PhEntity

Project Haystack entity. This is base class for all entities in the Haystack ontology. It defines every tag as a global slot to ensure consistent usage of terminology.

Cooling process using energy from heat source such as hot water

Relating to alternating current (AC) electricity

Working, operative, effective

Equipment to move or control a mechanism. Actuators may be manually operated or automated via a control system to convert an energy source into mechanical energy. Typically the energy source is electricity, hydraulics, or pneumatics.

Air Handling Unit: An enclosure with a fan that delivers air to a space via ductwork and performs one or more of the functions of cleaning, heating, cooling, humidifying, dehumidifying, ventilating or circulating the air. See AHUs chapter.

The mixture of gases which surrounds the earth

Cooling by dissipating heat into the surrounding air

Air flows from the referent to this entity

Notification of a condition which requires attention

Measurement of the relative difference in direction between two vectors or phasors

Perceived quantity

Area of a shape or floor space

Aquifer Thermal Energy Storage system. See ATES chapter.

The ATES uses closed piping to transport a water/glycol mixture through the ground. The system works like a heat exchanger; there is no ground water transported.

The ATES has one or more pairs of a separate warm and cool well.

The ATES is as a doublet, but with specific warm and cool wells linked together. These linked wells do not exchange water with other wells.

The ATES has only one physical well. This well is deep enough to penetrate two layers of groundwater.

Similar to a doublet, but water always flows in the same direction from the extraction to the infiltration well.

Attribute is a single datum of static information on an entity. Attributes often represent nameplate data or design/rated data.

Related to the atmosphere of the earth

Average; central or typical value; median

ASHRAE building automation and control protocol

Relating atmospheric pressure

Base URI for normalizing relative URIs

Equipment used to store electric energy

Plant or animal material used as fuel to produce electricity or heat

Heating by the combustion of biomass

Removal from container or pipe

Blowdown water flows from the referent to this entity

Short range wireless communication protocol

Equipment to generate hot water or steam for heating

Branch selector used for heat recovery in a VRF system. These are control devices directing the liquid refrigerant or gas refrigerant to zones requiring cooling or heating. See VRF chapter.

Pipe used to bypass an equipment

An assembly of one or more insulated conductors.

Constant air volume terminal unit. CAV systems use a constant air flow rate with a variable air temperature.

Compression via a continuous flow of fluid through an impeller

Formaldehyde (CH₂O)

Methane (CH₄)

Substance is cooled using cooling process

Conditions a space using a heat exchanger integrated into the ceiling

AHU supplies air to chilled beam terminal units

Cooling using transfer of heat to chilled water

Chilled water flows from the referent to this entity

Equipment to remove heat from a liquid. Chillers typically use a vapor compression or an absorption refrigeration cycle.

Pipe used to circulate fluid through an equipment or system

Electrical circuit and its associated components such as breakers. See Elec Panels chapter.

Percentage of sky obscured by clouds. This is also known as cloudiness, or cloud amount.

Point is a command, actuator, AO/BO. See Points chapter.

Carbon monoxide (CO)

Carbon dioxide (CO₂)

Carbon dioxide equivalent

Combustible sedimentary rock

Heating by the combustion of coal

Constrained Application Protocol

Having low degree of heat

Duct carries air for cooling

Device for mechanically increasing the pressure of a gas or refrigerant vapor by reducing its volume.

Computed point. See Synthetics chapter.

Indicates a relationship that is computed from its reciprocal. Computed defs cannot be used as tags themselves.

See Synthetics chapter.

General purpose computer.

Abundance of substance in the total volume of a mixture.

Liquid phase produced by the condensation of steam or other gas

Condensate flows from the referent to this entity

Device or related to process of condensation

Working fluid is kept separate from fluid used for heat transfer into the atmosphere

Removal of heat through the process of water condensation

Uses working fluid itself for evaporation into the atmosphere

Condenser water flows from the referent to this entity

Related to cleaning, heating, cooling, humidifying, dehumidifying, ventilating or circulating  air. 

Delivers a constant volume of air flow. Typically this means equipment with a single speed fan.

