Misplaced Pages

#296703

110-615: It is a platform-neutral, open data schema specification that is not controlled by a single vendor or group of vendors. It is an object-based data schema with a data model developed by buildingSMART (formerly the International Alliance for Interoperability, IAI) to facilitate interoperability in the architecture , engineering and construction (AEC) industry, and is a commonly used collaboration format in Building information modeling (BIM) based projects. The IFC model specification

220-495: A data processing problem". They wanted to create "a notation that should enable the analyst to organize the problem around any piece of hardware ". Their work was the first effort to create an abstract specification and invariant basis for designing different alternative implementations using different hardware components. The next step in IS modeling was taken by CODASYL , an IT industry consortium formed in 1959, who essentially aimed at

330-443: A wind tunnel which has thousands of changes per hour. The highest air change rates are for crowded spaces, bars, night clubs, commercial kitchens at around 30 to 50 air changes per hour. Room pressure can be either positive or negative with respect to outside the room. Positive pressure occurs when there is more air being supplied than exhausted, and is common to reduce the infiltration of outside contaminants. Natural ventilation

440-487: A building in a high dust environment, or a home with furry pets, will need to have the filters changed more often than buildings without these dirt loads. Failure to replace these filters as needed will contribute to a lower heat exchange rate, resulting in wasted energy, shortened equipment life, and higher energy bills; low air flow can result in iced-over evaporator coils, which can completely stop airflow. Additionally, very dirty or plugged filters can cause overheating during

550-729: A building that was not designed to receive it) because of the bulky air ducts required. (Minisplit ductless systems are used in these situations.) Outside of North America, packaged systems are only used in limited applications involving large indoor space such as stadiums, theatres or exhibition halls. An alternative to packaged systems is the use of separate indoor and outdoor coils in split systems . Split systems are preferred and widely used worldwide except in North America. In North America, split systems are most often seen in residential applications, but they are gaining popularity in small commercial buildings. Split systems are used where ductwork

660-517: A carefully chosen data structure will allow the most efficient algorithm to be used. The choice of the data structure often begins from the choice of an abstract data type . A data model describes the structure of the data within a given domain and, by implication, the underlying structure of that domain itself. This means that a data model in fact specifies a dedicated grammar for a dedicated artificial language for that domain. A data model represents classes of entities (kinds of things) about which

770-481: A central location such as a furnace room in a home, or a mechanical room in a large building. The heat can be transferred by convection , conduction, or radiation . Space heaters are used to heat single rooms and only consist of a single unit. Heaters exist for various types of fuel, including solid fuels , liquids , and gases . Another type of heat source is electricity , normally heating ribbons composed of high resistance wire (see Nichrome ). This principle

880-549: A circulator, which is a pump, to move hot water through the distribution system (as opposed to older gravity-fed systems ). The heat can be transferred to the surrounding air using radiators , hot water coils (hydro-air), or other heat exchangers. The radiators may be mounted on walls or installed within the floor to produce floor heat. The use of water as the heat transfer medium is known as hydronics . The heated water can also supply an auxiliary heat exchanger to supply hot water for bathing and washing. Warm air systems distribute

990-440: A cohesive, inseparable, whole by eliminating unnecessary data redundancies and by relating data structures with relationships . A different approach is to use adaptive systems such as artificial neural networks that can autonomously create implicit models of data. A data structure is a way of storing data in a computer so that it can be used efficiently. It is an organization of mathematical and logical concepts of data. Often

1100-535: A company wishes to hold information, the attributes of that information, and relationships among those entities and (often implicit) relationships among those attributes. The model describes the organization of the data to some extent irrespective of how data might be represented in a computer system. The entities represented by a data model can be the tangible entities, but models that include such concrete entity classes tend to change over time. Robust data models often identify abstractions of such entities. For example,

1210-462: A concept of identity (having a GUID ), along with attributes for name, description, and revision control. Non-rooted entities do not have identity and instances only exist if referenced from a rooted instance directly or indirectly. IfcRoot is subdivided into three abstract concepts: object definitions, relationships, and property sets: IfcObjectDefinition is split into object occurrences and object types. IfcObject captures object occurrences such as

SECTION 10

#1732905862297

1320-513: A concept of ports where elements may have specific connections for various services, and connected together using cables, pipes, or ducts to form a system. Various connectivity relationships are used for building elements such as walls having openings filled by doors or windows. Materials may be defined for products as a whole, or as layers, profiles, or constituents for specified parts. Representations may be defined for explicit 3D shape, and optionally as parametric constraints. Each representation

1430-442: A data expert, data specialist, data scientist, data librarian, or a data scholar. A data modeling language and notation are often represented in graphical form as diagrams. A data model can sometimes be referred to as a data structure , especially in the context of programming languages . Data models are often complemented by function models , especially in the context of enterprise models . A data model explicitly determines

