Building science is the science and technology-driven collection of knowledge in order to provide better indoor environmental quality (IEQ), energy-efficient built environments, and occupant comfort and satisfaction. Building physics, architectural science, and applied physics are terms used for the knowledge domain that overlaps with building science. In building science, the methods used in natural and hard sciences are widely applied, which may include controlled and quasi-experiments, randomized control, physical measurements, remote sensing, and simulations. On the other hand, methods from social and soft sciences, such as case study, interviews & focus group, observational method, surveys, and experience sampling, are also widely used in building science to understand occupant satisfaction, comfort, and experiences by acquiring qualitative data. One of the recent trends in building science is a combination of the two different methods. For instance, it is widely known that occupants' thermal sensation and comfort may vary depending on their sex, age, emotion, experiences, etc. even in the same indoor environment. Despite the advancement in data extraction and collection technology in building science, objective measurements alone can hardly represent occupants' state of mind such as comfort and preference. Therefore, researchers are trying to measure both physical contexts and understand human responses to figure out complex interrelationships.
Building science traditionally includes the study of indoor thermal environment, indoor acoustic environment, indoor light environment, indoor air quality, and building resource use, including energy and building material use. [1] These areas are studied in terms of physical principles, relationship to building occupant health, comfort, and productivity, and how they can be controlled by the building envelope and electrical and mechanical systems. [2] The National Institute of Building Sciences (NIBS) additionally includes the areas of building information modeling, building commissioning, fire protection engineering, seismic design and resilient design within its scope. [3]
One of the practical purpose of building science is to provide predictive capability to optimize the building performance and sustainability of new and existing buildings, understand or prevent building failures, and guide the design of new techniques and technologies.
During the architectural design process, building science knowledge is used to inform design decisions to optimize building performance. Design decisions can be made based on knowledge of building science principles and established guidelines, such as the NIBS Whole Building Design Guide (WBDG) and the collection of ASHRAE Standards related to building science.
Computational tools can be used during design to simulate building performance based on input information about the designed building envelope, lighting system, and mechanical system. Models can be used to predict energy use over the building life, solar heat and radiation distribution, air flow, and other physical phenomena within the building. [4] These tools are valuable for evaluating a design and ensuring it will perform within an acceptable range before construction begins. Many of the available computational tools have the capability to analyze building performance goals and perform design optimization. [5] The accuracy of the models is influenced by the modeler's knowledge of building science principles and by the amount of validation performed for the specific program. [4]
When existing buildings are being evaluated, measurements and computational tools can be used to evaluate performance based on measured existing conditions. An array of in-field testing equipment can be used to measure temperature, moisture, sound levels, air pollutants, or other criteria. Standardized procedures for taking these measurements are provided in the Performance Measurement Protocols for Commercial Buildings. [6] For example, thermal infrared (IR) imaging devices can be used to measure temperatures of building components while the building is in use. These measurements can be used to evaluate how the mechanical system is operating and if there are areas of anomalous heat gain or heat loss through the building envelope. [7]
Measurements of conditions in existing buildings are used as part of post occupancy evaluations. Post occupancy evaluations may also include surveys [8] of building occupants to gather data on occupant satisfaction and well-being and to gather qualitative data on building performance that may not have been captured by measurement devices.
Many aspects of building science are the responsibility of the architect (in Canada, many architectural firms employ an 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.
Indoor environmental quality (IEQ) refers to the quality of a building's environment in relation to the health and wellbeing of those who occupy space within it. IEQ is determined by many factors, including lighting, air quality, and temperature. [9] Workers are often concerned that they have symptoms or health conditions from exposures to contaminants in the buildings where they work. One reason for this concern is that their symptoms often get better when they are not in the building. While research has shown that some respiratory symptoms and illnesses can be associated with damp buildings, [10] it is still unclear what measurements of indoor contaminants show that workers are at risk for disease. In most instances where a worker and his or her physician suspect that the building environment is causing a specific health condition, the information available from medical tests and tests of the environment is not sufficient to establish which contaminants are responsible. Despite uncertainty about what to measure and how to interpret what is measured, research shows that building-related symptoms are associated with building characteristics, including dampness, cleanliness, and ventilation characteristics.
