Marcelo Rossi

1st Prize -Tahlia Tower - Multi-purpose Tower - Jeddah, Saudi Arabia - 2010

Project: TAHLIA TOWER – Mixed use Building
Year: 2010
Professional services / Tipo:
Preliminary and Definitive Project

Authors:  PRAS & M.A.M.ROSSI + AiKu


• Jeddah city, major centre in Makkah province, represents, in a certain way, all Saudi Arabia, thanks to its strategic position on the Red sea (its harbour is the first on the Red sea). Jeddah is a fixed leg for Millions of pilgrims travelling to Makkah city.
• The importance of Jeddah comes from this crucial position from the religious and commercial point of view, but also for the international connection network that have been developed during the years and finally thanks to the growth of new fields of development such as tourism, industry and many others.
• The city is built with the mountains, as a natural evolution of the desert, at his back and it is developed along the sea. In Jeddah, it can be said, the Desert and the Sea comes together.
• Tahlia Tower, in our vision, wants to be a new urban landmark. The tower is on the edge of Tahlia street, one of the main commercial road in the city, and will be located between well marked out buildings.
• Respecting the character of the buildings around, with moderation, the projects wants to shape Jeddah's dualism, the mountains and the desert, strong and arid matter, and the sea, soft, sinuous, and fresh.
• In the shape of the building live together the strong matter on the east side and the soft and sinuous look on the West side.
• Mixed activities such as retail, restaurants, offices, residential and hotels are included in the program. All the activities are service-industry and tourism oriented making the building a meeting, trading and interconnection point for different cultures.


• The West Façade
• The West façade, looking over the sea, presents a wave shape. It moves vertically creating a full/void texture with green gardens and terrace at different levels

• The "hard" Lower Block
• The tower is conceptually founded on a larger basement block. The ground floor, 90cm higher than the street level, allow to keep away the risk of flooding and guarantees the required privacy to the inner space.
• The entrance of the underground parking is protected by movable bulkheads to be used in case of extreme weather condition.

• Façade cut on Tahlia Street
• The façade on Tahlia street has been developed as a 4 floor height portal (like the lower block height), but it grows up until the roof level, attracting the attention up to the suspended crowning element. This portal, together with the main ribbing structures, encircles the building and melts the lower block heaviness together with the waving skin lightness. It encloses but let evaporate the building, highlights the shape but makes it translucent. At night the façade brightens of artificial lights, while the daylight is reflected in many directions thanks to the many facets of the glazed surface

• Suspended crowning element
• The suspended crowning element flies in the air to attract everyone attention. It is an architecture-integrated sculpture as it crowns the building but at the same time it is stripped of all architectural finishing.
• The crowning element is a "wing" to fly and dominate the air, but at the same time is a "kite", symbol of friendship and sport competition.

• Entrances
• Each activity has a separate access form the street to the lobby but trough doors and glazed walls can communicate and be in connection with the other activities
• The lobby is conceived as a common and organic space that push the visitor to explore the whole building, but all the different functions and activities work, as required, independently.
• With respect to the shops, the TOR was suggesting rectangular premises overlooking Tahlia Street. This layout creates a clear-cut division from the other activity. As an amendment, the project proposes a single entrance through which is possible to enter all the shops. This common space allow to strengthen the belonging of the shops to the building. The shops can then profit of the presence of restaurants, hotels, offices and flats inside the building. The common space becomes an arcade with two, three, four levels, a single volume cleaned out inside, overlooking in all directions, with a pleasant game of interconnections. Each shop is also overlooking the street having its own entrance in order to provide independent and separated functions as requested.
• Energy savings
• On the south side of the building PV (photovoltaic) panels are included, in continuity with the brise-soleil panels of the side façades; these are connected to an exchange system located in the technical floors. The panels can reduce the building energy demand and allow to exploit the considerable rate of radiation of the site. The photovoltaic panels themselves, on the south side, play the role of brise-soleil. Thanks to the mechanized devices the panels can rotate around its axis both optimizing the angle of exposure (horizontal configuration) or decreasing the accumulation of sand on the surface (arranged vertically) in case of storms.
• The Brise-Soleil guarantee the presence of shadows on the façade and consequently the reduction of radiant effect. In garden areas, where no brise-soleil are placed, the shadows are provided by palms and threes. Glazed surfaces will be equipped with UV protection films in order to further reduce the radiant effect. The shadows pattern along the façade allows air flows to be generated so that heat transfer outside the the building can be increased reducing the energy requirements for HVAC.
• Tech Floor Group 1 (above the 2nd floor)
• The technical Group 1, located above the second floor, serves the four basement floors, halls, shops and restaurants, and five floors of offices.
• It is equipped as a roof garden. HVAC equipments are distributed between trees and bushes, in the external area, while the pumping equipment rooms, electrical etc.. are placed in the footprint of the central core of the tower. The garden is only visible from below and from above, only accessible for maintenance from the technical level.

• Tech Floor Group 2 (above the 12th floor)
• The tech floor group 2 serves five floors of residences and five floors of the hotel. At this floor also some services of the hotel (laundry, storage, etc.) are located.

