Rule to calculate energy used to heat the pool

[stritti]

I created a openHAB rule to calculate the energy (kWh) wich is used to heat the pool:

'use strict'

var poolTempItem = itemRegistry.getItem('PoolController_Temperature')
var poolSize = 18000 //Liter

var logger = Java.type('org.slf4j.LoggerFactory').getLogger('org.openhab.rule.' + ctx.ruleUID)

var QuantityType = (this.QuantityType === undefined) ? Java.type("org.openhab.core.types.QuantityType") : this.QuantityType
var PersistenceExtensions = Java.type("org.openhab.core.persistence.extensions.PersistenceExtensions")
var ZonedDateTime = Java.type("java.time.ZonedDateTime")

var now = new Date()
var sinceDate = ZonedDateTime.now().minusHours(1)

var historicTempItem = PersistenceExtensions.historicState(poolTempItem, sinceDate)
var energyUnit = new QuantityType("0 kWh")

if (historicTempItem != null) {
  
  var currTemp = poolTempItem.getState()
  var historicTemp = historicTempItem.getState()
  var deltaTemp = new QuantityType( currTemp - historicTemp + " K")
  
  if (deltaTemp > 0) {
    // 1grad pro 1000l ~1.162kWh
    var energyUnit =  deltaTemp * poolSize * 1.162 / 1000 
    energyUnit = new QuantityType(energyUnit + " kWh")
    logger.info('aktuelle Temp: ' + currTemp + ' vor einer Stunde: ' + historicTemp + '-> delta: ' + deltaTemp + ' Energie: ' + energyUnit)
  }
}

events.postUpdate("PoolController_Energy", energyUnit);