THE USE OF PASSIVE COOLING STRATEGIES IN DUBAI MOVING TOWARDS SUSTAINABILITY Mahmoud A. Haggag (PhD) Associate Professor, Department of Architectural Engineering, College of Engineering
Based on the climatic conditions of Dubai, This paper attempts to reduce energy consumptions in buildings by adopting passive cooling strategies in the modern building process in Dubai
In this context, four issues are considered:
urban transformation patterns of Dubai,
sustainable building practices in terms of energy consumption
passive cooling strategies, and
lessons of experience: Madinat Jumeirah
Aim and Objectives
Urban transformation of Dubai can be motivated by three issues:
The city of Dubai is an international trading centre; a "global city".
The dramatic development in terms of population increase, economic growth, and the development of the new central area, "Sheikh Zayed Road".
Dubai’s emerging status as an urban region.
Dubai and its Urban Transformation Pattern
The architectural ideologies in Dubai have been moved from a traditional vernacular style to a modern approach . The traditional fabric and planning ideologies of the pre-modern era (1950s) reflects three dominant factors :
the climatic condition,
the cultures and customs of the residents, and
the locally available building materials.
This pattern is characterized by high-density buildings, narrow shaded alleys, courtyard houses and wind-towers.
In 2000, population number was about 900,000 In 2006, population number has reached 1.5 million. In 2020, population number is expected to reach 3 million. Traditional fabric of Al-Shindagha Traditional fabric of Bastikia
Sheik Saeed Al-Maktoum House , is a typical example of the traditional architecture. It was the former ruler’s residence (1912–1958). In 1986, it was converted into a Museum of Historical Photography and Documents of Dubai.
The living quarters open on to the main courtyard to generate wind circulation.
Rooms are provided with a shaded verandah overlooking the courtyard.
Windows are mostly on the inside looking in towards the courtyard . Windows on the exterior walls are limited to narrow slits and semi-decorative openings.
Wooden ventilating screens (Mashrabbia) were also used to keep out the sun, allow the passage of cool breezes, and provide privacy.
The wind-towers , the most distinctive architectural elements, take advantage of natural ventilation to bring fresh cooling air through the house without mechanical systems.
Local high mass materials ; including coral stone, lime, plaster, and palm fronds respond to the needs of the climate.
Sheikh Zayed Road is a typical example of the modern architectural style of Dubai.
The modern approach, which was established during the second half of the 20th century, was concerned with highly specialized building techniques.
Building industry and urban fabric had been strongly affected by: the importing of building materials and the establishment of foreign factories in the city ; and planning organization was based mainly on occidental codes and dominated by foreign professionals.
Burj Al-Arab: the tallest hotel in the world (321m), Dubai The Emirates Twin Towers: the 2 nd tallest twin towers in the world (350m office tower, 305m hotel), Dubai Burj Dubai: the World's tallest tower with one of the largest retail spaces in the world
[a, b, and c] THE PALMS, Three man-made residential islands ( Jumeirah , Jabal Ali and Deira). a b c [d] BURJ DUBAI , the World's tallest tower with one of the largest retail spaces in the world. d [e] THE WORLD PROJECT , 300 artificial islands with 750,000 inhabitants. e [f] MADINAT AL-ARAB , new communities with an area of about 81-million-square metres. f j [j] THE ARABIAN CANAL , a man-made canal with new neighborhoods. k [k] MADINAT JUMEIRA , designed and built in an ecological and resource-efficient manner
The Palm Project Dubai Land: entertainment, retail, and sport facilities Falcon City of Wonders: commercial, residential, educational, and entertainment facilities
Sustainable development refers to a socio-ecological process characterized by the fulfillment of human needs while maintaining the quality of the natural environment .
Sustainable development could be achieved by architects, engineers, town planners, and manufacturers of building products working cooperatively to produce green buildings that are designed, built, renovated, operated, or reused in an ecological and resource efficient manner .
Minimizing the inpact of urban development on the natural environment and the efforts to improve the ecological performance were the main concerns of sustainable building process in Dubai
Buildings consume about 45% of total energy use; 25% of water consumption; 70% of electricity consumption, and about 40% of carbon dioxide emissions.
Dubai has been listed as one of the highest per capita in energy consumption . Despite that fact, the environmental impact of buildings is often underestimated , while the costs of building green are overestimated .
The main question could be asked is: "how could cities with rapid urban development, like Dubai, sustain their building practices in term of energy consumption?"