1540-455: A data model is sometimes referred to as the physical data model , but in the original ANSI three schema architecture, it is called "logical". In that architecture, the physical model describes the storage media (cylinders, tracks, and tablespaces). Ideally, this model is derived from the more conceptual data model described above. It may differ, however, to account for constraints like processing capacity and usage patterns. While data analysis

1650-417: A data model might include an entity class called "Person", representing all the people who interact with an organization. Such an abstract entity class is typically more appropriate than ones called "Vendor" or "Employee", which identify specific roles played by those people. The term data model can have two meanings: A data model theory has three main components: For example, in the relational model ,

1760-413: A data modeling language.[3] A data model instance may be one of three kinds according to ANSI in 1975: The significance of this approach, according to ANSI, is that it allows the three perspectives to be relatively independent of each other. Storage technology can change without affecting either the logical or the conceptual model. The table/column structure can change without (necessarily) affecting

1870-409: A design can be detailed into a logical data model . In later stages, this model may be translated into physical data model . However, it is also possible to implement a conceptual model directly. One of the earliest pioneering works in modeling information systems was done by Young and Kent (1958), who argued for "a precise and abstract way of specifying the informational and time characteristics of

1980-527: A facility to be heated and cooled by a single piece of equipment by the same means, and with the same hardware. Free cooling systems can have very high efficiencies, and are sometimes combined with seasonal thermal energy storage so that the cold of winter can be used for summer air conditioning. Common storage mediums are deep aquifers or a natural underground rock mass accessed via a cluster of small-diameter, heat-exchanger-equipped boreholes. Some systems with small storages are hybrids, using free cooling early in

2090-410: A heat pump system in which a compressor is used to drive thermodynamic refrigeration cycle , or in a free cooling system that uses pumps to circulate a cool refrigerant (typically water or a glycol mix). It is imperative that the air conditioning horsepower is sufficient for the area being cooled. Underpowered air conditioning systems will lead to power wastage and inefficient usage. Adequate horsepower

2200-416: A heating cycle, which can result in damage to the system or even fire. Because an air conditioner moves heat between the indoor coil and the outdoor coil, both must be kept clean. This means that, in addition to replacing the air filter at the evaporator coil, it is also necessary to regularly clean the condenser coil. Failure to keep the condenser clean will eventually result in harm to the compressor because

2310-455: A huge difference for the environment and help expand the knowledge of using different methods. HVAC is based on inventions and discoveries made by Nikolay Lvov , Michael Faraday , Rolla C. Carpenter , Willis Carrier , Edwin Ruud , Reuben Trane , James Joule , William Rankine , Sadi Carnot , Alice Parker and many others. Multiple inventions within this time frame preceded the beginnings of

SECTION 20

#1732905862297

2420-475: A larger district heating (DH) or district cooling (DC) network, or a combined DHC network. In such cases, the operating and maintenance aspects are simplified and metering becomes necessary to bill for the energy that is consumed, and in some cases energy that is returned to the larger system. For example, at a given time one building may be utilizing chilled water for air conditioning and the warm water it returns may be used in another building for heating, or for

2530-694: A product installation having serial number and physical placement. IfcTypeObject captures type definitions (or templates) such as a product type having a particular model number and common shape. Occurrences and types are further subdivided into six fundamental concepts: actors ("who"), controls ("why"), groups ("what"), products ("where"), processes ("when"), and resources ("how"). IfcRelationship captures relationships among objects. There are five fundamental relationship types: composition, assignment, connectivity, association, and definition. IfcPropertyDefinition captures dynamically extensible property sets. A property set contains one or more properties which may be

2640-515: A research project experimenting with turning IFC into a binary format. IFC defines an EXPRESS based entity-relationship model consisting of several hundred entities organized into an object-based inheritance hierarchy. Examples of entities include building elements such as IfcWall, geometry such as IfcExtrudedAreaSolid, and basic constructs such as IfcCartesianPoint. At the most abstract level, IFC divides all entities into rooted and non-rooted entities. Rooted entities derive from IfcRoot and have

2750-494: A room for the purpose of reducing the perceived temperature by increasing evaporation of perspiration on the skin of the occupants. Because hot air rises, ceiling fans may be used to keep a room warmer in the winter by circulating the warm stratified air from the ceiling to the floor. Natural ventilation is the ventilation of a building with outside air without using fans or other mechanical systems. It can be via operable windows, louvers, or trickle vents when spaces are small and

2860-503: A semantic logical data model . This is transformed into a physical data model instance from which is generated a physical database. For example, a data modeler may use a data modeling tool to create an entity–relationship model of the corporate data repository of some business enterprise. This model is transformed into a relational model , which in turn generates a relational database . Patterns are common data modeling structures that occur in many data models. A data-flow diagram (DFD)

