Static Shading Devices in Office Architecture Theory, Shape und Potential Oliver Hans Static shading devices in office architecture Theory, shape und potential Thesis an der Universität Wuppertal im Rahmen des Master Studiengangs Architektur in der Vertiefungsrichtung Ressourcen optimiertes Bauen Dipl. Ing. Oliver Hans MSc an der Bergischen Universität Wuppertal Prof. Karsten Voss Wuppertal, 19.09.2006 Hiermit versichere ich, dass ich die vorliegende Arbeit „Static shading devices in office architecture - Theory, shape and potential“ selbstständig, ohne Hilfe Dritter, mit Zunahme der angegebenen Quellen verfasst zu haben. Die Arbeit wurde bisher weder im Inland noch im Ausland in gleicher oder ähnlicher Form einer anderen Prüfungsbehörde vorgelegt und ist noch nicht veröffentlicht. Wuppertal, 19.09.2006 1. Prüfer: Professor Dr.-Ing. Karsten Voss 2. Prüfer: Professor Frank R. Werner Contents Abstract 9 About this text 9 1. Introduction and background 10 1.1 Energy und Envelope 10 1.2 Climate factors 11 2. Thermal comfort in the office workplace 12 2.1 Normative requirements 12 3. Summer heat protection - Shading 14 3.1 Interior adjustable shading 14 3.2 Exterior adjustable shading 15 3.3 Static shading 16 4. Evaluation criteria 18 4.1 Daylight 19 4.2 Warmth 19 4.3 Unobstructed view 20 4.4 Glare, visual comfort 20 5. Shape - Formal typologies of static shading 21 5.1 Horizontal projections 22 5.2 Vertical projections 23 5.3 Combined forms 23 5.4 Prepositioned screens 24 6. Exemplary analysis 25 6.1 �ethod 2 25 6.2 Project example 26 6.3 Results 28 7. Simulation as a planning tool - new concepts 30 7.1 Geometric projection of the solar path 30 7.2 Illustration of the amount of irradiation 31 8. Conclusion und outlook 35 References 3 Abb. 1 Das Ideal der gläsernen Box. NARVA-Tower, Berlin, Architekten Schweger + Partner, (Quelle: Flickr.com) Static shading devices in office architecture │  8 │ Static shading devices in office architecture Abstract The measured and forecasted changes in climate have an immediate influence on the planning of buildings and building services. The requirements toward the energy efficiency of buildings is increasing. Due to rising temperatures, the reduction of summer heat loads will become a dominant factor in the tempering of buildings. Static and angle selective shading devices are an appropriate measure in the process of reducing summer gains and allowing the winter passive use of solar energy. They are independant of control mechanisms or user behaviour and are therefore more robust energetically and more predictable when dimensioning building services as opposed to moveable shading. Static shading is a plastic architectural medium. It dominates facades as an invariant graphic element and offers high design potential. This thesis shows a basic formal typology of static shading devices and simple methods of valuating their influence on daylight, warmth and view. It concludes with a presentation and evaluation of tools for their exact dimensioning and their generation. About this text The details in this text refer to Europe and the Northern Hemisphere. Therefore a south oriented facade has the highest solar altitude. The longest day is the 21.June, the shortest is the 21. of December. However the information concerning orientation can simply be reversed to be adapted to the Southern Hemisphere. In which case the sun would have its highest position in the north, the winter and summer solstice would be on the 21. June und 21. of December respectively. Static shading devices in office architecture │ 9 1. Introduction and background 1.1 Energy und Envelope The transparent facade enjoys a steady popularity in administrative architecture. The demand for thermal protection in summer usually conflicts with the potential use of daylight and possible winter solar gains. The EC directive on the energy performance of buildings1, has led to the amendment of German energy saving regulations and the introduction of the computational tool of the DIN 185992. The electrical energy consumption of air-conditioning technology and lighting systems in administrative buildings is now considered for the first time and flows into the overall energy balance. Now a growing importance falls to the precise consideration of the building envelope to minimise energy for cooling, heating and artificial lighting. Solar protection plays a decisive role in the interaction of these factors. Automated variable vertical solar protection devices often lack the necessary user acceptance. User-controlled solar protection devices, such as venetian blinds, lead to a raised need in cooling due to false application and impair the visual connection to the outside. Another disadvantage of outside adjustable systems is their necessity of maintenance and their wind sensitivity. Static solar protection is a more robust system energetically and technically. Nevertheless, it needs a precise interpretation, because of its consequences for the interior climate and thus energy consumption, as it is not alterable. Hence, the design of static solar protection must be such, that it contributes permanently to a higher user comfort and to the lowering of the building‘s energy consumption. It can be considered as a prosthetic extension of the construction to the outside. Through it, the building envelope experiences an increase in functionality. This study categorises a basic formal typology of static shading systems and indicates simple assessment methods of their effectiveness. The methodology is applied to a comparative examination of built examples. Finally design tools and their methods of precise dimensioning and generation of static solar protection are compared and evaluated. 