Architects and engineers are challenged to create modern facades that set buildings apart, provide views and natural light, but are also energy efficient and functional. This is why technologies for facade design are advancing rapidly and professionals are considering algorithms to deal with complex designs.

The expectation of modern facades is multilateral. Not only do they define buildings in terms of aesthetics, but they have to perform on many different levels to protect the building against weather extremities, regulate thermal comfort inside the building, let in natural light but minimise glare, contribute to energy efficiency and limit the building’s overall carbon intensity.

Therefore, facade materials are typically at the forefront of technological advances and innovation. And to realise ambitious architectural designs, facade engineers are pushing the boundaries where pre-made systems just don’t cut it.

In a competitive world, and with demands from regulations, clients and more, developers are looking to create more ambitious and more iconic buildings. According to a whitepaper presented at the Facade Design and Engineering UAE Conference, realising this kind of ambition requires the design and delivery of next-generation facades that present the finished building in a way that resembles the architect’s vision as closely as possible.

In South Africa, facade engineers are more and more being challenged to design bespoke systems, especially in terms of shading, as architects are incorporating external shade screening into the architecture as definitive features instead of add-ons. Nothing is left as an afterthought.

As such, facade design is developing fast with technologies and construction materials (old and new) demonstrating their potential as part of advanced facades around the world. Some of these, which were highlighted at the Facade Design and Engineering UAE Conference, are:

3D printing
Although 3D printed materials still cost much more than regular brick and mortar, it is already having a huge impact in the fields of architecture, engineering and construction, and applications are extending further every year.

Imagine the possibility to keep heritage buildings exactly as they were – when renovating, one could just scan the interior and print a new infill. Imagine affordable housing developments being 3D printed, with potential savings in time, labour and transportation.

Since the first fully 3D printed building was completed in 2015, the implications for facade design in terms of aesthetic, sustainability and cost-savings have become even more real.

One example is the white facade at the entrance of the Europe Building in Amsterdam, which was 3D printed using bio-plastic made out of linseed oil. Inspired by the sailing ships that used to be built in the area, the waving facade was parametrically designed by DUS Architects, and thanks to the precision of computer design and printing, it features benches that slot in perfectly into the alcoves. The seating has a concrete finish, showing how old and new techniques can be combined.

Fire-prevention technologies
The fire that destroyed the upper floors of a Dubai skyscraper early in 2015 has emphasised the need for building materials, especially cladding, that are safe and adhere to the highest standards. Generally, solid walls are a good choice to increase a building’s fire rating, but with the rising popularity of glass facades, improving the fire resistance and other protective elements of facade glass has become a much higher priority.

Examples like wired glass, specially tempered glass and glass ceramics can prevent the spread of fire and smoke, but won’t stop radiant heat transfer. For fire-resistant glass that prevents the spread of fire and smoke, as well as stops radiant and conductive heat transfer, a laminated assembly is generally created, which combines layers of glass with heat-resistant interlayers.

To create smoke vents in an unbroken glass facade, parallel-opening vent windows can be installed and automated so that the entire casement moves sideways and outward to allow for efficient air exchange.

Solar glass
Everyone wants views and natural light, and now the technology of solar glass can turn glass surfaces into unobtrusive photovoltaic solar cells that can transform solar energy into electricity. According to solar glass lead researcher at Michigan State University, Richard Lunt, it can be used on windows of buildings and even mobile devices such as phones and tablets.

The main constraints so far have been commercially unviable efficiency rates and the achievement of only partial transparency. But recent prototypes have achieved complete transparency with no colouration of dispersed light. Although efficiency rates remain low between 1% and 10%, a whole building facade composed of solar glass would still make an impact, such as at the Copenhagen International School.

Designed by CF Møller Architects, the school’s facade is covered in 12 000 solar panels, each individually angled. Intended to supply more than half of the school’s annual electricity use (about 300Mwh per year), the solar cells cover 6 048m², making it one of the largest building-integrated solar power plants in Denmark.

Electrochromic glass
The downside to lovely expansive views offered by glazed facades is the heat gain, which subsequently causes buildings to use lots of energy to keep cool on warm days. But what if the facade could adapt to the conditions, both inside and out?

Electrochromic “switchable” glass can be dimmed to block sunlight to regulate lighting and temperature inside a building. This is achieved through applying voltage to the glass panels, which activates an ultra-thin layer of tungsten oxide nanoparticles and makes them turn blue and reduce translucence.

This technology has been installed on 1 000m² of the Festo Automation Centre in Germany. The 441 sandwich panels are “switched” on and off automatically by a facility management system in response to a signal from sensors, and take about 20 to 25 minutes to change from the brightest to the darkest colour. When dimmed, only 12% of the light can get through, while the rest is reflected. In addition, the 8 500m² glass facade has been designed as an exhaust air facade where the air is continually siphoned off between the inner anti-glare shield, aluminium components and glazing, which prevents heat to transfer into the building.

Traditional materials
Even manufacturers of traditional facade materials and cladding are working to advance their product for better performance or integration with new technologies, as well as to ensure that manufacturing processes are sustainable and environmentally friendly.

But it is not only the materials that are advancing. Processes to keep tabs on all the different requirements for performance and aesthetics are also important.

