In the history of architecture, a number of outstanding glass-designs have transformed the profession. The 1922 competition entry for a transparent high-rise in Friedrichsstrasse, Berlin by Ludwig Mies van der Rohe is one such example. Although technically not feasible at the time, the design manifested a powerful vision for the future of high-rise buildings and the use of glass as a transparent building material.
Cover Image: The Glass Pixelation, P.C. Hooftstraat 140-142, Amsterdam, 2017-2019 ©Evabloem
Since then, we have witnessed the development of a large variety of design applications, alongside very extensive industry developed facade systems and structural glass solutions that push the boundaries of what is possible with this magical material. There have also been significant advances in laminating and fritting techniques, alongside technical advances in insulating and applying heat-reflective layers in order to prevent heat gain and energy loss in buildings. Visually combining transparent properties with physical properties (such as a gas layer, fritting, interlays etc.), has led to the performance improvement of buildings from which ultimately its users benefit.
As such, glass is undoubtedly one of the most versatile building materials in use today. For architects, it is a long-lasting material that provides opportunities for the development of innovative, energy efficient building envelopes for both new build and renovation projects. The possibilities to recycle glass for various further uses makes it an extremely environmentally friendly and circular material. However, for the end-user, it is the most apparent property of the material, its transparency, which makes it essential for the quality of the spaces we live and work in.
Renovating, Retrofitting and Remodelling
Today, we are increasingly witnessing a new awareness of the benefits of retrofitting buildings, rather than demolishing and replacing them with new builds. This is especially true in Europe and in several large cities in Asia. Increasingly, developers are seeing both the environmental and the economic advantages of remodelling buildings, while integrating new sustainable strategies. In fact, for some clients, a retrofit-in-place is actually a more affordable and reliable option when a building is in need of renovation, while for designers, the goal of such projects is also to provide long-term value.
If we retrofit and remodel existing buildings, we are doing so to expand the lifespan of these structures. However, one day these new retrofits will also become ‘old’. As such, when updating facades today, we also have to consider how adaptive these will be in the future and plan ahead from the outset of the design.
In order to do this successfully, we need to devise integrated solutions during the design phase. This includes the integration of technology beyond that already being developed by the glass industry. Technology can of course simply be approached as an add-on, but we do not believe that this approach is sufficient to truly exploit the magical properties that glass has to offer. In fact, one way or another, we consider the integration of technology in our design approach essential for a project to succeed.
In this article I will use four remodelling projects carried out by UNStudio to illustrate the different roles that glass and the integration of technology have played in adaptively retrofitting existing buildings to prepare them for the future.
Galleria West Luxury Hall Departments Store, Seoul
While with every new build it is good practice to apply the most technically advanced facade systems, sometimes with a remodelling project the constraints encountered in the existing structure and building require a non-standard design approach. At UNStudio, we prefer to use glass that is consistent with the underlying concept of the project.
For the remodeling of the Galleria West Luxury Hall Departments Store facade in Seoul, the client’s ambition was to completely transform the department store; to ‘dress it up’ in a way that has never seen before. Design works on the project started in late 2003, while the opening of the ‘newly dressed’ building was set to take place in September 2004. This allowed only a two month window in the summer of 2004 for the construction of both the interior retrofit and the new facade.
The existing pre-fabricated concrete structure, the structural grid, the measurements of the existing building and the budget proved to be further constraints, but the request to design a ‘new dress’ for the building inspired our design thinking. As a result, our team researched the possibilities of combining a new exoskeleton composed of large glass discs with iridescent foils. The objective was to create a mother-of-pearl effect once light hit the surface of each of the 4.330 glass discs that were custom designed to clad the existing concrete structure.
Whilst this effect determined the daytime appearance of the building, the project was located in an area of the city that is especially active during late afternoon and evening. Therefore the nighttime appearance had to be equally, if not more, spectacular than the shimmering effect of the facade during daytime. For this reason, we investigated – then new on the market – LED technology that could be programmed to change colour, and how this would interact with the laminated discs. In the end we opted for one individually controllable fixture to be mounted behind each of the glass discs. This form of lighting had the effect of dematerialising the glass shingles and wrapping the building in a fluid field of colours, allowing the facade to become – what was at that time – the largest media facade in the world.