10 │ Static shading devices in office architecture 1.2 Climate factors Current climate predictions and simulations forecast a temperature rise for Europe. The researchers‘ estimations of the increase to worldwide temperature averages for the time frame of the next 100 years, range between 1,4-5,8˚C3. The general warming of ambient temperatures will lead to an increase of extreme weather conditions. Extreme summers like the ‚summerof the century‘ in 2003, have shown what temperature stress buildings and their inhabitants can be exposed to. The duration of such heat periods will likewise increase in the future.3 The amount of solar irradiation remains constant, while air temperatures are forecast to rise. Therefore to achieve energy-optimised cooling, the direct summer solar gains must be reduced by the building‘s skin. Yet the passive gains of the cold season must remain accessible to lower or to avoid the power demand for heating. The occurring climate change shows clear consequences for the dimensioning of sustainable climate control systems to adequately temper non-residential buildings. For active systems it signifies an increase of energy consumption at peak load times, passive systems can reach the limits of their capacity with unfavourable building constructions, because the transfer of heat to the surroundings will become more difficult.4 Night ventilation, for example, will show a lower potential. The use of primary energy for active automated cooling is becoming an unpredictable expense factor in building operation, due to the present development of energy prices. The use of energy-efficient technology and methods is therfore ecological and also increasingly economic pragmatism. Static shading devices in office architecture │ 11 2. Thermal comfort in the office workplace Heat loads effecting office buildings occur simultaneously in day operation. Through people, devices, electric lighting and solar irradiation, administrative buildings (with high insulating quality of the envelope) start overheating at occupancy times, from an outside temperature from 5°C5. Considering rising air temperatures, the reduction of summer heat loads is of growing importance for the comprehensive energetic assessment of office buildings. A decrease of heat loads in office buildings can be achieved by: • building shape, situation and orientation on the site • reduction of internal heat sources • installation of air-conditioning equipment • increase of the thermal mass or inertia of the construction • reduction of the glass percentage of the building facades • solar preventive measures If the glazed facade surfaces are not reduced, e.g. for reasons of spacial and daylight quality, a protection of these surfaces from solar irradiation in summer is of elementary importance for the temperature ratio and lasting comfort of the interiors. 2.1 Normative requirements Due to the ‚26°C-judgement‘ of the Bielefelder district court6 the discussion about thermal comfort criteria in the workplace has increased. The court appeals here to the ‚should’ guideline of the workplace directive ASR 6/1,3.3 and the old version of the DIN 1946-2 of 19608. However, the DIN 1946-2 is applicable only for spaces with air-conditioning equipment. A strict observance of the maximum interior air temperature of 26°C up to outside temperatures of 32°C as the Bielefelder judgement requires, would however demand an active cooling system in the majority of German administration buildings9. This demand stands in hard contrast to the political and social targets of sustainability. Furthermore, the judgement opens the possibility for office employees to demand days off, as well as the possibility of abatement of rent for the times of the temperature excess. Claims for compensation towards the planner are likewise to be expected. 12 │ Static shading devices in office architecture The definition of thermal comfort requires the consideration of physiological conditions, activity, clothes, the interior climatic factors, humidity, airflow rates and temperatures of the surfaces and the air, in relation to the external conditions. As well as the influence of weather changes and seasonal variations. This is discussed by Ruck10 in detail. The PMV value (predicted mean vote), tries to join these factors to a unit, enabling a better forecast of a comfort probability. It is applied within the DIN ISO 3011. The DIN 1408, section212 introduces the ‚solar entry value‘ for the reduction of the external solar loads. The computationally to be determined value considers the influence of transparent components on their importance for summer overheating. In the formation of the solar entry value the glazed areas of the facade are considered in relation to their location. The percentage of window surfaces of the facades and the total solar energy transmittance of the glass flow into the calculation connected to the solar protection as a basis. The value can be reduced by increase of the buildings thermal mass and the use of night cooling. The influence of shading devices is integrated into the calculation through a coefficient (Fc). (Chapter. 4-2). Static shading devices in office architecture │ 13 3. Summer heat protection - Shading As shown in chapter 3, an energy-efficient possibility for the reduction of heat loads in administrative buildings is the use of solar protection devices. Simplified there a 3 typologies defined by their position and adaptability: • inside adjustable • outside adjustable • outside static The typology does not take shading in the glass surface into consideration, i.e. electrochromic glazings or antisun glasses. 