Facades give you the first impression of a building. The facades expose the unique of the particular building as well as being a part of larger context with the neighboring building characters in the cityscape, together with balanced masses arranged in the skyline of a city. You may experience the facades aerially, passing by with a high speed vehicle or walking around on foot. All scales to be taken into careful consideration in the context of architectural process in order to create an impressive & well functioning space.
The facades should all be treated different from one another. Some should even be treated differently in both shape & materials. Architectural treatment of buildings include form, materials, colors, transparency & shading and should be varied in respect to orientation to enhance energy saving opportunities. A sustainable design approach towards ecological balances & green architecture is always encouraged. Material & colors are naturally integrated parts of the façade architecture. As each façade contributes the overall context, creating a balance between colors & materials.
The use & special requirements for each building influences the architecture of facades. Careful consideration is taken, as how public & retail areas impact the facades. It totally depends about the main use & function of a building, replicating pedestrian movements in & around the building structures. Special requirements for the transparency of the facades in areas where facades should be open & welcoming in order to create a vibrant city.
As the facades shape the perceptions of the building & its context, they also serve the crucial function of a building providing shelter from weather & climate. The specific geographic conditions in Kingdom of Saudi Arabia & Middle East require special consideration in order to make shade on the facades & when selecting materials for the facades. Sustainable solutions are highly recommended for such situations.
CATEGORIES OF FACADES
The facades are described according to different categories, which depends on situation to situation & volume of work & development. Broad classification is as stated:
Landscape Facade: Landscaped areas to constitute an urban space , a cross point for people to meet for informal meetings , to have a break during the day or a day off with family, children & friends. Such green areas are somewhat to relax with the possibilities of hardscape elements, other landscape furniture around the building structures in the form of external areas.
Access Roads: The access roads supply the attractive green urban space while effectively managing a large amount of traffic. Buildings on such locations are highly exposed. The access roads are the internal road network from where all vehicular movement is distributed.
All buildings must be located within required building line. Building lining the access roads must sharply define corners, roads & squares. All facades on all buildings should be considered equally important architecturally. Front, side & rear facades shall have equal level of architectural quality. Building lining the access road sharply define the pedestrian area. The facades facing the access roads have their own identity. At lower level the façade shall be open & transparent towards the access roads
Streets: The streets are more local & have a lower speed limit. Supplying an attractive green urban space while managing the traffic. All buildings facing the streets must be located within the required building line. Building lining the streets must sharply define these & the pedestrian areas. The street facades have their own identity.
Cul de Sac: Cul de Sac is somewhat a pedestrian area with minor restaurants, retail spaces & tit bit shops & kiosks together with informal seating areas. All buildings must be located within the required building line. Buildings lining the Cul de Sac sharply define the pedestrian area. The facades towards the Cul de Sac will have their own identity. All facades of all buildings shall be considered equally important architecturally. Front, side & rear facades shall have equal level of architectural quality.
USE OF SOLAR PANELS ON FACADES
Solar panels can be used in the design of the facades in several ways which can reduce the overall usage of fossil fuels and CO2 gas emissions:
Outdoor shading: Recent advancements in solar energy have led to the development of various types of solar panels that can easily be mounted on the building envelope while maintaining the overall aesthetics of the structure. Solar panels not only contribute to the quality of the urban spaces by reducing CO2 gas emission & also serve the purpose of building grace with architectural form & identity. Outdoor parking space can be covered with photo-voltaic panels which can be used as shading devices for cars while producing energy which can be consumed for local use.
Solar panels produce energy at full capacity when placed perpendicular to sunlight. Outdoor parking spaces give the advantage of using panels more efficiently as they are placed on flat horizontal surface.
Solar cells as shade for the interior space: Photo-voltaic panels can also be used in interior spaces where light is not available frequently. New technologies have allowed the development of transparent photo-voltaic panels that can be used for interior design purposes. These panels come in different colors and sizes that not only beautify the interior space but can also generate energy in dim/low light conditions. Such panels can be used in walkways and entrances where sunlight manages to transmit through exterior glass of the building. Triple glazed insulation units is one the advancements that needs special attention when designing the interiors of a building.
