Session 01

Fundamentals

01 l Fundamentals 00.00

Introduction 00.00 Skin and Shelter 01.01

Functional Requirements 01.02

Internal and External Conditions 00.00 Coping with Climate 01.03

User Comfort 01.04

Structural Performance 00.00 The Structure of the Façade 01.05

Waterproofing 00.00 Covering and Waterproofing 01.06

Thermal Performance 00.00 Insulation 01.07

Heat Flow and Vapour Diffusion 01.08 Solar Radiation 01.09

Others 00.00 Building Processes 01.10

Sound and Noise 01.11

Bibliography 00.00

01 .01 l Skin and Shelter

Fig. 01.01.01. Irish Cottage with Thatched Roof. Photo: iidudu.com

functions that a facade serves: it defines

the architectural appearance of the building, provides views to the inside and outside, absorbs push and pull forces from wind loads, bears its self-weight as well as that of other building components. The facade allows sunlight to penetrate into the building while usually providing protection from the sun at the same time. It resists the penetration of rainwater and has to handle humidity from within and without. The facade provides insulation against heat, cold and noise and can facilitate energy generation” (Knaack 2007, 36).

“The building envelope, as it provides protection against the weather and against enemies, and for storage provisions, represents the primary and most important reason for building. In contrast to structures such as bridges, towers, dams or cranes, buildings contain rooms whose creation and utilisation must be regarded as intrinsic elements of human civilisation, closely linked with the necessities forced upon us by climate” (Herzog 2004, 09).

“The facade separates the usable interior space from the outside world. Before addressing today's facade constructions we would like to call to mind the different

Fig. 01.01.02. A bubble, a minimum separation between two spaces.

Skin - Protective & regulatory functions:

Resistance Pressure Control Temperature Control Humidity Control Light Control etc.

Outside – Local conditions

Pressure A1 Temperature A1

Humidity A1 Solar Radiation A1

Inside - Requirements Pressure A2

Temperature A2 Humidity A2

Solar Radiation A1 etc.

“If we see the facade as the human body's "third skin" (after that of the body itself and our clothing), the analogy of the design objective becomes clear: the fluctuations of the external climatic conditions on our bodies have to be reduced by each of these functional layers in turn in order to guarantee a constant body temperature of approximately 37"C. However, the climatic conditions also give rise to requirements that cannot be exclusively allocated to either side; rather, they are due to the difference between inside and outside. They lead to mechanical loads on the materials of the façade and the

construction details, and are primarily the result of temperature, moisture and pressure differentials. Such loads must be accommodated by suitable means such as expansion joints and flexible connections” (Herzog 2004, 19).

Recommended Reading: Herzog, T. et al (2004) Façade Construction Manual. Birkhäuser, Basel. p09-25. Knaack, U. et al (2007) Façades. Principles of Construction. Birkhäuser, Basel. p07-13, p36-38.

01.02 l Functional Requirements

Fig. 01.02.01. General requirements

Fig. 01.02.02. Structural Requirements

A. Internal and external conditions

“The façade separates the usable interior space from the outside world. […] it defines the architectural appearance of the building, provides views to the inside and outside, absorbs push and pull forces from wind loads, bears its self-weight as well as that of other building components. The façade allows sunlight to penetrate into the building while providing protection from the sun at the same time. It resists the penetration of rainwater and has to handle humidity from within and without. The façade provides insulation against heat, cold and noise and can facilitate energy generation”.

(Knaak 2007, 36)

So main functional requirements are structural performance (A), waterproofing (B) and thermal insulation (C), but also permeability with respect to air, permeability with respect to light –or rather, radiation- or sound insulation. B. Actions. Structural performance

“The façade must safely withstand the forces to wich it is subjected and transmit these to the (primary) loadbearing structure. Every façade design, even a non-loadbearing one, must be conceived and designed as a secondary loadbearing structure to carry the following loads:

· Vertical loads: dead loads, special loads (e.g. temporary scaffolds), imposed loads (e.g. persons), snow and ice loads [and also the self-weight of the façade components, of course].