Microprocessor based device used in a control system. Controllers interact with the physical world through direct I/O to sensors and actuators or via network protocols.

Associated with the control system for an industrial process

Associted with low temperature or cooling processes. When used on a point, this tag is associated with the control of cooling. When paired with a substance, this tag indicates the substance is relatively cool in comparison to another substance, without being actively cooled by e.g. a chiller.

Cooling mode or process

Measurement of a chiller ability to remove heat measured

Coil used to cool air.

Equipment without heating

Equipment to transfer waste heat into the atmosphere

Device that joins two components together.

Computer Room Air Conditioner: An FCU designed to condition a computer room. See AHUs and Data Centers chapters.

Supports current value

Error description when curStatus indicates error condition

Status of point's current value reading. The curVal is only available when curStatus is "ok" or "stale". However a "stale" value should be used with caution since the local system does not have a fresh value. It is recommended that the curVal tag is removed from a point when the curStatus is not "ok" nor "stale".

Current value of a point. The current value is only available when the curStatus is "ok" or "stale".

Movement of fluid or electricity

Digital Addressable Lighting Interface protocol for lighting

Damper equipment or control point.

Space used to house computer and networking gear. See Data Centers chapter.

Time between sunrise and sunset

Relating to direct current (DC) electricity

The range in a process where no changes to output are made. May also indicate the difference between a base setpoint and effective setpoint.

Differential of fluid between entering and leaving sensors.

Rate required for a process.

Obsoleted

Data related to intended design and operating conditions. This includes sizing and other data specified by design engineers and engineered drawings. Also see rated.

Decreases humidity from air using a substance which absorbs moisture.

Microprocessor based hardware device. This is the general term for all computers, mobile phones, controllers, and I/O modules. See Devices chapter.

Device which controls a monitors this entity

Dew point temperature at which water vapor will form dew

Liquid fuel specifically designed for use in diesel engines

AHU supplies air directly to the zone

Compass direction measured in degrees: North: 0° = 360°, East: 90°, South: 180°, West: 270°

Display name for an entity. See Ontology chapter.

Duct for air leaving an equipment

Equipment that releases a specific amount of a substance.

Three way valve which inputs one pipe and diverts between two output pipes.

Dedicated Outside Air System: An AHU that brings in 100% outside air and no recirculated air in order to provide ventilation to spaces. See AHUs chapter.

For human use

Domestic water flows from the referent to this entity

Two ducts: combination of hotDeck, coldDeck, or neutralDeck

Conduit used to convey air for HVAC

Config point on a vav for duct area measured in ft² or m²

Number with a unit of time

Cooling using direct expansion of a refrigerant vapor. Also see dxHeating and heatPump.

Heating using direct expansion of a refrigerant vapor. Also see dxCooling and heatPump.

Duct to access fresh outside air only for economizing, not ventilation

Energy reduction mode which augments heating/cooling with outside air.

Current control setpoint in effect taking into account other factors

Efficiency point of a chiller measured in "COP" or "kW/ton".

Associated with electricity or with electrical force, power, or energy. This is often opposed to mech mechanical energy.

Heating by the conversion of electrical energy

Average of L1, L2, L3 measurements

Average of L1-L2, L2-L3, L3-L1 measurements

Quadrant used to describe the flow of AC electric power

Electricity flows from the referent to this entity

Enclosure used to move people between floors.

Amount of a substance discharged into the air

Secondary on/off point of an equip especially used with a vfd. Enable is used with Bool points where true indicates on and false indicates off. Equip with an enable should always also define a run point which indicates the primary on/off state of the equipment.

Container or housing that surrounds and protects equipment or components. Enclosures may be cabinets, sealed boxes, weatherproof housings, or other protective structures that provide physical protection, environmental sealing, or safety isolation.

Measure of ability to do work

Pipe conveys fluid into an equipment

Total heat content of a system. It is defined as internal energy of the system plus the product of pressure and volume.

