Keywords

1 Introduction

In architecture, sustainability is an important approach that each building should achieve to help saving the environment. Develop and change of building’s facades are linked with new ideas related to style, environment issues, availability of materials, technological application, time and building deterioration. Extreme climates require extreme design response: a need to re-think building envelops in a more sustainable, eco-responsive manner. Hot climate areas are one of the most important to consider the sustainable facade to resist the heat and protect the environment through energy efficiency solutions.

The reason behind choosing this topic to explore is the high importance of achieving sustainable design in building’s design and save the environment. The building facades play an important role in the technical performance as they are the largest and most important elements in buildings. Moreover, facade design is the link between the building’s interior and the exterior environment, in addition to being a deciding factor for architects to help them selling the idea to the client, as a result, I focused in my research on the building’s facades only.

As the UAE has a very hot and arid climate, it is very important to take benefit of the façade design to provide shading for the building’s occupants and reduce the energy consumption that is needed to cool the air inside the building. The strategy of façade design is to control the heat gain by preventing the sun heat to come into the building, while allowing the daylight and views. In addition, all windows that are located within the sun path should have shading elements that will prevent the harsh sun from coming inside the building and heat the indoor environment (GUIDE, 2009).

The aim of advanced façade systems can be summarized as follows:

  • Making natural daylight and light levels available hence offering visual comfort

  • Providing access to external views.

  • Achieving efficient level of thermal comfort.

  • Reducing energy consumption required for heating/cooling and lighting (Kambil, 2009).

In accordance to the Energy Information Agency (EIA, 2000), energy consumed due to a building’s running costs including lighting and thermal control accounts for approximately 84% of energy consumption of the building over its lifespan. As building’s facades separate between outdoor and indoor environments, the degree of success in accomplishing high efficiency thermal control in a building is highly dependent on the process selection, design, and selection of materials (Kambil, 2009).

2 Literature Review

2.1 What is a Living Architecture Façade?

The term of living architecture facade has been recently adopted in architecture to learn and mimic the design of natural systems. Rachel Armstrong, applied scientist, innovator and professor at the Bartlett School of Architecture, University College London, said that a living architectural façade consist of reactive systems that react to the different changes and effect on achieving the comfort levels indoors and outdoors. The only possible way to construct living architectural facades is by connecting them to the environment, not insulating the building’s interior form exterior nature through the facade. R. Armstrong added that this development of facades is going to take a while, but gradually it will lead us to a sustainable connection between the buildings and the natural world (Armstrong, 2009).

According to Lindsey Kindrat, Owner and Director, Principal Sustainable Building Specialist, she said that we are all afraid of green buildings, although our target is to make our lives green and apply the right thing, but we are losing the connection with nature. The main goal of green buildings is to let nature in and connect the residents of buildings with the environment. (Kindrat, 2013). Emma Flynn, a practicing architect, and design researcher at London-based architecture practice Astudio, explains that living systems, unlike the majority of the machine-like building stock contributes positively to the biosphere, playing an essential role in wider ecosystems linked together through nutrient and energy flows. It is this collective nature that guarantees survival. By incorporating fundamental dynamic processes found in living systems, architecture has the potential to adapt or respond to changes in climate, seasons, or extreme acts of nature, just as our natural green landscapes respond to the availability of water, sunlight, and wind (Flynn, 2016). On the other hand, Katia Perini, Marc Ottelé, E. M. Haas, and Rossana Raiteri, are faculties of Architecture at University of Genoa Stradone S. Agostino - Italy, they agreed that living architectural facades refer to green facades (Katia Perini, Marc Ottelé, E. M. Haas, Rossana Raiteri, 2011).

All the above theories have somehow linked the concept of “Living Architecture Facade” to Sustainability, flexibility, adaptive capacity, sensor technology, integration of installations and façades, building management systems, renewable energy and the development and management, maintenance, and operational services during the lifespan of the buildings (Ulrich Knaack & Tillmann Klein, 2009).

2.2 Characteristics of a “Living Architectural Façade”

The Living Architectural Façade provides links between indoor and outdoor environments, which both emphasize comfort resulting in positive effects such as energy generation (renewable energy), expressive and aesthetic experience resulting an ideal working environment along with productivity levels. Moreover, the facade of living architecture designed as a zone or space with different facilities in addition to the original protective shell facility. The facade is considered as a transitional space in a way that it adjusts and combats all the undesired outdoor effects on the indoor environments and vice versa. In addition, it has the ability to adapt and balance between the indoor and outdoor environments based on their situation. The facade of living architecture is intelligent living system that can adjust itself to different possibilities through technology or changes in demands. As a result, the living architectural facade is considered sustainable as the specifications, engineering and developments depend on this desire to be adjustable, as well as focusing on the functionality and technology to modify the overall appearance and material use (Ulrich Knaack & Tillmann Klein, 2009).

