Building science
Encyclopedia
Building science is the collection of scientific knowledge that focuses on the analysis and control of the physical phenomena affecting buildings. It traditionally includes the detailed analysis of building materials and building envelope
systems. In Europe, building physics is a term used for the knowledge domain that overlaps heavily with building science, and includes fire protection, sound control, and daylighting as well as the heat and moisture concerns that tend to dominate North American building science. The practical purpose of building science is to provide predictive capability to optimize building performance
and understand or prevent building failures.
This is the architectural-engineering-construction technology discipline that concerns itself with the 'mainly detail-design' of buildings in response to naturally occurring physical phenomenon such as:
The building science of a project refers to strategies implemented in the general and specific arrangement of building materials and component-assemblies.
The practical outcome of building science knowledge is reflected in the design of the architectural details of the building enclosure (see building envelope
),and ultimately in the long-term performance of the building's 'skin'. The scope can be, and is, much wider than this on most projects; after all,engineering is applied science mixed with experience and judgement. When architects talk of "building science", they usually mean the 'science' issues that traditional engineering disciplines traditionally avoided, albeit there are emerging disciplines of 'building scientists', 'envelope consultants', and 'building engineers'.
Many aspects of building science are the responsibility of the architect
(in Canada, many architectural firms employ a architectural technologist
for this purpose), often in collaboration with the engineering disciplines that have evolved to handle 'non-building envelope' building science concerns:
Civil engineering
, Structural engineering
, Earthquake engineering
,
Geotechnical engineering
, Mechanical engineering, Electrical engineering, Acoustic engineering, & fire code engineering. Even the interior designer will inevitably generate a few building science issues.
and dynamic
.
The static ones are tied to the structure’s dead loads added to the so-called live loads (of people, furniture, etc.), the dynamic ones are tied to the natural, abnormal, and artificial movements (earthquake
and loads wind
) the structure can sustain during its life cycle
.
The parameters which characterize structure dynamics are tied to the geometry
of the building and to the physical and mechanic
properties of its composition. 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 structure stiffness; very tall and then very flexible buildings as skyscrapers (low oscillation frequencies) oscillate slowly with respect to lower and squat buildings, and according to the building mass.
The second parameter takes into account all the dissipation
phenomena tied to the viscosity
of materials and to friction phenomena.
The mode shape describes the way of deformation which the structure is subjected to during the seismic event, and highlights whether or not the structures presents a good seismic behavior.
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.
design, thermal comfort
, indoor air quality
(IAQ), lighting
, acoustics
, and control systems.
Building envelope
The building envelope is the physical separator between the interior and the exterior environments of a building. Another emerging term is "Building Enclosure". It serves as the outer shell to help maintain the indoor environment and facilitate its climate control...
systems. In Europe, building physics is a term used for the knowledge domain that overlaps heavily with building science, and includes fire protection, sound control, and daylighting as well as the heat and moisture concerns that tend to dominate North American building science. The practical purpose of building science is to provide predictive capability to optimize building performance
Building performance
Building performance or home performance is a comprehensive whole-house approach to identifying and fixing comfort and energy efficiency problems in a home....
and understand or prevent building failures.
This is the architectural-engineering-construction technology discipline that concerns itself with the 'mainly detail-design' of buildings in response to naturally occurring physical 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 pointDew pointThe dew point is the temperature to which a given parcel of humid air must be cooled, at constant barometric pressure, for water vapor to condense into liquid water. The condensed water is called dew when it forms on a solid surface. The dew point is a saturation temperature.The dew point is...
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 project refers to strategies implemented in the general and specific arrangement of building materials and component-assemblies.
The practical outcome of building science knowledge is reflected in the design of the architectural details of the building enclosure (see building envelope
Building envelope
The building envelope is the physical separator between the interior and the exterior environments of a building. Another emerging term is "Building Enclosure". It serves as the outer shell to help maintain the indoor environment and facilitate its climate control...
),and ultimately in the long-term performance of the building's 'skin'. The scope can be, and is, much wider than this on most projects; after all,engineering is applied science mixed with experience and judgement. When architects talk of "building science", they usually mean the 'science' issues that traditional engineering disciplines traditionally avoided, albeit there are emerging disciplines of 'building scientists', 'envelope consultants', and 'building engineers'.
Many aspects of building science are the responsibility of the architect
Architect
An architect is a person trained in the planning, design and oversight of the construction of buildings. To practice architecture means to offer or render services in connection with the design and construction of a building, or group of buildings and the space within the site surrounding the...
(in Canada, many architectural firms employ a architectural technologist
Architectural technologist
The Architectural Technologist , also known as a Building Technologist, provides building design services and solutions and is trained in architectural technology, building design and construction. They apply the science of architecture and typically concentrate on the technology of building design...
for this purpose), often in collaboration with the engineering disciplines that have evolved to handle 'non-building envelope' building science concerns:
Civil engineering
Civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
, Structural engineering
Structural engineering
Structural engineering is a field of engineering dealing with the analysis and design of structures that support or resist loads. Structural engineering is usually considered a specialty within civil engineering, but it can also be studied in its own right....
, Earthquake engineering
Earthquake engineering
Earthquake engineering is the scientific field concerned with protecting society, the natural and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels...
,
Geotechnical engineering
Geotechnical engineering
Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials. Geotechnical engineering is important in civil engineering, but is also used by military, mining, petroleum, or any other engineering concerned with construction on or in the ground...
, Mechanical engineering, Electrical engineering, Acoustic engineering, & fire code engineering. Even the interior designer will inevitably generate a few building science issues.