Defines an eumeration of string key names. The range may also be applied to format a Bool ordered as "false,true". The value of this tag may be formatted in one of five ways:

• dict of dicts keyed by name and Dict values for meta such as doc tag
• comma separated names on one line
• names separated by a "\n" newline character
• markdown unordered list formatted as a series of "- name: description\n"
• ref to a Xeto sys::Enum spec

Enum names should follow valid tag naming rules (start with lowercase ASCII letter and contain only ASCII letters and numbers). However in cases where mapping directly to external enumerations enum names can contain arbitrary characters such as space.

Equipment asset. See Equips chapter.

Reference to equip which contains this entity

Moving staircase used to move people between floors.

Mechanism used to convert a refrigerant from its liquid to gaseous state.

Electric Vehicle Supply Equipment. See EVSE chapter.

Physical type of EvseCable.

Duct used to expel air back outside

Supplied out of a system

Taking a substance out of another substance

Point of an ahu indicating air flow is by-passing the heating/cooling coils. If a boolean point, then true indicates the unit is in by-pass mode and false indicates by-pass is disabled. If the point is an analog point then 100% indicates full by-pass mode and 0% indicates by-pass is completely disabled.

Fan equipment or control point

Device with a fan

Fan Coil Unit: A unitary, factory-made enclosure with a fan and coil that recirculates air in a space and performs one or more of the functions of cleaning, heating, cooling, humidifying, dehumidifying, or ventilating the air. Unit heaters are examples of FCUs. See AHUs chapter.

Feature namespace of definitions formatted as feature:name

Apparent temperature perceived when considering humidity, wind chill, and heat index

Filename extension such as "csv"

File format type definition

Related to an air or fluid filter.

Haystack filter string. See Filters

Storey of a building. See Spaces chapter.

Unitless integer indicating the floor's distance from ground level. The ground floor is always defined as zero. Additional floors above ground are numbered 1, 2, 3, etc. Subterranean floors are numbered -1, -2, -3, etc. This convention is consistent with how most European buildings number floors. In North America its common to label the ground floor as the first floor; however Haystack requires the ground level to be assigned a floorNum of 0.

Measure of volumetric flow of fluid

System to change direction of substance flow

Duct for exhausting combustion

Measurement through a given surface

A boolean point of an ahu indicating a freezing condition. This might require a control sequence to protect the equipment. If true then a freeze condition is detected, or false if not.

Occurrences per unit time

File Transfer Protocol

Petroleum based oil burned for energy

Heating by the combustion of fuel oil

Fuel oil flows from the referent to this entity

Ventilation equipment to limit exposure to hazardous fumes.

Petroleum derived liquid used as a fuel source

Gasoline flows from the referent to this entity

Free form street address. Best practice is to follow local norms for a postal address. Typically this string includes the geoStreet, geoCity, geoState (in US), and geoPostalCode:

Examples: "1600 Pennsylvania Avenue NW, Washington, DC 20500"

"10 Downing St, Westminster, London SW1A 2AA, United Kingdom"

"Champ de Mars, 5 Avenue Anatole France, 75007 Paris, France"

Geographic city or locality name

Geographic coordinate as C(latitude,longitude)

Geographic country as ISO 3166-1 two letter code

Geographic subdivision of US state

Elevation above sea-level of the location

Geographic place

Geographic postal code; for US this is a five digit zip code

State or province name; for US this is two letter state code. May be used in other countries to model administrative area between the geoCity and geoCountry level.

Geographic street address and name

Related to the surface of the earth. Used to indicate electrical current being measured on an electrical ground conductor when applied to a point entity that has the elec and current tags.

Haystack HTTP protocol for exchanging tagged data

Pipe used as central connection or manifold for other piping runs.

Associated with a heating process. When used on a point, this tag is associated with the control of heating.

Equipment to transfer heat between two working fluids.

Equipment that employs a vapor compression cycle with a reversing valve to provide heating or cooling. For vapor compression heating without a reversing valve, such as for a heat pump water heater, see dxHeating which should be used.

Transfer of heat from one substance to another to reduce energy consumption.

Boolean point indicating command state of AHU's heat wheel.

Heating mode or process

Coil used to heat air.