Sustainable building practices in terms of energy consumption
To minimize the energy loads, passive solar design can be effective .
In Dubai's hot climate, where cooling is a primary concern, much can be done to keep buildings cool and comfortable. Combining proper design for building skins, good ventilation, courtyards, wind-towers, shading devices, thermal mass, and insulations can reduce energy loads.
Building skin is a selective pathway for a building to work with the climate, responding to heating, cooling, ventilation, and natural lighting needs .
Typical reduction in solar transmission through (a) Clear glass (b) Double glazed heat-absorbing glass (c) Double glazed reflective 'mirror' glass. “ Reid, 2001”
Building forms, volume, openings, orientation, and glazing systems have significant impacts upon the efficiency of the building skin.
In terms of energy efficiency, the use of double skin facades (DSFs) has been acknowledged in many buildings in Dubai since it can provide about 30% reduction in energy consumption, provide natural ventilation, and noise reduction .
To get a clear picture of the real financial incentives of using DSF, a cost-benefit analysis study was carried out by the author in 2006 . The methodology of the study was based on: 1) in-depth interviews with building designers and maintenance engineers, 2) simulation of single glazed façades, and 3) simulation of double skin facades .
The study emphasized that the potential savings offered by the DSF strategy can overcome the high construction cost . Moreover, building performance and comfort can be maximized.
Renaissance Dubai Hotel was selected as a case study. It was built in 1992 and is situated close to Dubai International Airport.
The study has concluded that:
U-value of the used DSF (box-window system) is 0.9 W/m 2 (between 0.2 – 0.5 less than double glazing single skin facade ).
It has an acoustical insulation that is better than single glazed façade ( the difference is about 8 dB )
The temperature of the inner skin is usually kept lower than it would be. This reduces the conduction, convection and radiation from the inner skin to the internal space.
As a result, U-value is reduced, less energy is required, visual transmittance is high, and acoustical insulation is provided .
Renaissance Dubai Hotel Floor plan Inner double glazed operable windows with internal blinds Outer single glazed panel Horizontal division with laminated sheets (act as sunshades and help to avoid sound transmission and to control fire)
The Use of Passive Cooling Strategies in Madinat Jumeirah
Madinat Jumeirah (City of Jumeirah) , the largest resort in Dubai built in 2004.
It comprises two 300 room hotels (Al-Qasr and Mina Al-Salam), courtyard summer houses (Dar Al-Masyaf), a traditional souk and cultural village.
Madinat Jumeirah forms a virtual island looking down upon wind-towers, courtyard houses, pools, meandering waterways with traditional water taxis, and a private beach.
The architectural concept was based on a theme of old Dubai in a luxurious context ( a combination of green design techniques ) .
Architect: Creative Kingdom; developer: Mirage Mille Al-Qasr Mina Al-Salam Dar Al-Masyaf Conference Hall Dar Al-Masyaf Al-Qasr Hotel Mina Al-Salam Hotel
Various strategies were adapted to develop energy-efficient buildings, cooling load avoidance and minimize the need for mechanical cooling systems . These strategies include proper shading, natural ventilation, thermal mass, careful siting, and good landscaping .
Buildings were designed to take advantage of natural ventilation. The wind-tower has been used to increase the air flow in buildings. Other features include fresh air inlets located near floor level, use of atriums , and courtyards that have been adapted to enhance the stack effect and to speed the indoor air flow.
- Fixed shading devices are installed mainly on the south-facing windows. - External insulation , and dense materials like concrete, bricks, have been used in passive design to absorb, store, and re-release thermal energy. - Trees are properly located and used for shading. Vegetation, pools and canals around buildings contribute to an evaporative cooling strategy. - Al-Qasr Mina Al-Salam Dar Al-Masyaf Conference Hall Souk
Despite the fact that Dubai is one of the hottest cities in the Gulf region , architects seem to adopt the idea of transparent buildings more frequently .
It comes with a significant increase in operational costs , particularly for cooling systems , due to the higher solar gain.
To overcome such problems and minimize the impact of urban development on the natural environment as the main concern of sustainable building practices; there is a need to integrate building's architecture, materials selection and mechanical systems to reduce cooling loads .
These passive cooling strategies have been acknowledged by international architectural firms to design and construct projects that are energy efficient, environmental friendly, and architecturally remarkable, like Madinat Jumeirah .