2970-801: A single value (e.g. string, number, unit measurement), a bounded value (having minimum and maximum), an enumeration, a list of values, a table of values, or a data structure. While IFC defines several hundred property sets for specific types, custom property sets may be defined by application vendors or end users. IfcProduct is the base class for all physical objects and is subdivided into spatial elements, physical elements, structural analysis items, and other concepts. Products may have associated materials, shape representations, and placement in space. Spatial elements include IfcSite, IfcBuilding, IfcBuildingStorey, and IfcSpace. Physical building elements include IfcWall, IfcBeam, IfcDoor, IfcWindow, IfcStair, etc. Distribution elements ( HVAC , electrical , plumbing ) have

3080-440: A type of data model, but more or less an alternative model. Within the field of software engineering, both a data model and an information model can be abstract, formal representations of entity types that include their properties, relationships and the operations that can be performed on them. The entity types in the model may be kinds of real-world objects, such as devices in a network, or they may themselves be abstract, such as for

3190-440: Is a common term for data modeling, the activity actually has more in common with the ideas and methods of synthesis (inferring general concepts from particular instances) than it does with analysis (identifying component concepts from more general ones). { Presumably we call ourselves systems analysts because no one can say systems synthesists . } Data modeling strives to bring the data structures of interest together into

3300-470: Is a graphical representation of the "flow" of data through an information system . It differs from the flowchart as it shows the data flow instead of the control flow of the program. A data-flow diagram can also be used for the visualization of data processing (structured design). Data-flow diagrams were invented by Larry Constantine , the original developer of structured design, based on Martin and Estrin's "data-flow graph" model of computation. It

3410-403: Is a key factor in reducing the spread of airborne illnesses such as tuberculosis, the common cold, influenza, meningitis or COVID-19. Opening doors and windows are good ways to maximize natural ventilation, which would make the risk of airborne contagion much lower than with costly and maintenance-requiring mechanical systems. Old-fashioned clinical areas with high ceilings and large windows provide

Industry Foundation Classes - Misplaced Pages Continue

3520-433: Is a primary function of information systems . Data models describe the structure, manipulation, and integrity aspects of the data stored in data management systems such as relational databases. They may also describe data with a looser structure, such as word processing documents, email messages , pictures, digital audio, and video: XDM , for example, provides a data model for XML documents. The main aim of data models

3630-514: Is a technique for defining business requirements for a database. It is sometimes called database modeling because a data model is eventually implemented in a database. The figure illustrates the way data models are developed and used today. A conceptual data model is developed based on the data requirements for the application that is being developed, perhaps in the context of an activity model . The data model will normally consist of entity types, attributes, relationships, integrity rules, and

3740-410: Is air change rate or air changes per hour : the hourly rate of ventilation divided by the volume of the space. For example, six air changes per hour means an amount of new air, equal to the volume of the space, is added every ten minutes. For human comfort, a minimum of four air changes per hour is typical, though warehouses might have only two. Too high of an air change rate may be uncomfortable, akin to

3850-515: Is also used for baseboard heaters and portable heaters . Electrical heaters are often used as backup or supplemental heat for heat pump systems. The heat pump gained popularity in the 1950s in Japan and the United States. Heat pumps can extract heat from various sources , such as environmental air, exhaust air from a building, or from the ground. Heat pumps transfer heat from outside the structure into

3960-519: Is an abstract model that organizes elements of data and standardizes how they relate to one another and to the properties of real-world entities . For instance, a data model may specify that the data element representing a car be composed of a number of other elements which, in turn, represent the color and size of the car and define its owner. The corresponding professional activity is called generally data modeling or, more specifically, database design . Data models are typically specified by

4070-877: Is channeled through the space to enhance cooling and ventilation. Cross ventilation is most effective when there are clear, unobstructed paths for airflow within the building. In more complex schemes, warm air is allowed to rise and flow out high building openings to the outside ( stack effect ), causing cool outside air to be drawn into low building openings. Natural ventilation schemes can use very little energy, but care must be taken to ensure comfort. In warm or humid climates, maintaining thermal comfort solely via natural ventilation might not be possible. Air conditioning systems are used, either as backups or supplements. Air-side economizers also use outside air to condition spaces, but do so using fans, ducts, dampers, and control systems to introduce and distribute cool outdoor air when appropriate. An important component of natural ventilation

4180-402: Is common practice to draw a context-level data-flow diagram first which shows the interaction between the system and outside entities. The DFD is designed to show how a system is divided into smaller portions and to highlight the flow of data between those parts. This context-level data-flow diagram is then "exploded" to show more detail of the system being modeled An Information model is not

4290-675: Is dropped, as in HACR (as in the designation of HACR-rated circuit breakers ). HVAC is an important part of residential structures such as single family homes, apartment buildings, hotels, and senior living facilities; medium to large industrial and office buildings such as skyscrapers and hospitals; vehicles such as cars, trains, airplanes, ships and submarines; and in marine environments, where safe and healthy building conditions are regulated with respect to temperature and humidity, using fresh air from outdoors. Ventilating or ventilation (the "V" in HVAC)

