Energy Conservation Measure
Biased Economizer Sensor: Outdoor RH
Name
biased_economizer_sensor_outdoor_rh
Display Name
Biased Economizer Sensor: Outdoor RH
UID
cb5d34a2-7980-44bb-8a41-1f2cb262fd81
Version ID
e81a0900-68b7-42f2-acdb-7b1d70f31a62
Class Name
BiasedEconomizerSensorOutdoorRH
Version Modified
20180828T211344Z
Schema Version
3.0
Attributes
| Measure Type | EnergyPlusMeasure |
| Intended Software Tool | OpenStudio Application |
| Intended Software Tool | Parametric Analysis Tool |
| Intended Software Tool | Analysis Spreadsheet |
Details
| Description | When sensors drift and are not regularly calibrated, it causes a bias. Sensor readings often drift from their calibration with age, causing equipment control algorithms to produce outputs that deviate from their intended function. A positive bias in the economizer outdoor relative humidity (RH) sensor leads to a higher estimate in the outdoor air enthalpy, which shifts the economizer switch-off point and could cause higher cooling or heating energy consumption. This measure simulates the biased economizer sensor (outdoor air RH) by modifying the Controller:OutdoorAir object in EnergyPlus assigned to the heating and cooling system. The fault intensity (F) for this fault is defined as the biased RH level (%). A positive number means that the sensor is reading a relative humidity higher than the true relative humidity. This measure was authored by Herrick Laboratory researchers at Purdue University in collaboration with staff from the National Renewable Energy Laboratory. For assistance using this measure please post to https://unmethours.com/questions/ | |
| Modeler Description | Nine user inputs are required, based on these user inputs, the outdoor air RH reading in the economizer will be replaced by the equation below, where RHoaF is the biased outdoor air RH reading, RHoa is the actual outdoor air RH, F is the fault intensity and AF is the adjustment factor. RHoaF = RHoa + F*AF. To use this measure, choose the Controller:OutdoorAir object to be faulted. Set the level of relative humidity sensor bias between -100 to 100 that you want at the outdoor air duct for the economizer during the simulation period. For example, setting F=3 means the sensor is reading 25% when the actual relative humidity is 22%. The time required for the fault to reach the full level is only required when user wants to model dynamic fault evolution. If dynamic fault evolution is not necessary for the user, it can be defined as zero and the fault intensity will be imposed as a step function with user defined value. However, by defining the time required for the fault to reach the full level, fault starting month/date/time and fault ending month/date/time, the adjustment factor AF is calculated at each time step starting from the starting month/date/time to gradually impose fault intensity based on the user specified time frame. AF is calculated as follows, AF_current = AF_previous + dt/tau where AF_current is the adjustment factor calculated based on the previously calculated adjustment factor (AF_previous), simulation timestep (dt) and the time required for the fault to reach the full level (tau). | |
Files
| misc_eplus_func.rb |
| ControllerOutdoorAirFlow_RH.rb |
| measure.rb OpenStudio 2.4.0 Min Compatible Version: 2.4.0 Max Compatible Version: 2.4.1 |
| LICENSE.txt |
Content visibility
Use group defaults
Measure Arguments
| Name | Display Name | Short Name | Description | Units | Type | Required | Model Dependent | Default Value | Choices | Min Value | Max Value |
|---|---|---|---|---|---|---|---|---|---|---|---|
| econ_choice | Choice of economizers. | - | - | - | Choice | true | false | - | - | - | - |
| oa_rh_bias | Enter the bias level of the return air relative humidity sensor. A positive number means that the sensor is reading a relative humidity higher than the true relative humidity. [%] | - | - | - | Double | false | false | -10 | - | - | - |
| time_constant | Enter the time required for fault to reach full level [hr] | - | - | - | Double | false | false | - | - | - | - |
| start_month | Enter the month (1-12) when the fault starts to occur | - | - | - | Double | false | false | 6 | - | - | - |
| start_date | Enter the date (1-28/30/31) when the fault starts to occur | - | - | - | Double | false | false | 1 | - | - | - |
| start_time | Enter the time of day (0-24) when the fault starts to occur | - | - | - | Double | false | false | 9 | - | - | - |
| end_month | Enter the month (1-12) when the fault ends | - | - | - | Double | false | false | 12 | - | - | - |
| end_date | Enter the date (1-28/30/31) when the fault ends | - | - | - | Double | false | false | 31 | - | - | - |
| end_time | Enter the time of day (0-24) when the fault ends | - | - | - | Double | false | false | 23 | - | - | - |