College of Architecture and planning Architecture planning Year: 2017-2018
Sustainable practice in hot and dry climate
Student Name: Abdulrahman Mahmood Mohammed ID: 2130009782
A. Introduction. In every country, heritage and climate has had influence architecture and sustainable styles. The main goal is to achieve a year-round comfortable environment which was and currently is the main challenge in hot and dry climates. Energy consumption in forms of heating and cooling systems is relatively high compared in hot and dry climates to other tropical climates. Unfortunately, the blind imitation in designing buildings following other developed countries style has escalated a major problem. In other words, it is looked as if the country is ranked developed with modern towers forgetting and ignoring the vernacular style of the region which accommodate the climate and was a result of accumulated experience over time of trial and error. The traditional architecture techniques were adopted with the nature and was harmonizing to fit the harsh conditions with less mechanical equipment’s need and a principle “necessity is the mother of invention”. Nowadays, our modern buildings are useless and failed to confront the regional climate. This is obvious which can be seen with the injections of faceless glass towers in the middle of the desert with high energy demands besides it doesn’t reflect the social identity of the region. The consequences of our ignorance won’t be seen in the immediate present but will rather be a long-term crisis for the next generations to come. Furthermore, the vernacular passive architecture illustrated in the paper has introduced many generic ideas and passive cooling techniques with lots of similarities to the middle eastern environments and Islamic architecture style of buildings. Thus, the relevance and linkage of the content is totally identical which can be used and developed to suit the technological advancements for further research. Most of the points, if not all, can be found in the Islamic city model where street width is narrow, and buildings are congested and dense to cast shadow on each other. Examples of courtyards, verandah, and wind towers can be found in the old Islamic architecture. The writer’s mythology of study was based not only on exploring other references and books in that context but also on observations of the local traditional culture in India including Jodhpur, Bharatpur, Pune, Mandu…etc that exist long time ago and summarizing the strategies used in them.
B. solar passive techniques In this section, the writer has elaborated the solar passive techniques to mitigate the undesirable impact in hot and dry climate, all techniques were a response using three water, sun, and wind.
many of the elements;
B.1 passive techniques and features. Thermal load whether external or internal is critical, so it should be analyzed precisely prior to A generic model of vernacular model construction of the building. In vernacular architecture, the distribution of the service area including kitchen and bathroom were facing the façade and the living spaces has inward looking to the courtyard. Consequently, the air movement will cool the service area through small windows to lower the heat exposure of the sun.
B.2 Considerable factors to mitigate impact of heat loads. In this segment the writer has written common factors that will affect the heat loads, each factor is further investigated for more clarification supported with diagrams and sketches. B.2.1 orientation and shape of building. Orientation and shape of the building can reduce the energy significantly, rotation of the building can influence the heating and cooling energy demand on a long-term basis, so it is essential to find out the optimal orientation angle as well as building shape. Regarding the shape, the compact layout in old Islamic town Different configurations of the same building reduces the sun exposure. Different optimizations can be formed from the same cubic mass, solar analysis is conducted on each model to see the default energy consumption and figure out the “optimum shape”. The main principles are as follows: 1- The square shape isn’t an optimum shape for energy conservation 2- The optimum shape has the long axis somewhere along the east west direction 3- Shape that are square has better efficiency than those elongated in the northsouth direction.
B.2.2 Insulation of the building envelope/ verandahs. the traditional home in Saudi Arabia was mainly built from mud that was available in the site, this mud has a high thermal heat storage which Rashwan façade in Mecca keeps a time lag between the day and night. Also, buffers like verandah’s and double skin elements like mashrabiyahs can be found in the old houses as shown in the figures.
Verandah with screening in Crater, Yemen
B.2.3 weather stripping/ external surfaces. Weather stripping is beneficial to reduce the heat loss and decrease the heat exchange between the inside with the outside. Many substances and chemicals can be used. For instance, a sealant and rod applied to the edges of the window or door. Also, a rubber foam tape. The usage of weather proofing can prevent heat loss at night and keep cool air inside during the day.
