TL;DR - I think that your best approach is to use EMS to override the amount of heat added or removed from the warehouse due to incoming product using an OtherEquipment object.
Interesting question! Here are my initial thoughts:
- The InternalMass object will only account for heat exchange between the internal mass surface (i.e. products) and the zone that contains the internal mass surface (i.e. warehouse receiving or storage zones). The Engineering Reference gives more details about how this impacts radiation and convection heat transfer.
- EMS is a great tool to apply custom changes that EnergyPlus normally doesn't allow, but it doesn't give you total control to override ANYTHING in the model. The things that you can override are called actuators, and you can see that it is a pre-set list. For example, there is no actuator option for anything related to InternalMass objects.
Here are my responses to your questions about the best approach:
- Model the flow of wood as an internal heating or cooling load using OtherEquipment and some schedule or EMS script. I believe this is your best option. This would be a load provided from the wood into the zone, which EnergyPlus then accounts for when determining new HVAC system requirements to provide to the zone. OtherEquipment objects also don't have any energy use metered by EnergyPlus to represent natural heat exchange, which is what you want to represent. You would use a similar equation like the other post you linked to determine what that heat exchange value should be based on warehouse zone air temperature and wood temperature and use the Power Level actuator for OtherEquipment.
- One option to model the effect of wood temperature more accurately is to draw a surface object representing wood in the model. This wood surface object would then calculate a surface temperature at both the inside face touching the warehouse zone and the outside face (also touching the warehouse zone). However, even using EMS, you cannot use an actuator to override both faces (inside and outside) -- only the outside surface boundary conditions for convection air temperature and radiation effective temperature.
- Yes -- a Construction:InternalSource could be used in combination with InternalMass. The InternalMass object would reference the Construction:InternalSource object to know the material layers and where the heating element is located between those layers. The easiest way to define the heating element is with a ZoneHVAC:LowTemperatureRadiant:Electric object, since that can define electric element heating on its own. The alternative would be a hydronic (water-based) radiant object, which would require creating an EnergyPlus plant loop so that the water flowing through the wood gets heat from a boiler or some other means. However, all radiant objects try to meet heating/cooling thermostat setpoints in zones, so you would need to use EMS to override that heating capacity to a proper heat transfer value depending upon wood temperature. EMS actuator options for radiant systems are limited to water flow rate through hydronic panels and none exist for electric panels. So, quite messy.
- You could use a "zone in the zone" to model these wood products, meaning that you draw surfaces to represent the wood as a zone inside of the warehouse zone. The construction of wood zone's surfaces should use the same actual wood properties in the warehouse (density, specific heat, etc), but alter the thickness so that the total volume of all wood zone surfaces match the actual wood volume in the warehouse and account for heat storage accurately. Then, each of those surfaces could use the same EMS actuators for outside face convection and radiative temperatures I mentioned above. This will be more accurate than using the OtherEquipment object, but take more EMS scripting and longer simulation times (more zones and surfaces for EnergyPlus to calculate heat transfer every time
step).step). HOWEVER, the volume of wood in the warehouse would be fixed -- you cannot use EMS actuators to change surface area or other geometry aspects of a zone. This is the main reason that I recommend the first option, since the OtherEquipment power actuator could take wood volume into consideration.