· Horizontal loads: wind load (pressure and suction generally occur in the ratio 8:5, but near the edges suction loads can be considerably greater), imposed loads (e.g. impacts) [as we are including, in our subject, the relationship with the ground, ground loads and ground water pressure should be included in this list].

· Restraint forces, caused by thermal or moisture-related volume changes”.

(Herzog 2004, 29)

Fig. 01.02.02. Structural performance

Fig. 01.02.02. Waterproof performance

Fig. 01.02.04. Thermal performance

C. Waterproofing

Our facades and roofs must deal with water, whether it comes from rain, from condensation or from the soil. There are several ways to do so:

“The uppermost layer of the roof construction must protect the building from precipitation of all kinds. There are basically two ways of doing so: either the water is drained away from the building via the quickest route, or it is intercepted before being drained away from a suitable point. The first of these principles in the fundamental one behind the pitched roof, the second is the principle of the flat roof. There are various ways of achieving drainage”.

(Schunck 2003, 105)

The image shows waterproofing layers in flat and pitched roofs, but also those areas where the building envelope is in contact with the soil. It also shows drainage and piping systems.

D. Thermal performance

“According to ASHRAE (formerly the American Society of Heating, Refrigerating and Air Conditioning Engineers) thermal comfort is defined as follows: ‘Thermal comfort is that condition of mind, which expresses satisfaction with the thermal environment’. […] DIN EN ISO 7730 specifies thermal comfort in form of a predicted percentage of dissatisfied people, measured in PPD (predicted percentage of dissatisfied). For light summer clothing, the minimum number of dissatisfied is reached at +25 °C”. [still we will consider a comfortable room air temperature that between 20-23 ºC]

(Bilow 2012, 175-176)

Thermal insulation is only a small part of the building user’s comfort. In its analysis aspects such as shading or ventilation should be taken into account

Recommended Reading: Herzog, T. et al (2004) Façade Construction Manual. Birkhäuser, Basel. p27-29. Knaack, U. et al (2007) Façades. Principles of Construction. Birkhäuser, Basel. p70-84.

01.03 l Coping with Climate

“The prevailing local climate has always

influenced building methods or architecture in general. It is therefore understandable that building typologies found around the world are very divers. Humans created protection from the climate by building shelters that were adapted to the climatic conditions they were in. The home, often very simple in its construction, and storage areas for food and other live-sustaining goods often of higher priority to the community attest to this principle […]

Climate, a term derived from the Ancient Greek word for inclination, describes the entirety of the weather conditions and temperatures, observed over a longer period of time in a particular region. It describes the interaction of atmospheric conditions and weather phenomena at the earth’s surface in the characteristic progression of a particular location or region (climate zone).

Climate can be further subdivided into megathermal, mesothermal and microthermal climates. The megathermal climate describes conditions observed over a wide area. A region can be determined by its position on the grid of longitudes and latitudes. Megathermal climates are seen as the basics of climate research and are the main focus of a climate analysis. Generally, the world climate is also a part of the megathermal

Humid continental

Mediterranean Dry Mid-latitudeMarine West Coast

HumidSubtropical

EcuatorialRain Forest

TropicalMonsoon

Trade Wind Litoral

Tropical Savanna

Dry Tropical

Fig. 01.03.01. Strahler’s Classification of Climates . Low Latitude Climates.

Fig. 01.03.02. Mid Latitude Climates. Fig. 01.03.03. High Latitude & other

Climates. Subarctic Marine

Subarctic

Tundra Ice Cap Highland Climates

1. Oceánico costero 2. Oceánico de transición 3. Climas de montaña 4. Mediterráneo continentalizado subhúmedo. 5. Mediterráneo continentalizado de inviernos fríos 6. Mediterráneo continentalizado de inviernos cálidos 7. Mediterráneo cálido de interior. 8. Mediterráneo costero. 9. Mediterráneo árido y subárido. 10. Subtropical.