4400-503: Is encapsulated using IfcProjectLibrary [IFC2x4] along with IfcRelAssociatesLibrary and IfcLibraryInformation to identify the particular revision of the imported project library. Projects support revision control where any IfcRoot-based entity has a unique identifier and may be marked as added, modified, deleted, or having no change. Such capability allows multiple IFC files to be merged deterministically, ensuring data integrity without human intervention. Data model A data model

4510-401: Is identified by IfcShapeRepresentation with a well-known name. Placement may indicate position, vertical angle, and horizontal angle. Quantities may be defined for take-off purposes such as Gross Area, Gross Volume, Gross Weight, Net Weight, etc. IFC defines various quantities specific to each element type and the method of calculation according to geometry and relationships. IfcProcess is

Industry Foundation Classes - Misplaced Pages Continue

4620-478: Is inexpensive. Natural ventilation is not practical in much of the infrastructure because of climate. This means that the facilities need to have effective mechanical ventilation systems and or use Ceiling Level UV or FAR UV ventilation systems. Ventilation is measured in terms of Air Changes Per Hour (ACH). As of 2023, the CDC recommends that all spaces have a minimum of 5 ACH. For hospital rooms with airborne contagions

4730-499: Is known as room air distribution . In modern buildings, the design, installation, and control systems of these functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity and type of system needed and then design the system, selecting the appropriate refrigerant and various components needed. For larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify

4840-581: Is needed to improve the performance of ventilation in terms of ... In scenarios where outdoor pollution would deteriorate indoor air quality, other treatment devices such as filtration may also be necessary. Methods for ventilating a building may be divided into mechanical/forced and natural types. Mechanical, or forced, ventilation is provided by an air handler (AHU) and used to control indoor air quality. Excess humidity , odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates more energy

4950-450: Is not feasible or where the space conditioning efficiency is of prime concern. The benefits of ductless air conditioning systems include easy installation, no ductwork, greater zonal control, flexibility of control, and quiet operation. In space conditioning, the duct losses can account for 30% of energy consumption. The use of minisplits can result in energy savings in space conditioning as there are no losses associated with ducting. With

5060-523: Is open and available. It is registered by ISO and is an official International Standard ISO 16739-1:2024. Because of its focus on interoperability the Danish government in 2010 made the use of IFC format(s) compulsory for publicly aided building projects. In 2017 the Finnish state-owned facility management company Senate Properties started to demand use of IFC compatible software and BIM in all their projects. Also

5170-436: Is required for any air conditioner installed. The refrigeration cycle uses four essential elements to cool, which are compressor, condenser, metering device, and evaporator. In variable climates, the system may include a reversing valve that switches from heating in winter to cooling in summer. By reversing the flow of refrigerant, the heat pump refrigeration cycle is changed from cooling to heating or vice versa. This allows

5280-458: Is required to remove excess moisture from ventilation air. Kitchens and bathrooms typically have mechanical exhausts to control odors and sometimes humidity. Factors in the design of such systems include the flow rate (which is a function of the fan speed and exhaust vent size) and noise level. Direct drive fans are available for many applications and can reduce maintenance needs. In summer, ceiling fans and table/floor fans circulate air within

5390-497: Is the process of changing or replacing air in any space to control the temperature or remove any combination of moisture, odors, smoke, heat, dust, airborne bacteria, or carbon dioxide, and to replenish oxygen. It plays a critical role in maintaining a healthy indoor environment by preventing the buildup of harmful pollutants and ensuring the circulation of fresh air. Different methods, such as natural ventilation through windows and mechanical ventilation systems , can be used depending on

5500-408: Is the process of exchanging or replacing air in any space to provide high indoor air quality which involves temperature control, oxygen replenishment, and removal of moisture, odors, smoke, heat, dust, airborne bacteria, carbon dioxide, and other gases. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, and prevents stagnation of

5610-460: 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"

SECTION 50

#1732905862297

5720-400: Is to be stored in a database . This technique can describe any ontology , i.e., an overview and classification of concepts and their relationships, for a certain area of interest . In the 1970s G.M. Nijssen developed "Natural Language Information Analysis Method" (NIAM) method, and developed this in the 1980s in cooperation with Terry Halpin into Object–Role Modeling (ORM). However, it

5830-497: Is to support the development of information systems by providing the definition and format of data. According to West and Fowler (1999) "if this is done consistently across systems then compatibility of data can be achieved. If the same data structures are used to store and access data then different applications can share data. The results of this are indicated above. However, systems and interfaces often cost more than they should, to build, operate, and maintain. They may also constrain

