modeling an indoor pool in eQuest

5 posts / 0 new
Last post

Hello,

I am looking for general guidelines on how to model an indoor pool in eQuest, including energy requirements to heat the pool water, and energy requirements to heat/cool/dehumidify the air. If anyone has any resources to point me towards, that would be greatly appreciated. The pool in question is located in northern Alberta, where the temperature dips to as low as -22 ?F in winter. The pool has two small windows. Its roof is part of the building envelope, but its walls are not - the walls are adiabatic.

Thanks,
Matthew

Matthew Yarmon's picture
Offline
Joined: 2020-08-21
Reputation: 0

Good morning Matthew,

There are a few considerations when modelling pools in eQUEST.

Pool water heating -

This piece might be the most straightforward. The pool water heating requirements will be modelled as a peak flow and schedule as a direct load on either a hot water loop or a DHW Loop where it will be part of the building DHW energy as an end use. The peak flow and schedule here will be determined as the greater of the pool water evapouration or the make-up water if there is greater make up flow due to water per swimmer requirements. If the pool water heating is added as a direct load to a hot water loop, it will show in the ?equipment? end use. Generally, where building boilers are used to provide pool heating along with space heating, my practice is to create a secondary pool hot water loop to the main hot water loop as it makes isolating and reviewing the pool heating easier in the PS-D and PS-H reports of the .sim. A dedicated primary hot water loop for pool is appropriate when the pool heating equipment is dedicated and/or when heat is recovered from the pool air handling equipment.

Conditioning the pool air space -

In order to model the dehumidification of the pool zone, you will need to impose the latent load caused by pool evapouration. There are a few sources for the calculation of evapouration from pools. I recommend "Methods for Calculation of Evaporation from Swimming Pools and Other Water Surfaces," ASHRAE Transactions, vol. 120, part 2, 2014 which is available from the author?s website here: https://mmshah.org/publications.html (item 23). However you determine the evapouration rate, you will impose it on the space as an ?Internal Energy Source? on the ?Equipment? Tab of the pool space. The ?Input power? will be the peak evapouration with a sensible HG ratio of 0 and a latent HG ratio of 1. I have been using the latent heat of evapouration of 1,046 BTU/lbm of water evapourated for an 84?F pool. Depending on your pool surface area and temperature, activity factor and the natatorium air conditions, I expect your peak evapouration to be in the range of 150,000 to 500,000 BTU/hr. A schedule is required for the occupied and unoccupied evapouration taking the pool activity factor into consideration. Given that the energy for heating of the water evapourated is covered in the pool water heating above ? I recommend setting the Source Type for the evapouration to Process ? that way it is not ?double counted? on the utility bill.
[cid:image002.png at 01D676F7.7BA66370]

Dehumidification is achieved by setting the maximum humidity keyword in the air handling system serving the pool area. Note that the space temperature of the pool air volume is often kept higher than the rest of the building and will need to be set appropriately. The ventilation rates will be set for dehumification requirements. Heat recovery from the dehumiditication system is common with condenser energy often being used to preheat outdoor air as well as heating the pool water. Personally, I have not had good success using the DX waste heat keywords to transfer condenser heat to a DHW loop. My practice has been to use a heat recovery chiller to do the heat recovery to a hot water loop. Note that the heat recovery chiller keywords are not recovering heat to the hot water loop in DOE-2.3 so I recommend DOE-2.2 for pool modelling (at least if you have heat recovery to the pool water heating). A heat recovery chiller can recover to either a HW or a DHW loop. If you use a DHW loop, you will have to reduce the loop delta-T to below 70F or eQUEST will throw an error.

Cheers,

Brian

Footprint

Brian Fountain
Associate
d 416 572 8501 m 416 562 6831

Brian Fountain's picture
Offline
Joined: 2019-05-02
Reputation: 0

Hello Matt:

Here's a rather dated paper on how a proxy model was created for the Rec Center at the University of Colorado in 1985. The simulation was with DOE-2 and was actually calibrated to the indoor conditions at the pool, as well as the monthly energy use. The 1987 paper has additional information about how the measurements were used to create an expert system for diagnosing operation and maintenance issues.

Obviously, the DOE-2 program was not created to do this sort of thing, but it can be tricked into giving answers that mimic the measured performance.

Jeff

PS: The building also had a skating rink above the women's locker room that was also modeled (or mimicked) with DOE-2

Haberl, J., Claridge, D. 1985. ?Retrofit Energy Studies of a Recreation Center,? ASHRAE Transactions-Research, Vol. 91, Pt. 2, pp. 1421 ? 1433 ESL-PA-85-12-01 (December).

Haberl, J., Claridge, D. 1987. ?An Expert System for Building Energy Consumption Analysis: Prototype Results,? ASHRAE Transactions-Research, Vol. 93, Pt. 1, pp. 979 - 998 ESL-PA-87-07-01 (July).

Jeff S. Haberl, Ph.D., P.E.inactive, FASHRAE,FIBPSA

Department of Architecture

Texas A&M University

College Station, TX 77845-3581

Office: 979-845-6507, Lab: 979-845-6065

Fax 979-862-2457

jhaberl at tamu.edu,www.esl.tamu.edu

Jeff Haberl2's picture
Offline
Joined: 2011-10-02
Reputation: 200

Great responses!

Jeff and Brian have pretty much covered it. I commonly end up with models including most of not all of the inputs described.

I might only add that, for indoor heated pools in northerly climates, I have experienced some interesting and unique situations concerning ventilation and dehumidification of such spaces. In one case, I was charged with modeling an existing scenario where "cloud formation" was a regular occurrence we were charged with fixing. Juxxz Resolving this issue required a combination of replacing active (but ineffective) dehumidification units within the pool space, opening up some (then blocked-off) grills between the pool and adjoining locker rooms (locker exhaust was a critical component to achieve a more effective ACH rate) which incidentally helped to resolve some related odor/ventilation issues in the locker spaces, and adjusting the reheat capacity of the associated AHU with a new coil.

This is all primarily to suggest: I would advise deliberation before excluding from your model any adjoining spaces/systems which may play an impactful role on the operations of your pool conditioning systems. You might later wish you had those spaces/zones incorporated from the get-go.

Oh and if ever you were in search of a good application for solar HW heating as an ECM... Active indoor pools at northerly latitudes are a solid starting point. Just be extra mindful of snow cover in application/design ;-).

Best of luck!

~Nick

~Nick

Nicholas Caton2's picture
Offline
Joined: 2019-03-25
Reputation: 0

... don't forget to take a look at the classic 1975 report by Francis de Winter, Atlas Corp.

Here's the link. There's a complete chapter on how to calculate the heat loss of a pool -- which would be the sensible and latent heat gain into the A/C or heater for the pool zone.

"How to design and build a solar swimming pool heater, Francis de Winter, Santa Clara, CA, 1975". Available at the ecotopia web site:

Jeff

http://www.ecotopia.com/dewinter/de_winter_how_to_design_build_solar_swimming_pool_heater_cda_1975.pdf

Jeff S. Haberl, Ph.D., P.E.inactive, FASHRAE,FIBPSA

Department of Architecture

Texas A&M University

College Station, TX 77845-3581

Office: 979-845-6507, Lab: 979-845-6065

Fax 979-862-2457

jhaberl at tamu.edu,www.esl.tamu.edu

Jeff Haberl2's picture
Offline
Joined: 2011-10-02
Reputation: 200