Building Physics BUILDING PHYSICS AND ARCHITECTURAL AERODYNAMICS. London United Arab Emirates Hong Kong Kuala Lumpur Houston New York

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1 Building Physics BUILDING PHYSICS AND ARCHITECTURAL AERODYNAMICS London United Arab Emirates Hong Kong Kuala Lumpur Houston New York

2 Design challenges facing the building industry are frequently associated with building physics problems such as ventilation, envelope, microclimate and pollution. BMT Fluid Mechanics provides specialist consultancy services in building physics to designers, planners and architects to enhance and optimize building performance and energy efficiency using state of the art technology. Building Physics addresses several different areas in building performance including air movement, thermal performance, control of moisture, ambient energy, acoustics, light, climate and biology. This field employs creative ways of manipulating these principal aspects of a building s indoor and outdoor environments so that a more eco-friendly standard of living is obtained. Building Engineering Physics is unique from other established applied sciences or engineering professions as it combines the sciences of architecture, engineering and human biology and physiology. Building Engineering Physics not only addresses energy efficiency and building sustainability, but also a buildings internal environment conditions that affect the comfort and performance levels of its occupants. The rapid acceleration of computer technology in recent decades has resulted in computer hardware and software that is now capable of numerically solving these equations and problems to time scales that fit within project schedules. BMT are specialists in the use of numerical modeling for building physic applications. The company is backed by in house high performance computing facility, wind tunnel facilities that are used for validation, and most importantly, a very experienced team of engineers who deliver clear interpretations and explanations of the results as well as recommendations for improving design. The versatility of the tool and the unprecedented ability to visualize and quantify the behaviors has meant that CFD and zonal analytical software has become an indispensable tool whenever practical analysis and engineering design work involving building physics is required. Benefits such as maximizing process efficiency, lowering production costs and meeting environmental concerns are all typical outcomes of using BMT s building physics consulting team. KEY SERVICES Internal Airflow Modeling Thermal Comfort Sun Microclimate / Internal Daylighting Stack Effects / Façade Bulk-Flow Air quality Fire & Smoke Wind Induced Noise Wind Driven Rain Blasts / Explosions Tel: Fax:

3 NATURAL, MECHANICAL AND MIXED MODE VENTILATION Physical phenomena causes air flow and pollutant transport (e.g. ventilation designs) in multizone buildings and to develop modules to be integrated in a multizone air flow modelling system. Special emphasis was to be given to providing data necessary to use the system (e.g. wind pressure distribution, default values for leakage of building components, material properties like absorption and desorption). Carpark ventilation Bulk air movement Airchange rates & local air flow patterns Dead zone analysis Vented & double skin façade analysis Internal CFD simulations can be used to assess the impact of system design and the distribution of heat and movement of air within spaces such as atria can be assessed, determining the impact of the supply air location, flow rate and temperature, extract location and other dynamics within the space. This can be used to fine-tune air distribution systems (both mechanical and passive) and examine specific design issues such as downdraughts, stack effect, condensation risk and smoke movement. THERMAL COMFORT Thermal comfort is affected by heat conduction, convection, radiation, and evaporative heat loss. Thermal comfort is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. Any heat gain or loss beyond this generates a sensation of discomfort. It has been long recognized that the sensation of feeling hot or cold is not just dependent on air temperature alone. Internal Spaces (Office environment) External Spaces (External Pedestrian Areas/Stadia & Arena) ROBIN IMAGES BMT is able to assist designers, builders, architects to judge that thermal comfort level by the variables of predicted mean vote (PMV) and percentage of people dissatisfied (PPD) according to thermal comfort factors. enquiries@bmtfm.com Website:

4 SUNLIGHT/DAYLIGHT BMT Fluid Mechanics provides comprehensive consultancy services to assess the environmental impact on microclimate of building complexes and largescale masterplans. Support is provided to designers, developers and planning agencies at all stages to assess and quantify potential beneficial and adverse environmental impacts in accordance with local and regional body legislative requirements.rs. SUNLIGHT Environmental Impact Analysis Pitch Microclimate Sunlight Radiance & Solar Reflectivity Modelling STACK EFFECTS The characteristics of pressure distribution are caused by stack effect in high-rise buildings and stack effect problems occur during the cold season. Stack pressure difference in high-rise buildings acted on interior partitions rather than on exterior walls, so serious problems due to large pressure differentials can occur on the inside of the building, e.g. internal zone highly pressure different, lift piston movement, lift door closing problems etc. Stack effect driven air movement and pressure gradients in elevator shafts Their impact on HVAC systems/lift operation/façade air tightness requirements Positive and sucking pressure on double skin façade Tel: Fax:

5 GAS DISPERSION AND POLLUTANT Environmental issues are of paramount importance from the planning and conceptual stages of project design through completion of development activities and beyond. Throughout the world increasingly strict attention is being paid to emissions from industrial processes to the environment and the resulting effects. Internal pollutant dispersion Bad & used air circulation Dispersion of ingested external pollutants FIRE & SMOKE The design of smoke management and smoke control systems for large and geometrically complex spaces such as atria and subway stations, as well as underground tunnels, is becoming more common as a result of increased computer speeds at lower costs and the availability of CFD models. BMT has the experience and tools necessary to carry out detailed CFD simulations of fires and smoke control within the built environment. BMT s staff has extensive experience in CFD modeling of fires and smoke movement and work closely with designer and fire engineers to provide practical solutions which fulfill the requirements of clients and the regulatory authorities. Fire & smoke scenarios to validate fire system, opening designs & evacuation strategy Smoke dispersion patterns and pollutants concentration in car parks Fire and smoke ventilation systems design strategies enquiries@bmtfm.com Website:

6 WIND-INDUCED NOISE Wind flowing across, around and through building features can result in audible tones arising from aero-acoustic phenomena such as resonances. A review of possible wind-induced noise mechanisms is therefore essential during design so that costly mitigation measures are avoided. BMT identifies the dominant wind-noise sources and mechanisms produced by façade in buildings as the first step towards prediction and treatment. A parametric study is undertaken to establish the relationship between the façade, sound pressure level, wind speed through the opening and the frequency (or wavelength) of the resonant peak. Façade features on buildings Windows or doors opening designs Lift shafts and stairwell tightness WIND DRIVEN RAIN The concerns of visual and thermal comfort under the shades are designed for daylight distribution and airflow movement. One of the most important aspects of pedestrian/spectators comfort under the shades is the protection from weather influences such as wind and rain. This wind-driven rain can reach a large area of the stand underneath the shades, resulting discomfort for the pedestrians/spectators in this area. Ignoring the influence of the wind and WDR during shades design can give rise to discomfort for the pedestrians/spectators that are walking, standing or sitting due to insufficient protection from WDR. The performance of the shades is evaluated based on the percentages of wetted surface area. Identify ground level wetting patterns for large span roofs (stadia & arena) Large canopies / drainage system performance under extreme weather The specific shapes of shades, with an open louvres and sometimes also open corners and façade of buildings will give rise to particular wind-flow patterns and therefore also specific WDR distributions that are largely unknown and very difficult to predict without using CFD. Tel: Fax:

7 BLASTS/EXPLOSIONS In recent years, considerable attention has been given to explosive loads on landmark structures as a result of both accidental and intentional events. At the same time, building designers the world over have been increasingly pushing the boundaries on design with ever more demanding architectural and structural forms and utilizing advanced structural materials and methods. Understanding how these designs and materials are able to withstand blast loads and maintain structural integrity is now no longer possible with semi-empirical methods without making highly conservative assumptions that drive up asset cost and compromise design. Identification and assessment of likely threat scenarios and guidance on risk based design criteria Blast load and non-linear structural response Prediction Determination of protection levels and development of mitigation / protection measures The balance of compromising design for the safety of the structure is heavily influenced by the acceptable level of risk. A risk-based approach to design for blast loading should be taken where accurate methods are employed to assess the consequence of an event, and combined with the likelihood of an event occurring. BMT have taken their extensive experience in risk-based explosion load analysis from the Oil and Gas industry and coupled it with class-leading software for non-linear dynamic structural finite element analysis (FAE), and unparalleled knowledge of structural environmental loadings to provide the construction industry a complete package for blast load design. The approach that BMT provide through all stages of design ensures that the risk posed to building occupants and structural integrity from terrorist and other explosions is significantly reduced. enquiries@bmtfm.com Website:

8 For further information contact: Tel: Fax: Website: BMT Fluid Mechanics Limited, 67 Stanton Avenue, Teddington, Middlesex, TW11 0JY, UK