5940-480: The constraints that bind them. The basic graphic elements of DSDs are boxes , representing entities, and arrows , representing relationships. Data structure diagrams are most useful for documenting complex data entities. Data structure diagrams are an extension of the entity–relationship model (ER model). In DSDs, attributes are specified inside the entity boxes rather than outside of them, while relationships are drawn as boxes composed of attributes which specify

6050-568: The dew point , moisture in the air condenses on the evaporator coil tubes. This moisture is collected at the bottom of the evaporator in a pan and removed by piping to a central drain or onto the ground outside. A dehumidifier is an air-conditioner-like device that controls the humidity of a room or building. It is often employed in basements that have a higher relative humidity because of their lower temperature (and propensity for damp floors and walls). In food retailing establishments, large open chiller cabinets are highly effective at dehumidifying

6160-423: The relational model for database management based on first-order predicate logic . In the 1970s entity–relationship modeling emerged as a new type of conceptual data modeling, originally formalized in 1976 by Peter Chen . Entity–relationship models were being used in the first stage of information system design during the requirements analysis to describe information needs or the type of information that

6270-455: The requirements for a conceptual definition of data because it is limited in scope and biased toward the implementation strategy employed by the DBMS. Therefore, the need to define data from a conceptual view has led to the development of semantic data modeling techniques. That is, techniques to define the meaning of data within the context of its interrelationships with other data. As illustrated in

6380-433: The structure of data ; conversely, structured data is data organized according to an explicit data model or data structure. Structured data is in contrast to unstructured data and semi-structured data . The term data model can refer to two distinct but closely related concepts. Sometimes it refers to an abstract formalization of the objects and relationships found in a particular application domain: for example

6490-421: The CDC recommends a minimum of 12 ACH. The challenges in facility ventilation are public unawareness, ineffective government oversight, poor building codes that are based on comfort levels, poor system operations, poor maintenance, and lack of transparency. UVC or Ultraviolet Germicidal Irradiation is a function used in modern air conditioners which reduces airborne viruses , bacteria , and fungi , through

6600-458: The HVAC systems. Specialty mechanical contractors and suppliers then fabricate, install and commission the systems. Building permits and code-compliance inspections of the installations are normally required for all sizes of buildings Although HVAC is executed in individual buildings or other enclosed spaces (like NORAD's underground headquarters), the equipment involved is in some cases an extension of

6710-684: The International Alliance for Interoperability. The new Alliance was reconstituted as a non-profit industry-led organization, with the goal of publishing the Industry Foundation Class (IFC) as a neutral AEC product model responding to the AEC building lifecycle. A further name change occurred in 2005, and the IFC specification is now developed and maintained by buildingSMART . The following IFC Specification versions are available IFC defines multiple file formats that may be used, supporting various encodings of

SECTION 60

#1732905862297

6820-505: The Norwegian Government, Health and Defense client organisations require use of IFC BIM in all projects as well as many municipalities, private clients, contractors and designers have integrated IFC BIM in their business.. The popularity of the IFC data schema in construction has continued to grow, primarily for the purpose of exchanging geometry. The IFC initiative began in 1994, when Autodesk formed an industry consortium to advise

6930-433: The air inside. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates. They can also operate in reverse to cool an interior. In the case of heated water or steam, piping is used to transport the heat to the rooms. Most modern hot water boiler heating systems have

7040-484: The architecture permits. ASHRAE defined Natural ventilation as the flow of air through open windows, doors, grilles, and other planned building envelope penetrations , and as being driven by natural and/or artificially produced pressure differentials. Natural ventilation strategies also include cross ventilation , which relies on wind pressure differences on opposite sides of a building. By strategically placing openings, such as windows or vents, on opposing walls, air

7150-479: The base class for processes and is subdivided into tasks, events, and procedures. Processes may have durations and be scheduled to occur at specific time periods. Processes may be sequenced such that a successor task may start after a predecessor task finishes, following the Critical Path Method . Processes may be nested into sub-processes for summary roll-up. Processes may be assigned to products indicating

7260-483: The blood, forming carboxyhemoglobin, reducing the blood's ability to transport oxygen. The primary health concerns associated with carbon monoxide exposure are its cardiovascular and neurobehavioral effects. Carbon monoxide can cause atherosclerosis (the hardening of arteries) and can also trigger heart attacks. Neurologically, carbon monoxide exposure reduces hand to eye coordination, vigilance, and continuous performance. It can also affect time discrimination. Ventilation

7370-440: The building design and air quality needs. Ventilation often refers to the intentional delivery of the outside air to the building indoor space. It is one of the most important factors for maintaining acceptable indoor air quality in buildings. Although ventilation is an integral component of maintaining good indoor air quality, it may not be satisfactory alone. A clear understanding of both indoor and outdoor air quality parameters