Shading device
Add to that the horizontal louvers is advisable on the south side to block summer sun and allow winter sun to enter and warm the building. B.2.4 Pale color Materials selection is highly important, Shibam hadramout, the oldest skyscraper in the world, which was built in hot and arid climate, selection of the reflective white materials on the top exposed surfaces make only light received through the narrow street and reflect the heat The solar analysis for Shibam city in Hadramout, Yemen has revealed lower heat gain and absorption (blue color in the center as indicator of lowest temperature). because of the vertical expansion and the extreme dense layout between the buildings has yielded to prevent much of the solar radiation and casting shadow on the narrow streets below. The visitor to the city can feel a thermal comfort because of wind breeze tunneling up which keeps the temperature lower inside the city.
Dark vs. cool roof surface. temperatures
using solar analysis of urban fabric in the city of ShibamHadramout
B.2.4 courtyards/ wind towers Courtyards are essential component in the traditional Islamic architecture, since the idea of privacy and inward looking are principles to fulfil. The internal environment of the courtyard can be modified and multiuse. 1-use of water for evaporative cooling 2- planting trees and green areas. 3-Enclosing the space to form an atrium with air shafts to cool the medium.
Courtyard and decorative windows in a Qatif house Saudi arabia
B3. Urban climate The importance to study urban heat island is highly important nowadays. In old times, the urban heat island intensity wasn’t a problem as city “CBD” and the surrounding areas has little difference in temperature. The reasons lie in low existence of mechanical Eastern province of urban equipment’s for heating and cooling and vehicle emissions add to that the heat island overtime (a) 1990, (b) 2002. asphalt absorb and store the heat instead of reflecting it. The writer explained that atmospheric heat is low in the morning but gradually increased even after the sunset because the slow release of heat. To face this dilemma, trees are the solution in which it acts as heat sinks. This can be in forms of green roofs with water sprinklers on the top to add moisture, or creating a green belt space in every cluster of buildings in the metropolitan. The reduction of asphalt exposure which is the major contributor to urban heat island effect by blocking it from gaining heat. Moreover, asphalt can be treated to make porous asphalt to let water penetrate and alleviate the stored heat. Also using cool paving materials for roads, sidewalks and parking lots. On the other hand, the adaptation of western regulations and imposing th em in the hot and dry climate in which is currently happening in Saudi Arabia has formed many drawbacks like vehicles dependent society, social ties break up, and dispersed urban fabric with vacant areas.
B4. MICROCLIMATE The micro climate differs in its characteristics and rates from the general temperature of the area. For the architect, this term represents the immediate climate surrounding the construction site or several buildings and has different factors depending on the general climate of the region
B.4.1 landform So what the article suggests if landform isn’t a concern if the site is flat but in case of slopes, the windward side has high breeze until the crest and the speed decrease in the leeward side. B.4.2 Water body The water body shouldn’t be used extensively as it would humidify the air more
Maximum wind speed from leeward to the crest
B.4.3 Street width and orientation The major streets should be parallel to prevailing winds. Also the width can be minimized to avoid early afternoon and late morning sun radiation if the building surrounding it is low-rise. B.4.5 Open space and built form Some space like kitchen and toilets should be ventilated. One way to do that is using an open plan to penetrate the prevailing winds. Moreover, if the
Open plan along east west axis
building is raised on the ground floor it will help winds to circulate on the ground level.
B5. Various method to reduce heat gain in a building
Rising the building up for ventilation
B.5.1 Building Orientation and shape: Prevention of sand storm penetration
The optimal orientation in the article is using the long axis to be east and west, thus less sun radiation can be received in the two sides. Looking to the traditional housing the houses were closely to be square or rectangular. Houses distribution forms the street network to be randomize with narrow width which can be refered to as “mud-lump” or closely-knit community shown in the Recent pattern of low-rise, high density Traditional housing pattern area near diagram. These group of structures and courtyard houses near Al-Batha souq, castle Marmask in Riyadh Riyadh courtyards are stacked and dense together to prevent dusty winds from penetration to inside add to that a green belt of palm trees surrounding the clusters.
B.5.2 Shading by neighboring buildings The article classified clusters to three types; pavilion, streets and courts. Pavilion is also known to be like vaults found in many vernacular buildings. Shade and shadow can help reduce the thermal storage significantly keeping the space cool at night and temperate during the day.