Equipment without cooling

Dimensional height of the asset

Hydrofluorocarbons

Supports historization of data

Last historized timestamped sample

Error description when hisStatus indicates error condition

Indicates the way that history data is collected for a point.

Number of historical timestamped samples historized by point

First historized timestamped sample

Status of point's history collection or synchronization

Indicates values which are a continuous stream of totalization. History data reads and should be normalized by computing the delta.

Having high degree of heat

Duct carries air for heating

Heating using energy of hot water

Hot water flows from the referent to this entity

Hypertext Transfer Protocol which is foundation of the web

Adding moisture to air

Percent relative humidity; measure of moisture in the air

Heating, ventilation, and air conditioning

Operational mode for HVAC equipment

Water in its solid form

Luminous flux hitting the inside of the sphere at a specific point.

Also see ies.org

Internet Message Access Protocol for retrieving email

Lacking balance

Received into a system

Operates inside the conditioned space

Permeation of a substance into another substance

Duct with air entering an equipment

Entity inputs a substance which flows from another entity

Unitless integer number

Measure of an electromagnetic field

Energy received at a surface by area

Actuator used to isolate an equipment from a pipe or ductwork system

Kind name used to identity a value data type

KNX protocol commonly used for lighting systems

Portable laptop computer.

Pipe conveys fluid out of an equipment

Dimensional length of the asset

Range from 0% to 100%. When paired with a fluid this implies a fill level where 0% is empty and 100% is full.

Electromagnetic radiation in the visible spectrum

Systems associated with illumination in the built environment

Chiller point to command or measure the chiller's load as a percentage from "0%" to "100%". When paired with cmd this models the chiller's load limit. When paired with sensor this models the chiller's current load factor.

Light fixture using electricity to provide illumination

Energy of light in a given direction.

Also see ies.org

Relating to light as perceived by the eye

Size or extent

Restore something missed or lost

Makeup water flows from the referent to this entity

Company name that produced the asset.

Date the asset was produced by the manufacturer.

Makeup Air Unit: A DOAS that provides make-up air for a separate, dedicated exhaust system. That is, this equip does not contain an exhaust air section. See AHUs chapter.

Maximum

Inclusive maximum for a numeric value.

Associated with a machine or its mechanical force, torque, power, or energy. This is often opposed to elec electrical energy.

Equipment to meter a substance or phenomenon. See Meters chapter.

Mime type formatted as type/subtype

Minimum

Inclusive minimum for a numeric value.

Duct where fresh outside air and return air is mixed together

Three way valve which inputs two pipes and outputs a mixture between the two to a single output pipe.

Machine learning point. See Synthetics chapter.

Training period description, known as the identification period or baseline, utilized during the model training process.

List of independent variables, also known as model inputs or features, associated with a machine learning model.

See Synthetics chapter.

Goodness-of-fit metrics provided in the form of a simple dictionary. For example: {r2:0.7889, cvrmse:58}.

Result of model identification, which may appear as a list of model parameters for simpler models or as a reference to a stored model, in the form of a file uri. The structure of the dict is user-specific.

Dependent variable, also known as the model output or target, associated, with a machine learning model. Represents the predicted outcome generated by the model.

Machine learning variable representing both model inputs and outputs.

Filter used for querying points by tags, providing more flexibility than mlVarPoint, although it is not mandatory.

Reference to a point associated with a machine learning variable, known as a machine learning variable point.

Reference to a machine learning variable.

Relating to mobile phones, hand-held computers, and similar technology

Register based communication protocol used with industrial devices.

Manufacturer assigned identifier for a general product line. For example, modelSeries is "iPhone 12", but modelNumber is "MGF43LL/A". The modelSeries tends to be a marketing name and not an exact identifier. Always use modelNumber for the actual model identifier.

Manufacturer assigned alphanumeric identifier for a specific product configuration. For example, modelSeries is "iPhone 12", but modelNumber is "MGF43LL/A".

Indicates equipment or point with variable output from 0% to 100%, as opposed to binary on/off or discrete staged control.

Equipment that converts electrical energy into mechanical energy. See Motors chapter.

Conveyor to move people across a horizontal or inclined plane.

