Rainwater and graywater in EnergyPlus
I am trying to model a rainwater collector on the roof of a building that will be sent to a rainwater tank as a WaterUse:Storage
component in EnergyPlus. That tank is then connected to my DHW WaterUse:Connections
component as the "Supply Water Storage Tank Name" to supply cold water when the tank has ample volume, otherwise mains water will be used. Here are my issues:
- When it is raining, my output .csv file doesn't show a change in rainwater tank volume from the initial value.
- My annual simulations show no change in mains water used for DHW loads whether rainwater is collected or not.
- The volume for the graywater tank also doesn't change from the initial value.
Here is an excerpt from the .idf file:
WaterUse:Connections,
Restroom DHW Connections,!- Name
Restroom DHW Inlet Node, !- Inlet Node Name
Restroom DHW Outlet Node, !- Outlet Node Name
Rainwater Tank, !- Supply Water Storage Tank Name
Graywater Tank, !- Reclamation Water Storage Tank Name
, !- Hot Water Supply Temperature Schedule Name
, !- Cold Water Supply Temperature Schedule Name
, !- Drain Water Heat Exchanger Type
, !- Drain Water Heat Exchanger Destination
, !- Drain Water Heat Exchanger U-Factor Times Area {W/K}
Restroom DHW Equipment; !- Water Use Equipment 1 Name
WaterUse:RainCollector,
Rainwater Collector ,!- Name
Rainwater Tank , !- Storage Tank Name
CONSTANT, !- Loss Factor Mode
0.2 , !- Collection Loss Factor
, !- Collection Loss Factor Schedule Name
100000, !- Maximum Collection Rate
Rainwater Collector Surface ; !- Collection Surface Name
WaterUse:Storage,
Rainwater Tank, !- Name
Rainwater Harvesting, !- Water Quality Subcategory
, !- Maximum Capacity {m3}
5, !- Initial Volume {m3}
, !- Design In Flow Rate {m3}
, !- Design Out Flow Rate {m3}
, !- Overflow Destination
None, !- Type of Supply Controlled by Float Valve
, !- Float Valve On Capacity {m3}
, !- Float Valve Off Capacity {m3}
, !- Backup Mains Capacity {m3}
, !- Other Tank Name
ScheduledTemperature , !- Water Thermal Mode
Rainwater Temp Schedule , !- Water Temperature Schedule Name
, !- Ambient Temperature Indicator
, !- Ambient Temperature Schedule Name
, !- Zone Name
, !- Tank Surface Area {m2}
, !- Tank U Value {W/m2-K}
; !- Tank Outside Surface Material Name
Schedule:Constant,
Rainwater Temp Schedule, !- Name
Any Number, !- Schedule Type Limits Name
16; !- Hourly Value
I have created a Site:Precipitation object with an annual schedule from the PrecipitationSchedulesUSA.idf dataset, and that works fine. Any help would be greatly appreciated. I've thought about if there should be a pump connected to the rainwater loop, but there aren't input or output nodes for the WaterUse:RainCollector
or WaterUse:Storage
components.
Could you attach the entire idf as a link in your question? At minima, are you sure you have actually defined a demand for cold and hot water? Is the level in your tank always "high"? (meaning the initial value = tank is filled).