[Equest-users] Baseboard Heating Out of Control?

[Bishop, Bill]

Bryan,
Modeling the radiant panels as baseboards is a good approach. Since you are calibrating the model for an existing building, I suggest manually entering the baseboard heating capacity zone-by-zone based on the installed radiant panel capacity, and manually entering the RTU heating capacities and flowrates. If you can't get the design/installed values, pay close attention to the DOE-2 help description for the default autosizing of BASEBOARD-RATING. Be sure to enter a "0" capacity in zones that have no radiant panels. eQUEST will prioritize the baseboard heating when you use a BASEBOARD-CTRL of THERMOSTATIC. The panels are often controlled by OA temperature, in which case you need to specify the BASEBOARD-SCH at the system level and use OUTDOOR RESET for the zonal BASEBOARD-CTRL. Since you are proposing a heating energy ECM, it is important to know how the radiant panels are controlled - you may consider changing the controls as part of the ECM to put more of the load on the heat pumps. Some other things that could throw off your RTU heating vs. radiant panel heating are 1.) ventilation rates, 2.) thermostat setpoints and setback, 3.) lighting/equipment/occupant loads and schedules and 4.) inaccurate modeling of the envelope.

Regards,
Bill

William Bishop, PE, BEMP, BEAP, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Russo, Bryan
Sent: Tuesday, January 28, 2014 5:59 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Baseboard Heating Out of Control?

Hello eQuest Community,

I'm modeling a ~40,000 SF office served via two packaged VAV with DX cooling and electric heating RTUs. As it is a high aspect ratio building, nearly every zone also has an electric, ceiling mounted radiant panel. As eQuest cannot model a zone with both radiant panels and a VAV system, I've attempted to approximate the contribution of these radiant panels with electric baseboard heat.

As I've been calibrating the model, I've nearly approach the building energy consumption levels and the model has a good match to the annual consumption profile. However, when I review the detailed simulation output, I find that the baseboard are responsible for 90% of the building heat load while the VAV system picks up the remaining 10%. Based on my visits to the building, this does not feel intuitively likely. However, eQuest seems to prioritize baseboard over the forced air system, despite my attempts to placate it with higher discharge air temperatures and experiments with baseboard control schedules. As the proposed retrofit is a heat pump, the model as is suggests there is very little room for improvement as only 10% of the heat is supplied by the ventilation system, which doesn't bode well.

Does anyone have a better approach? The only other thought I had is to simulate the heat output of the baseboard with a parallel box zone heater with near 0 fan power consumption.

Many thanks,

Bryan

_______________________________________________________________________
Bryan Russo
Conservation Resources Management
Tacoma Power

email: brusso at ci.tacoma.wa.us<mailto:brusso at ci.tacoma.wa.us>
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cell        253.306.0670
fax          253.502.8276

Visit our website at www.knowyourpower.com<http://www.knowyourpower.com/> for ways to save money while conserving energy

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