Integration on façade: Solar cells can be integrated as the primary material on façade or as secondary material on or in another material.
Maintenance for Solar Panels: Solar panels need regular cleaning & maintenance for them to sustain an optimal functionality. Both the solar panels on the roofs & the solar panels that are incorporated in the facades need special attention. Dust, sand dirt & pollution can cover them with a layer that prevents them from absorbing sunlight and affects efficiency.
Horizontal roofs are highly recommended as location for placing solar cells. Vertical facades may in some places be acceptable for placing solar cells. It is not recommended to place solar cells on the lower levels, because of shadows projected generally on such levels.
THERMAL INSULATION FOR BUILDING ENVELOPE
The parameter variation for thermal insulation regarding the building envelope is simulated without insulation & with an insulation thickness of 50 to 100 mm. In the thermal simulation the selected insulation material is expanded polystyrene with a thermal conductivity at 0.038 W/m2K. With a thermal insulation of 50 mm it is possible to minimize the cooling requirement & the total energy consumption with 30%. As a result, an insulation thickness of minimum 50 mm is recommended as the optimum thickness irrespective of the insulation type.
THERMAL INSULATION FOR WINDOWS
The parameter variation for thermal insulation regarding windows describes the effect of different window types. The model is simulated with three different thermal transmissions coefficient:
1. Single glazing – 5.8 W/m2K
2. Double glazing – 1.8 W/m2K
3. Triple glazing – 1.0 W/m2K
By choosing double glazing compared to single glazing it is possible to minimize the cooling requirement & the total energy consumption with 20%. As a result , a window type with a thermal transmission coefficient <1.8W/m2K (double glazing) is recommended as an optimum solution.
NIGHT COOLING & VENTILATION
In a hot desert climate like Riyadh, Saudi Arabia high thermal mass with night ventilation can provide comfort even with high daytime temperatures because of low relative humidity & large diurnal temperature swings. The aim is to achieve an acceptable indoor climate with a lower cooling demand during the daytime.
The model simulates without night cooling & with air flows twice & four times per hour. Night cooling can be an effective solution to minimize the cooling demand. As a result, night cooling with airflow at minimum 2 times per hour is recommended as a good solution.
TRANSPARENCY OF FACADE
The parameter variation of transparency of façade describes the effect the window area has on the total energy consumption. The model is simulated with a dynamic span between 20% & 80% window areas of the outer wall. The effect is illustrated for the south & north oriented facades respectively.
Total energy consumption when the façade becomes more transparent – As a result, a window area of outer wall between 15% to 30% is recommended as an optimum solution for the south oriented facades.
Total energy consumption when the façade become more transparent – Compared to south façade, it is less dramatic. As a result, a window area of outer wall between 20% to 50% is recommended as an optimum solution for the north oriented facades.
To meet the increasing demands of low energy consumption & a comfortable indoor environment & the general wishes for more sustainable buildings a prioritized design practice has to be adopted. An approach is suggested, focus on increasing the quality of indoor environment because of the amount of time we spend inside & the economic benefits obtained from higher productivity.
Indoor air quality of a building varies. It is influenced by changes in building operation, occupant activity & outdoor climate. However it can be controlled by a combination of efficient source control & ventilation. To ensure a high quality of the indoor environment, & thereby ensure a high productivity. Is it very important to employ different design technologies at an early stage. All things effect each other, so it is not only a matter of designing an efficient ventilation system, as one also has to design a proper fenestration & shading system with regard to maximum daylight & potential overheating & choose materials with low emission rate. To ensure a high standard of the indoor environment & indoor air quality a prioritized method has to be adopted & all parameters effecting the environment taken into account.
INTELLIGENT DESIGN OF BUILDING ENVELOPE
The indoor environment is also affected by the thermal environment in the space. The thermal environment depends on several factors & is generally controlled by an efficient heating & cooling system. The heat gain from the sun may in periods effect the thermal environment & cause high temperatures in the space or in defined volume. Therefore, efficient shading has to be designed & implemented at an early stage.
