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Final review: STACKED BALCONIES


A perforated concrete facade with randomly positioned openings wraps the skeleton of the Piraeus Tower. The homogenous texture of openings breaks with the strong verticality of the skeleton and introduces a notion of mass, pronouncing the strong presence of the tower at Piraeus port.

The openings are occupied by three different types of windows:
Type A: A simple window
Type B: A box-type window consisting of a simple window in combination with a exterior glass panel. This window type operates as a natural ventilation device. The hot air in the buffer zone rises and evacuates air from the interior spaces.
Type C: A balcony between a recessed window and exterior glass panels. The balconies create natural ventilation as well, but only if several of them are stacked on top of each other forming a vertical shaft.

Each opening is assigned a window type according to the three main environmental parameters: Noise, sun and wind. The data describing these parameters is translated into image maps. Using the RGB additive color model, all information can be condensed into to a single image.

The window types are assigned as described in the last post:

A script evaluates the parameters for each window position. A lot of noise or wind demands a box-type window that offers more protection than just a simple one. Where the sun intensity gets more important than noise pollution or wind forces, a simple window is preferred because it diminishes the danger of overheating the interior as there is no heat radiation from a heated thermal buffer space. The balconies are only placed in areas without strong noise so that they always offer a calm recreation space. Once the window types are assigned, there’s a recursive function that analyses the stacking of the balconies that is required to contribute to the natural ventilation of the building. Only stacks of at least three balconies are admitted. The remaining balconies are reassigned and become openings of type A or B.
Then an other script places the exterior glass panels in front of the balconies. These glass panels have their own rhythm that is independent from the rhythm of the openings. The glass screen becomes an autonomous layer added to the perforated concrete facade. These two facade layers are working together and against each other at the same time. The resulting panel pattern gets analyzed and recursively modified within the script: Where there are columns of at least six panels on top of each other, the proportions of the thermal buffer required to produce a chimney effect allow an increasing depth of the balconies.

A heatmap illustrates the ventilation covering of each floor by analyzing the distances to the next ventilating window. This feedback allows to detect problematic zones with a lack of ventilation. In turn, parameters can be changed in order to achieve a satisfying result (red area limited to the core of the tower).

The south eastern facade turned out to be the most delicate in terms of ventilation covering due to it’s high percentage of type A windows. That’s why the fire escape stairs are located at this facade. The shaft of the stairs operates, like the stacked balconies, as a climatic device contributing to natural ventilation. The path of the stairs is defined a script within the engine: The stairs avoid balconies and cover the areas on the facade that are the least ventilated. It introduces a fourth window type, the stairs type, that fills the ‘gaps’ on the south eastern facade.

Further possible reactions to an unsatisfying heatmap feedback are relaunching the initial random window repartition, changing the number or the dimensions of the openings or change the ratio between small and large openings. The latter is usually set around fifty-fifty in order to create the typical facade image of the stacked balconies creating stepped shafts.

The plinth with it’s regular window interval is wrapped with glass panels as well. These glass panels are placed by a random based engine that takes in count three layers of information contained in a single gradient map (curtain effect gradient, noise protection, passage openings). A script places the panels by evaluating the map to calculate chance of a panel being placed for each possible panel position.

All these steps lead to the following facade proposal. The stacked balconies create a distinct drawing on the facade of the Piraeus Tower and turn it into an iconic landmark.



The concrete facade is made out of precast insulated elements, which are attached to the existing slabs. The exterior glass panels are hold in place by articulated metal beams that make the transition from the rhythm of the concrete facade to the rhythm of the glass panels. These beams penetrate the concrete facade and are fixed to the existing slabs as well. A cross bracing that allows to absorb the lateral forces is achieved by polygonal beams that follow the contour of the balconies joining the cantilevered beams.


Grasshopper canvas



Grasshopper screen shot


Grasshopper file
Pin up pdf A0 1
Pin up pdf A0 2


1:10 partial model





Stacked Balconies


A facade in precast concrete elements wraps the structure of the Piraeus Tower and introduces a notion of mass. A pixelised texture of two different sizes of openings breaks with strong verticality of the skeleton.