2.3 Limitations of a “Living Architectural Façade”

Developers and designers still do not see the value of living architectural facade other than providing luxurious and iconic view to the building. In some types of facades, it is too expensive in terms of providing the design, operational cost and the maintenance, and the payback will be on the long term. In addition, many developers and owners still do not understand the need to protect our natural resources like saving the water or energy. However, everyone in the society should do their role to enhance the building sustainability and save the natural resources of environment, because every little bit counts (Kindrat, 2013).

3 Case Studies of Sustainable Skins in the UAE

3.1 The Masdar Institute’s GRC Residential Facade

The Masdar Institute is the first phase and development to be built in Masdar City to house residents and it is completely powered by renewable solar energy. The GRC material was the selection choice as a construction material for the Masdar Institute to match with the sustainable context of the city. The main purpose of using GRC that it will dispense the material transport and embodied energy, because it can be made locally in Abu Dhabi. The main goal of designing the façade was to respond to their orientation, provide shading to the interior environment of the building and to the nearby buildings and streets below as well. These required using computational modelling techniques in addition to the physical techniques to help choosing and finalizing the form of building. The facades consist of multiple layers, containing external screen layer with balconies, insulation layer and inner façade. These layers provide functional response to deal with UAE’s desert environment, while the external balconies provide good shading to what is below, as shown in Fig. 1 (Palmer, 2011).

Fig. 1.
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The Masdar Institute’s GRC Residential Facade - Different exterior shots for the curved forms of the Institute’s GRC residential facade - (Palmer, 2011)

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3.2 Siemens Middle East HQ

The Siemens Middle East Headquarters, located in Masdar City, achieved LEED platinum certificate, and considered one of the first buildings in the region. The design of the building combines the traditional design and parametric analysis to provide a compact and efficient form that achieves sustainability through using fewer materials and reduces the embodied carbon (Siemens HQ in Masdar City/Sheppard Robson, 2014).

The envelope design of the building presented as a box within a box, as shown in Fig. 2. The inner layer designed with highly insulted airtight facade to minimize the thermal conductivity. The exterior layer covering this inner layer will be an external lightweight aluminium shading element which helps in minimizing the solar gain and allows for daylight to enter the interior environment along with the maximizing the views from the building. The external shading system consist of lightweight aluminium fins that provides a strong architectural language for the building as each facade designed to suit its solar orientation (Siemens HQ in Masdar City/Sheppard Robson, 2014).

Fig. 2.
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Siemens Middle East HQ - The details of the External shading system in the Siemens Middle East HQ- (Siemens HQ in Masdar City/Sheppard Robson, 2014)

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3.3 Al Bahr Towers in Abu Dhabi, UAE

The main design goal of Al Bahr towers was to achieve an environmentally friendly project with sustainable features that can withstand in the world’s hottest climates, in addition to full response to the cultural and environmental context. The design was achieved using outer skin “Mashrabiya” that covers the two towers on the west, east, and south side that are automatically open and close in response to the sun path over the surface. The dynamic shading device is programmed to respond to the sun path, providing shade in the morning to the eastern side of the building and moving towards the western side with the sun throughout the day, as shown in Fig. 3 and 4. The sustainable towers achieved 50% reduction in the energy consumption and 80% reduction in the solar gain within the two towers. The project is a landmark in Abu Dhabi and crowned as the “Best Overall Project in the Middle East” (Al Bahar Towers, Abu Dhabi, 2013).

Fig. 3.
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Al Bahr Tower - The 1049 Mashrabiya shading devices are programmed to respond to the sun path- (Al Bahar Towers)

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Fig. 4.
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The layers of Al Bahr Tower’s façade skin- (Al Bahar Towers)

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Reference to the mentioned examples earlier, there is a strong connection between the architectural design and the environmental thinking in the façade system, where sustainable principles can be applied to achieve the Living Architectural Façade design. The Living Architectural Façade can contain a combination of electronic devices, building components and mechanical installation. As the UAE has hot desert climate, it is important to take into consideration the type of façade used in the buildings, as the façade should resist the harsh sun while providing natural light, ventilation, access view to the exterior and achieve the energy efficiency of the building.

4 Methodology

The case study of Baynunah Hilton Tower will be used to study and apply the energy simulation on the facades using the computer software “FormIt”. This will include analysing the energy performance of the facades for the base case scenario, and next applying the four design principals to analyse the façade performance in terms of energy efficiency.