7480-498: The business rather than support it. A major cause is that the quality of the data models implemented in systems and interfaces is poor". The reason for these problems is a lack of standards that will ensure that data models will both meet business needs and be consistent. A data model explicitly determines the structure of data. Typical applications of data models include database models, design of information systems, and enabling exchange of data. Usually, data models are specified in

7590-610: The cardinality. A data model in Geographic information systems is a mathematical construct for representing geographic objects or surfaces as data. For example, Generic data models are generalizations of conventional data models. They define standardized general relation types, together with the kinds of things that may be related by such a relation type. Generic data models are developed as an approach to solving some shortcomings of conventional data models. For example, different modelers usually produce different conventional data models of

7700-588: The company on the development of a set of C++ classes that could support integrated application development. Twelve US companies joined the consortium. These companies included AT&T, HOK Architects, Honeywell, Carrier, Tishman and Butler Manufacturing. Initially named the Industry Alliance for Interoperability, the Alliance opened membership to all interested parties in September, 1995 and changed its name in 1997 to

7810-511: The components of HVAC systems went hand-in-hand with the Industrial Revolution , and new methods of modernization, higher efficiency, and system control are constantly being introduced by companies and inventors worldwide. Heaters are appliances whose purpose is to generate heat (i.e. warmth) for the building. This can be done via central heating . Such a system contains a boiler , furnace , or heat pump to heat water, steam, or air in

7920-414: The conceptual model. In each case, of course, the structures must remain consistent with the other model. The table/column structure may be different from a direct translation of the entity classes and attributes, but it must ultimately carry out the objectives of the conceptual entity class structure. Early phases of many software development projects emphasize the design of a conceptual data model . Such

8030-413: The condenser coil is responsible for discharging both the indoor heat (as picked up by the evaporator) and the heat generated by the electric motor driving the compressor. HVAC is significantly responsible for promoting energy efficiency of buildings as the building sector consumes the largest percentage of global energy. Since the 1980s, manufacturers of HVAC equipment have been making an effort to make

8140-450: The constraints that bind entities together. DSDs differ from the ER model in that the ER model focuses on the relationships between different entities, whereas DSDs focus on the relationships of the elements within an entity and enable users to fully see the links and relationships between each entity. There are several styles for representing data structure diagrams, with the notable difference in

8250-446: The control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a direct expansion "DX" unit), thus saving energy. The control system can compare

8360-415: The cooling season, and later employing a heat pump to chill the circulation coming from the storage. The heat pump is added-in because the storage acts as a heat sink when the system is in cooling (as opposed to charging) mode, causing the temperature to gradually increase during the cooling season. Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing,

8470-445: The customers, products, and orders found in a manufacturing organization. At other times it refers to the set of concepts used in defining such formalizations: for example concepts such as entities, attributes, relations, or tables. So the "data model" of a banking application may be defined using the entity–relationship "data model". This article uses the term in both senses. Managing large quantities of structured and unstructured data

8580-414: The data and their relationship in a database, the procedures in an application program. Object orientation, however, combined an entity's procedure with its data." During the early 1990s, three Dutch mathematicians Guido Bakema, Harm van der Lek, and JanPieter Zwart, continued the development on the work of G.M. Nijssen . They focused more on the communication part of the semantics. In 1997 they formalized

8690-425: The definitions of those objects. This is then used as the start point for interface or database design . Some important properties of data for which requirements need to be met are: Another kind of data model describes how to organize data using a database management system or other data management technology. It describes, for example, relational tables and columns or object-oriented classes and attributes. Such

8800-506: The differences less significant. A semantic data model in software engineering is a technique to define the meaning of data within the context of its interrelationships with other data. A semantic data model is an abstraction that defines how the stored symbols relate to the real world. A semantic data model is sometimes called a conceptual data model . The logical data structure of a database management system (DBMS), whether hierarchical , network , or relational , cannot totally satisfy

8910-482: The domain context. More in general the term information model is used for models of individual things, such as facilities, buildings, process plants, etc. In those cases the concept is specialised to Facility Information Model , Building Information Model , Plant Information Model, etc. Such an information model is an integration of a model of the facility with the data and documents about the facility. HVAC Heating, ventilation, and air conditioning ( HVAC )

9020-646: The emission of carbon monoxide , nitrogen oxides , formaldehyde , volatile organic compounds , and other combustion byproducts. Incomplete combustion occurs when there is insufficient oxygen; the inputs are fuels containing various contaminants and the outputs are harmful byproducts, most dangerously carbon monoxide, which is a tasteless and odorless gas with serious adverse health effects. Without proper ventilation, carbon monoxide can be lethal at concentrations of 1000 ppm (0.1%). However, at several hundred ppm, carbon monoxide exposure induces headaches, fatigue, nausea, and vomiting. Carbon monoxide binds with hemoglobin in