Fig. 01.03.04. Climate subdivisions in Spain, as described by the Instituto Geográfico Nacional. Fig. 01.03.05. Mesothermal climates.

climate but local occurrences such as the monsoon or the earth-spanning jet streams are also called megathermal climate elements. In terms of dimension, occurrences spanning up to 500 kilometres or 310 miles are considered megathermal climates. Mesothermal climates describe local climates or area climates; thus the climate of a particular city can be called a mesothermal climate. In terms of dimension, mesothermal climates are usually climates that span several hundred metres to a few hundred kilometres. However, the transition from mega- to mesothermal climate is fluent.

Microthermal climate describes the climate immediately around us. It deals with the local conditions on the smallest scale. Thus, the shading of buildings or vegetation as well as wind factors caused by the geographic situation, e.g. hillside or valley location, determine the microthermal climate. Microthermal climates can range from just a few metres up to several hundred metres. Contrary to the more permanent macrothermal climate, the microthermal climate is subject to constant changes and can also be altered by vegetal or building related activity”.

(Bilow 135, 2012).

Recommended reading: Bilow, M. (2012) International Façades. Climate Related Optimized Façade Technologies. ABE – TuDelft. Rotterdam. P39-135. Neila, F. (2012) Los climas de latitudes bajas. Instituto Juan de Herrera. Madrid. p03-16.

01.04 l User Comfort

Fig. 01.04.01. Psychrometric chart with overlapping of function and location. Las Vegas (as in Bilow 2012, 134)

Fig. 01.04.02. Classification of climate zones in a psychrometric chart (as in Bilow 2012, 131)

“The specifications of temperature

ranges for rooms and buildings are regulated by many local legislative directives. Temperatures should always be evaluated in relation to the outside […] A difference of 5-6 °C […] compared to the outside temperature has proven to be a viable definition whereby room temperatures of more than 26°C should be avoided. […] users show higher acceptance of the room temperature if the temperature can be regulated by operable windows. Users are typically less satisfied if the temperature is controlled by a central air-conditioning unit that they cannot regulate.

“Room air humidity plays an equally important role as the thermal aspects. The human body senses the climate as muggy at water vapour contents of approximately 14g. Since air absorbs water vapour depending on the tempera-ture, we need to differentiate between absolute and relative humidity. A com-fortable level of R.H. lies between 30 and 65%; A.H. can be easily derived in a chart. At 25°C, for example, the chart shows R.H. at 50% and A.H. at 10g/kg. If the temperature drops relative humidity rises, whereas absolute humidity remains constant”

(Bilow 2012, 207)

The method of calculating the comfort level according to DIN EN ISO 7730 enables consultants to estimate the user comfort level depending on the room temperature, the activity performed and clothing worn. This method of calculation provides a predicted mean user rating, from which a predicted percentage of dissatisfied users can be derived. The method is based on the thermal balance of the human body […] as well as air temperature, mean radiation tempera-ture, relative air flow and humidity. The goal is to strive for a percentage of dissatisfied users lower than 10%”

(Knaak 2007, 72)

Fig. 01.04.03-05. Parameters influencing thermal comfort. (Knaak 2007, 70-73) Fig. 01.04.06. Comfort range depending on room air temperature and the surface temperature of the room enclosing surfaces. (Knaak 2007, 71) Fig. 01.04.07. Possible ventilation schemes in a building. (VV.AA. 2007. Un Vitruvio ecológico. Gustavo Gili. Barcelona, Spain, p.16-17)

“The human body not only absorbs and emits heat through the air by convection, […] but is also influenced by the surrounding surfaces through radiation. Therefore heat transfer by both convection and radiation needs to be considered when trying to achieve thermal comfort. Because of these heat transfer mechanisms, temperature is specified as ‘felt temperature’ or ‘room temperature’. This measurement corres-ponds approximately with the mean value of the air temperature in the room and the mean radiation temperature from the enclosing surface areas.”