Indoor environments are highly complex and building occupants may be exposed to a variety of contaminants (in the form of gases and particles) from office machines, cleaning products, construction activities, carpets and furnishings, perfumes, cigarette smoke, water-damaged building materials, microbial growth (fungal, mold, and bacterial), insects, and outdoor pollutants. Other factors such as indoor temperatures, relative humidity, and ventilation levels can also affect how individuals respond to the indoor environment. Understanding the sources of indoor environmental contaminants and controlling them can often help prevent or resolve building-related worker symptoms. Practical guidance for improving and maintaining the indoor environment is available. [11]
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, HVAC design, thermal comfort, indoor air quality (IAQ), lighting, acoustics, and control systems.
The mechanical systems, usually a sub-set of the broader Building Services, used to control the temperature, humidity, pressure and other select aspects of the indoor environment are often described as the Heating, Ventilating, and Air-Conditioning (HVAC) systems. These systems have grown in complexity and importance (often consuming around 20% of the total budget in commercial buildings) as occupants demand tighter control of conditions, buildings become larger, and enclosures and passive measures became less important as a means of providing comfort.
Building science includes the analysis of HVAC systems for both physical impacts (heat distribution, air velocities, relative humidities, etc.) and for effect on the comfort of the building's occupants. Because occupants' perceived comfort is dependent on factors such as current weather and the type of climate the building is located in, the needs for HVAC systems to provide comfortable conditions will vary across projects. [12] In addition, various HVAC control strategies have been implemented and studied to better contribute to occupants' comfort. In the U.S., ASHRAE has published standards to help building managers and engineers design and operate the system. [13] In the UK, a similar guideline was published by CIBSE. [14] Apart from industry practice, advanced control strategies are widely discussed in research as well. For example, closed-loop feedback control can compare air temperature set-point with sensor measurements; [15] demand response control can help prevent electric power-grid from having peak load by reducing or shifting their usage based on time-varying rate. [16] With the improvement from computational performance and machine learning algorithms, model prediction on cooling and heating load with optimal control can further improve occupants comfort by pre-operating the HVAC system. [17] It is recognized that advanced control strategies implementation is under the scope of developing Building Automation System (BMS) with integrated smart communication technologies, such as Internet of Things (IoT). However, one of the major obstacles identified by practitioners is the scalability of control logics and building data mapping due to the unique nature of building designs. It was estimated that due to inadequate interoperability, building industry loses $15.8 billion annually in the U.S. [18] Recent research projects like Haystack [19] and Brick [20] intend to address the problem by utilizing metadata schema, which could provide more accurate and convenient ways of capturing data points and connection hierarchies in building mechanical systems. With the support of semantic models, automated configuration can further benefit HVAC control commissioning and software upgrades. [21]
The building enclosure is the part of the building that separates the indoors from the outdoors. This includes the wall, roof, windows, slabs on grade, and joints between all of these. The comfort, productivity, and even health of building occupants in areas near the building enclosure (i.e., perimeter zones) are affected by outdoor influences such as noise, temperature, and solar radiation, and by their ability to control these influences. As part of its function, the enclosure must control (not necessarily block or stop) the flow of moisture, heat, air, vapor, solar radiation, insects, or noise, while resisting the loads imposed on the structure (wind, seismic). Daylight transmittance through glazed components of the facade can be analyzed to evaluate the reduced need for electric lighting. [22]
Part of building science is the attempt to design buildings with consideration for the future and the resources and realities of tomorrow. This field may also be referred to as sustainable design. Apart from the design field, around 40% of energy consumption [23] and 13% carbon emissions [24] are related to building HVAC systems operation. In order to mitigate rapid climate change, renewable energy sources, such as solar and wind energy are adopted by the building industry to support electricity generation. However, the electricity demand profile shows imbalance between supply and demand, which is known as the 'duck curve'. This could impact on maintaining grid system stability. [25] Therefore, other strategies such as thermal energy storage systems are developed to achieve higher levels of sustainability by reducing grid peak power. [17]
A push towards zero-energy building also known as Net-Zero Energy Building has been present in the Building Science field. The qualifications for Net Zero Energy Building Certification can be found on the Living Building Challenge website.