3.1 Interior adjustable shading Devices behind the transparent skin, e.g. roller shades or venetian blinds, have the disadvantage of only influencing the penetrating heat after its transmission through the glazing. The air in the space between the pane and the shading element is heated. The element in addition is heated through solar irradiation and gives off the heat into the room via radiation. Hence, the effectiveness of the same system is lower than if installed before the facade. (Fig. 3.1-1) dia Coating n tio n Solar protective glazing Insulative glazing Shading Irra tio Coating dia Shading Irra Fig.3.1-1 Influence of the position of the heat-reflective coating of the glazing on the caloric entry in combination with inside solar protection. On the left solar protective glazing, heat insulation glazing on the right. In the left case the heat is reflected by the inside solar protection device and is absorbed in the external glass pane, on the right in the internal pane. (Source: Author) A further disadvantage of interior mounted shading is the impediment of window service. The possibility of opening windows and with it passive ventilation should be 14 │ Static shading devices in office architecture maintained. That is why, among other reasons, adjustable solar protection devices are also accommodated in the space between the glazing planes. The solar protection effect is slightly raised, as the heat radiation does not immediately reach the internal glass plane. 3.2 Exterior adjustable shading Adjustable solar protection mounted before the facade, based on the same the same technical system, shows a higher effect concerning solar reduction than if mounted inside. It limits the entry of heat before it reaches the glass plane. As outside equipment is exposed to higher wind and weather strain, they must be be carried out more stable than those mounted on the interior. Motor operated solar protection devices can be controlled by ‚wind guards‘ in order to be retracted, preventing their damage in the case of strong wind. By coincidence of shading need and wind effect, necessary solar protection can be absent for 2 hours on up to 10% of working days depending on the wind resistance of the device.13 Due to wind loads a mounting of adjustable systems is also not applicable to arbitrary building heights. Airflow conditions within the city scape can also burden the system. Electrosensory controlled mobile systems on the outside have a higher effectiveness, because they react immediately to irradiation, but impair the user’s contentment. Manual intervention by the office user must be possible, to take individual comfort needs into account. Operating errors concerning heat reduction effects are problematic for heat insulation calculations and thus also for the efficient assessment of building heating and cooling systems.14 User behaviour has been examined towards this several times already to derive prediction methods.15, 16 Criteria of visual comfort have proven to be dominant in the adaptation of solar protection. The heat protection function is operated as such only when direct radiation strikes the user immediately. The requirement for a visual contact to the outside, glare reduction and daylighting are put before the necessary heat reducing function. It is proven, that users accept an amount of glare for a free view to the outside.1 To make daylight available when the solar protection is closed, venetian blinds with concave louvres in Static shading devices in office architecture │ 15 the upper third are used. Thus daylight can partially be used through ceiling reflection. (Fig.4.2-1) 3.3 Static shading Static shading is established by projecting facade elements or elements prepositionend to the building face. These can be vertical or horizontal in their main orientation or be designed three-dimensional. The elements are fixed with regard to the course of the sun and the resulting solar angles. By geometry and formal composition the elements attain an angle selectivity. The elements can be shaped to intercept the summer sun and let the winter sun pass. (Fig.3.3-1) Abb.3.2-1 Typical office situation with shut adjustable solar protection on the outside. In this case the clerestory windows are unobstructed and provide for indirect daylight through light-reflecting louvres. The view is obstructed. The situation equals that of inside solar shading. (Source: Solarbau:MONITOR) Static shading on office buildings is often established by self-shading through extended roofs or balconies. Next to its function of shading it is combined synergetically with other functions. Typically the solar protection function is combined with escape routes and cleansing surfaces or the outside structure is utilized. 16 │ Static shading devices in office architecture Because of the solar altitude in the course of the day, the south facade is shaded easiest by horizontal elements. East and west elevations are less easy to shade from direct solar radiation through overhangs due to the angle of incidence of the sun. Vertical eleSummer 60-65° Fig. 3.3-1 In Central Europe the sun changes its angle of solar altitude in an annual rhythm between 60-65 ° in summer and 13-18 ° in winter. Because of this natural alternation the direct sun can be blocked on facades oriented south in summer with angle-selective shading while the the winter radiation can be still used to temper the Building. By intercepting the direct radiation for the greatest parts of the year, glare protection can be avoided and the view to the outside be preserved. (Source: Author) Winter 13 -18° ments can possibly prevent winter gains. Vital for the effectiveness of static solar protection systems in relation to the reduction of overall building energy consumption is their precise calculation. Daylight quality and possible solar gains are reduced through oversizing, by underestimating the necessary extent avoidable solar loads must be diminished by additional measures. Static shading devices in office architecture │ 1 4. Evaluation criteria The geometry of wall openings in combination with the solar protection must fulfil various tasks in combination with solar protection and can be judged on these. These requirements are partly oppositional. The interaction of these factors is important to the valuation of solar protection while the core themes can differ according to project and energy concept (fig. 4-1). In accordance to the demands of the IEA18 Minimization of summer loads Energy optimization Warmth/Cooling Use of winter gains