Message Queuing Telemetry Transport publish/subscribe protocol

AHU discharge air is split into a duct per zone

Nitrous oxide (N₂O)

Not available used to indicate invalid or missing data. See Kinds chapter.

Fossil fuel energy source consisting largely of methane and other hydrocarbons.

The energy content of natural gas varies by region within a range determined on impurities in the gas. You can find a table of these conversions here

Heating by the combustion of natural gas

Natural gas flows from the referent to this entity

Difference between import and export

Logical communications network between two or more devices. See Devices chapter.

Associates a device which communicates on specific a network.

Related to data communication networks

when applied to a point entity that has the elec and current tags, indicates electrical current being measured on an electrical neutral conductor.

Duct carries air which by-passes both heating and cooling coils

Nitrogen trifluoride (NF₃)

Ammonia (NH₃)

Nitrogen dioxide (NO₂)

Marks a function or operation as having no side effects. The function may or may not be pure in that calling it multiple times with the same arguments always evaluates to the same result.

Undocumented and not officially supported

Do not include source code in documentation

Oxygen (O₂) - the common dioxygen allotrope in the air

Ozone (O₃)

XML based Open Building Information eXchange protocol.

Occupied mode of a space. See Zones chapter.

Number of occupants in a space. See Zones chapter.

People who use the built environment. See Zones chapter.

Setpoint or sensor indicating occupancy of a space. See Zones chapter.

Expected value type of a collection, reference, or choice

Operation for HTTP API. See Ops chapter.

Apply to str enum tags where the enumeration range is open ended. User interfaces should support data entry for arbitrary strings, but also provide a dropdown for the predefined enumeration.

operates outside the conditioned space

Entity outputs a substance with flows to other entities

Duct to access fresh outside air for both ventilation and economizer.

Enclosure for electrical and control equipment. Panels may be used to isolate electrical connections and provide environmental protection.

Circuit with multiple paths of flow

Auxiliary heating points associated with a vav

Electric power factor; which is the ratio of active power to apparent power in an AC electric power system. Measured with values in the range of -1.0 to 1.0 or 0.0 to 1.0 without a unit. When the range of -1.0 to 1.0 is applied, a negative value for power factor indicates the electrical current leads the electrical voltage and a positive value indicates the electrical current lags the electrical voltage.

Displacement power factor, which accounts for the phase angle between voltage and current but excludes effects of nonlinear waveforms ( harmonic distortion).

Distortion power factor, which measures the component of power factor attributable to harmonic distortion in voltage and current waveforms.

Power factor according to the IEC convention defines a positive or negative sign based on the direction of active power flow. Power factor is positive when active power flows into a load. Power factor is negative when active power flows out of a load.

Power factor according to the IEEE convention defines a positive or negative sign based on whether the load is capacitive or inductive. Power factor is positive when the load is capacitive, or when voltage lags behind current. Power factor is negative when the load is inductive, or when current lags behind voltage.

True power factor, which includes effects of harmonic distortion. Power factor is assumed to be true power factor when PfScope is not defined. However, it is recommended to specify a scope for power factor to help avoid misinterpretation of data.

Perfluorocarbons

Single-phase measurement of an electric quantity in a multi-phase AC electric power system.

Telephone used for voice telecommunication.

Conduit used to convey a fluid

Central plant used to generate a substance for a process. See Plants.

Particulate matter 0.1; atmospheric pollutant of fine particles with an aerodynamic diameter of 0.1 micrometers or less

Particulate matter 10; atmospheric pollutant of fine particles with an aerodynamic diameter of 10 micrometers or less

Particulate matter 2.5; atmospheric pollutant of fine particles with an aerodynamic diameter of 2.5 micrometers or less

Data point such as a sensor or actuator. See Points chapter.

See Synthetics chapter.

Post Office Protocol version 3 for retrieving email

A gateway or opening used to transfer a substance.

Energy consumed per unit time

Converts one electrical waveform to another using power electronic circuitry. Involves the use of one or more power modules.