(Knaak 2007, 71)

”Ventilation is very important for our sense of comfort. The room climate that a user is surrounded by is influenced by the presence or absence of ventilation. Depending on the activity level, a human body can dissipate several litres of water per day into the room air in form of vapour. Exhaling raises the CO2 content of the air and the temperature level. The CO2 content should be reduced to 0.1-0.15 % max. Ventilation regulates the temperature as well as the humidity in a room; exhausted air is replaced and odours and harmful substances carried away”

(Bilow 2012, 198)

Recommended Reading: Bilow, M. (2012) International Façades. Climate Related Optimized Façade Technologies. ABE – TuDelft. Rotterdam. P185-214. Knaack, U. et al (2007) Façades. Principles of Construction. Birkhäuser, Basel. p70-84. Herzog, T. et al (2004) Façade Construction Manual. Birkhäuser, Basel. p21-23.

01.05 l The structure of the façade

Fig. 01.05.01. Schematic diagram of a loadbearing façade Fig. 01.05.02. Schematic diagram of a standing façade

Fig. 01.05.03. Schematic diagram of a suspended façade · Primary structure (shell of building)

forming the main loadbearing structure of the building. · Secondary structure, which is the loadbearing structure for the façade and constitutes the connecting element between levels one and three. · Infill elements.

The primary purpose of this assembly lies in the separation of the above mentioned functional requirements that the façade needs to fulfil. The functions are distributed among several different components. This arrangement simpli-fies the connection of individual façade components with each other and

provides options to compensate for moving parts.

The primary structure takes on the loadbearing function of the entire building and transfers the loads from the façade to the foundation.

The secondary structure comprises the loadbearing structure of the façade. It transfers its loads onto the primary structure. […] Of course there are also façade constructions where primary and secondary structures form one component, i.e. both are is part of the loadbearing structure of the building.”

(Knaack 2007, 37)

“Standing and suspended facades One fundamental distinction regarding the loadbearing behaviour is whether the facade is supported from below (standing) or from above (suspended), i.e., whether the planar or linear components need to be designed for tension and bending, or compression and bending and hence also buckling (stability problems)”

(Herzog 2004, 29)

“In the following we will describe the principles of construction using a metal and glass façade as an example. Three main areas of construction can be defined within the façade:

Fig. 01.05.04. A suspended façade at BBV Building (Saenz de Oiza, 1981) Fig. 01.05.05. Plan and section of the façade at Torre Sacyr (Rubio-Álvarez-Sala, 2009) Fig. 01.05.06. Position of the plane façade in relation to the loadbearing structure.

“Geometrical position in relation to loadbearing structure

Apart from leading to different connection conditions, the position of the facade in relation to the loadbearing structure has consequences for the performance and the appearance of the facade. In principle, we can distinguish between the following positions (considered from outside to inside) in the case in the case of non loadbearing facades. · On the front face of columns · Between slabs · Between the grid · Inside the grid *

These geometrical positional relation-ships determine the role of the loadbearing structure as an architectural element, whether the divisions in the façade are influenced by the loadbearing structure, the detail of junctions with partitions, the extent to which the façade penetrates column and floor planes, etc. The incorporation of the horizontal loadbearing elements (floor slabs) into the vertical ones is another distin-guishing criterion.

(Herzog 2004, 51)

* This is a simplified version of Herzog’s list, including only most common cases

Recommended reading: Herzog, T. et al (2004) Façade Construction Manual. Birkhäuser, Basel. p27-31, 51. Knaack, U. et al (2007) Façades. Principles of Construction. Birkhäuser, Basel. p38-40.

01.06 l Covering and Waterproofing

Fig. 01.06.01.

Cathedral of Santiago de Compostela.

Fig. 01.06.02. Disposition of main

elements (loadbering, protective and

insulating layers) in a pitched roof.

Loadbering layer

Protective layer

Insulating layer “Apart from the fundamental protective

function of the roof, i.e. providing shelter for human beings, keeping the water out is the main task of the roof. External influences (sunshine, rain, wind) but also those from inside (water vapour pressure) and the resulting problem of water vapour diffusion give rise to further strains in the roof construction. In order to do justice to these diverse demands, a multi layer structure is necessary, which has led to two layering principles. One of these systems is chosen depending on the given overriding conditions, the loadbearing structure […] or the roof form.

Cold deck.