Daylighting Lighting necessity Glare reduction Comfort View to the outside Abb.4-1 Catalogue of criteria in accordance to the demands of the IEA for the assessment of solar protection devices. Starting point is an energetic optimisation of the building in dependence of the achievement of user comfort. The basic requirements for the solar shading can be divided into the areas of light and heat (cooling). The basic requirements are broken down into an overview of requirements. There are contradictions between single requirements. (Source: Author) ) In addition, the following requirements should likewise be fulfilled: • guarantee of the possibility of ventilation • economic efficiency: Easy and secure fixing, operation, servicing and lasting resistance • minor influence on the spectral composition of daylight in the interior and thus of colour and colour reproduction qualities • 18 │ aesthetics Static shading devices in office architecture 4.1 Daylight Daylight penetration is influenced by the implemented shading device. The daylight factor (D) is one of the key values in the quantitative analysis of daylight effect for a building. It is determined as a percentage ratio between the illuminance in a given point ‚Ei’ (at the working level in the interior as a rule) to the unshaded illuminance outside ‚Eo’ under completely overcast sky conditions (Equ. and Fig. 4.1-1). Fig.4.1-1 Determination of the daylight factor by the relation of illuminance in a point inside to the illuminance outside under a completely overcast sky. (Source: Author) Equ.4.1-1 Equation for the calculation of the daylight factor as a proportional value. Eo D = Eo · 100% Ei Ei The model of the ‚overcast sky’ is independent of geographic position, time and orientation. Hence, it can be used to evaluate the daylighting influence of a shading geometry independent of location. 4.2 Warmth The reduction factor is used for the determination of the shading effect toward solar radiation based to the equation in prEN 1450119 (Equ. 4.2-1). solar irradiation with shading solar irradiation without shading = reduction factor Fc Equ.4.2-1 Equation for the determination of the reduction factor Fc. Defined for the surface of the glazing, the derived value refers exclusively to the shading element. . However, the values the DIN are standardised, simplified and imprecise. For the precise determination of the Fc value for a specific window, the inclusion of local weather data, Static shading devices in office architecture │ 19 angle of incidence, orientation, material qualities of the shading, its geometry and overshadowing of the surroundings is necessary. The reduction factor lies in an area between 0 and 1 where a low value signifies higher solar protection of the system. In summer, when outside temperatures are high, a low Fc value (~0) will be aimed at whilst in winter a high value (~1), allowing the use of solar gains. Hence, a variable Fc value in the annual course is advantageous. 4.3 Unobstructed view Factors of visual comfort play an essential role in the user’s acceptance of an office building. The user comfort in the offices is an essential criterion for the contentment at the workplace20. The solar shading influences the view to the outside during the day, the moderation of light, the contrast ratio between working surface and background and the light colour. The protection from insights or darkening, e.g. for conference rooms, can likewise be of importance. The description of the unobstructed view of an aperture in connection with its solar shading construction is presented by means of shading masks after Olgyay21. The spacial geometry of the room is projected onto a hemisphere from an internal point (Fig.4.31). An angle of 360 ° is taken into account, so that the areas of the space behind the viewer are usually mapped as shaded, the areas in front depict the visible sky and prepositioned obstacles. Solar radiation (direct and diffuse) arriving from this free area has an immediate effect on the window. 4.4 Glare, visual comfort Consideration of a glare probability for specific static shading geometry and a parameter definition have not been a part of this work. Other factors of visual comfort were also excluded. They are to be examined in further studies. 20 │ Static shading devices in office architecture 5. Shape - Formal typologies of static shading The search for suitable solar protection is an architectural decision above all. Static shading has a strong formal structuring effect on the appearance of elevations. The formative individuality of a building can be produced by its application. It can be arranged in 3 basic formal typologies: • horizontal projections • vertical projections • prepositioned screens By construction, execution and material choice they can be widely varied. By combination of the elements, the number of possible formal variants is large. They do however differ in their impact considerably. On the following pages a basic overview of the different typologies with their shading masks and an executed example are shown. (cf. Olgyay)21/22 The models depict the shade on April 30th 8:15, for a window oriented to the Fig.4.3-1 Method of deriving shading masks after Olgyay. Shading masks illustrate the geometrical conditions of the shading from a point in the room and thus likewise the visible portion of the sky. The view-restricting elements are projected onto a hemisphere positioned above the point of view and are then illustrated in plan view. (Source: Olgyay, design with Climate22) east in Cologne, 50.9 northern latitude. The window opening has a width of 3.4m and a height of 2m. The height of the view point for the shading masks lies at 0.85m and is 1m from the opening in room axis. For better readability the shadow masks are south-oriented, the illustrations of the shading elements are lightened for clarity. The depth of the shading elements in the model is specified separately. The example projects were chosen