May convert:

• ac to dc
• ac to ac
• dc to dc
• dc to ac

Note: An AC/AC power converter performs the same task as a power transformer but using power electronics. Similarly, a DC/DC power converter transforms an input DC voltage to an output DC voltage at another level.

Amount of atmospheric water vapor fallen including rain, sleet, snow, and hail

Defines a preferred unit to be used with a quantity

Measure of force applied

VAV damper modulates to control space temp; dependent on duct pressure being maintained

VAV damper or a control valve that modulates to maintain desired flow setpoint; independent of the duct pressure

Primary function of building as US Energy Star key

Pipework which circulates closest to the energy source. In a central plant, the primary loop indicates the pipes and equipment within the central plant. In context of heat exchangers between the primary and secondary loops, this tag indicates the side closest to the plant.

Industrial or HVAC process

By-product of natural gas processing and petroleum refining (C₃H₈)

Heating by the combustion of propane

Communication protocol used for devices on a network.

Pump equipment or control point

Associated with a cleaning process to remove contaminants. Most commonly it indicates purging water or air by using a filter or by letting out a certain amount of the substance at a high flow rate.

Quantity measured against standard metric

Enclosure or chassis used to mount computer and networking gear. Devices are mounted to rails of a standard width, typically 19 or 23 inches. Height is measured in rack units where one 1U is 1.75 inches. A full rack has a height of 42U. See Data Centers chapter.

Heats a space using pipes or cables embedded beneath floor.

Heats a space using exposed pipes or coils. Hot water and steam radiators are often cast iron and installed directly in the space or along the baseboard. Electric radiators are typically installed on the baseboard.

Data specified by a manufacturer or rating organization. Typically this information is from the equipment data plate or cut sheet. Also see design.

Relating to reactance

Piston compressor driven by a crankshaft

Fluid used in refrigeration and heat exchange. Refrigerants typically alternate between liquid and gas state.

Refrigerant flows from the referent to this entity

Command point for reheating process

Duct returning air back to equipment

Envelope covering the top of a building

Enclosed room of a building

Rotary screw compression

Device used to route data packets

Roof Top Unit: A unitary AHU that is weatherized for outdoor use. See AHUs chapter.

Primary on/off point of an equip especially used with a vfd. Run is used with Bool points where true indicates on and false indicates off. When paired with cmd this is the commanded state of the equipment. When paired with sensor this is the actual status of the equip. If the equipment also defines an enable point then both must be commanded on in order to run the equipment.

Scalar is an atomic value kind

Pipework which circulates closest to the building or end use. In a central plant, the secondary loop indicates the pipes and equipment between the central plant and the building. In context of heat exchangers between the primary and secondary loops, this tag indicates the side closest to the building.

Point is a sensor, input, AI/BI. See Points chapter.

Manufacturer assigned unique, alphanumeric identifier for a specific asset.

Circuit with single path of flow

Hardware or software which provides services for other programs or devices.

Ratio of the maximum continuous output capacity at which a machine or system may operate without damage to the machine or system’s nominal output capacity.

Sulphur hexafluoride (SF₆)

Simulation point. See Synthetics chapter.

See Synthetics chapter.

See Synthetics chapter.

See Synthetics chapter.

See Synthetics chapter.

One single duct

Single-phase AC electricity. Power is provided by a single AC voltage source with a 2-wire connection.

Site is a geographic location of the built environment. Typically site maps to one building with its own unique street address. See Sites chapter.

Main meter for the associated site

Reference to site which contains the entity

Simple Mail Transfer Protocol for sending email

Simple Network Management Protocol for managing IP devices

Relating to energy from the sun

Substance with definite shape and volume

Sedona Framework UDP based communication protocol

Point is a setpoint, soft point, internal control variable, schedule. See Points chapter.

Space is a three-dimensional volume in the built environment. See Spaces chapter.

Reference to space which contains this entity

Distance per unit time

Split-phase AC electricity. Power is provided by a single AC voltage source with a 3-wire connection, consisting of two hot wires (phases), separated from each other by a 180-degree phase angle, and one neutral wire. Despite having two labeled phases, split-phase AC electricity is not a true two-phase system.