4.1 Case Study

The Baynunah Hilton Tower shown in Fig. 5 is a landmark in Abu Dhabi, two kilometres away from the city centre, located on the coast of Abu Dhabi Corniche. It has been constructed in 1995 and considered as the tallest building in UAE at that time and remained the tallest until 1999. The main intention of the architects in designing this tower was to provide dynamism when looking to it from different angles. The tower consists of three wing towers 25, 31, and 37 floors and structured around a cylindrical core that rises to 42 floors (BESIX).

Base Case Scenario:

The Baynunah tower consists of drilled reinforced concrete piles as a foundation with a concrete structure was built on top of it. The three-winged towers are covered with blue tinted glass curtain wall façade, while the three outer cylinders have concrete facades decorated with arabesque motifs. The interior’s finishing of the tower contains a usage of large amounts of marble and high-quality granite (BESIX).

Energy Performance and Modelling:

An energy performance analysis has been done on the base case scenario of the façade for the Baynunah Tower using FormIt software. Figures 6 and 7 show the analysis results using FormIt software. The building consumes 428 Kwh/m2/Yr of energy. The solar heat gaining on the façade is ranging between moderate to high percentage, while on the roof is gaining high percentage of solar heat. The tower’s facades are gaining a lot of solar heat all over the year, specifically in the months of June, July and August, where the electricity consumption reaches the highest point. As the façade is fully glazed with no external shading or additional layers to prevent the heat gain, the tower has high electricity consumption. The tower has high energy consumption with high Co2 emission, where they can reach to 3,000 metric tons/Yr. Due to the façade type and the lack of any energy generation in the building.

Fig. 5.
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The Baynunah Hilton Tower in Abu Dhabi – North elevation and ground floor plan.

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Fig. 6.
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The 3D of Baynunah Hilton Tower model on FormIt with the energy consumption test for the existing facade - FormIt

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Fig. 7.
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Year Cumulative Solar analysis for the facade of The Baynunah Hilton Tower - FormIt

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The three-winged towers are covered with blue tinted glass curtain wall façade, which allow for large amount of solar heat to pass through it inside the building as appearing the analysis previously. A new external layer will be proposed to be as a screen between the existing glass curtain wall and the external environment surrounding the tower. The material of this external layer will be lightweight aluminium and will consist of arabesque pattern that acts as shading element to help in minimizing the solar gain while allowing for daylight to enter the interior environment along with maximizing the views from the building. The arabesque pattern idea is derived from the three cylinders which have concrete outer facades decorated with arabesque motifs; this will provide a strong architectural language for the building as the same arabesque pattern will continue on the glass and concrete side.

4.2 Proposal for Sustainable Retrofit for the Façade of Baynunah Tower

By using FormIt software, an energy performance analysis has been done on the new proposed facade to test the difference between the existing facade and the new design in terms of energy efficiency. As per the Fig. 8, the new added layer is enhancing the energy efficiency of the building. The amount of energy consumed through this design can reach 263 Kwh/m2/Yr.

Fig. 8.
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The 3D of Baynunah Hilton Tower model on FormIt with the energy consumption test for the new proposed facade - FormIt

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The Table 1 shows the difference between the existing façade “blue tinted glass curtain wall” and the new proposed layer for façade “Light-weight Aluminium with Arabesque pattern” in terms of solar heat gained using Revit software.

Table 1. The difference between the façade of the base case scenario and the new proposed façade in terms of solar heat gained.
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The added layer is affecting positively on the energy performance of the building, reduces the amount of CO consumption, saves the electricity bill, and protects the non-renewable energy to save the environment. Figure 9 shows the difference in energy consumption between the existing facade and the new proposed facade. The energy consumption reduced by almost 38% after applying the retorting design to the façade.

Fig. 9.
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A Comparison between the existing façade and the new proposed one in energy consumption Kwh/m2/Yr.

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5 Conclusion

To conclude, applying sustainable design in the projects plays an important role in saving our non-renewable resources and the environment. As the population is continually increasing, the CO2 emission and the amount of energy consumed will be increased as well. As a result, the next generation will face problems in surviving in such a damaged environment. That is the reason why all projects should be designed using sustainable strategies to enhance and save the green environment, protect the resources, and minimize the CO2 emission.

The UAE is one of the countries that took an immediate action after paying attention to this issue to solve and reduce the overall energy consumption of the country. The Living façade acts as a concept for change, where a new direction in the façade sector have been represented and developed. The living façade features and solutions require using the most advanced technological capabilities to test the design before applying it on the site. The Living façade acts as a concept for change, where a new direction in the façade sector have been represented and developed. The living façade features and solutions require using the most advanced technological capabilities to test the design before applying it on the site. The living façade contains a combination of electronic devices, building components and installation. At the end, the goal of sustainability is to provide possibilities and not limiting the options. All people are responsible for their actions toward the environment to achieve an environment that doesn’t need protection. Architecture and sustainable strategies should be linked together when designing the facades of buildings.