due to their clarity of representation and their formal integration of the respective typology of static shading. . Static shading devices in office architecture │ 21a 21b│ Static shading devices in office architecture 5.1 Horizontal projections 5.1-1 Opaque overhangs Efficient with high standing sun. Hence typical solar protection on south facades. The portion of the visible sky is limited according to the size of the projection. With adjusted dimensioning the incidence of solar radiation is possible in winter. The depth of the overhang is 1 m. Example: City Hall London, Norman Foster Location: 51,3° n.lat., London, England 2002 (Source: Flickr.com) 5.1-2 Translucent overhang Efficient with high standing sun. It is possible to select the angle of incidence. The portion of the visible sky can be higher than that of the opaque overhang, depending on material and execution. The light yield is higher due to its transmittance of diffuse light compared to the opaque overhang. The depth of the overhang is 1 m. Example: Chiswick Park, Richard Rogers Partnership Location: 51,3° n.lat., London, England 2004 (Source: Richard Rogers Partnership) 5.1-3 Lightshelf A combination of daylighting and shading. There is a shading effect only below the element, above the component is light-guiding. The light is directed into the depth of the room and the space is illuminated more evenly. By defining the surface and the elements geometry, influencing the depth of the reflection is possible. By shading of glass area below, the absolute amount of light is reduced. Low solar angles can increase the risk of glare, thus the insertion of diffusing glas is advisable in the upper glazing area. Example: Academy Mont-Cenis, Jourda + Perraudin Location: 51,3° n.lat., Herne-Sodingen, Germany 1999 (Source: C. Hui) 22 │ Static shading devices in office architecture 5.2 Vertical projections 5.2-1 Wingwall Limited effect on the south side as irradiation from the solar zenith is not held back. Effective on east and west facades in combination with horizontal projections. Depending on the axis distance and element depth the view is narrowed. By selecting the angle the solar azimuth can be taken into account. The depth of the element is 60cm. Example: Metroplitan, Norman Foster Location: 52,1° n.lat., Warsaw, Poland 2003 (Source: Foster and Partners) 5.3 Combined forms 5.3-1 Overhang and Lightshelf Combination of light reflection into the depth of the room and strong reduction of solar irradiation. Often in a shifted assembly to reach the maximum effect for both elements. In the displayed form it is also effective for low solar angles. The depths of the elements are 1 m.. Example: University of Lausanne, Cube/Niv-O Location: 46,3° n.lat., Lausanne, Switzerland 1995 (Source: Detail magazine) 5.3-2 Brise-Soleil (Sun breaker) Combination of vertical and horizontal projections. Mostly positioned in front of fully glazed facades. Usually also fulfils the function of a balcony. The depths of the elements are 1 m.. Example: Ernsting Service Center, David Chipperfield Location: 51,5° n.lat., Coesfeld, Germany 2001 (Source: El Croquis) Static shading devices in office architecture │ 23 5.4 Prepositioned screens 5.4-1 Textile screens Seldom designed as a static shading system. Light and heat radiation are reduced depending on the transmission values of the textile material. Restricted view depending on the position and height of the ‘sails‘. Example: Olivetti Headquarters, Egon Eiermann Location: 50,4° n. lat.,Frankfurt, Germany 192 (Source: Stahl und Form) 5.4-2 Louvers Louver screen in distance to the facade. A precise check of the inclination is necessary. Restriction of the view. Usually as a adjustable construction or only in the areas of the glazing not necessary for continous view. Example: ViTa, MGF Architekten Location: 48,3° n. lat., Tübingen, Germany 2005 (Source: Glas - Architektur und Technik) In the built surrounding the shown typologies are used in divers variations. By combination of the types, choice of material and construction the number of possible solutions is varied. (Model illustrations and shading masks: Author) 24 │ Static shading devices in office architecture 6. Exemplary analysis 3 buildings were examined exemplarily with the defined parameters towards their effect of solar protection. The shading was checked concerning its effect on daylight, reduction of the solar gains and influence for the unobstructed view. The choice of the buildings occurred on grounds of their shading typology and the formal importance of the shading for their overall architecture. The following projects were examined: • Ernsting Service Center, Coesfeld - David Chipperfield Architects • Olivetti Headquarters, Frankfurt - Egon Eiermann • City Hall, London - Norman Foster Architects- 6.1 �ethod The parameters were simulated with help of computational models. The daylight quotient was additionaly measured, in physical scale models, scale 1:20 and 1:25. After a phase of software search and evaluation, the tool Ecotect 5.523 was used its current beta version. The user friendly scriptable software allows the simulation of solar irradiation on the basis of imported weather data, as well as light calculations by means of the internal interface to the scientificaly approved tool Radiance24. Additionaly, modules for the generation by ideal shading geometries are integrated into the software which were evaluated in the conclusion of this work. Essential parts of the modelling were done in Sketchup25. The program enables the quick and simple production of polygon-based 3D models. The models were imported into the simulation surroundings via the dxf format. The examined spaces and the shading geometry were modeled in Ecotect to avoid discrepancies and interpretation mistakes. A separate LUA26-based Script was written to determine differentiated values of diffuse and direct radiation in Ecotect. The necessary weather data was exported from the Meteonorm2 