The openings are occupied by three different types of openings:
Type A: A simple window
Type B: A box-type window consisting of a simple window in combination with a exterior glass panel. This window type operates as a natural ventilation device. The hot air in the buffer zone rises and evacuates air from the interior spaces.
Type C: A balcony between a recessed window and exterior glass panels. The balconies create natural ventilation as well, but only if several of them are stacked on top of each other forming a sort of chimney.

Each window is assigned a window type according to the three main environmental parameters: Noise, sun and wind. The data describing these parameters is translated into image maps. Using the RGB additive color model, all information can be condensed into to a single image.


A script evaluates the parameters for each window position. A lot of noise or wind demands a box-type window that offers more protection than just a simple one. Where the sun intensity gets more important than noise pollution or wind forces, a simple window is preferred because it diminishes the danger of overheating the interior as there is no heat radiation from a heated thermal buffer space. The balconies are only placed in areas without strong noise so that they always offer a calm recreation space. Once the window types are assigned, there’s a recursive function that analyses the stacking of the balconies that is required to contribute to the natural ventilation of the building. Only stacks of at least three balconies are admitted. The remaining balconies are reassigned and become openings of type A or B.
Then an other script places the exterior glass panels in front of the balconies. These glass panels have their own rhythm that is independent from the rhythm of the openings. The glass screen becomes an autonomous layer added to the perforated concrete facade. These two facade layers are working together and against each other at the same time. The resulting panel pattern gets analyzed and recursively modified within the script: Where there are columns of at least six panels on top of each other, the proportions of the thermal buffer required to produce a chimney effect allow an increasing depth of the balconies.

A heatmap illustrates the ventilation covering of each floor by analyzing the distances to the next ventilating window. This feedback allows to detect problematic zones and react to the lack of ventilation by changing some initial parameters (like for example the number of windows, their dimensions or the ratio between small and large windows) or simply by re-running the original random window repartition. The information made visible by the heatmaps defined the location of the security stair on the south eastern facade. The shaft created by the stairs contributes to the ventilation and covers an area that was marked by a deficient natural ventilation.

The plinth with it’s regular window interval is wrapped with glass panels as well. These glass panels are placed by a random based engine that takes in count three layers of information that modify the chance of a panel being placed for each possible panel position.
The trhee layers are:
1. A vertical gradient producing a ‘curtain effect’ (high density of panels at the top, lower density towards the ground)
2. The street noise (more panels along the main road and the parking entrance as acoustic protection)
3. A set of entrances, exits and passages that have to stay panel-free.
As a result, the completely liberated ground floor become a protected public space that works as an extension to the nearby market.

The glass curtain wrapping the plinth unifies the tower with it’s base and grounds the whole building.

Facade detail

The relation between the new facade with its recessing loggias and the existing concrete skeleton is critical in some configurations. The following taxonomy lists the different possible constellations. Some of them might demand a adaption of the shape of the balcony to avoid useless spaces or perhaps even to take profit of the pillars as a spatial divider.


Grasshopper definition

Grasshopper screenshot

box and plane surface in VB

How can you create a plane surface / a box in vb.net by it’s corner points?
I wasn’t able to make sense of the information I found in the rhino sdk.

Collecting Data

I was looking at standard solutions for facades with two layers of glazing and their properties.
Source: CIimaDesign, Lösungen für Gebäude, die mit weniger Technik mehr können, Callwey Verlag, München, 2005,

Box-type window:
- Good acoustic isolation
- Typical use: Sites with strong winds and a lot of noise
- Thermal aspect: Overheating between the glass panes

Exterior panel:
- Limited acoustic isolation
- Typical use: Sites with medium winds and medium noise exposure
- Thermal aspect: Little overheating between the glass panes

Corridor facade:
- Good acoustic isolation
- Typical use: Sites with strong winds and high exposure
- Thermal aspect: Overheating between the glass panes

Box-type window:
-  Good acoustic isolation
- Typical use: Sites with strong winds and a lot of noise
- Thermal aspect: Overheating between the glass panes

The study of these example shows that wind, noise and the sun are the main criteria that influence the choice of a facade system. So I analyzed  the three factors on the site of the Piraeus Tower.

