HVAC Electric and thermal consumption very diferent

asked 2018-01-16 12:57:08 -0500

cirulo gravatar image

updated 2018-03-08 15:29:30 -0500

I'm trying to simulate an existing building, with real equipment, and I'm having a hard time.

The system is an air-to-air PHPT with a Unitary Object in the zone (I'm using Templates). When I try to launch the simulation with all the fields filled, without "autosizing", the program gives an error, asking me to activate the sizing objects in SimulationControl (I thought I didn't need it for hardsized simulation, I get For autosizing of AirTerminal:SingleDuct:Uncontrolled THERMAL ZONE 1_LOCAL AIR TERMINAL, a zone sizing run must be done). Finally, I activate these objects.

The difference between EnergyPlus (Calculated) and my system (User) are very large in sizing thermal load (allthough I don't understand why I get sizing results if I'm using hardsized, and why "users results" are not my own system / capacity). The space has a large natural ventilation to simulate an open door (12.5 1/hr), so it's going to need a big heating/cooling load, but the owner didn't say us the existing Heat Pump is not giving her enough energy_temperature). The E+ proposal is 39323.14/63752.33 W, and the user design load is 10633.10/36525.49 W (cooling/heating).

The most disconcerting is that there is a difference between the electrical consumption of the HVAC system (via Facility Total HVAC Electric Demand Power in Output:Variable) and thermal consumption (kW electric <> kW thermal divide COP_ERR). For example, I get 10633.10 W thermal for cooling, when the maximun electricity consumption in the summer is around 10000 W electric.

image description

I really want to improve in existing building simulation but I don't find the way.

edit retag flag offensive close merge delete


@cirulo could you post a link to your model?

Avi gravatar image Avi  ( 2018-01-21 14:05:59 -0500 )edit

IDF file, and thermal and electricity consumption (table screenshots).

I changed somethings respect to my above post. I didnt take account summer/winter design days; I know I should have defined it for sizing. I started in OS and I carried on E+, then it has some objetcs I dont use, and I had to define some new schedules. Around zone is not important for me; my space are shop and store (local thermal zone).

I think the relation between electricity and thermal values is COP/ERR, but I dont see it in the images I attach

cirulo gravatar image cirulo  ( 2018-01-22 17:09:44 -0500 )edit

@cirulo I am unable to find the idf in the link you posted.

Avi gravatar image Avi  ( 2018-01-23 12:58:00 -0500 )edit

Strange, link is working for me.

New link

cirulo gravatar image cirulo  ( 2018-01-23 14:15:32 -0500 )edit