[Equest-users] mystery heating load

David Eldridge DEldridge at grummanbutkus.com
Thu Dec 20 11:33:31 PST 2018

That last sentence is the issue – the system is providing some amount of air including return and OA to the space, without a heating coil, meanwhile the thermostat may be expecting 70F all of the time.

The issue could be resolved by “upgrading” the unit to heat, removing/reducing the OA quantity, or by relaxing or removing the thermostat schedules depending on what your goals are for the project.


David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Chris Hadlock via Equest-users
Sent: Thursday, December 20, 2018 1:05 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] mystery heating load

I've had a few responses requesting the modeling files so I've attached the INP and PD2 file (weather file is CWEC\Toronto.bin). The zone in question is "L0 Elev Lobby S" and I've already removed all exterior surfaces from this space (i.e. there are no Child Components). I've assigned this zone to it's own system (it's the last system on the air-side tab) called "Test System". I've already created the hourly reports where you'll see all of the underheated hours (which only occur in the winter). The LS-B report shows no (zero) htg load. I realize the system is not really providing any heating to this zone the way it's setup.


On Thu, Dec 20, 2018 at 1:26 PM Chris Hadlock <cjhadlock at gmail.com<mailto:cjhadlock at gmail.com>> wrote:

I've created a model using eQuest 3.65 (DOE 2.2) build 7173 that is of a 20 storey multi-residential building located in Toronto, Ontario (Canada). There is a basement with a elevator lobby that is an interior space (no exterior walls).

My model keeps telling me I have underheated hours for this lobby. I'm trying to figure out why there is a heating load and I'm stumped. I have removed what I believe to be all potential sources of heat loss. I've deleted the underground floor (which was R-100 anyway), I've deleted the interior walls (just to be thorough), there is no infiltration, and I've set the ventilation to zero. In my mind, there is no source of heat loss. I've even added a significant (10 W/ft2) equipment load and yet there are still underheated hours (I've even reduced my Tstat setpoint to 60F).

I've run an hourly report to help figure out the loads for both the space ("Sum of all weighted loads except infil and latent") and zone ("Load Calc'd SPACE Sensible load at const temp (Btu/hr)"). These reports all indicate a positive load (i.e. net heat gain) from my lights, plug loads and occupants. However through this process I'm also questioning these reports as the lighting, people and equipment load being reported don't exactly align with my modeled schedules for these loads....but I've put a pin in that.

Regardless, I have no idea how to figure out what may be resulting in net heat loss for this zone. To be thorough, I checked the elevator lobby on the ground level and the same thing is happening. Has anybody seen this before...any ideas what might be causing heat loss for a zone with no ventilation and no walls and no infiltration? It does seem to be seasonal (i.e no underheated hours in the summer) so it has some connection to weather file but does not correlate exactly.

If you do take the time to read this, a big thank you. If you provide the answer, you'll for sure be on Santa's "nice" list.

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