WIND

NOISE

SUN

The three layers of information (wind – cyan, noise – magenta, sun – yellow) can be added to a single image map in CMY color code so that every pixel contains a value between 0 and 100 for each of the three main criteria.

Furthermore I was looking at different ventilation concepts. The evacuation of air trough the facade is very efficient in combination with supply air being brought in by conduits. (up to 5h-1 air renewal)

Looking at my window configurations it becomes clear, that the standard box-type window s operate as ventilation units individually. The exterior panels on the other hand produce a ventilation effect in certain configurations only. First the  space between the two layers of glazing has to be closed downwards. So that the hot air that rises evacuates air from the building and is not just being replaced by other outside air. Secondly the effect gets stronger the higher the ‘chimney’ ,  meaning the more balconies are stacked on top of each other.

I wrote a VB component that detects the possible locations of such stacked balconies.

Grasshopper file screen shots:
All possible balcony locations, at least two balconies on top of each other
at least three balconies on top of each other, at least four balconies on top of each other

Response: Performant Icon

Moving forward I will have to explore the potential that lies in a system composed of two autonomous layers in terms of their performance as a climatic device. Simultaneously, it has to be clarified what kind of iconic appearance is desired  and how it can be achieved using this double layered system.

SPRAWLING WINDOWS

CONCEPT

Two layers are added to the existing structure: A perforated concrete façade and a screen of glass panels.

The perforated concrete facade wraps the skeleton breaking with its emphatic verticality and replacing it with a more homogenous texture of openings. The materiality of this added layer and its perforations introduce a notion of solid, which underlines the strong presence of the tower in Piraeus. The openings are positioned within a grid by an engine that tends to create bigger windows the higher the floor to accentuate the stunning views over the port of Piraeus and the city of Athens.

In the typical condition, the openings in the concrete façade are occupied by box-type windows composed by two layers of glazing. The box-type windows operate as a functional unit providing a natural ventilation effect. Locally inserted balconies make the space between the two layers of glazing habitable: The exterior layer is pushed outwards and the box-type window splits up in an interior weather barrier and an exterior glass panel, which protects the balconies.

Starting from the balconies, glass panels are spreading over the facade following the logic of the diffusion-limited aggregation (DLA). This algorithm simulates an organic growth based on randomly moving particles (in this case glass panels), which aggregate to clusters.

The two northern facades provide a high number of balconies. These balconies, being joined together by the sprawling glass panels, lead to a very textural character of the glass screen. On the southern facades on the other hand, the original box-type windows prevail, due to their performance in terms of creating natural ventilation. At the same time these two facades are the most representatives and the relatively few exterior glass panels are drawing an expressive figure: The transformed window, which sprawls over the facade, is creating a distinct pattern that reveals the iconic potential of the Piraeus Tower as a landmark within a larger context.


MATERIALS

The concrete facade is made out of non load-bearing prefabricated elements. These elements consist of two layers of white concrete with insulation in between, held together by reinforcement. Due to the prefabrication process, the production and the mounting of the elements is very efficient. Furthermore very thin material thicknesses are possible, reducing the weight of the elements, which are clipped to the existing slabs by means of a metal juncture.
The windows are composed of two layers of glazing. In the typical condition these two window panes are both situated within the thickness of the facade and operate as a box-type window with the interior glazing being the actual weather barrier. The increase of temperature between the two layers of glazing produces a natural ventilation effect and thermal buffer: hot air rises through the gap between the exterior glazing and the concrete facade, which in turn evacuates air from the interior of the building.
Where the exterior glazing becomes larger and is placed on the exterior of the facade, the glass panels are held in place by metal beams, which are attached directly to the existing slab. These beams are also carrying the balconies that occur between the glass screen and the concrete facade. To increase the performance of the glass panels, they are reinforced with a DuPont SentryGlas structural interlayer.


OVERALL LAYOUT

pdf version


GRASSHOPPER DEFINITION

Canvas overview:

Grasshopper screen-shot:

x5: perforated facade vs. panels

Work in progress poster dating from the 1/4/2010:

pdf version

transition between panels / panel repartition WIP

Smooth transition between panels:

14 possible panel types:

The PANELS DLA script within the GH definition calculates which type to use for each panel position.