data base in TMY2Format. Static shading devices in office architecture │ 25 The reflections of the model surfaces were defined according to the DIN 5034-128 for all daylight simulations as follows: : • walls: 50% • ceiling: 0% • floor: 20% • Transmittance τ of the glazing 80% Sketchup Basic model Meteonorm Weather data Model Measurements Ecotect Ecotect Solar radiation Radiance Light simualtion Script Shaded Non shaded Reduction factor Shaded Shading mask Non shaded Daylight factor Fig.6.1-1 Scheme to determine the defined parameters of shading quality, daylight relevance, and view to the outside for the entered 3D models. (Source: Author) 6.2 Project example The results of the project example ‚Ernsting service centre‘ are explained exemplarily. The location of this administration building for a textile firm in Coesfeld-Lette in 26 │ Static shading devices in office architecture Germany, 51.5 n. lat. A ,Brise-Soleil’ is superimposed on all facades regardless of their orientation as roofed balconies with a depth of 1.6m, width of .6m and height of 3.8m. The vertical side walls are in extension of the inner office walls. The width of the office units lying behind it have approx. .6m in width, the depth of the room is 5.9 m with a ceiling height of 3.4 m. The reflection of the balcony surfaces in concrete was estimated to be 50%. The filigree balcony balustrades have a height of 90 cm. They were not taken into consideration in the model, because their influence on the results was expected to be of subordinated importance. The glass fronts are established by a vertically divided fully glazed stick-system. A B Fig.6.2-1 Illustration of the examined spaces in the model. Partially the shading is a results of the building geometry. (Source: El Croquis) Fig.6.2-2 Ernsting Service Center by David Chipperfield Architects. A balcony is positioned before the offices with a fully glazed facade as a ‚brise-soleil‘. In some areas an additional mobile solar protection is available. It is not taken into consideration. (Source: El Croquis) Static shading devices in office architecture │ 2 Fig.6.2-3 Measurements of the Model room (Source: Author) 6.3 Results Die office rooms were examined utilizing the method proposed under 6.1. The results were evaluated. 6.3.1 Daylight The curves of the resulting daylight factors for the examined orientations differ partly due to the shading of the building. The daylight factors in 2m distance to the facade lie in an area between 2.8 and 4.6. in spite of the deep brise-soleil. This is explained by the unusual space dimensions. Daylight factors no shading East GF B West 1.F Model East 1.F A East 1.F B South 1.F North 1.F Fig.6.3.1-1 Daylight factors of the examined spaces. Project: Ernsting Center. The model measurements have an accuracy of ± 10%. (Source: Author) distance from window 6.3.2 Shading effect Die reduction of heat radiation differs considerably according to the azimuth of the facades. 28 │ Static shading devices in office architecture Fig.6.3.2-1 Display of the determined monthly shading factors Fc for: north and south facing rooms (top) and the east upper floor (1.Fl.) A and west facade (below) Reduction factor It is demonstrated that the north facade faces the highest shading effect during the winter months caused by the deep Brise-Soleil , while the south facade shows an energetically desirable curve. Both series of calculations apply to the upper floor (1.F). Total South Direct South Diffuse South Total North Direct North The Fc values of the west and east facade (1.Fl. A) are similar. The increase of the shading effect during the winter months on the east facade is explained by the shading of the building wings. (Source: Author) Diffuse North Reduction factor Total East 1.Fl A Direct East 1.Fl A Diffuse East 1.Fl A Total West 1.Fl A Direct West 1.Fl A Diffuse West 1.Fl A 6.3.3 View Shading masks were created for the examined spaces to illustrate the effect the elements produce toward the unobstructed view from a point 80cm obove the floor and 1m from the facade in room axis. Fig.6.3.3-1 Shading mask for the room upper floor west (left) and upper floor east A (right). The extended building wings cause an additional restriction to the field of view. (Source: Author) Static shading devices in office architecture │ 29 . Simulation as a planning tool - new concepts Traditional proceedings to attain the fulfilment of static solar shading requirements (cf. Olgyay21 and Mazria30), employ an iterative process of shaping, testing and reworking. This process can be accelerated and simplified by means of computer-aided tools. 3 of the tools and their underlying methods and approaches are presented here. 7.1 Geometric projection of the solar path The Ecotect23 module Optimised Shading Device offers Marsh‘s30 ‚Cut off date projection’ of the geometric projection of the solar path as a possible method for the generation of an optimal shading contour. The vertexes of a window are projected onto a plane following the solar path. The designer must define the starting and ending points of the periods in demand of shading in the annual and daily course. The determination of the optimal contour is achieved by means of connecting the different contours of the ‘cut off ‘ (beginning and end) times (Fig. .1-1). Fig..1-1 Schematic description of the process of charting the solar path on a surface in relation to a window after Marsh. Depending on beginning and end date, and time of day with a shading necessity. The shading plane is between window and sun. The inclination and precise position of the surface is of no importance to its functionality. In the first step the two lower vertexes of the window are projected onto the plane for the daily beginning and ending hour in relation to the suns annual course. This returns the least necessary width with the clear analemma curves. In the following step, the depth is aquired through the ‚cut off’ dates of the defined time range. The first