• Roof garden
• The building roof above the hotel was developed as a roof garden, partly covered by the west facade that runs continuously, and partially covered by medium-sized trees and palm trees; fountains, splashing water and nebulizers complete the framework to create a cool microclimate, even in seasons of extreme heat. This space, for exclusive use of the hotel, creates the conditions for enjoying the view over the city and the sea.

• Flexibility
• The flexibility of the building was conceived as the possibility of interchanging activities between floors, with few changes for the plant and toilets and kitchens. The vertical structure has been designed with a rigid central core, containing elevators, stairs, technical ducts and services, stiffened with two parallel rows of concrete walls; the horizontal structure is composed of thick floors cantilevered from the central core, so as not to constrain the position of the outer skin, and therefore also of the internal partitions.

• Windows Cleaning
• External Windows and glazed surfaces are mostly located in correspondence of balconies and terraces allowing an easy access for cleaning purposes. The wide glazed surface developed along the central cut on Tahlia street façade and the other few glazed surfaces higher than 4m will be realized with opaque glasses with self-cleaning properties in order to make not necessary the surface cleaning.

• Security & Vandalism
• The tower will be equipped along the whole perimeter with CCTV, alarms, intrusion detection devices. At ground floor a security office will be located to monitor continuously the whole building and to coordinate the required intervention in case of vandalism, intrusion, terrorism.

• Structures
• In order to allow for the maximum flexibility in the architectural composition and to withstand the vertical and horizontal forces acting on the tower an integrated structural system has been studied.
• With respect to the vertical elements, three different systems can be identified: the concrete walls that compose the central core of the tower, the concrete columns disposed in the basement area and in the lower floors with regular disposition and the steel pipes composing the irregular network around which the full-height glazed surface on the Tahlia Street façade is developed.
• Horizontal surfaces are realized through ribbed concrete slabs where the weight is reduced thanks to special lightening elements integrated in the slab itself. The slabs, at upper floors, are realized with a 7m span cantilever configuration, with 70cm height and with anchorage to the central concrete core.
• Both vertical and horizontal structures will be realized in concrete in order to avoid the effect of thermal gradients coming for the combination of different materials.
• The central concrete core, that hosts lifts and services, is developed to guarantee the required stiffness in both principal directions in particular with reference to the wind forces.
• A detailed FE (Finite Element) Analysis was developed for the block composed by the Central-Core/Slabs in order to evaluate the global behaviour and to optimize the element sizes.
• The Structure can withstand the design forces and guarantee limited displacements even in case of extremely high wind loads (140km/h)

• M/E Plants
• The mechanical equipment have been divided into two main blocks, spaced along the height of the building. The first technical floor (technical group 1) serves four floors of shops, lobby and restaurants, and the offices above. The second technical floor (technical group 2) serves the residences and the hotel.
• In the basements the electrical equipment rooms, transformer stations and power generators are located together with water tanks provided with pressurization systems for fire protection purposes.
• Two large shafts provide connection between all floors.
• In the Technical Floor Group 1, above the commercial floors, mechanical and HVAC equipment for "thickly crowded floors" i.e. commercial, restaurants, reception and lobbies have been located. The equipment located on this technical floors will serve also the offices floors. With respect to the "thickly crowded area" the system has been conceived as a chilled water system produced by tropicalized heat pumprefrigeration units with heat recovery. These groups, through pumping units, will feed a number of AHUs (Air Handling Units) which introduce conditioned air (both in temperature and humidity) in thickly crowded areas, restaurants and lobbies.
From the heat recovery units will be taken out the hot fluid needed for the post - heating batteries (summer). In winter time, if necessary, the groups can work as heat pumps, heating mode.
The smaller rooms of these floors will be conditioned with fan-coils and primary air. With regards to the floors above, used as offices, it was decided to adopt a mixed system of fan-coil and primary air and AHU's installed on the same Tech Floor Group 1. The fan coils will be ideally positioned above ceiling with a modular pattern in order to obtain the required space flexibility, ie allowing to organize the area both as an "open space" or as traditional individual offices.
• With respect to the technical floor Group 2, between the residential floors and the hotel floors, the equipment for these two functions have been located. In this case a direct-expansion air conditioning systems with variable refrigerant volume (VRV) was adopted, and in particular, a technology powered by anendothermic engine (fed by methane), which allows a great recovery of heat from the engine cooling plant. This heat can be exploited for the production of domestic hot water, a key issue especially for the hotel.
With this type of technical approach, we estimate that about 80% of the heat required to produce hot water will be provided free of charge from the heat recovery described above. The remaining 20% will be produced by thermal plants with solar panels.
• Concerning the electrical installations of the building, they will start from the transformer stations placed in the 1st basement floor from the adjacent Low Voltage Main distribution panels (LVMP).
Near the transformer units will also be positioned back-up power generators with automated transfer switches in case the prime power supply fails.
Through the vertical shafts, the Low Voltage cables will feed the different sectors of the building with individual independent systems.
• At the basements floors -2 and -3, water tanks for fire protection purposes with pressurization systems will be located. The entire building will be protected by fire hydrants and portable fire extinguishers;"sprinklers" will be installed (in addition to the hydrants) inside underground parking and plans and in thickly crowded areas i,e. Commercial floors, restaurants lobbies and reception.

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