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Hello, I'm having trouble with controlling the air temperature in the zone, I added an active layer with temperature of 30 degrees as an input, and the heating in TRNbuild is 20, but the temperature of the zone keeps getting higher than the set points, I can not control it, What should i do to do?
When you say "the heating in TRNBuild is 20", do you mean that you added a heating type to the zone with a setpoint of 20? Or do you mean something else?
There are two ways to control temperature in a multizone building in TRNSYS. One way is by "energy rate control." With energy rate control, TRNSYS compares the zone's net heat loss/gain at each timestep to the capacity of the heating/cooling type specified for the zone; if the heating/cooling type's capacity is greater than the net loss/gain of the zone (or the type's capacity is unlimited), the zone is maintained at the temperature set by that heating/cooling type, else the temperature falls or rises. The "Heating" (flames icon) and "Cooling" (snowman icon) options in TRNBuild are actually used for this energy rate control approach, not to provide setpoints for other heating/cooling equipment. I'm guessing you added a heating type with a setpoint of 20, but you didn't add a cooling type, so there's no way for the heating type to control what happens when the zone temperature rises and keeps rising. But that's good for now, because you can see that the zone is getting too hot!
The temperature shouldn't be rising over 50 from the influence of the outside air and an active layer at 30 degrees alone, so there must be an oversized/unintended heat gain somewhere in the zone. Unfortunately, I can't say what it is from the limited information here. Maybe a lighting, equipment, or occupancy gain is too large? Turn off the heating type, take out the active layer or leave its flow rate at the default 0 kg/hr, and see if you can get the unconditioned zone temperature to fluctuate somewhere between the desired temperature and the outside air temperature. Once the unconditioned zone is behaving as expected, you can start adding conditioning through the active layer.
Conditioning the zone through the active layer is an example of "temperature level control". With temperature level control, you add elements such as an active layer or forced air ventilation to supply heated or chilled fluid to the zone, then (in the Simulation Studio project, outside of TRNBuild) you connect a pump/fan, heating/cooling equipment (boiler, chiller, heat pump, etc.), and a thermostat to the fluid loop, controlling the supply of heated or chilled fluid based on the zone temperature. There is a tutorial for moving from energy rate control to temperature level control in the Tutorials document in your TRNSYS/Documentation folder. (The tutorial uses a forced air ventilation loop rather than an active layer liquid loop, but the procedure for connecting a liquid loop through an active layer is very similar).
Good luck!
tagreedwael Topic starter
02/11/2025 10:28 am
@a_weiss thanks! i added a cooling type with temperature of 26 degrees, and it worked, for multipule zones.
also i have a question, about adding a heat pump to the system, i want to add a air to water heat pump type 941 but i don't have it in my TESS library, is there like another way to add it? or another type?.
thanks for clearing the idea!
You didn't actually fix the problem, you just covered it up. Turning on heating and cooling types in TRNBuild is like adding a "magic" source of conditioning. To model "real" conditioning units (active layers, heat pumps, etc.), you need to turn the heating and cooling types in TRNBuild "off", and add pumps/fans/thermostats, etc. to the TRNSYS project to control those units. It's a bit of an involved process, and the tutorial I directed you to walks through how to do it in much more detail. I think you're trying to turn heating or cooling "on" to control the active layer you added, which is not at all how it works.
Your zones are still way too hot for normal apartment loads. Turn off the heating and cooling types, remove any equipment/lighting/occupancy loads, and see if the zones behave as unconditioned zones (they should lag the outside air temperature, with maybe a small daily bump for solar gains if there are windows in the zone). You should only add conditioning to the zones once you've verified that they behave as expected without any conditioning. (Hint: whatever the crazy high heating load is, it turns on at about 8 AM on the first day, and the run time seems to be different on weekdays versus weekends. Changing the number of X axis gridpoints from 12 to 7 will make the day by day temperature trends more obvious).
A_Weiss 02/11/2025 2:20 pm
Regarding heat pumps: Type 941 is in the TESS HVAC Library. It can be purchased by going to https://trnsys.com/tess-libraries/how-to-order.php.html and filling out an order form at the bottom of the page. If you don't have the TESS Libraries, you could instead use one of the heat pump models in the standard HVAC library. But you really need to fix the heat gains from equipment, lighting, occupancy, and other sources before adding conditioning equipment.
