life span of up to five years, and will leave no ecological footprint. The team used traditional building methods as a source of inspiration, employed simple, locally obtainable materials, and involved the refugees in the construction process. The initial intention was to build on a site in the Bekaa Valley so that the school would be close to the major refugee camps. Consequently the design studies were based on the valley’s climate data. However, acquiring an official site proved difficult. Since the goal was to erect a low-cost prototype quickly, it was decided to build the school on a private site further south. Climatic conditions on both sites are similar and allow informative comparisons to be made. The valley lies at the foot of the Anti-Lebanon mountain range, at an altitude of 1000 metres on a plateau in the interior of the country. This dry region suffers from seasonal extremes of temperature. The summers are very hot with the temperature reaching 40 °C, while snowfall is frequent during the winter. The construction, layout and orientation of the classrooms are based on an analysis of the local climate and the exclusive use of passive measures. Exterior walls are built from stacked, recycled, 30 cm-thick bags filled on site with earth and held in position by trussed frames. It was initially planned to use goat’s wool with a minimum thickness of 10 cm as insulation but in the end dried pine needles – a traditional and locally available material – were used instead. The earth-filled bags provide thermal mass that helps reduce the impact of the dramatic changes in the outdoor temperature on the spaces. Thermal simulations showed that, as a result, the room temperature in the interior can be raised by up to 3 °C in winter, and reduced by up to 5 °C in summer. The shadow cast on the facade helps avoid excessive solar heat gains in summer; while in winter light and heat from the low level sun can enter the spaces.
The ventilation of the classroom is provided by ducts running in the ground, built from horizontally laid “hourdis” – precast concrete blocks with tubular voids –, which introduce fresh air into the space after it has been cooled by the lower temperature of the ground. The system is based on a fresh air requirement of 20 m³/(h. per person) at a low pressure loss of less than 10 Pa. The air flow in the ducts, with a very low maximum velocity of just 1m/s, is achieved by thermal buoyancy, created by exhaust vents in the roof. The shape and orientation of the vents accelerate the airflow by introducing a chimney effect. Solar air collectors 10 m² in area and positioned close to the openings help to warm the exhaust air. Steel sheets on the collectors are painted black to maximize the warming effect. The reflective surface of the metal on the remainder of the roof reduces heat gain in the interior. A translucent panel in the north side provides additional daylight for the classroom. Following completion of construction the temperature, humidity, and daylight in the building were measured to check the efficiency of the design. The measurements reveal that in combination with the solar chimney the ground duct has a cooling effect of up to 5 °C. Thanks to passive solar gains, the air-preconditioning, and thermal mass thermal comfort is optimised both in summer and winter. The quality of the daylight in the interior meets international standards. Only the sealing of the facade and the pine needle insulation revealed a number of flaws, as the compacting of this layer led to gaps in the upper area. However, by simply adding more material this weak point could be eliminated.
Shams Library
The experience gained from the Nasma prototype was applied to the design of the next project, the Shams Library in Majdel Anjar (Bekaa Valley). Part of an existing school complex, it was planned by the participants in the Smart Structures for Refugee Facilities workshop and erected with the help of the later users. The Transsolar Academy assisted the students from the American University of Beirut’s Department of Architecture and Design in devising the energy and comfort concept. The library serves a refugee school of 300 children and combines a frame that can be quickly erected with climate-responsive passive strategies. The three-pin arch of the frame allows a large span of 8 metres. Easy-to-use steel parts that connect the timber elements facilitate prefabrication and assembly on site. The construction of the pitched roof consists of MDF boards, waterproofing, air layer, insulation, and roofing of white galvanized zinc. In this building, too, the facade is made using locally available bags which were filled with sand and fixed by timber sections to the vertical members of the frames. On the inside the construction is lined with white plasterboard panels. Thanks to the sand-bags the construction has a high thermal mass and good acoustic qualities. Shelving between the frames provides space for books and toys. A translucent layer in the upper part of the north facade provides the room with a generous amount of diffused daylight. In the library thermal comfort is ensured by a 40 metre long geothermal duct running in the ground beneath the school complex. The planners had to dispense with hollow concrete elements in the ground, as concrete foundations were to be made on the central plaza. But the nature of ground allowed 1 m of earth to be excavated manually so that locally available barrels could be inserted as ventilation tubes and outlets made in the foundations. Modelling showed a level of efficiency comparable with that of the solution using hollow concrete blocks. Fans are used to increase the rate of air movement, as due to the higher occupancy levels there is a considerably greater need for ventilation than in the Nasma School and, additionally, the period during which the building is used is to be extended. They ensure the supply of fresh air and by increasing the air flow speed an additional cooling effect can be provided in summer. The perceptible cooling effect is up to 3 °C. Natural air exhaust is through defined facade leakage. In the future the power for the fans is to be provided by PV panels on the roof. These inexpensive strategies tangibly improved the learning environment. Precise measurements check the efficiency of the concept and provide further research insights. The use of local materials ensures a low carbon footprint and reduces the environmental impact. Through their involvement in the project the users develop a positive attitude to learning, which is the ultimate goal of this educational project.
Marvin Hall
In comparison to the low-budget projects in the Lebanon the goal in designing the extension in Kansas was a building with a long useful life and high quality interior design. The Forum is an addition to Marvin Hall – the historical School of Architecture building at the University of Kansas. It meets the school’s need for a central common space and an auditorium. It was designed and constructed by 18 post-graduate students and participants in Studio 804, the Department of Architecture’s Design/Build program, with support from various experts from the field of industry. Transsolar advised on the design and architectural integration of the double-wall facade and the natural ventilation strategy. The double skin creates a buffer zone that operates to the rhythm of seasonality. It is made of two separate panes of insulated glass, one metre apart from each other. The space between them provides room for the cedar louvers that shade the auditorium. These louvers are controlled by a rooftop weather station, and are programmed to adapt to the changing position of the sun. Motorized flaps are located at the top and bottom of the outer pane. Fresh air is drawn from the area in shade underneath the raised building. An efficient displacement ventilation system brings cool air into the interior, where it is distributed through the raised floor and the stepped seating. In winter time, the vents in the facade are closed, cloaking the building in a warm blanket provided by heat gained from the sun. In summer the vents at the top and bottom are opened, creating thermal buoyancy and drawing the cooler air from underneath the raised building into the space between the panes. It is warmed there and escapes at the top. During the hot months additional mechanical cooling is needed. On mild days natural displacement ventilation is activated. Here again fresh air flows in at the bottom of the facade, however the upper vents remain closed and the air is distributed in the space through the raised floor. It escapes through the facade opposite, which is opened at the top. Thermal simulations confirmed the effectiveness of the facade concept. The roof and floor frame are insulated with 30 cm PIR-panels, which achieve an insulation value about three times the minimum required by the energy code. The living wall of ferns and begonias improves the acoustics in the lecture space by absorbing and dissipating sound. It is watered from a 1100-gallon rainwater cistern. The lush vegetation helps to improve the quality of the indoor air by natural filtration. The integrated passive design measures reduces space heating and cooling demands, resulting in estimated energy savings of over 50 %. In addition, a rooftop array of 45 photovoltaic panels makes the Forum independent of outside energy providers. The master students agreed that achieving the seemingly impossible task of not only designing, but also building Marvin Hall in the space of one year was a most rewarding experience. The students of the School of Architecture now have an inspiring educational environment: a “structure built by us and for us”, as the Dean of the University puts it.
