Salutations!
I just completed a LEED model, but after reviewing the data results, I think something is wrong.
The baseline building is showing no energy used for space heating, heat rejection, and service water heating. I have the 2 boilers modeled, per G3.1.3.2. This sort of makes sense because the model was showing high unmet heating hours, while the proposed building had had unmet cooling hours (successfully resolved).
I set up the system 5 equipment (Packaged VAV with reheat) in the wizard, but it doesn't seem to show a heating component in the DDE. I'm going to keep looking, but wanted to see if someone could point me in the right direction.
Regards,
Matt Clough
Post the .pd2 and .inp file for this project and we may be able to help you better.
Timothy Howe, MS, LEED? AP BD+C
Unmet heating hours will probably go away once you get your heating operational. I'd caution against internally justifying/rationalizing one set of unmet hours with another - keep in mind unmet hours are an indicator/symptom of a problem, not a problem in and of themselves.
For HW consumption, open both models and review the DHW loop, schedules, process loads, and equipment. Generally everything should be identical excepting HW heater efficiency inputs.
Reheat coils are set up at the terminal units (zone inputs). Those relying on wizards can easily miss some required edits to make reheat operate correctly - see attached discussion from the [Bldg-sim] archives for a recap.
~Nick
[cid:489575314 at 22072009-0ABB]
NICK CATON, P.E.
1. Make sure your systems are set to cycle on any
2. Make sure you have your reheat Delta T Set correctly.
This should take care of the problem - otherwise its probably something more sinister.
Vikram Sami, LEED AP BD+C
I have attached the .pd2 and .inp for the baseline building.
I have changed the reheat deltaT, but this has not decreased the unmet hours (which explains the lack of energy used for heating)
I'm fiddling with HMAX-FLOW-RATIO at the suggestion from the archives, and may try increasing the boiler capacity incrementally.
But I'm feeling pretty stuck on this one. Just have to keep reading.
Thanks for the help
I ran the file you sent - it has heating consumption values, unmet hours is
just 200. Strange thing is that the % of hours should be 2.2% or so,
instead it is 8.2% - not sure why that is happening - may be the calc
procedures have changed for the % calcs?
-Rohini
Matt,
Before looking into the Systems, I would suggest taking a closer look at the inputs on the building shell and internal loads.
For example, you are using 0.025 w/sf as equipment/plug load for many of your classroom spaces, which is too low. Depending on
the type of equipment (TV, Computers, Projection Eq., SmartBoards), the plug loads could range between 0.25-0.5 w/sf for an elementary school.
Also, I noticed your glazing types have U-value > 0.7.