5 steps to creating a high-performance facade
Engrossed in high-performance design with a mission to promote sustainable buildings, software company, Sefaira, has set out five steps that will facilitate the design of an optimised building envelope:

1.    Determine the building’s energy profile
Understand the building in context and take into account the impact of surrounding structures, area-specific weather and the use of the building on its performance. Run analyses on the modelled building to identify problematic energy loads and determine which issues are most important to address. For example, a high heat load would require strategies that reduce heat loss, such as air tightness or insulation.

2.    Find the best glazing ratio and location
Glass gives a building a modern feel and clients often want the greatest views possible, but it is imperative to specify the appropriate amount of glazing to intelligently manage solar gains. An ideal design would affect sufficient illuminance and views, low glare and low energy use.

3.    Consider shading
To address glare and unwanted heat gain, it is important to align the shading strategy with the architectural intent and consider the building context. Different shading devices should be investigated to determine their implications on the aesthetics.

4.    Investigate materials
To retain optimum daylight levels, but keep glare to a minimum and reduce energy use intensity, the right kind of materials, as well as appropriate wall thicknesses and more, need to be specified. The properties of materials that need to be tested are thermal mass, wall structure and type, U-values, glazing SHGC, insulation, ventilation strategies and more.

5.    Design and repeat
In taking each of these steps, some factors will prove to have a greater impact than others, differing from building to building. Continuing the design, architects should use performance feedback to inform their decisions. Testing their ideas will help them to understand the trade-offs between their design and the building’s performance. Using the combination of robust data and creativity can produce a high-performance outcome.

Using algorithms in facade design
As the demands on structures and the methods to design these become more complex, so does the calculations. Sushant Verma, former architect at Zaha Hadid Architects, computational designer and founding partner and research head at rat[LAB] – Research in Architecture & Technology, explains that when designing a building facade, all the parameters including environmental conditions, structural feasibility and materiality can be quantified as data, which in turn can be used in computation to deal with the complex dynamics of design.

He notes that using an algorithmic method of designing a building skin or facade can help control the parameters and data embedded in design, and use this data to optimise the system for various criteria. “In facade design, an algorithmic approach is helpful to have a rational control on design fabrication data, assembly process, material usage and cost,” he states.
The process of a genetic algorithm

Genetic algorithms have several basic elements that follow a logical process of selection, crossover and mutation. If the end-result doesn’t fit the criteria, the algorithm loop restarts, using the new offspring as the initial population.
Source: www.interactivearchitecture.org

Architectural adaption
Compared to other ways for optimisation, such as Hill Climbing, Simulated Annealing and Artificial Neural Network, Siyuan Jing, architectural designer and master degree student at the Interactive Architecture Lab, says he found genetic algorithms to be most suitable for architectural adaption since they could generate numerous adaptive possibilities, provide methods for kinetic architectural structures to behave efficiently and have the functions to satisfy architectural optimisation.

“People may argue that the random seeking method is unconsidered, without contextual cognition. However, because of the elimination system based on the fitness criteria, not every random chromosome is able to evolve to participate in the next computing loop. Therefore, the fitness criteria is a crucial element for humans to control the computing process, in order to achieve the architectural evolution and optimisation,” Jing explains.

Keep in mind
However, algorithmic designs and building simulations aren’t without limitations, warns Witold Rybczynski in his article “Parametric design: What’s gotten lost amid the algorithms”.

He explains that existing building simulations treat aspects such as heating, air-conditioning, ventilation and daylighting separately, rather than as integrated wholes. Also, while heat and light are relatively simple to model, something like natural ventilation involves many unpredictable, external variables and has so far resisted precise modelling.

In addition, while it is simple to calculate the R-value of a wall or the reflectivity of a surface, research on modelling human behaviour is still in its infancy, but the fact is that building occupant behaviour such as opening and closing windows, raising and lowering blinds, switching lights and other electrical equipment on and off, and adjusting thermostats greatly influence the dynamic energy performance of the building.

“Somewhere between the vagaries of parametricism and the analytical precision of building simulation lies the Holy Grail: Design informed by data gleaned from how buildings actually perform, and how people actually behave in them. This would require integrating building simulations, creating interaction between different domains, incorporating a myriad of variables and, above all, devising a dynamic approach that accounts for the vagaries of human behaviour, both over time and between individuals,” Rybczynski states.

Full thanks and acknowledgement are given to www.facades-uae.com, www.steelconstruction.info, DUS Architects, www.cfmoller.com, www.glasstec-online.com, Sefaira, architectureupdate.in, www.interactivearchitecture.org and www.architectmagazine.com for the information given to write this article.

In this article:
–    Materials for facade design.
–    Five steps to creating a high-performance facade.
–    Using algorithms for complex design dynamics.
–    Project highlights.

Caption: 3D printed facade
The facade at the entrance of the Europe Building in Amsterdam was parametrically designed by DUS Architects with large-scale bio-plastic 3D prints. The facade resembles sails of ships previously built in the area, with 3D printed benches in the European Union (EU) blue inserted in the alcoves. The design was specifically done for the Dutch EU Presidency 2016 and printed locally with the XXL 3D printer of the 3D Print Canal House in Amsterdam. This life-size printer can print elements up to 2m x 2m x 3,5m. Innovatively, the bio-plastic can be shredded and reprinted after the presidency is over.
© Ossip van Duivenbode