SIEMENS New Headquarters Brazil Sustainable Environmental Design - Report November,2012
Table of Contents Environmental Agenda
Building Orientation and Solar Control
Environmental Agenda The design proposal for the new Siemens Headquarters in Brazil was underpinned by environmental sustainability criteria in order to comply with Siemens Office standards of construction, thus adding value to the building by enhancing work spacesâ€™ environmental quality and reducing their operational costs ( see Figure 01).
Figure 01: Initial Costs vs Operational Costs: Local standard compared to sustainable standard. Source: Siemens Office. Guidebook for Implementation(2010)
Based on Siemens Guidebook (2010), the project brief took upon recommendations, addressing issues of daylight and also of the potential application of natural ventilation in work environments, in order to improve health, well being conditions and productivity, while achieving significant energy savings (see Fig.02). In order to comply with these requirements the specific literature (Baker and Stemmers,2002) recommends that the plan depth should have the proportion of approximately twice the distance of the floor to ceiling height (as seen in the figure 03), which in this case is 3 meters. As a result the daylit zone will have about 6 meters to each side of the faĂ§ade, giving a plan depth of around 12m. Nevertheless it is known that, the corridor area doesnâ€™t have the same lighting requirements as the workstations, allowing the plan to be slightly deeper if the later is located in the middle of the layout (Fig. 04). For all of the above, the plan depth defined for this project is of 15 m, which also complies with the requirements for the application of the Siemens Office layout.
Figure 02: Construction guidelines for Office Buildings. Source: Siemens Office. Guidebook for Implementation(2010)
Figure 04: Schematic floor section showing the potential daylit zones.
Figure 03: Daylight profile of side-lit room. Source: Baker and Steemers (2002)
Daylight In order to ensure that daylight will be enough to achieve the minimum recommended level of illuminance of 300 Lux for offices (CIBSE Guide A), daylight simulations were carried out using the software Autodesk Ecotect. The sky conditions and sky illuminance levels used as inputs were extracted from Meteonorm 6.1, which provides climatic data from Sao Paulo in a 10 year period (1995 â€“ 2005). The purpose of this detailed study was to guarantee that the offices would be able to achieve a maximum independence from artificial lighting during the working hours. Figure 05 shows a simulation of a working environment oriented due north â€“ south, at 9:00 am, which is generally the beginning of the working hours and also the time of the day when the sky have the lowest daylight levels together with late afternoon. Despite the fact that this is the worst case scenario to attain enough daylight levels, the simulation confirmed that a minimum of 300 lux can be achieved at early hours. However, after 17:00, as seen in the appendix 01, the sky illuminance levels decrease considerably, which might require the use of artificial light until the end of the working hours (19:00). Finally, it is possible to conclude that artificial light might be required for two hours/day, which will result in energy savings of 80% in comparison to a deep plan office building (10h/day of artificial lighting). The potential energy savings are expressed in the Figure Ib (appendix 01).
Figure 05: False colour image showing daylight conditions in July at 09:00 - Overcast Sky (30 Klux). Plan depth 15 meters. Source: Autodesk Ecotect Simulation
Building Orientation and Solar Control Strategy According to Yannas (2000), where there is choice over orientation, facing the glazed openings due south (for the south hemisphere), is more appropriate for buildings where solar gains are not desirable but in which daylight is required and views are valuable (which is the case of office buildings). This design decision, allows a considerable reduction or even the elimination (in some locations) of further means of solar control since this orientation receives lower incidence of solar radiation throughout the year. Therefore for this building, most of the working areas are oriented due south or north as seen in the Figure 06.
Figure 06: Sun path diagram, showing low solar incidence on the south facing facade. Source: Autodesk Ecotect Simulation
The use of solar control in this building for all exposed orientations is considered a fundamental measure to be adopted since it will contribute to reducing significantly the cooling loads. In addition, the shading devices will help to prevent sunlight falling onto the occupants, which could trigger actions of putting the blinds down and consequently turning the artificial lights on. In the north orientation, as seen in the figure 06, the sun is in a high angle in the sky; therefore simple overhangs will be enough to block the direct solar radiation. The overhangs can be also used to redirect the sun light to the back of the room, providing a deeper daylight penetration, thus optimizing the uniformity of light within the room. In this case, the overhang will adopt the function of a light shelf as seen in the figure 07.
