Inspired by the northern lights and the dramatic Icelandic scenery, Harpa – Reykjavik Concert Hall & Conference Centre emerges on the border between land and sea. With spectacular façades, designed by Henning Larsen Architects and artist Olafur Eliasson, the building stands out like a large, radiant sculpture reflecting the sky and harbour space as well as the vibrant city life. Harpa was officially inaugurated in August 2011.
The main inspiration for the design of the building was the Icelandic nature and the unique building site, situated between land and sea, framing a magnificent view of mount Esja. The design aims to invite nature into the building whilst at the same time reflecting the sky, the sea and the mountains in the outer skin. The work with the designing and constructing of the façades was therefore crucial to this project.
The quasi brick façade
The Harpa building consists of three different façade types. The first type is an “add on steel”/ structural glazing façade which forms the base of the building. The second type is a non-standard grid façade based on an add-on steel system. This façade appears like a spider’s web and is called the “cut quasi façade”. It covers the building to the east, west and north. The third and final façade type is the “quasi brick façade”. This south facing façade is a three-dimensional, self-supporting steel frame clad in glass on both sides. The “quasi brick façade” is inspired by basalt columns, which occurs when red hot lava penetrates the earth’s crust and meets a glacier. These hexagonal basalt rock formations show an extremely rigid structure compared to the rest of the wild, Icelandic Nature. The quasi brick is a twelve-sided, self supporting steel frame, which in combination with the other bricks in the façade, is capable of transferring the loads from the surrounding construction. This fact makes it possible to avoid columns on the inside of the foyer.Furthermore, the quasi brick is characterised by a certain shape which allows the bricks to be stacked without leaving any cavity between the single units. By using stacked quasi bricks in the south façade, the skin developed into a piece of art and at the same time fulfilled the purpose of the envelope.
The outside geometry of the brick was decided early in the project phase based on the studies by Olafur Eliasson. The internal geometry of the brick was modified later in order to make the profiles as slim as possible and to determine the daylight factor through the façade. All profiles and cross sections in the bricks were studied. This led to no less than twelve different diamond shaped profiles. In order for the structure to be able to withstand the wind and dead loads, the profiles had to be made of 10 mm steel plates.
“ The “quasi brick façade” is inspired by basalt formations created when red hot lava penetrates the earth’s crust and meets a glacier ”
Designing Corners
To connect the profiles and also to make sure the structure takes up the loads in the façade, the corners are cast in steel then welded together with the profiles. The cast solution makes it possible to design the corners with countersunk holes for the bolts heads. The bolts are visible, but discretely hidden in the corners, so all the bricks boldly stand out with individual elements exposed.A benefit of casting the corners is the possibility to shape the outside corners with an extra washer-like thickening. These thickenings act as load transfer points, the points that touch the next brick, that is. After assembling a brick, it is possible to measure the exterior geometry and in accordance to that, adjust the size by grinding down the washer thickenings. This solution solves the problem of transferring the loads from brick to brick and helps to absorb the tolerances.
To finish off the bricks, all welds are grinded down and painted to make the individual bricks appear as one unit. Since the south façade is part of Olafur Eliasson’s artwork, it was only natural that he chose the colour of the steel frames. The colour chosen for the steel frame is therefore “telegrau” or “electric grey”.
A silicone gasket is mounted on top of the frame. In order to make the gaskets seal properly, cast silicone corner pieces were custom designed to fit directly upon the steel corners. By using a cast corner gasket it is unnecessary to join the gaskets in and on the corner where it is most vulnerable. Instead the gaskets are connected to the straight part of the profile where it is a lot easier to fabricate a correct gasket solution. After adding the gaskets to the frame, the quasi bricks are covered in glass.To avoid thermal movements in the steel structure, double glazed units are placed on the outside. The double glazed units consist of 2 x 6 mm tempered and heat strengthened glass with three layers of PVB foil. The cavity is 16 mm using argon filling and again 2 x 6 mm laminated tempered and heat-strengthened glass. The unit altogether is 42 mm thick.
Variation of Glass
The project makes use of a great variation of advanced glass types shared among all four façades. In total, nine different types of glass are used. As part of the art, Olafur Eliasson wished to use a number of dichromatic filters on the south and north façades. In approximately 5% of the south and north façades three different types of dichromatic glass are used instead of the primary glass type. A DGU with a U-value of 1,1 and a g-value of 41%, that is, intended to be as clear as possible. Dichromatic filters use the principle of thin-film interference and produce colours in the same way as oil films on water. The dichromatic filters make the surface appear in different colours, depending on the visual angle from where the spectator looks at the object. The glass may appear blue from one side and orange from another. The glass with dichromatic filters is produced by Prinze Optic near Stuttgart in Germany. Their surface treatment consists of several steps. Firstly, the glass is cleaned and taken to a clean room where a robot dips it into a special fluid. Secondly, the glass is dried in an oven before receiving the entire treatment again. The colour of the glass changes according to the number of treatments. For example, to get the colour blue, the glass has to undergo 13 treatments. Towards the foyer, on the inside of the quasi bricks, laminated glass is used. On the outside, as well as on the inside of the bricks, we detailed solutions with staggered glass edges, and to avoid visible fixings or cover plates, we chose to toggle fix the glass. The glass used on the outside is laminated because of the overhang in the façade. The façade itself has an overhang of approximately seven degrees, but the individual quasi bricks actually have an overhang of 12.8 degrees. The Glass performance for the glazing is a U value of 1.1 W/m2 K, this was achieved with a double silver Low-E coating. At the same time the solar control factor was agreed to be 0.3. The coating is fused by pyrolysis, which makes it possible to integrate it with the surface of the glass. The coating is applied to the outer face. Finally a highly reflective glass as well as an antireflective glass type is used in this project.
The “cut quasi façade”
The second façade type in the project is called the “cut quasi façade”. The “cut quasi façade” is based on a modified pattern. The “true cut quasi pattern” was developed in a 3D computer model by stacking the quasi bricks in the entire building volume, starting from the south façade, and then cutting along the outer shape of the house. But because the east and west façades were not perpendicular to the south façade, the pattern was not consistent, but in constant change and characterized by an almost endless number of glass sizes. In order to make the “cut quasi” façade buildable, the pattern had been modified. So based on the “true cut quasi pattern” and after analyzing the main lines in the façade, an optimized façade solution has evolved – the “cut quasi pattern”. For architectural reasons and because of structural significance, it is important that the transoms meet in the corners. But because of the modified pattern none of the profiles did at first. Therefore, all corners were designed in 3D to make the outer sealant meet. Still, it was almost impossible to make the inside of the transoms meet because of the sloping façades. And so, vertical steel plates were introduced in the corners – each custom made for every profile.
Because of some very large spans in the “cut quasi” façade, it has been necessary to use a “add on steel” system for mullions and transoms, though the design didn’t allow more than 60 x 260 mm profiles. The profiles are fabricated as rectangular hollow steel sections, welded from four 10 mm steel plates. Still, in some areas, the forces on the façade are bigger, and in order to keep the same outer dimension profiles in these areas are made of 10 mm steel on the sides, but 25 mm steel plates in the front and back of the profile. This system uses silicone gaskets to secure water tightness.
Today, when you visit Reykjavik you can experience how the glass captures the light of the sun and colours of the sky and see how Harpa appears as a giant, illuminating sculpture, reflecting the sky and harbour. Behind the glass facade, a spectacular foyer rises. It is an overwhelming, adventurous space sparkled by the light bouncing through the façade. Art and architecture are harmoniously united in Harpa.