In the cold deck the waterproofing layer is so far removed from the layer of thermal insulation that a dry air cavity is formed between the two. This captures the water vapour diffusing out of the insulation and carries it away. A pitched cold deck has two air cavities, one between the roof covering and the secondary waterproofing covering layer, and one between this latter layer and the insulation, although it is this second cavity that actually qualifies the roof to be called a cold deck”.

(Deplazes 2009, 248)

“Covering and sealing.

The uppermost layer of the roof construction must protect the building from precipitation of all kinds. There are basically two ways of doing so: either the water is drained away from the building via the quickest route, or it is intercepted before being drained away from a suitable point. The first of these principles in the fundamental one behind the pitched roof, the second is the principle of the flat roof. There are various ways of achieving drainage”.

(Schunck 2003, 105)

Fig. 01.06.03. General section of a pitched roof. Texsa Catalogue. Fig. 01.06.04. General section of a flat roof. Texsa Catalogue. Fig. 01.06.03. General section of a waterproof foundation wall. Texsa Catalogue.

“Warm deck.

In the warm deck the waterproofing layer or a diffusion retardant layer, e.g. in a pitched roof a secondary waterproofing / covering layer, is laid immediately above the thermal insulation. The water vapour diffusing out of the insulation could therefore condense on the non venti-lated cold side of the insulation and saturate this. A vapour barrier installed on the inside prevents the warm, vapour-saturated air entering the insulation and thus prevents damaging condensation.

Relationships between roof pitch and roof covering material.

The pitch of the roof depends on the roof covering material, the roof form, the fixings and the type of jointing. A flat roof must exhibit a seamless waterproof roof covering. On the other hand, a roof covering of overlapping elements with its high proportion of joints is better suited to a pitched roof. The more watertight the roof covering element and its joints with neighbouring elements, the sha-llower is the allowable pitch.”

(Deplazes 2009, 248)

Recommended reading: Deplazes, A. (2009) Constructing Architecture. A Handbook. Birkhäuser, Basel. pp236-249. Schunk, E. et al. (2003) Roof Construction Manual. Pitched Roofs. Birkhäuser, Basel. pp105-106.

01.07 l Insulation

Fig. 01.07.01. Situation of the insulation layer in different façade solutions.

“On concealment and exposure

The “multi-layer wall construction”, designed to satisfy the thermal performance requirements of a building, grew out of the oil crisis of the 1970s and the subsequent realisation that we must reduce our consumption of energy. The outermost layer of our wall –now resolved into layers- serves to protect the (usually) unstable insulation from the weather. The insulation in turn encloses the loadbearing structure for the whole building, to which it is fixed, like a wool coat”.

(Deplazes 2009, 139)

“Solid wall construction

People who lived in cold climates […] preferred wall constructions that were as solid as possible. […] The objective

was to build a wall that would stand up to climatic influences while still keeping the building method as uncomplicated as possible. Though the construction and finishing of such solid structures has naturally developed in line with advances in technology – present day solid walls are either built up of structural units with both loadbearing and thermal insulation properties or are provided with elements for this purpose – the basic principle remains unchanged.

[And, about multiple layer façades:]

Warm façade, cold façade

Two different types of solid wall construction may currently be distin-guished: warm façades, where the insulating layer is mounted directly on the outside or the inside of the façade construction, and cold façades, where

the insulating layer is separated from the climatic protection layer by a layer of air. The latter principle allows the insulating layer to dry out if water penetrates into the façade as a result of damage to the protective layer”.

(Knaack 2007, 14)

Recommended reading: Deplazes, A. (2009) Constructing

Architecture. A Handbook. Birkhäuser, Basel. pp139-145.

Knaack et al (2007) Façades. Principles of Construction. Birkhäuser, Basel. pp14-15.

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01.08 l Heat Flow and Vapour Diffusion

Fig. 01.08.01. Heat flow through a wall (Deplazes 2007, 313).

Fig. 01.08.02. Diffusivity and conductivity of construction materials.