The controlled distribution of daylight in buildings is a cornerstone of sustainable & low energy design. Day lighting is a key to good energy performance, as well as occupant satisfaction, productivity & health. Day lighting must be addressed early in the schematic design because requirements for successful day lighting usually has major implications for building massing & zoning activities.
It is rather important to distinguish between direct sunlight & diffuse daylight. In most situations, direct sunlight causes excessive heat & light leading to visual & thermal discomfort. Natural daylight affects the need for artificial lighting, & with an effective use of the general daylight levels the cooling demand may be reduced to a reduction of the artificial lighting. By this assumption the total energy consumption may be reduced. Effective use of natural daylight includes a proper shading strategy that has to be implemented at an early stage. Knowing the applicable path of the sun round the year allows the designer to create a shading device, which provides shade when necessary.
In warm & hot climate like Saudi Arabia & Middle East a well designed & effective shading strategy is very important. Shading devices can reduce building heat gains from solar radiation significantly while maintaining opportunities for daylight, views & natural ventilation. The focus for placing shading devices is often on the window or skylight, but walls & roofs may also be shaded to help reduce heat gains through the opaque building envelope.
By implementing solar shading in early stage of the design process the overall cooling demand can be lowered. Different strategies & technologies are available, before implementing the right solar shading. Following requirements shall be considered:
· Protection of direct sunlight – to ensure that direct sunlight does not penetrate the building.
· Control of glare – the system should not only prevent direct sunlight, but should also control glare. This is of essential importance in offices, where computer screens are used.
· Control solar gain – the system should reduce the level of solar gain entering the building. Installing the shading system externally, can reduce solar gain by up to 95% reducing or even potentially eliminating the need for air conditioning.
· Maximization of natural daylight – when external light level is low, the shading system should be able to be retracted to optimally use of the natural daylight available.
· Protection from cold – the shading system should be able to help insulate the building by reducing the amount of light cooling during winter months.
· Communication – the system should allow a view to the exterior ensuring that the building occupants do not feel cut off from the outside world & their surroundings.
· Different solutions for shading have been chosen – without shading / internal roller blinds / coated glass / fixed internal blinds / dynamic external blinds / façade depth / overhang / double skin façade / double skin façade with fixed external blinds.
Using of different types of solar shading it is possible to lower the total energy consumption with 15% to 30%. As a result, external solar shading like horizontal blinds or well designed overhang should be considered as integrated parts of the façade design. A shading device should not compromise the other amenities that a window can provide – namely daylight, views & breezes. External shading devices do not necessarily have to be separate objects attached to a building exterior. Recessed window openings & façade geometry can allow a building to act as its own shading device.
Lighting concept usually focus on the design themes of overall architectural massing, defining vertical & the separation of architectural volumes. Main entrance having its own importance, perhaps integrating dynamic & animated lighting installations. Low level lighting to establish a strong base for the upper volume & to establish a reference for pedestrian movements in & out of the building structures. The main facades glow at night through the interior usage , emphasizing the function of the building.
The lighting to the landscape creates a strong but calming atmosphere & responds to the functional approach of public & semi-public areas. Lighting to trees & water features enhances the feeling of being in an outdoor space. Lighting at the pathways provides functional illumination as well as a strong effect with the character of individual space.
City of Riyadh in Saudi Arabia is lucky to have abundant global solar radiation, which causes the climate to become hot & dry. The average solar radiation is 6 kWh/m2, which is much bigger at least three times as compared to European countries. One of the key issues when making sustainable designs is therefore to harvest the vast amount of solar energy & deploy an effective shading strategy to reduce overheating. In general special consideration to be taken to optimize the energy consumption of the buildings & extensive measures have to be taken in order to create a comfortable climate & environment.
Internal & external spaces combine & work together, creating a lively & comfortable hierarchy of interior defined volumes & exterior unlimited three dimensional space dominating the human scale & identifying the miracles of our great nature.