Figure 07: Detail section showing the efficacy of the light shelf. Sun rays on May 21th at 12:00. Source: After Autodesk Ecotect Simulation
The effectiveness of the solar control strategy adopted can be seen in the figure 08, where the solar incident radiation on the north faรงade (proposed scenario) is compared to a conventional fully glazed faรงade without solar protection. It is possible to infer that the average daily incident solar radiation on the fully glazed faรงade exceeds 4000 Wh, while in the light shelf scenario this value drops to less than 700 Wh. As seen in the figure 09, few parts of the building are oriented due east and west. One of them is the main vertical circulation, where all the services are concentrated. In this area the lighting requirements does not ask for high illuminance levels, thus horizontal louvers tilted 45 degrees can be applied in order to block direct radiation from the low solar angles. The other area is an office environment, which is one floor lower than the entire complex. The reason behind this is that, as seen in the figure 10, the main vertical circulation is obstructing the direct radiation from the low solar angles on west orientation. This way it is possible to use Light Shelves to block the direct radiation when the sun is in a higher angle in the sky, thus providing better daylight conditions.
B Figure 08: Average daily incident solar radiation for December, January and February (Summer) on the North Facade. (A) Fully glazed scenario. (B) Proposed scenario applying the light shelf. Source: Autodesk Ecotect Simulation
Figure 09: Key plan showing the section line for the Figure 10.
Main Vertical Circulation
Main Vertical Circulation
Figure 10: Cross Sections showing sun rays striking the west facade on January 21th. (A) at 15:00 the light shelves of the office area will provide efficient solar control while improving daylight conditions (B)at 16:30 the Main Vertical Circulation will obstruct the sunlight from low solar angles Source: Autodesk Ecotect Simulation
Natural Ventilation As stated in Siemens guidebook (2010), the applicability of natural ventilation in working environments is preferred primarily for healthy and well being purpose and for consequently achieving effective energy savings, thus reducing the building operational costs. It is known that the possibility of applying natural ventilation strategies will depend also on the climatic conditions. As seen in the figure 11, Sao Paulo has a mild climate. The temperatures can go up to 33°C in the summer and as low as 8°C in the winter, however for most of the year they stay between 15°C and 25°C. The high range of diurnal fluctuation, which is around 10°K, indicates a potential for applying passive cooling solutions through thermal inertia and night time ventilation. Even thought the internal heat gains are quite high in office buildings, the climate analysis indicates the possibility of having natural ventilation for at least a significant part of the year, which could result in a mixed –mode building. Amongst the natural ventilation strategies, cross ventilation is the most effective. In order to be able to apply cross ventilation, the plan depth should follow a specific proportion in relation to the floor to ceiling height (similarly to daylighting). As seen in the figure 12, the recommended proportion is 5 times the floor to ceiling height, which in this case is 3m. This way, one can conclude that a plan depth of 15m besides attending the requirements for daylighting, it also complies with the requirements for natural ventilation. Figure 13 shows a CFD simulation which demonstrates that most of the office areas will have the façades facing the prevailing wind direction (southeast).
Figure 11: Monthly diurnal average temperatures for São paulo Source: Ecotect Weather Tool (data: Meteonorm 6.1)
Figure 12: Recommended plan proportion for the application of cross ventilation Source: CIBSE (2005)
Air velocity m/s
3.9 3.6 3.2 2.8 2.4 2 1.6 1.2 0.8 0.4 0
N Figure 13: Plan.CFD ( Computer Fluids Dynamics) Simulation showing Sao Pauloâ€™s prevailing wind(southeast) Source: Autodesk CFD Simulation 2013
Figure 14: Aerial View
Figure 15: West facing facade
Figure 15: East facing facade. Visitor access.
Figure 16: North facing facade
Figure 17: South facing facade
Bibliography Baker,N and K. Steemers (2002). Daylight Design of Buildings. James & James Science Publisher. CIBSE (1999). Daylighting and Window Design. Lighting Guide LG10. Chartered Institution of Building Services Engineers, London. CIBSE lighting guide 7 (2005). Office lighting.Chartered Institution of Building Services Engineers, London. CIBSE (2005). Natural ventilation in Non-Domestic Buildings. Application Manual AM10.Chartered Institution of Building Services Engineers, London. CIBSE (2006). Environmental design. Guide A, 7th Edition. Chartered Institution of Building Services Engineers, London. SIEMENS (2010). Paradigm Shift. Siemens Office.Guidebook for Implementation.SRE. Yannas, S. (Ed. 2000). Designing for Summer Comfort. EC Altener Programme. Environmental & Energy Studies Programme, AA Graduate School, London.
Figure I a: Global Horizontal Illuminance for S達o Paulo, monthly mean of hourly values (klx) After Meteonorm 6.1
Annual Lighting Consumption in a deep plan office building: 55 Kwh/m2 (CIBSE,2005) Potential for saving in a shallow plan : 80% of the working hours( Saving 44 Kwh/m2 year) Kwh cost in Sao Paulo: U$ 0,16 (Aneel,2012) New Office Building Area: 20.000 m2 Annual Saving Potential: U$ 140.800,00 Figure I b: Potential annual energy saving - Daylighting.