In the assessment of use-cases for the IEP Model, the team identified many cases that will only involve a portion of the overall data model. To avoid the requirement that implementations incorporate the entire data model, the team separated the IEP Modelinto a multiple schemas that include and reference each other as necessary. This allows for the use of only the appropriate schema or schemas by each particular implementation.
The Project schema consists of all elements utilized to describe the energy project. This schema describes the project using supporting elements. Such elements include Participant, Site, Measure, ScopeOfWork, ExistingLighting, ExisitingHVAC, etc.
The Participant schema describes any party involved in an energy project. This schema includes the Participant element and other supporting elements. The Participant schema captures an entity’s contact information, role, and any additional specific information. Possible roles may include, but not limited to consumer, service provider, contractor and energy auditor.
The Site element describes the property on which the project is being considered or implemented. It describes ownership and jurisdictional information, as well as physical attributes. It inlcudes elements describing both buildings and grounds. The Site element is particularly useful for capturing site audit data prior to defining specific measures, including relevant data about locations for where proposed energy system equipment can be placed.
The Building schema utilizes many elements to describe all aspects of a building. The Building element and supporting Envelope elements describe the building characteristics. Possible depicted building characteristics include age, building use, number and age of occupants, energy systems, and detailed shell information.
MeasureType describes an energy improvement recommendation for a project. The recommendations involve modifications to energy systems or building envelopes. A measure consists of a measure action that describes the type of improvement such as the addition, modification, removal or replacement of existing energy equipment e.g. the addition of a PV system, or replacement of an existing HVAC system with a higher efficiency model. The measure also contains the cost and benefit information as estimated by the participant recommending the measure.
Common: The purpose of this schema is to define a set of types and quantities that are frequently used by other schema and can be referenced in a consistent manner. Each object is a ComplexType that includes a Value attribute and a Units attribute, which refers to an associated enumeration of units of measurement.
CommonElectrical: This schema defines the common attributes used by electrical systems.
CommonSystemProperties: This schema defines the common attributes used by all systems.
This energy system schema contains the Appliance element, which is used to describe appliances and other plug loads (a generic device or system that draws electricity from a wall outlet). Generally, the Appliance element is to be used to represent any energy consuming system that one would like to be included in an energy analysis that is not captured by one of the other four Energy Systems (Lighting, Distribution, HVAC and Water Heating). The Project schema utilizes an element called ExistingAppliance of the ApplianceType to describe the original appliance intended to be changed in a project.
This schema contains the DistributionSystem element and other supporting elements that describe a mechanical system for transporting water or air. This mechanical system includes pipes or ducts, which transport the medium and a prime mover (fan or pump) that drives the medium. This system is commonly instanced by HVACSystem and WaterHeatingSystem, though it may be instanced on its own. For example, if an HVAC system conditions a zone by blowing conditioned air into the zone, it may instance a DistributionSystem, which defines the supply and return ductwork.
This schema contains the HVACSystem element, which describes a heating ventilation and air conditioning (HVAC) system. The HVACSystem element includes a CoolingSystemType and HeatingSystemType named CoolingSystem and HeatingSystem respectively. CoolingSystem and HeatingSystem describe the operation, capacity and energy consumption of the cooling and heating systems.
The HVACSystem element references the ID in DeliverySystem of the distribution system it uses to condition the zone. A distribution system may be defined to describe a pump or fan and piping or ducting if these are desired for the model. This distribution system is one that the HVACSystem uses to condition a zone, not one that serves the HVACSystem (i.e. a heat source or sink for the HVACSystem, such as a condenser water loop or water source for a heat pump). Note that no more than one distribution system may be defined for each HVAC system. Therefore, if a building has a hydronic radiant coil heating system and an air-to-air heat-pump cooling system, two HVAC systems must be defined.
This schema contains the WaterHeatingSystem element, which describes a boiler or water heater. The end use may be HVAC, domestic hot water or another. The element contains properties to describe the tank volume (zero if none/instantaneous) and insulation, the temperature setpoint (type schedule), solar heater attributes and other typical water heater nameplate and manufacturer specification information. The WaterHeatingSystem element also references a DistributionSystem ID which may be defined to describe a pump and hot water piping.
This schema contains the LightingSystem element, which describes one light fixture or a collection of light fixtures. LightingSystem contains complexTypes to describe the input and output (power) of individual fixtures contained found in SystemProperties, the illuminated area and light level located in LightingZones, the control type found in LightingControlGroup, and the lamps and the ballasts defined in LightingFixture.
The PVSystem schema contains different types to describe a PV system from basic to complex levels of detail.
The PVSystemBasic type communicates a very basic and generic system description and operational assumptions. It is commonly used for running simple performance simulations or cost estimations. It does not include any specific component specifications.
Additional complex types in PVSystem capture:
Detailed property descriptions of specific module and inverter makes and models used in the design
Description of planes (roof surfaces and or mounting structures) on which arrays can be mounted
A means for describing the wiring connections made between system components
A means for describing the method for interconnecting the AC side of an inverter to the existing utility system (to be included at a later date)
A variety of means for describing shade affecting the system (Shading.xsd)
Ability to spatially define the system's components in 3 dimensional space relative to a defined origin