Facade tectonics:

Panel repartition:
The normal double glazed window is the most efficient window in terms of producing the best ventilation effect. This type dominates in the southern facades. The few balconies that there are are positioned with additional constraints in the VB script so they stay closer together and the DLA algorithm linking them produces a distinctive ‘drawing’ that gives the tower in iconic appearance. On the northern facades the number of balconies is considerably higher and produces, in combination with the safety stairs, a more homogeneous, texture-like repartition of the panels.
The panels wrapping the plinth are less coupled to the facade and adapt to the surrounding like a curtain.

linking the layers

MODULE/MATERIALS

Facade in prefabricated concrete elements:
- 2 layers of concrete (5cm each) with insulation in between hold together by reinforcement
- Attached to the slabs with a metal juncture: one part screwed onto the slab, the other part cast in the concrete element and then clipped to the first part

Two layers of glazing:
-Interior glazing: actual weather barrier, can be opened
-Exterior glazing: glass pane mounted with a gap between the pane and the concrete
-The exterior layer reflects a important part of the sunlight and serves as sun protection.
-The increase of temperature between the two layers of glazing produces an natural ventilation effect.

Glass panels:
-The exterior glazing can become larger and be placed on the exterior of the concrete facade forming a grid of panels.
-These panels can take a distance to the facade that allows a balcony in between.
-The panels are fixed 4-armed with metal beams attached to the slab and reinforced with a DuPont Sentryglass interlayer to increase their performance.

-The panels might change their materiality: Opaque elements as sun protection or photo voltaic panels.


PLACEMENT

The openings in the concrete facade are still placed by an algorithm that chooses a random position and one of four sizes for each window. The higher the floor, the more probable to get a large opening. These random  openings however stay in a rigid grid. This grid allows a compatibility with the layer of  glass panels, that sticks to the same grid. The algorithm also defines the location of balconies (at the moment the balcony positions correspond to first defined windows of type L). These balconies are used as starting points for the DLA algorithm that defines the placement of the glass panels.There are 3 types of panels: panels close to the concrete facade, panels distant enough to wrap a balcony and a third type in between. The panels that were first created by the algorithm are the most distant to the concrete facade. The spreading panels produce a distinctive image linking the different balconies.

Furthermore I added two new options to the VB function:
-You can choose if the algorithm works in 8 or in 4 directions (if panels the touch each other only at a corner are considered neighbors)
-Number of neighbors needed to stop the panel from moving (1 or 2)

These options allow to get a denser repartition of the panels with less branches.

GH screenshot


GH canvas

gh definition
vb code for perforated facade
vb code for panels

x4: windows, glass panels

To analyze  the joints and junctures of the facade of the Forum 3 building by Diener & Diener I marked the key elements in section and plan. (source)

Worth mentioning is that the carrying structure starts on the ground floor at the inside of the weather barrier and switches on the first level to the outside. Where the bearing columns are on the outside the loads of the horizontal beams have to go through the facade . This demands a joint that is resistant, waterproof and thermally insulated. A reduction of columns the ground level demands larger beam in the ceiling. These larger beams however don’t have to perforate the weather barrier thanks to the shifting of the windows.
The metal bars that hold the glass panels are suspended from the top of the steel structure and invisibly anchored in the concrete foundation below the ground. Metal clamps fixed at the edge of each slab hold them in place.

In the plan a problem due to the corner geometry appears: The vertical metal bars of the exterior facade are not equidistant anymore. Other than that the building corner is very simple and reduced.

Piraeus facade detail drawing:

The perforated facade layer does not have to be load carrying because it is directly attached to the skeleton. It can be cast in insulating concrete which is less resistant but more insulating thermally than normal concrete. The glass panels are attached at big vertical bars. These pars are attached to the concrete facade from time to time, for example through balconies. The floor of the baconies as wella s the railings are made in glass to maintain a high degree of transparency and lightness.

Up to now, the rhythms of the perforated facade and the glass panel screen were completely independent. If the balconies take a structural role, these two rhythms have to be related somehow to guarantee a big enough number of joints.