Stage number of staged equipment operation, such as coil or pump. The first stage is 1, second stage 2, etc. Used on boolean points that correspond to a specific stage.

Readiness mode of a space

State of charge (SoC) of an electric battery. Uses a percentage in the range of 0% to 100%, where no charge is indicated as 0% and full charge is indicated as 100%.

Water in its gas form

Heating using energy of steam

Steam flows from the referent to this entity

Submeters measure usage of a sub-system or equipment within a site

Reference to parent meter which is immediately upstream of this meter

Below the surface of the earth

Device for toggling state or routing data

Synthetic point with computed operational data. The computed data if classified as:

• ml for machine learning
• sim for simulation
• computed as catch all for other computations

See Synthetics chapter.

See Synthetics chapter.

See Synthetics chapter.

Grouping of related equipment dedicated to a single application. See Systems chapter.

Reference to system

Mobile device with touch screen for user input.

Tank used to store a substance for temporary holding

Temperature - measure of hot and cold

Pipework which circulates within the building.

Total harmonic distortion

Related to energy of heat

Senses and controls temperature of space in HVAC system. Thermostats may provide an interface for setpoint control.

Three-phase AC electricity. Power is provided by three AC voltage sources, each separated from the others by a 120-degree phase angle. May have a 4-wire connection with a neutral (Wye) or a 3-wire connection without a neutral (Delta).

Complete or absolute

Three ducts: hotDeck, coldDeck, or neutralDeck

Total volatile organic compound (TVOC).

Two-phase AC electricity. Power is provided by two AC voltage sources, separated from each other by a 90-degree phase angle. Two-phase systems are extremely rare in modern buildings; they have been replaced by modern threePhase systems.

Timezone identifier from standard timezone database

Unit identifier from standard unit database

Unit Ventilator: An FCU that has direct access to outside air to provide the space with ventilation. See AHUs chapter.

Unoccupied mode of a space. See Zones chapter.

Uninterruptible power supply

Data value type

Valve equipment or control point

Delivers a variable volume of air flow. Most variable volume systems are powered by a VFD fan. However other techniques such as inlet vanes may be used in older systems.

Variable air volume terminal unit. VAV systems use a constant air temperature with a variable air flow rate. See VAVs chapter.

AHU supplies air to VAV terminal units

Speed in a given direction

Duct to access fresh outside air only for ventilation, not economizing

Version string formatted as decimal integers separated by a dot

Variable-frequency drive. See Motors chapter.

Distance at which light can be clearly discerned

Electrical potential difference or electromotive force.

Three dimensional space occupied by a substance

Variable refigerant flow. See VRF chapter.

Relatively warm in comparison to another substance, without being actively heated. The substance can be used as a source of energy for a heating process, for example a warm water well in an ates system.

Water in its liquid form

Cooling using transfer of heat to water which is not explicitly chilled

Associated with atmospheric air or phenomenon. See Weather chapter.

Enumeration of weather conditions

Logical weather station and its measurement points. See Weather chapter.

Reference to weather station for to use this entity

Weight of the asset

A well is a source of groundwater and potentially thermal energy. When used within an ATES system, the well facilitates thermal energy exchange with the ground warm and cool water sources. In this case, a well can be either a closed system that transports water through pipes in the ground, or an open system that pumps up and returns ground water.

Wet bulb air temperature. Temperature which the air would have if cooled to saturation by the evaporation of water into it.

Dimensional width of the asset

Hyperlink to the subject's page on Wikipedia

Flow of air on surface of the Earth

Cabling used to convey electricity or data

Supports writing data

Error description when writeStatus indicates error condition

Current priority level for writeVal as number between 1 and 17. The value 17 indicates the relinquish default value.

Current status of a writable point output

Current desired value to write to output. This is the current "winning" value of the priority array indicated by writeLevel. If this tag is missing then the winning value is null/auto.

Extended string - type name and string value encoding. See Kinds chapter.

Original year of construction as four digit year such as 1980

Low power wireless communication protocol for home automation

Related to spaces from a system perspective

Low power wireless communication protocol for home automation