POE is a survey-based method to measure the building performance after the built environment was occupied. The occupant responses were collected through structured or open inquiries. Statistical methods and data visualization were often used to suggest which aspects(features) of the building were supportive or problematic to the occupants. The results may become design knowledge for architects to design new buildings or provide a data-basis to improve the current environment.
Although there are no direct or integrated professional architecture or engineering certifications for building science, there are independent professional credentials associated with the disciplines. Building science is typically a specialization within the broad areas of architecture or engineering practice. However, there are professional organizations offering individual professional credentials in specialized areas. Some of the most prominent green building rating systems are:
There are other building sustainability accreditation and certification institutions as well. Also in the US, contractors certified by the Building Performance Institute, an independent organization, advertise that they operate businesses as Building Scientists. This is questionable due to their lack of scientific background and credentials. On the other hand, more formal building science experience is true in Canada for most of the Certified Energy Advisors. Many of these trades and technologists require and receive some training in very specific areas of building science (e.g., air tightness, or thermal insulation).
Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.
Ventilation is the intentional introduction of outdoor air into a space. Ventilation is mainly used to control indoor air quality by diluting and displacing indoor pollutants; it can also be used to control indoor temperature, humidity, and air motion to benefit thermal comfort, satisfaction with other aspects of the indoor environment, or other objectives.
Green building refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's life-cycle: from planning to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the contractor, the architects, the engineers, and the client at all project stages. The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort. Green building also refers to saving resources to the maximum extent, including energy saving, land saving, water saving, material saving, etc., during the whole life cycle of the building, protecting the environment and reducing pollution, providing people with healthy, comfortable and efficient use of space, and being in harmony with nature. Buildings that live in harmony; green building technology focuses on low consumption, high efficiency, economy, environmental protection, integration and optimization.’
Building automation (BAS), also known as building management system (BMS) or building energy management system (BEMS), is the automatic centralized control of a building's HVAC, electrical, lighting, shading, access control, security systems, and other interrelated systems. Some objectives of building automation are improved occupant comfort, efficient operation of building systems, reduction in energy consumption, reduced operating and maintaining costs and increased security.
Displacement ventilation (DV) is a room air distribution strategy where conditioned outdoor air is supplied at a low velocity from air supply diffusers located near floor level and extracted above the occupied zone, usually at ceiling height.
Underfloor heating and cooling is a form of central heating and cooling that achieves indoor climate control for thermal comfort using hydronic or electrical heating elements embedded in a floor. Heating is achieved by conduction, radiation and convection. Use of underfloor heating dates back to the Neoglacial and Neolithic periods.
Passive cooling is a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort with low or no energy consumption. This approach works either by preventing heat from entering the interior or by removing heat from the building.
Building performance is an attribute of a building that expresses how well that building carries out its functions. It may also relate to the performance of the building construction process. Categories of building performance are quality, resource savings and workload capacity. The performance of a building depends on the response of the building to an external load or shock. Building performance plays an important role in architecture, building services engineering, building regulation, architectural engineering and construction management. Furthermore, improving building performance is important for addressing climate change, since buildings account for 30% of global energy consumption, resulting in 27% of global greenhouse gas emissions. Prominent building performance aspects are energy efficiency, occupant comfort, indoor air quality and daylighting.
The Center for the Built Environment (CBE) is a research center at the University of California, Berkeley. CBE's mission is to improve the environmental quality and energy efficiency of buildings by providing timely, unbiased information on building technologies and design techniques. CBE's work is supported by a consortium of building industry leaders, including manufacturers, building owners, contractors, architects, engineers, utilities, and government agencies. The CBE also maintains an online newsletter of the center's latest activities called Centerline.
Thermal comfort is the condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation. The human body can be viewed as a heat engine where food is the input energy. The human body will release excess heat into the environment, so the body can continue to operate. The heat transfer is proportional to temperature difference. In cold environments, the body loses more heat to the environment and in hot environments the body does not release enough heat. Both the hot and cold scenarios lead to discomfort. Maintaining this standard of thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC design engineers.
Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces.