9130-474: The entities used in a billing system. Typically, they are used to model a constrained domain that can be described by a closed set of entity types, properties, relationships and operations. According to Lee (1999) an information model is a representation of concepts, relationships, constraints, rules, and operations to specify data semantics for a chosen domain of discourse. It can provide sharable, stable, and organized structure of information requirements for

9240-498: The entity boxes rather than outside of them, while relationships are drawn as lines, with the relationship constraints as descriptions on the line. The E-R model, while robust, can become visually cumbersome when representing entities with several attributes. There are several styles for representing data structure diagrams, with a notable difference in the manner of defining cardinality. The choices are between arrow heads, inverted arrow heads (crow's feet), or numerical representation of

9350-419: The essential messiness of the real world, and the task of the data modeler to create order out of chaos without excessively distorting the truth. In the 1980s, according to Jan L. Harrington (2000), "the development of the object-oriented paradigm brought about a fundamental change in the way we look at data and the procedures that operate on data. Traditionally, data and procedures have been stored separately:

9460-414: The figure. The real world, in terms of resources, ideas, events, etc., are symbolically defined within physical data stores. A semantic data model is an abstraction that defines how the stored symbols relate to the real world. Thus, the model must be a true representation of the real world. Data architecture is the design of data for use in defining the target state and the subsequent planning needed to hit

9570-587: The first comfort air conditioning system, which was designed in 1902 by Alfred Wolff (Cooper, 2003) for the New York Stock Exchange, while Willis Carrier equipped the Sacketts-Wilhems Printing Company with the process AC unit the same year. Coyne College was the first school to offer HVAC training in 1899. The first residential AC was installed by 1914, and by the 1950s there was "widespread adoption of residential AC". The invention of

9680-433: The greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion. Natural ventilation requires little maintenance and

9790-417: The heated air through ductwork systems of supply and return air through metal or fiberglass ducts. Many systems use the same ducts to distribute air cooled by an evaporator coil for air conditioning. The air supply is normally filtered through air filters to remove dust and pollen particles. The use of furnaces, space heaters, and boilers as a method of indoor heating could result in incomplete combustion and

9900-450: The information system provided the data and information for management purposes. The first generation database system , called Integrated Data Store (IDS), was designed by Charles Bachman at General Electric. Two famous database models, the network data model and the hierarchical data model , were proposed during this period of time". Towards the end of the 1960s, Edgar F. Codd worked out his theories of data arrangement, and proposed

10010-568: The interior air. Methods for ventilating a building are divided into mechanical/forced and natural types. The three major functions of heating, ventilation, and air conditioning are interrelated, especially with the need to provide thermal comfort and acceptable indoor air quality within reasonable installation, operation, and maintenance costs. HVAC systems can be used in both domestic and commercial environments. HVAC systems can provide ventilation, and maintain pressure relationships between spaces. The means of air delivery and removal from spaces

10120-494: The internal air. Conversely, a humidifier increases the humidity of a building. The HVAC components that dehumidify the ventilation air deserve careful attention because outdoor air constitutes most of the annual humidity load for nearly all buildings. All modern air conditioning systems, even small window package units, are equipped with internal air filters. These are generally of a lightweight gauze-like material, and must be replaced or washed as conditions warrant. For example,

10230-524: The manner of defining cardinality . The choices are between arrow heads, inverted arrow heads ( crow's feet ), or numerical representation of the cardinality. An entity–relationship model (ERM), sometimes referred to as an entity–relationship diagram (ERD), could be used to represent an abstract conceptual data model (or semantic data model or physical data model) used in software engineering to represent structured data. There are several notations used for ERMs. Like DSD's, attributes are specified inside

10340-419: The method Fully Communication Oriented Information Modeling FCO-IM . A database model is a specification describing how a database is structured and used. Several such models have been suggested. Common models include: A data structure diagram (DSD) is a diagram and data model used to describe conceptual data models by providing graphical notations which document entities and their relationships , and

10450-400: The opening of this vent. Typical fresh air intake is about 10% of the total supply air. Air conditioning and refrigeration are provided through the removal of heat. Heat can be removed through radiation , convection, or conduction . The heat transfer medium is a refrigeration system, such as water, air, ice, and chemicals are referred to as refrigerants . A refrigerant is employed either in

10560-456: The output produced by the work performed. IfcResource is the base class for resources and is subdivided into materials, labor, equipment, subcontracts, crews, and more. Resources may have various costs and calendars of availability. Resources may be nested into sub-resources for granular allocation. Resources may be assigned to processes indicating tasks performed on behalf of a resource. IfcProject encapsulates an overall project and indicates

10670-569: The overall heating-portion of the DHC network (likely with energy added to boost the temperature). Basing HVAC on a larger network helps provide an economy of scale that is often not possible for individual buildings, for utilizing renewable energy sources such as solar heat, winter's cold, the cooling potential in some places of lakes or seawater for free cooling , and the enabling function of seasonal thermal energy storage . By utilizing natural sources that can be used for HVAC systems it can make