The forecasted lifetime of this new department store facade was about 10 years, after which the client expected that a new dress would be required. By designing a facade that could change its appearance in the evenings, the expectation that the ‘new dress’ would quickly become outdated could be managed, as with the integration of the programmable LED technology, it could in fact be updated daily.
However, as it was conceived as a temporary add on to an existing building, the new facade was designed to make it possible to remove and replace it one day with minimal cost and effort. Due to the short time available for construction, the steel-structure that carries the glass discs was pre-fabricated offsite, then assembled on site by connecting it to the building’s existing structure. The base grid, together with a modular system of horizontal pins and steel-clamps, was custom designed to hold each large disc at three points. As such, its parts are demountable and each individual glass disc can be lifted out, also for repair during its lifespan. The LED lighting system is mounted on to the back-wall independently of the back structure, making it easy to replace when updated lighting technology becomes available.
While the remodelling of the Galleria department Store could perhaps be compared to a caterpillar turning into a butterfly, it is an outer facade remodel with limited requirements for waterproofing or insulation. Other, more complex contexts require a different approach to retrofitting. The following projects use glass in an unprecedented manner, but arguably had less radical freedom than the brief to ‘design a new dress’.
Hanwha HQ, Seoul
For the renovation of the Hanwha HQ in Seoul, one of the main constraints for the design was determined by the typology of the building, which was office high-rise. Initially it was necessary to understand the existing building in order to connect the existing structure to the new design. It was essential to upgrade the building and develop a unique design that contrasted with its previous appearance, while simultaneously addressing a full technical upgrade of the building envelope, the building systems and the interior fit out. Our ambition was to bring an unconventional appearance to an administrative building, while creating a light and pleasant indoor environment for the people who work there.
In this project, we also experimented with the use of BIPV panels. Glass has invaluable use in renewable solar energy technologies, and while we were simultaneously working on the design of energy generating glass panels (Solar Visuals), for the Hanwha HQ retrofit we integrated conventional photovoltaics modules in the building envelope. Displaying a non-standard application of conventional PV elements meant using the facade as a renewable energy generating surface, which enables the reduction of operating costs and of CO2 emissions.
For this retrofit, it was essential to link the interior programmes with the outside urban context. For the inside-out approach, the requirements of the office workers for views, daylight, ventilation and shading were translated into parameters that would vary at different locations in the facade. For the outside-in approach, we took into account the surrounding buildings, the shadowing they create and the orientation of the facade surfaces.
We divided the 3.60m grid of the existing structure into elements of 1.2m in width. The height of the individual glazing elements and of the proportion of the sunshading panels varies depending on their function. The tallest glazed elements are located in the more public areas, while the elements with the larger integrated PV panels are located on the upper, non-shaded areas of the south facade. This family of facade elements was combined in a coordinated way with the intention of creating a visually continuous facade field. The elements on the north facade are slightly different, as they do not have as much depth as the ones on the other facades, where the frames also have an important shading effect. Fine-tuning was also necessary in relation to the framing of the glass panels, as we wanted to reduce the amount of material used while increasing the transparency of the façade.
For this remodelling project, the client elected to remain in the building during construction, with the benefit that the building did not have to close and the staff were not relocated during construction. To achieve this, the refurbishment started at the lowest level of the building and construction took place three floors at a time. The remaining floors were fully occupied and operational throughout. This meant that we had to devise a systematic approach to the retrofit that linked parametric design thinking with the construction sequencing. As such, the new facade is composed of a variety of repetitive elements that are based on a modular system. The glass panels and aluminum frames were produced in the factory and brought to the site for direct assembly. The total construction time, including the full interior renovation – which took place simultaneously – was an undertaking of 42 months. In the end, UNStudio developed a performative facade that is fully inclusive and energy producing and where the facade response is about both the urban context and the experience of the people that occupy the building.
P.C Hooftstraat, Amsterdam
For the remodelling of two neighbouring projects on P.C. Hooftstraat in Amsterdam, the driving constraints came from the strict regulations concerning the preservation of the appearance of the historic buildings that line both sides of this famous shopping street. These design constraints required specific concepts that could balance the old with the new and had to be different for the both projects.