or last day of the year requiring total shading. Again for both lower vertexes. The sum of the points is simplified by elimination of the superfluous curve segments. The contour of the shading geometry can now be traced. (Source: Marsh, Computer-optimised shading design) 30 │ Static shading devices in office architecture Conclusion: • the generation of a contour including the shading surroundings cannot be achieved • material properties,e.g. transparency are not taken into consideration • actual amounts of solar radiation are not illustrated • solar profits in equator-distant locations are not considered. In contrast, to the actual necessity, the geometries are particularly large here because of the low solar angle. • therefore the method must to be considered conditionally 7.2 Illustration of the amount of irradiation The requirement for the consideration of irradiation to determine a shading necessity, leads to the development of alternative generation methods. Two approaches are evaluated here. 7.2.1 Point cloud raytrace method In the course of the process, likewise developed by Marsh30, rays are dispached from the surface to be examined (window) by random principle‚ sent out ,backward’ in the direction of the sun. When a ray strikes an obstacle, the value of the direct radiation at that time is determined from the weather data and recorded for this point. After the simulation has run, the accumulation can be read as a shaded ‚point cloud’ of the relative distribution of solar intensity. The shape of the shading device can be adapted by the planner. Fig..2.1-1 Simulation results of the ‚Point cloud Raytrayce’ method for a south, east and west oriented window 2/3 m, in Stockholm. Shading period is 800-1800, from the 10th April to the 01st of September. The blue surfaces receive a low, orange to yellow surfaces a higher amount of direct solar irradiation. It is recognizable that neighbouring obstructions have an influence on the shading necessity due to the low angle of solar incidence. (Source: Author) Static shading devices in office architecture │ 31 Fig..2.1-2 Shading contours from the traced point cloud simulated in Fig..2.1-1 with summed irradiation values between 900 and 1000 W/m2 (values not evaluated). (Source: Author) ) Conclusion: • areas with shading necessity are defined by their relative amount of solar irradiation • shading by the surroundings are taken into account • the method is blurred, but sufficient enough in early design phases, to mark zones with likely need for shading • Irradiation is considered exclusively as a avoidable heat source. Energetically sensible solar profits are not taken into consideration. The quality of the output depends decisively on the quality of the weather data for the specific location. 7.2.2 Cellular �ethod The method of ‚cell calculation’ by Kaftan31 aims at the development of a maximum energy efficiency of shading geometry. The developed algorithm assigns a necessity for shading or for solar gains to every cell of a defined shading grid, by a scheme of criteria.(Fig..2.2-1) This is done with an immediate relation to the interior. Criteria for user comfort flow in onto the calculation. The developed computational tool ‚Optimal Shading Form’ (OS-Form) is based on MS Excel spreadsheets.(Fig..2.2-2) 32 │ Static shading devices in office architecture 1.To the determine the borders of the shading surface following parameters are considered in this first step: window geometry, inclination and orientation of the window, Fig..2.2-1 Methodical principle of the ‚cellular calculation’ after Kaftan HSP - Hourly shading projection 1.Check if a cell is passed by direct radiation HSE Hourly shading effect 2.Calculation of the sum of direct radiation that reaches the interior through the cell. HSP Hourly shading schedule 3.Review of the hourly indoor climate 4.Shading necessity of each cell in the grid (Source: Kaftan) the incline of the shading surface, the movement of the sun and shading from the surroundings. 2. In the following step the direct radiation which reaches the room through the grid is summated for every cell. Angle of incidence and glass definitions are taken into consideration. 3.In the third segment of calculation it is determined whether shading is desirable or undesirable dependent of time. Climatic conditions and requirements of visual and thermal comfort in the room establish the basis. This is calculated without mechanical ventilation system and artificial lighting. The necessary input data is derived from energy simulation programs and weather data for the site. The shading contour is estimated , because it has not yet finally been calculated at this point. Static shading devices in office architecture │ 33 Fig..2.2-2 Illustration of the optimised shading contour for a south oriented window in Stockholm for the period a year. Window measurements 2/3 m. Shading period is 800-1800. The blue areas show areas with need of shading, the necessary areas for solar gains are red. (Source: Kaftan) (Source: Kaftan) Conclusion: • the MS Excel tool ‚OS-Form’ requires data from other simulation software (or measurements) • the method takes into consideration the requirement for solar gains, daylight and shading. • hence, annual simulations are sensible • shadings of the surroundings are taken into consideration • local climate and indoor climate of the office space are considered • material qualities, e.g. transparency are considered • the derived values enable the adaptation the building system • by positioning several grids at different heights, three-dimensional shading geometries can be determined The development of a plug-in for Ecotect on the basis of the described method is underway to integrate the data input and calculations into one process. The beta version is not freely accessible at present. 