Thermal Diffusivity A (w·m2)/J·106

Thermal Conductivity b (√s·w)/(m2·K)

Brick 0,40 890,0 Concrete 0,96 2350,0 Granite 1,08 2690,0 Steel 14,25 13250,0 Timber 0,16 410,0 Glass 0,53 1370,0 Plaster 0,40 630,0 Cement Mortar 0,56 1340,0 Expanded Polystyrene 1,10 35,0

reaches its saturation point, which

depends on the temperature. We therefore speak of the "relative humidity" (of the air). Moist air is fractionally lighter than dry air at the same temperature.

Water vapour flows from the side with the higher vapour pressure (partial pressure) to the side with the lower pressure. If there is a simultaneous severe temperature gradient, the temperature drops below the dew point and the water condenses out of the air (and hence leads to the risk of condensation collecting on surfaces and mould growth)”

(Herzog 2004, 23)

“To understand the functions of the facade, we must look at the scientific principles of the construction, e.g. heat flow, water vapoure pressure, radiation transfer […].

Thermal energy always flows from the hotter (higher-energy) side to the colder side. Three basic principles govern the transfer of heat energy: Conduction, Radiation and Convection. The thermal transmittanceU- (w/m2K) may calculated for planar components.

Thermal conductivity and heat capacity […] depend on the properties of material and generally increase with bulk density. […] Air can absorb water vapour until it

“The problem of heat flow and vapour diffusion

Cold air contains little water vapour (outside - dry air). Hot air contains considerable water vapour (inside - high humidity).

When hot air meets cold air or is quickly cooled, moisture in the air condensates as water (dew point). This can happen as a result of the temperature gradient within a layer of insulation (At = 21 .1 °C) within the construction. Moisture in the construction leads to damage to the building fabric. Condensation within the construction (interstitial condensation)

Fig. 01.08.03. Thermal bridge between wall and slab. Fig. 01.08.04. Visual damage as result of the drying process.

must therefore be prevented, or all moisture must be allowed to dry out or escape.

A "vapour barrier/check" must be integrated in order to prevent condensation. Two rules must be observed in conjunction with this: 1.- The vapour barrier/check must be attached to the warm side (inside) prior to fixing the thermal insulation, and 2.- The imperviousness (to vapour) of the materials must decrease from inside to outside. "Sealed loadbearing layer on the inside, vapour-permeable protective layer on the outside."

(Deplazes 2009, 313)

”Thermal bridges

The problem of thermal bridges occurs wherever the insulated building envelope is penetrated by components which allow the passage of heat from inside the building. Many buildings lose more heat via avoidable thermal bridges than over the entire uninterrupted wall. Transitions and junctions require special care:

– between window, wall and roof – between roller shutter and wall, – via shafts and flues at wall and roof, – via thresholds, window sills, lintels – via fasteners, e.g. for balconies”

(Deplazes 2009, 317)

Recommended reading: Herzog, T. et al (2004) Façade Construction Manual. Birkhäuser, Basel. p21-23. Deplazes, A. (2009) Constructing Architecture. A Handbook. Birkhäuser, Basel. p313-317.

01.09 l Solar Radiation

Fig. 01.09.01. Definition of solar position angles (Fuentes 2010, 54). Fig. 01.09.02. Definition of the hour angle (Fuentes 2010, 56). Fig. 01.09.03. Schematic Stereographic Sun Path Chart. (Fuentes 2010, 51). Fig. 01.09.04. Schematic Cartesian Sun Path Chart. At www.solardat.uoregon.edu/ sunchartprogram.php you can “create sun path charts in Cartesian coordinates for: (1) "typical" dates of each month (i.e.; days receiving about the mean amount of solar radiation for a day in the given month); (2) dates spaced about 30 days apart, from one solstice to the next; or (3) a single date you specify. You can select whether hours are plotted using local standard time or solar time. In addition, there are a number of options available to allow you to alter the chart's appearance”. (Quoted URL)

shadow produced by) a given device or to

specify a device. Horizontal shadow angle (HSA) is the difference in azimuth between the sun's position and the orientation of the building face considered, when the edge of the shadow falls on the point considered.

The vertical shadow angle (VSA) (or 'profile angle' for some authors) is measured on a plane perpendicular to the building face. VSA can exist only when the HSA is between -90o and +90o, i.e. when the sun reaches the building face considered.”

