On Tuesday, January 10, 2012, Jeff Haberl <jhaberl@xxxxxxxx> wrote: > > > > > FYI: > > > > There is also quite a bit about pool modeling in the following references, enough so to actually predict the pool water use:
> > > > 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 (January). >
> > > Haberl, J. 1986. ?An Expert System for the Analysis of Building Energy Consumption,? Ph.D. Thesis, Department of Civil, Environmental and Architectural Engineering, University of Colorado at Boulder.
> > > > This work was done at a Rec Center at the University of Colorado, which included a swimming pool (2 pools). The heat loss equations used the DeWinter approach. Of importance to this discussion is the fact that the water that gets splashed out of the pool and/or gets carried off on the bodies of the swimmers when the exit the pool is often times larger than the evaporative loss.
> > > > The data used for the thesis contains almost 18 months of daily makeup water measurements that showed this trend. Also, you?ll need some sort of variable for the filter type. In particular if it is a permanent media filter, there is a lot of water wasted to the drain when the filters are flushed. Finally, at the Rec Center in this 1986 study, the largest amount of water used was when they drained the pool each for maintenance and cleaning, which was cut in half by draining one pool at a time while working on the pool and pumping the water from the full pool into the empty pool.
> > > > Jeff > > > > 8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) 8=() 8=) 8=| 8=) :=') 8=)8=? > > Jeff S. Haberl, Ph.D.,P.E., FASHRAE.............. jhaberl@xxxxxxxx
> > Professor............................................................Office Ph: 979-845-6507 > > Department of Architecture.............................Lab Ph:979-845-6065 > > Energy Systems Laboratory.............................FAX: 979-862-2457
> > Texas A&M University.....................................77843-3581 > > College Station, Texas, USA, 77843..................URL:www.esl.tamu.edu >
> 8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) :=) 8=) 8=! 8=) 8=? 8=)8=0 > > > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Karen Walkerman
> Sent: Monday, January 09, 2012 1:21 PM > To: EnergyPlus_Support@xxxxxxxxxxxxxxx > Subject: Re: [EnergyPlus_Support] Outdoor swimming pool >
> > > > > Jim, > > > > Yes, I agree with what you say. I have modeled in the past many heated pools and always apply the evaporative losses to the pool heater, as this is the way it is dealt with in real life. An outdoor pool, or an unheated indoor pool lead to much more complex interactions between the air mass and water mass. I think an outdoor pool would actually be easier to model as the pool itself will have very little impact on the air mass, and evaporation, radiation heating and cooling can be calculated on an hourly basis. A pain in the ass, but achievable.
> > > > An indoor space with un-regulated pool has a large impact on the air mass, so the heat balance needs to be calculated by an additive or iterative process (results from one timestep feeding the next). Much more difficult.
> > > > -- > > Karen > > On Mon, Jan 9, 2012 at 2:10 PM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: >
> > > Dear Karen et al, > > As I think more about this, several things come to mind: > > · It?s a simple matter to calculate the amount of energy lost by evaporation; pool heater people have needed that information for a long time. It does not matter (to them) whether the energy for evaporation is taken from the air or water; they just need to replace it.
> > · For the purposes of pool water heating energy calculations, it doesn?t matter where the energy goes either; the pool water heater must replace it. > > · I reached out to a colleague who is the Engineering Manager for one of the major pool dehumidification (air handler) companies to clarify this, since I did actually keep falling asleep in Thermodynamics class. He says that essentially all of the heat of vaporization is removed from the pool?s water if the pool and surrounding air are the same temperature. (EngineeringToolBox.com says much the same, but my friend explained it better.)
> > · For an unheated pool, the evaporation would cool the pool?s water and create some sensible temperature exchange between the pool and surrounding air. It will also change the rate of evaporation.
> > o If the pool is heated and indoors, and the heater works properly, that won?t be true because the heater will act to maintain the water temperature at a constant value. > > o If the pool is heated and outdoors, the rate of evaporation will change as the outdoor temp and humidity change.
> > · The ASHRAE Handbook and my colleague reminded me about radiant heat transfer to the sky (at night) or from the sky (actually solar energy) for an outdoor pool. These are aspects that I have no clue how to calculate. I hope they balance J.
> >