Jeddah Albalad old streets with buildings shading each other where street can have social activity for seating in the afternoon
B.5.3 Shading by vegetation Besides using shading devices, vegetation can be used on the most spot that receive radiation, usually east and west get 50% more light than the north and south elevation. Traditionally, the reduction of the openings to the outside and make inward view was the approach. Today, more glass is being used even though it’s double or triple layered heat will penetrate making it a useless and costly regardless the beauty of looking.
Building shading each other and the narrow street in Crater city, Aden, Yemen
House in Al-Hassa, Saudi arabia
Use of climbers and vines e.g “Cairo morning glory” that is low maintenance and evergreen which doesn’t need much water can be implemented in modern houses in Saudi Arabia
B.5.4 Reflecting surfaces Unlike tropical and cold climates where sun radiation in needed, reflection of the radiation is one of the strategies to conserve energy. One approach is by Painting the surface with white or bright colors, another is using automatic louvers that reflect light when not needed and at the same time offer a view. Albahr tower in the United Arab Emirates is covered by automatic Al-Bahr tower with responsive façade to the desert sun triangular tents inspired by Islamic Mashrabiyah in Abu Dhabi controlled by sensors in the east and west facade to adopt with sun angle. The Mashrabiyah, a lattice screen, was changed from static to dynamic state to make it efficient for the climate. 50%-60% of energy is reduced. B.5.5 Building Surface Cooling The main idea in this part of the article is trying to make is how to encourage heat loss through evaporation and convection, and prevent heat gain through radiation. Water on the top will act as a medium to transmit the heat from inside the building to the ambient air
Roofscape were used traditionally as sleeping space at night, if needed people used to water the rooftop for cooling
Water is used in open space for evaporative cooling in Doha museum
Angawi House, Jeddah. The central courtyard of the house has a water body which humidify the atrium. The inner courtyard has all the spaces distributed from while having climbers hanging from the top to add both aesthetic and thermal comfort functionality
B.5.6 Roof Ponds and Gardens Roof ponds and garden are becoming popular and is one of the technique to reduce Urban Heat Island. The soil vegetation layer on the roof can help in cool and insulate the building actively reducing energy costs improving air quality, and lowering urban temperatures. Although the initial costs could be higher compared with conventional roofing, the payback of the green has short period. The king Abdullah KADF Conference Center Mega Roof, Riyadh financial district has incorporated indigenous desert grasses of various kind to reduce irrigation requirement. B.5.7 Solar chimney Although the high temperature and the harsh condition of the site, the Kaust is a great ideal example on how to utlize the solar chimney in hot and dry climate. While The design has reduced the temperature by the facades and overhangs, it was important to have natural lighting to the interior spaces to improve the productivity and comfortability of the users The chimney consists of double layer glass the outer layer is transparent to allow heat exchange and the inner layer of glass absorb the heat so that it can suck in the hot air and replace cooler air coming from the courtyard to form air flow in the interior space for natural ventilation. King Abdullah University of Science and Technology (KAUST) solar chimney
B.5.8 Courtyard effect As stated in the article, courtyard is effective in warm and humid climate. It acts as heat sinks to absorb heat during the day and warm at night. Dual courtyard can also be used; one for absorbing heat and the other with vegetation to cool the place by process of transpiration. In the old Saudi houses, courtyards are the central living hub of the space where all other components are distributed around it. The houses are grouped together sharing as many as three walls with each other. The internal environment can be customized by use of planning or use of water for evaporative cooling.
Village in a Wadi Hanifa protected by thick growth of palm trees
Closely-Knit community with courtyard remains protected from sun by shades
B.5.9 Air vents and wind tower Wind tower and air vents are popular even in modern architecture. it’s used not as an aesthetic element rather than practical in Saudi Arabia. Multi-dimensional wind towers which is open from four directions are the trademark of gulf architecture which is introduced in southern Iran with similar climate of hot and arid. During winter the wind tower is either closed on the top or at the room served which isn’t used Thermal details of Sheikh Issa’s house in Bahrain. cross ventilation diagram
B.5.10 Sensible and evaporative cooling/ The sensible cooling can be achieved using traditional windcatcher that can have pool of water so that the water converts the dry air to humid. Plus using a charcoal pots grafting will help to increase the air flow into the spaces.