‘The Looking Glass’ (P.C. Hooftstraat 138) sets the stage for a unique and distinctive flagship store by reimagining the display of clothes. Crystal-clear glass was used for special showcases, while curved glass was used structurally in order to underline the exclusivity of the display windows. Three curving glass panels flow down from the upper floors in a design that mimics billowing transparent cloth. This play with glass creates opening spaces on a pedestrian eye-level that unveil the latest designs within. The contrast with the brickwork, that follows the historic three-windowed vertical division of an Amsterdam town house, makes the tailored glass vitrines unique attractions on this high-end shopping street.
The design for ‘The Brick Pixilation’ next-door (P.C. Hooftstraat 140-142) lends the facade a more contemporary interpretation of a textile surface. Imagined as a veil of stainless steel bricks on the facade of this traditional Amsterdam townhouse, here the focus was on developing the design and the material effects of the smaller facade components. While the facade is made of custom cast stainless steel bricks with glass inlays at pedestrian level, it transitions across the second floor back to the anthracite brickwork of a traditional Dutch townhouse. The finer grain and the crafted details of the pixilation result in a facade that is transparent and textured, laced and translucent.
For both projects on P.C. Hooftstraat, the integration of technology is found in the production of the custom designed, digitally produced components. The way they have been manufactured manifests a combination of old and new technologies, both crafted and industrial.
These two tailored facades also provide a technical upgrade for the traditional Dutch townhouse buildings by providing better insulation, improved windows and physical properties that expand the lifetime of the buildings. At the same time, the new bespoke designs that remain anchored in the historic context of the street, have become more appealing to the new tenants and their customers, providing additional value to these retail properties.
Innovation fast forward
The above examples demonstrate that as designers, we never consider the building envelope as an isolated element. For us, it is integrally connected to what is taking place inside and outside, both physically and conceptually.
Functional interdependencies include daylight requirements for certain spaces (as per building regulations) being brought into balance with the heat gain or heat loss of the building’s facade: the energy performance.
Lifecycle interdependency has to take circular principles into consideration, such as the durability of the different parts of the building and the varying lifespans of these. For instance, as a result of exposure to weather conditions and sunlight (UV, wind, rainwater etc.), the facade will typically require renewal before the structure does.
So what if we were to consider the facade of the future as being similar to our skin? That it would be able to renew and repair itself? Such an approach could pave the way for new business models, in which facade systems could be leased and technically upgraded when required. The danger here is that generic facades could become a go-to option and constructed anywhere, regardless of context or concept.
Or should we instead see the facade as the face of the building, as reflecting identity, brand, uniqueness and relation to context?
We believe that a combination of both approaches is necessary. However, in order to achieve this, architects not only need to combine the technical and creative knowledge that it takes to design and build, they also need to push the boundaries of their knowledge and the materials they use in order to create new combinations and effects.
Innovations in glass technologies have come a long way in recent times and these are certainly advantageous to the comfort and energy performance of today’s buildings. However, it is the role of the designer to combine these advances with the face of the building: to understand the building as a communication device; to go beyond the pragmatic and experiment with the incorporation of further technologies in order to avoid generic solutions and devise context-based facades.
This article was originally published in IGS Magazines Winter 2020 Issue: Read the full Magazine here for more thought-leadership from those spearheading the industry
Author: Astrid Piber – Partner / Senior Architect UNStudio
Astrid Piber is a Partner at UNStudio and Senior Architect in charge of several design projects globally. Since joining UNStudio in 1998, she has worked on numerous projects, from the initial urban study and competition phases through to realisation. In projects such as the Arnhem Central Station masterplan and the Raffles City mixed-use development in Hangzhou, China, the interdependency of functional, economic and future-proofing criteria has led to building organisations that go beyond segregated typologies.
Working with a trans-scalar approach – from large-scale projects to their interiors – designing to add value through user experience has been key. The completed projects in China, Singapore, Taiwan, South-Korea, Germany and the Netherlands display this holistic approach to buildings and their envelope connect the scale of the environment with the scale of the user. In all cases, the projects are designed to be inherently contextual, while commanding their own unique presence.