34 │ Static shading devices in office architecture 8. Conclusion und outlook Starting point of this thesis is the assessment of the energetic and constructive disadvantages of adjustable solar protection systems. A formal overview of static solar shading typologies was provided. A simple method of testing their influence concerning heat protective effect, daylight relevance and view was suggested and demonstrated. A temporary overview of tools for the determination of their optimum extent was provided. Parameters of visual comfort, especially glare reduction have not yet been taken into consideration. Continuing research should include these factors. Further work in the field of the generation of optimum shading geometry is to be carried out and their usage evaluated in practice. The effectiveness of generated shapes is likewise to be validated in future research through measurements. Static solar protection offers great potential in formal and energetic areas in connection with upcoming energetic refurbishment of old building stock due to amendments of the law. New approaches in material and construction also provide further fields for research. Static shading devices in office architecture │ 35 References 1 Directive 2002/91/EC on the Energy Performance of Buildings of 16.12.2002, Official Journal of the European Communities, 4.1.2003 2 DIN V 18599-4:2005-0, Energetische Bewertung von Gebäuden – Berechnung des Nutz-, End- und Primärenergiebedarfs für Beheizung, Kühlung, Belüftung, Beleuchtung und Warmwasserbereitung – Teil 4: Beleuchtung. Berlin: Beuth-Verlag 2005 3 Max-Planck-Institut für Meteorologie: Klimaprojektionen für das 21. Jahrhundert, Hamburg, 2006 IPCC: Climate Change 2001: Synthesis Report, Summary for Policymakers, Wembley, 2001 4 Herkel S., Pfafferott J., Zeuschner A.:Thermischer Komfort im Sommer in Bürogebäuden mit passiver Kühlung, Fraunhofer ISE, Freiburg, 2005 5 Daniels K.: Technologie des ökologischen Bauens - Grundlagen und Maßnahmen, Beispiele und Ideen, Basel: Birkhäuser Verlag, 1995 6 Urteil des LG Bielefeld, Az: 3 O 411/01 - Verkündet am: 16. April 2003  ASR 6/1, Arbeitsstätten-Richtlinien zur Arbeitsstättenverordnung, ASR 6-1 Raumtemperaturen, Ausgabe Mai 2001 8 DIN 1946-2:1960-04 Lüftungstechnische Anlagen (VDI Lüftungsregeln), Lüftung von Versammlungsräumen. Berlin: Beuth Verlag 1960 9 Voss K., et al.: Bürogebäude mit Zukunft, Köln: TÜV Verlag, 2005 10 Ruck N.: Building design and human performance, New York: Van Nostrand Reinhold, 1989 11 DIN EN ISO 30:2003-10 (Entwurf), Ergonomie des Umgebungsklimas - Analytische Bestimmung und Interpretation der thermischen Behaglichkeit durch Berechnung des PMV- und des PPD-Indexes und der lokalen thermischen Behaglichkeit (ISO/DIS 30:2003) 12 DIN 1408, Teil 2: Wärmeschutz und Energie-Einsparung im Hochbau, Beuth-Verlag, Berlin, 2003 13 Rothweiler B., Ohne Sonnenschutz wird‘s heiss!, VSR - Verband Schweiz. Anbieter von Sonnen- und Wetterschutz-Systemen, Fachartikel 2 2002 14 SIA 380/1, Blendschutz – Berechnung monatliche Solargewinne, Bericht vom 18.11.2004 15 Reinhart C. F., Voss K.: Monitoring manual control of electric lighting and blinds. Lighting Research and Technology, 35:3 pp. 243-260, 2003 16 Inkarojrit V.: Balancing Comfort: Occupants’ Control of Window Blinds in Private Offices, PhD Thesis at the University of California, Berkeley, 2005 1 Wienold J., Christoffersen J.: Blendungsbewertung von Tageslicht am Büroarbeitsplatz, 2004 18 IEA, (International Energy Agency): Daylight in Buildings – a source book on daylighting systems and components, A report of IEA SHC Task 21/ ECBCS Annex 29, July 2000 19 prEN 14501, (Entwurf) Blinds and shutters — Thermal and visual comfort — Performance characteristics and classification, 12/2004 20 Kelter, J.: Office Index 2000, Ergebnisse einer empirischen Studie zur Untersuchung von Büro-Arbeitswelten und zukünftigen Entwicklungen, 2001 21 Olgyay V., Olgyay A.: Solar Control and Shading Devices, Princeton University Press, New Jersey, 195 22 Olgyay V.,: Design with climate, A biolclimatic Approach to architectural regionalism, Princeton University Press, New Jersey, 1963 23 Ecotect 5.5 (Beta), Square One, www.sq1.com, 2006 24 Radiance 3..2, Lawrence Berkeley National Lab, http://radsite.lbl.gov/radiance/, 2005 25 Sketchup 5.0.260, @Last Software, www.sketchup.com, 2006 26 LUA 5.1, www.lua.org, 2006 2 Meteonorm 5.1, www.meteotest.ch, 2004 28 DIN 5034-1, Tageslicht in Innenräumen, Allgemeine Anforderungen, Berlin: Beuth-Verlag 1983 29 Mazria E.: The passive solar energy book, Rodale Press, Emmaus, 199 30 Marsh A.: Computer-optimised shading design, IBPSA Conference, Netherlands, 2003 31 Kaftan E.: The cellular method to design energy efficient shading form to accommodate the dynamic characteristics of climate, Master Thesis, University of Arizona, 2001 The measured and forecasted changes in climate have an immediate influence on the planning of buildings and building services. The requirements toward the energy efficiency of buildings is increasing. Due to rising temperatures, the reduction of summer heat loads will become a dominant factor in the tempering of buildings. Static and angle selective shading devices are an appropriate measure in the process of reducing summer gains and allowing the winter passive use of solar energy. They are independant of control mechanisms or user behaviour and are therefore more robust energetically and more predictable when dimensioning building services as opposed to moveable shading. Static shading is a plastic architectural medium. It dominates facades as an invariant graphic element and offers high design potential. This thesis shows a basic formal typology of static shading devices and simple methods of valuating their influence on daylight, warmth and view. It concludes with a presentation and evaluation of tools for their exact dimensioning and their generation. Thesis an der Universität Wuppertal im Rahmen des Master Studiengangs Architektur in der Vertiefungsrichtung Ressourcen optimiertes Bauen Dipl. Ing. Oliver Hans MSc an der Bergischen Universität Wuppertal Prof. Karsten Voss