Let talk about home, hosing and buildingsPresentation Transcript
is the collection of scientificknowledge that focuses on theanalysis and control of the physicalphenomena affecting buildings. Ittraditionally includes the detailedanalysis of building materials andbuilding envelope systems.
In Europe, building physics is a term used for theknowledge domain that overlaps heavily withbuilding science, and includes fire protection, soundcontrol, and daylighting as well as the heat andmoisture concerns that tend to dominate NorthAmerican building science. The practical purpose ofbuilding science is to provide predictive capabilityto optimize building performance and understand orprevent building failures.
This is the architectural-engineering-constructiontechnology discipline thatconcerns itself with the mainlydetail-design of buildings inresponse to naturally occurringphysical phenomenon such as:
the weather (sun, wind, rain, temperature, humidity), and related issues:e.g. freeze/thaw cycles, dew point/frost point, snow load & drift prediction, lightning patterns etc. subterranean conditions including (potential for seismic or other soil + ground-water activity, frost penetration etc.). characteristics of materials,(e.g. Galvanic corrosion between dissimilar metals, permeability of materials to water and water vapor, construct-ability, compatibility, material-adjacency and longevity issues).
characteristics of physics, chemistry and biology such as capillary-action, absorption, condensation ("will the dew point occur at a good or bad place within the wall?"), gravity, thermal migration/transfer (conductivity, radiation and convection), vapor pressure dynamics, chemical reactions (incl. combustion process), adhesion/cohesion, friction, ductility, elasticity, and also the physiology of fungus/mold. human physiology (comfort, sensory reaction e.g.radiance perception, sweat function, chemical sensitivity etc.). energy consumption, environmental control-ability, building maintenance considerations, longevity/sustainability, and occupant (physical) comfort/health.
The building science of a projectrefers to strategies implementedin the general and specificarrangement of buildingmaterials and component-assemblies.
The practical outcome of building science knowledge isreflected in the design of the architectural details of thebuilding enclosure (see building envelope ),andultimately in the long-term performance of thebuildings skin. The scope can be, and is, much widerthan this on most projects; after all,engineering isapplied science mixed with experience and judgement.When architects talk of "building science", they usuallymean the science issues that traditional engineeringdisciplines traditionally avoided, albeit there areemerging disciplines of building scientists, envelopeconsultants, and building engineers.
Many aspects of building science are theresponsibility of the architect (in Canada, manyarchitectural firms employ a architecturaltechnologist for this purpose), often in collaborationwith the engineering disciplines that have evolved tohandle non-building envelope building scienceconcerns: Civil engineering, Structural engineering,Earthquake engineering, Geotechnical engineering,Mechanical engineering, Electrical engineering,Acoustic engineering, & fire code engineering. Eventhe interior designer will inevitably generate a fewbuilding science issues.
All kinds of structures are projected according totwo strain conditions: static and dynamic. The staticones are tied to the structure’s dead loads added tothe so-called live loads (of people, furniture, etc.),the dynamic ones are tied to the natural, abnormal,and artificial movements (earthquake and loadswind) the structure can sustain during its life cycle.The parameters which characterize structuredynamics are tied to the geometry of the buildingand to the physical and mechanic properties of itscomposition. The parameters are:
- The fundamental frequency of vibration (f) and the respective oscillation period (T=1/f) (see oscillation frequency); - The equivalent dumping coefficient (neq); - The mode shape (the way in which the structure buckles);
The first parameter varies according to the structurestiffness; very tall and then very flexible buildingsas skyscrapers (low oscillation frequencies) oscillateslowly with respect to lower and squat buildings,and according to the building mass. The secondparameter takes into account all the dissipationphenomena tied to the viscosity of materials and tofriction phenomena. The mode shape describes theway of deformation which the structure is subjectedto during the seismic event, and highlights whetheror not the structures presents a good seismicbehavior.
By monitoring the response of structures subject toearthquakes and by applying new knowledge andtechnologies, scientists and engineers continuouslydevelop design and repair techniques on buildings,so that their ability to control the earthquake effectswill grow. In order to reduce the destructive effectsof earthquakes both on new-built buildings andespecially on older ones, there exist some seismicadjustment techniques, with the aim of reducing thestrain effects that earthquake causes. Thesetechniques can be divided into two differentcategories:
Base isolation: it is aimed to untie the ground-foundation system, so that the structure can be seen as it is “floating” on the ground during the seismic event, thus reducing the strains. Dissipation systems: there exist various types of dissipation systems, but they all have in common the effect of increasing the previously seen viscous dissipation coefficient of the structure. The better known base isolation technique consists of inserting some special equipment (isolator (building design)) in the proximity of foundations. This equipment offers a high stiffness for vertical loads so that the structure is not subject to sinking, while offering a low stiffness for horizontal ones, which are peculiar of seismic events. This way all seismic effects are absorbed by the equipment, whereas the structure is subject to low oscillations and consequently to low strains.
The dissipation systems (dissipator (building design)) are made by a series of devices inserted on the inside of the building frame using different techniques, with the aim of slowing down the structure oscillation and dispelling seismic energy. Energy Efficiency In the US contractors certified by the independent organization Building Performance Institute advertise that they operate businesses as Building Scientists. This is questionable due to their lack of scientific background and credentials.
Building indoor environment covers theenvironmental aspects in the design, analysis, andoperation of energy-efficient, healthy, andcomfortable buildings. Fields of specializationinclude architecture, HVAC design, thermalcomfort, indoor air quality (IAQ), lighting,acoustics, and control systems.