10780-551: The project name, description, default units, currency, coordinate system, and other contextual information. A valid IFC file must always include exactly one IfcProject instance, from which all other objects relate directly or indirectly. A project may include multiple buildings, multiple participants, and/or multiple phases according to the particular use. In addition to project-specific information, an IfcProject may also reference external projects from which shared definitions may be imported such as product types. Each external project

10890-406: The rooms. Split systems are more efficient and the footprint is typically smaller than the package systems. On the other hand, package systems tend to have a slightly lower indoor noise level compared to split systems since the fan motor is located outside. Dehumidification (air drying) in an air conditioning system is provided by the evaporator. Since the evaporator operates at a temperature below

11000-495: The same domain. This can lead to difficulty in bringing the models of different people together and is an obstacle for data exchange and data integration. Invariably, however, this difference is attributable to different levels of abstraction in the models and differences in the kinds of facts that can be instantiated (the semantic expression capabilities of the models). The modelers need to communicate and agree on certain elements that are to be rendered more concretely, in order to make

11110-411: The same thing as Young and Kent: the development of "a proper structure for machine-independent problem definition language, at the system level of data processing". This led to the development of a specific IS information algebra . In the 1960s data modeling gained more significance with the initiation of the management information system (MIS) concept. According to Leondes (2002), "during that time,

11220-709: The same underlying data. IFC-SPF is in ASCII format which, while human-readable, suffers from common ASCII file issues, in that file-sizes are bloated, files must be read sequentially from start to finish, mid-file extraction is not possible, files are slow to parse, and definitions are non-hierarchical. In addition to ifcXML and ifcZIP, modern data formats include RDF/XML or Turtle (using the ifcOWL ontology), ifcJSON ( JavaScript Object Notation , broadly available) and ifcHDF5 ( Hierarchical Data Format v5, binary). In 2020, buildingSmart had two JSON projects underway: ifcJSON v4 (a direct mapping from EXPRESS-based IFC v4) and ifcJSON v5, plus

11330-438: The split system, the evaporator coil is connected to a remote condenser unit using refrigerant piping between an indoor and outdoor unit instead of ducting air directly from the outdoor unit. Indoor units with directional vents mount onto walls, suspended from ceilings, or fit into the ceiling. Other indoor units mount inside the ceiling cavity so that short lengths of duct handle air from the indoor unit to vents or diffusers around

11440-433: The structural part is based on a modified concept of the mathematical relation ; the integrity part is expressed in first-order logic and the manipulation part is expressed using the relational algebra , tuple calculus and domain calculus . A data model instance is created by applying a data model theory. This is typically done to solve some business enterprise requirement. Business requirements are normally captured by

11550-447: The system intended to maintain constant indoor air conditions. Outside, fresh air is generally drawn into the system by a vent into a mix air chamber for mixing with the space return air. Then the mixture air enters an indoor or outdoor heat exchanger section where the air is to be cooled down, then be guided to the space creating positive air pressure. The percentage of return air made up of fresh air can usually be manipulated by adjusting

11660-423: The target state, Data architecture describes how data is processed, stored, and utilized in a given system. It provides criteria for data processing operations that make it possible to design data flows and also control the flow of data in the system. Data modeling in software engineering is the process of creating a data model by applying formal data model descriptions using data modeling techniques. Data modeling

11770-478: The target state. It is usually one of several architecture domains that form the pillars of an enterprise architecture or solution architecture . A data architecture describes the data structures used by a business and/or its applications. There are descriptions of data in storage and data in motion; descriptions of data stores, data groups, and data items; and mappings of those data artifacts to data qualities, applications, locations, etc. Essential to realizing

11880-581: The temperature of the outside air vs. return air, or it can compare the enthalpy of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode. Central, "all-air" air-conditioning systems (or package systems) with a combined outdoor condenser/evaporator unit are often installed in North American residences, offices, and public buildings, but are difficult to retrofit (install in

11990-521: The use of a built-in LED UV light that emits a gentle glow across the evaporator. As the cross-flow fan circulates the room air, any viruses are guided through the sterilization module’s irradiation range, rendering them instantly inactive. An air conditioning system, or a standalone air conditioner, provides cooling and/or humidity control for all or part of a building. Air conditioned buildings often have sealed windows, because open windows would work against

12100-498: Was Terry Halpin's 1989 PhD thesis that created the formal foundation on which Object–Role Modeling is based. Bill Kent, in his 1978 book Data and Reality, compared a data model to a map of a territory, emphasizing that in the real world, "highways are not painted red, rivers don't have county lines running down the middle, and you can't see contour lines on a mountain". In contrast to other researchers who tried to create models that were mathematically clean and elegant, Kent emphasized

#296703