(Szokolay 2007, 15)

“Shading Design

Solar radiation incident on a window consists of three components: beam (direct) radiation, diffuse (sky) and reflected radiation. External shading devices can eliminate the beam component (which is normally the largest) and reduce the diffuse component. The design of such shading devices employs two shadow angles: HSA and VSA.

Shadow angles express the sun's position in relation to a building face of given orientation and can be used either to describe the performance of (i.e. the

“Sun-path diagrams

There are several ways of showing the 3-D sky hemisphere on a 2-D circular diagram. The sun's path on a given date would then be plotted on this representation of the sky hemisphere as a sun-path line.

In the United States the equidistant representation is used. […] The stereographic (or radial) representation uses the theoretical nadir point as the centre of projection. This is the most widely used method. (Fig. 01.06.03)”

(Szokolay 2007, 9)

Fig. 01.09.05. Horizontal devices giving the same VSA (Szokolay 2007, 16) Fig. 01.09.06. Examples of sunshading. A ship-like building in Bangalore, India. Fig. 01.09.07. Geometric sunshades in a building in Pamplona, Spain. Fig. 01.09.08. A complex sunshading strategy in Madrid, Spain.

“Fig. 01.06.05 shows the section of a window, with a canopy over it. The line connecting the edge of the canopy to the window sill gives the shading line. The angle between this and the horizontal is the VSA of the device. If the corresponding arcual line of the protractor is traced, this will give the shading mask of the canopy. Placed over the sun-path diagram it will cover the times when the device is effective. The task of shading design can be divided into three steps:

1. Determine the overheated period, i.e. the dates and times when shading should be provided. This can be taken as

the time when the monthly mean temperature is higher than the lower comfort limit. The daily temperature profile should be looked at to ascertain the hours when shading is necessary.

2. By using the appropriate sun-path diagram and the protractor establish the necessary horizontal or vertical shadow angles (or a combination of the two), as performance specification for the device to be designed.

3. Design the actual device to satisfy these performance specifications”

(Szokolay 2007, 17)

Recommended reading: Bilow, M. (2012) International Façades. Climate Related Optimized Façade Technologies. ABE – TuDelft. Rotterdam, 211-215. Szokolay, S.V. (2007) Solar Geometry. Queensland University. Brisbane, Australia. Others: Fuentes, V.A. (2010) Arquitectura Bioclimática. Limusa, UAM. México D.F.

10 l Building Processes

Figs. 01.10.01-02. Building the hanging façade of the Colon Towers, in Madrid.

The necessity for systemising the façade

is obvious, as the high demands of building performance now render the façade a particularly complex building component […]Manufacturers test their systems for resistance to wind-driven rain, thermal insulation, air permeability, sound insulation, fire resistance and building security. The design of the glass fixtures and the load-transfer joints between the post-and-beam sections are factory-certified. It is therefore possible to pick and choose from various systems”.

(Knaack 2007, 44)

“Systems used in façade construction

On surveying current building trends, it becomes apparent that almost all buildings use systemised façades. This means that specific parts of the structure comprise standardised components provided by façade suppliers. So why do we need systemised solutions and how do they affect the planning and design of the façade? [..] technical requirements have increased significantly, [and façades] are now fully regulated and can only be fulfilled by adopting sophisticated methods.

Fig. 01.10.03. Assembly

stages of a ventilated façade. Figs. 01.10.04-05. Possible modular solutions for a precast concrete façade.

6 7 8 9 10 11

12 13 14 15 16

1 2 5

1 2 3 4

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Castelló, D.; Calderón, J.M. (2002) Cuaderno técnico. Comportamiento energético de una fachada acristalada. ITEC - Hydro Building Systems. Barcelona.

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2009. Research in Architectural Engineering Series Knaack, U.; Klein, T. (2009) The Future Envelope 2: Architecture - Climate –

Skin. Research in Architectural Engineering Series Oesterle, E.; Lieb, R.; Lutz, M. (2001) Double-Skin Facades. Prestel, Munich Poirazis, H. (2004) Double Skin Façades for Office Buildings. Division of Energy

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