Earthquake/seismic Design
All kinds of structures are projected according to two strain conditions: staticStatics
Statics is the branch of mechanics concerned with the analysis of loads on physical systems in static equilibrium, that is, in a state where the relative positions of subsystems do not vary over time, or where components and structures are at a constant velocity...
and dynamic
Dynamics (mechanics)
In the field of physics, the study of the causes of motion and changes in motion is dynamics. In other words the study of forces and why objects are in motion. Dynamics includes the study of the effect of torques on motion...
.
The static ones are tied to the structure’s dead loads added to the so-called live loads (of people, furniture, etc.), the dynamic ones are tied to the natural, abnormal, and artificial movements (earthquake
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
and loads wind
Wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
) the structure can sustain during its life cycle
Building life cycle
Building life cycle refers to the view of a building over the course of its entire life - in other words, viewing it not just as an operational building, but also taking into account the design, installation, commissioning, operation and decommissioning phases...
.
The parameters which characterize structure dynamics are tied to the geometry
Geometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
of the building and to the physical and mechanic
Mechanic
A mechanic is a craftsman or technician who uses tools to build or repair machinery.Many mechanics are specialized in a particular field such as auto mechanics, bicycle mechanics, motorcycle mechanics, boiler mechanics, general mechanics, industrial maintenance mechanics , air conditioning and...
properties of its composition. The parameters are:
- The fundamental frequency of vibration (f) and the respective oscillation period (T=1/f) (see oscillation frequency);
- The equivalent dumping coefficient
Equivalent dumping coefficient
An equivalent dumping coefficient is a mathematical coefficient used in the calculation of the energy dispersed when a structure moves. As a civil engineering term, it defines the percent of a cycle of oscillation that is absorbed for the structure or sub-structure under analysis...
(neq);
- The mode shape (the way in which the structure buckles);
The first parameter varies according to the structure stiffness; very tall and then very flexible buildings as skyscrapers (low oscillation frequencies) oscillate slowly with respect to lower and squat buildings, and according to the building mass.
The second parameter takes into account all the dissipation
Dissipation
In physics, dissipation embodies the concept of a dynamical system where important mechanical models, such as waves or oscillations, lose energy over time, typically from friction or turbulence. The lost energy converts into heat, which raises the temperature of the system. Such systems are called...
phenomena tied to the viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
of materials and to friction phenomena.
The mode shape describes the way of deformation which the structure is subjected to during the seismic event, and highlights whether or not the structures presents a good seismic behavior.
Reducing the effect of earthquakes on buildings
By monitoring the response of structures subject to earthquakes and by applying new knowledge and technologies, scientists and engineers continuously develop design and repair techniques on buildings, so that their ability to control the earthquake effects will grow. In order to reduce the destructive effects of earthquakes both on new-built buildings and especially on older ones, there exist some seismic adjustment techniques, with the aim of reducing the strain effects that earthquake causes. These techniques can be divided into two different categories: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
Dissipation
In physics, dissipation embodies the concept of a dynamical system where important mechanical models, such as waves or oscillations, lose energy over time, typically from friction or turbulence. The lost energy converts into heat, which raises the temperature of the system. Such systems are called...
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
Stiffness
Stiffness is the resistance of an elastic body to deformation by an applied force along a given degree of freedom when a set of loading points and boundary conditions are prescribed on the elastic body.-Calculations:...
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)
Dissipator (building design)
A dissipator is a device mounted among some sections of a building to reduce strains during an earthquake by slowing down the shaking of the building. During an earthquake, the sections of the building are subjected to movements which are relative to each other...
) 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
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
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.
Indoor environment
Building indoor environment covers the environmental aspects in the design, analysis, and operation of energy-efficient, healthy, and comfortable buildings. Fields of specialization include architecture, HVACHVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...
design, thermal comfort
Thermal comfort
Thermal comfort is a term used by the American Society of Heating, Refrigerating and Air-Conditioning Engineers, an international body. It is defined as the state of mind in humans that expresses satisfaction with the surrounding environment...
, indoor air quality
Indoor air quality
Indoor air quality is a term referring to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants....
(IAQ), lighting
Lighting
Lighting or illumination is the deliberate application of light to achieve some practical or aesthetic effect. Lighting includes the use of both artificial light sources such as lamps and light fixtures, as well as natural illumination by capturing daylight...
, acoustics
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
, and control systems.
See also
- Seismic analysisSeismic analysisSeismic Analysis is a subset of structural analysis and is the calculation of the response of a building structure to earthquakes...
- Architectural engineeringArchitectural engineeringArchitectural engineering, also known as building engineering, is the application of engineering principles and technology to building design and construction...
- ArchitectureArchitectureArchitecture is both the process and product of planning, designing and construction. Architectural works, in the material form of buildings, are often perceived as cultural and political symbols and as works of art...
- Civil engineeringCivil engineeringCivil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
, Earthquake engineeringEarthquake engineeringEarthquake engineering is the scientific field concerned with protecting society, the natural and the man-made environment from earthquakes by limiting the seismic risk to socio-economically acceptable levels... - Galvanic corrosion
External links
- www.buildingscience.com
- Building Science Textbook for Building Enclosures
- The National Institute of Building Sciences
- Building Science Blog, Green Building Advisor
- To go into the oscillation phenomena and their characterizing parameters issue
- Do you like to watch at some animations of mechanical vibrations subjected to particular loads?
- Build your own model buildings and verify their behavior in the case of earthquake
- Click here to see how you can adopt new design strategies in order to protect structures from earthquakes
- Close examinations about all types and effects of isolation systems
- Close examinations about dissipation systems