Bastakiya village wind tower found in Dubai is one of the oldest wind towers in the region, the village was constructed in the preelectricity era and doesn’t use any mechanical equipment which is totally dependent on natural light and ventilation
B.5.11 Air Cooling by tunnels Heat pumps and air pumps are efficient methods taking into account energy consumption, space needs, low operating costs, maintenance and comfort and quality. Although this tunnel systems can’t be used alone, nevertheless it can reduce the load on mechanical equipments
Heat Pump project combining heating/cooling King Abdullah University Jeddah, Saudi Arabia
B6. Cooling and Heating Techniques using Thermal Mass B6.1. conventional wall and ceiling In the hot and dry climate, the control of the thermal transmission in building's outer shell vs. inner shell is to be determined by the amount of heat transferred to the building. It is necessary to select the materials according to the thermal characteristics. For example, the color of the building, the thickness of the wall, the use of double skin wall, all affect the transmission of heat. Thus, many methods to control the heat, projection of the floors to the outside, projections of masses in the façade, use of shading device, and use of the cavity wall B6.2. 4.6.6. The Vary Therm Wall. The most common materials in thermal storage are brick and stone and when used, the following should be considered; •
The thickness of the walls shall be at least 10 cm to absorb the heat
•
Regularly distribution of sunlight on the roof to cast shadow and shade.
C. conclusion The article has raised a big question to ask ourselves, can the future learn from the past or should we neglect the past and continue considering the old techniques are no longer suitable for present necessities. To answer this question, we have to compare present with the future in terms which is “more” sustainable in hot and dry climate regions. Although, the word sustainability was just recently used in the 20th century but was obviously existent in old buildings. Sustainability isn’t only a scale from 0 to 100 where achieving 100 make the building sustainable nor just installing solar panels or wind turbines make it more sustainable, it is rather a very broad term and a multi-dimensional
concept that has many practical implications with the principle of “building more with less”. The world after the industrial revolution tends to gear away from traditional concept towards what is called “renovation”. This era didn’t last long until it’s realized now not only unsustainable but also culturally destructive. So the simple answer to the question, is the integration and incorporation of traditional strategies and developing them to be suitable for specific region. The article has given ideas that are neither brand new nor an invention but existed in traditional buildings. These ideas won’t necessarily solve the energy crisis immediately but will help alleviate and change the people thinking eventually To conclude, focusing on the traditional elements and mimic it with the advanced technology as we saw in the examples is the best way to confront todays energy problem and form the urban harmony. On the other side, I believe that the blind fascination of western life-style has drawn us away from the sustainable road with much focusing on the building iconography and appearance overall. The consequences of our ignorance will have catastrophic impact socially, economically, and environmentally on the long run with the high population growing pace add to that the limited nonrenewable energy, fossil fuel and water, that will definitely run out some time in the future.
D. References 1- Books Konya, A., & Vandenberg, M. (2011). Design primer for hot climates. Reading, enk.: Archimedia Press Limited. Ragette, Friedrich. Traditional domestic architecture of the Arab region. Fellbach: Edition Axel Menges, 2012. Talip, Kaiser. Shelter in Saudi Arabia. London: Academy Editions, 1984. Olgyay, V., Olgyay, A., Lyndon, D., Olgyay, V., Reynolds, J. and Yeang, K. (n.d.). Design with climate.
2- websites FlashyDubai.com. (2017). Al Bastakiya Dubai: The Oldest Residential Area in Dubai. [online] Available at: http://flashydubai.com/al-bastakiya-dubai-the-oldest-residentialarea-in-dubai/ [Accessed 31 Dec. 2017].
3- Journals NaĂŻma, F., MĂŠbirika, B., Belkacem, D. and Claude-Alain, R. (2016). The Traditional House with Horizontal Opening: A Trend towards Zero-energy House in the Hot, Dry Climates. Energy Procedia, 96, pp.934-944.