Thanks, Ned.
This is very good practical information.
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Monday, December 8, 2014 20:10
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Pools application
I have not had to energy model a swimming pool, but here are a few thoughts from some load modeling work I’ve done and a lot of pool investigations/repairs.
There are several models for water evaporation. I recall an ASHRAE Journal article within the last 5 years that summarized them. You can schedule or EMS them. Probably the most difference between them is pool use. More splashing is more evaporation and energy use.
For a while there was some recycling of condensate water. If I find it I get rid of it, there is too much dirt in the air that winds up in the condensate and then messes with water quality.
There are no simple equipment models in E+ that represent available pool system equipment, you will have to be creative. I think some pool equipment manufacturers have used Transys to model their equipment. You have to know things like a Dectron cooling coil discharges 59 deg-F air in operation to dehumidify or heat pool water, a piece of DX HVAC cooling equipment would normally be colder. If someone ever did get accurate working models for available equipment, we might be able to calculate the actual energy use differences between different equipment in different situations.
Sticking with ASHRAE ventilation recommendations of min 4 ACH toatal air turnover usually results in OK air mixing in the pool space. Designers typically fail to realize that that air movement at the pool deck and over the water in necessary to get fresh air to the breathing zone. If you have an audience area, it is best to have a separate system. Ventilating showers and lockers with pool exhaust is also no longer a good idea.
A pool is always occupied by pool water and chemicals, so it needs fresh air ventilation. You may be able to limit audience fresh air ventilation, but basic pool deck and pool water ventilation is 24-7.
Air-to-air energy recovery is tricky in cold climates, things tend to freeze up and stop working.
Most energy codes will call for pool covers, most operators will not use them. I recommend them for building envelope protection should the mechanical systems fail. I only know of one pool where they were actually used regularly, and that was a residence with small children and the cover was also a safety device.
Pool water heat loss to the ground is very hard to quantify. I had one diving tank that was actually set into an underground flow of 50F water year round. At best you can guess a basement heat loss for the pool water.
A typical pool water heater is sized for recovery. If you fill the pool with fresh water at 50 deg-F, you would like it to reach operating temperature in a couple of days. This is typically much more heat than what is needed to maintain water temperature during use.
The actual water temperature depends on pool use. A competition pool may be mid 70 deg-F for an event, but it will be low 80s deg-F most of the time for training (Olympic training facilities keep about 82 deg-F for training). Any pool with water aerobics for seniors will be closer to 90 deg-F. Oh yes, changing pool water temperature is a slow process, so you don’t just turn it up for Friday afternoon class.
Pool water can easily be higher temperature than pool air. Really no big deal except for controls or of you have a very hot therapedic pool that tries to live in a cooler space. Remember that a large body of water at 90+ deg-F is a radiative heat source for the room and roof.
The recommendation for pools is also to operate at a slight negative pressure. I have yet to visit a pool where the envelope is really tight enough. Infiltration at the recommended negative pressure is often 1 to 2 times (or more) the required fresh air ventilation requirements. But then I also seldom see a negative pressure that is actually generated by the mechanical system.
Ned Lyon, P.E. (MA, WV)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
617.285.2162 mobile
781.907.9009 fax
www.sgh.com
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Monday, December 08, 2014 12:48 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Pools application
Thanks, Jim.
I also worte a ticket to helpdesk. We’ll how this turn out
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Monday, December 8, 2014 17:40
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Pools application
p.s., Ignore "MT". Use a blank field instead.
On Mon, Dec 8, 2014 at 11:34 AM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Artem,
I introduce moisture to the pool zone this way. The design level is calculated with the Shah method or similar and the variation in moisture is defined with "SchCpct_PoolEvap" in this case.
On Mon, Dec 8, 2014 at 8:47 AM, 'Artem Zhukov' az141208@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
Hello,
Please share some insights about modelling enclosed swimming pools application. I saw previous discussion and fond xls program for calculation of evaporation by hours, which could be used as a schedule. Is there another way to model evaporation in energyplus?
Thank you.
ARTEM ZHUKOV | HVAC/Mechanical Engineer | HVAC TPM | Energy Engineer | Building Physics Specialist | Sustainability Engineer | M: +420 774 081 898 | View LinkedIn profile | Web Cal
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James V Dirkes II, PE, BEMP, LEED AP
The Building Performance Team
1631 Acacia Drive, Grand Rapids, MI 49504
(M) 616 450 8653If I decide to act with strength and honor in some instances, but not always, I have made my integrity optional. It's all or nothing.
--
James V Dirkes II, PE, BEMP, LEED AP
The Building Performance Team
1631 Acacia Drive, Grand Rapids, MI 49504
(M) 616 450 8653
If I decide to act with strength and honor in some instances, but not always, I have made my integrity optional. It's all or nothing.
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Posted by: "Artem Zhukov" <az141208@xxxxxxxxx>
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