Underfloor air distribution (UFAD) is an air distribution strategy for providing ventilation and space conditioning in buildings as part of the design of a HVAC system. UFAD systems use an underfloor supply plenum located between the structural concrete slab and a raised floor system to supply conditioned air to supply outlets, located at or near floor level within the occupied space. Air returns from the room at ceiling level or the maximum allowable height above the occupied zone.
Sustainable refurbishment describes working on existing buildings to improve their environmental performance using sustainable methods and materials. A refurbishment or retrofit is defined as: "any work to a building over and above maintenance to change its capacity, function or performance' in other words, any intervention to adjust, reuse, or upgrade a building to suit new conditions or requirements". Refurbishment can be done to a part of a building, an entire building, or a campus. Sustainable refurbishment takes this a step further to modify the existing building to perform better in terms of its environmental impact and its occupants' environment.
Radiant heating and cooling is a category of HVAC technologies that exchange heat by both convection and radiation with the environments they are designed to heat or cool. There are many subcategories of radiant heating and cooling, including: "radiant ceiling panels", "embedded surface systems", "thermally active building systems", and infrared heaters. According to some definitions, a technology is only included in this category if radiation comprises more than 50% of its heat exchange with the environment; therefore technologies such as radiators and chilled beams are usually not considered radiant heating or cooling. Within this category, it is practical to distinguish between high temperature radiant heating, and radiant heating or cooling with more moderate source temperatures. This article mainly addresses radiant heating and cooling with moderate source temperatures, used to heat or cool indoor environments. Moderate temperature radiant heating and cooling is usually composed of relatively large surfaces that are internally heated or cooled using hydronic or electrical sources. For high temperature indoor or outdoor radiant heating, see: Infrared heater. For snow melt applications see: Snowmelt system.
Building performance simulation (BPS) is the replication of aspects of building performance using a computer-based, mathematical model created on the basis of fundamental physical principles and sound engineering practice. The objective of building performance simulation is the quantification of aspects of building performance which are relevant to the design, construction, operation and control of buildings. Building performance simulation has various sub-domains; most prominent are thermal simulation, lighting simulation, acoustical simulation and air flow simulation. Most building performance simulation is based on the use of bespoke simulation software. Building performance simulation itself is a field within the wider realm of scientific computing.
In building engineering, a climate-adaptive building shell (CABS) is a facade or roof that interacts with the variability of its environment in a dynamic way. Conventional structures have static building envelopes and therefore cannot act in response to changing weather conditions and occupant requirements. Well-designed CABS have two main functions: they contribute to energy-saving for heating, cooling, ventilation, and lighting, and they induce a positive impact on the indoor environmental quality of buildings.
ANSI/ASHRAE Standard 55: Thermal Environmental Conditions for Human Occupancy is an American National Standard published by ASHRAE that establishes the ranges of indoor environmental conditions to achieve acceptable thermal comfort for occupants of buildings. It was first published in 1966, and since 2004 has been updated every three to six years. The most recent version of the standard was published in 2023.
Sensitivity analysis identifies how uncertainties in input parameters affect important measures of building performance, such as cost, indoor thermal comfort, or CO2 emissions. Input parameters for buildings fall into roughly three categories:
Healthy building refers to an emerging area of interest that supports the physical, psychological, and social health and well-being of people in buildings and the built environment. Buildings can be key promoters of health and well-being since most people spend a majority of their time indoors. According to the National Human Activity Pattern Survey, Americans spend "an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles."
Occupant-centric building controls or Occupant-centric controls (OCC) is a control strategy for the indoor environment, that specifically focuses on meeting the current needs of building occupants while decreasing building energy consumption. OCC can be used to control lighting and appliances, but is most commonly used to control heating, ventilation, and air conditioning (HVAC). OCC use real-time data collected on indoor environmental conditions, occupant presence and occupant preferences as inputs to energy system control strategies. By responding to real-time inputs, OCC is able to flexibly provide the proper level of energy services, such as heating and cooling, when and where it is needed by occupants. Ensuring that building energy services are provided in the right quantity is intended to improve occupant comfort while providing these services only at the right time and in the right location is intended to reduce overall energy use.
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