[Equest-users] Modeling inefficiencies of existing buildings

[John Bixler]

Hello all,

I've been using eQuest recently to support studies of existing buildings, and to evaluate the energy savings of different options.

I've struggled with trying to model some of the problems we've discovered in the older buildings.  Any thoughts on the following would be greatly appreciated.


1.       Failed reheat valves:  Reheat valves that are stuck in the open position.  Not only does this increase the heating hot water use, but it should affect fan energy and chilled water use as well.

2.       Light troffer diffusers:  All the vogue in the 60s and 70s, these combination lights and diffusers result in a large thermal gain as the air enters the zone.  eQuest has "duct delta T", however that assumes a heat loss under cooling.  This condition is always a gain of heat (and technically this will vary based on the temperature of the air entering the zone).

3.       Duct Leakage:  A massive problem until recently, measured leakage values can often be 30% or more.  eQuest has an apparent entry for this, however, each time I've enabled it, I've seen large REDUCTIONS in energy use.  Again, this is a condition that results in increased usage of all utilities as the zones struggle to meet their setpoints.



Also, duct leakage is assigned at the system level.  It appears eQuest then wants you to assign what plenum the duct is leaking "to".  Depending on how I specified my systems in the wizard, I have ended up with a plenum zone for each zone on a floor (which might mean 30 zones per floor) or one big plenum per floor.  If I have a system that serves zones on several floors, it dosent seem like eQuest will let me assign the leakage to go all the plenums the system is assigned to, evenly.  I have to pick a SINGLE zone that all the leakage goes to.



Thanks,

John Bixler, LEED AP BD+C
Mechanical Designer
Sebesta Blomberg
sebesta.com | P  319.364.1005 | M  319.558.9299

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