Weird request to everyone

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Dear All,

Its a very weird request to all of you in your busy schedule. As in my
earlier thread for modelling of Water loop heat pump in equest and query
was regarding the low heating consumption. I am still doubtful about the
heating consumption in the Proposed case in which system is water loop heat
pump with supplemental boiler and cooling tower to maintain the loop

As the Proposed case is water loop heat pump with gas boiler, the baseline
case system type will be System Type 1 (PTAC with fossil fuel boiler). The
simulation results for baseline and proposed case shows around 97% energy
savings in Heating end-use. The climate type as per ASHRAE is 4A
(Washington DC). I have checked hourly loop temperature profile, boiler and
cooling tower operation hours and seems fine. The boiler is working in
winter months but with very little energy consumption.

Here, I am attaching the proposed case model with weather file and hoping
if anyone can look into the model. I will appreciate any suggestions to
improve the model.

Thank you.


Mayank Bhatnagar

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Joined: 2016-07-15
Reputation: 400

Hi Mayank,
You have a large model and there is a lot going on. Here are some comments:

- There are 184 systems and 81 of them are SUM systems. I never use SUM for simulations so I don?t know what effect it is having on your model. Understood that many of these are plenum spaces, but I usually assign these to the same system as the zone below.

- 60% of the zones are TYPE = UNCONDITIONED. Many of these are restrooms, corridors, stairways and storage spaces which are probably at least heated in the proposed design and may have ducted systems, so they should probably be modeled as CONDITIONED.

- The zone THROTTLING-RANGE has been increased to 4 and in many cases 6?F. This is likely unrealistic with the proposed design having tighter temperature control responsiveness.

- All systems have the same MIN-AIR-SCH which turns off ventilation at night, but the project appears to have a large residential component so this seems unrealistic. This is likely reducing the heating load considerably.

- The WLHP loop has LOOP-OPERATION=DEMAND-ONLY. This is unrealistic for a WLHP loop and STANDBY would make sense.

- The model has a high number of unmet hours (947 hrs heating; 5451 hrs cooling) even with the features above that tend to reduce them.

- It doesn?t make sense to compare the proposed design to a baseline until the unmet heating and cooling hours are fairly addressed. If the proposed model retains the features above after the unmet hours are minimized, make sure to duplicate these features in the baseline for a fair comparison.

William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

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134 South Fitzhugh Street Rochester, NY 14608

T: (585) 698-1956 F: (585) 325-6005

bbishop at

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via Equest-users's picture
Joined: 2016-07-15
Reputation: 400