[Bldg-sim] NECB Reference Building Fan Power

Aaron Smith asmith at mreng.ca
Tue Jul 16 07:14:04 PDT 2019

Hello Harshal,


Thanks for the response.  I’m more concerned about whether the fan power of both the DOAS and terminal unit should be added together for the calculation rather than how to model the system.  Unfortunately the NECB code committee does not respond to interpretation requests, they refer you to your AHJ.




Aaron Smith, P.Eng

Principal, Mechanical Engineer



M&R Engineering Ltd.


From: Gupta, Harshal [mailto:Harshal.Gupta at wsp.com] 
Sent: July-14-19 1:28 AM
To: Aaron Smith <asmith at mreng.ca>
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] NECB Reference Building Fan Power


Hi Aaron,

In case you are working on 3.65 : 7173 (2016 version) below will work. In 3.65 :7175 thier is a option to model DOAS. 

In this case you can devide DOAS fan conneted load from DOAS CFM to evulate DOAS kW/CFM. You can add the DOAS CFM to all terminal units/Fan coil and DOAS connected fan load to terminal fan load per cfm basis to calculate new fan power (terimanl+DOAS).  Suppose DOAS is catering 50 cfm to particular thermal zone of 500 dehumidification cfm, so new cfm will be 550 and fan load (terminal fan kW+ ((DOAS kW/DOAS CFM)* 50))

The issue is, in case if you are modelling fan coil you wont be able to model heat recovery on Fan coil in eQUEST. 

Another thing is fan coil will work on constant volume in eQUEST, so if your proposed FC is 2 speed or equiped with EC motor than it can be less consumption in building but i am afraid that it is not possible to model. You can check the possibility to load fan curve to work on that. 

It will include the fan load and latent load and increase your consumption accuracy, but will be not highly precise. 

Harshal Gupta

Energy Performance Analyst, iCRC US

T+91 1204808419

F+91 1204808480


FC-24, First Floor, Sector 16A,

Filmcity, Noida, Uttar Pradesh

201 301

From: Aaron Smith via Bldg-sim

Sent: Saturday, July 13, 02:42

Subject: [Bldg-sim] NECB Reference Building Fan Power

To: bldg-sim at lists.onebuilding.org <mailto:bldg-sim at lists.onebuilding.org> 



I’m curious about other’s take on Reference Building fan power for projects where the Proposed building has terminal units with a DOAS system.  Let’s say you have fan coil units and a central DOAS system with heat recovery.  In doing the 10kW fan power check, would you include fan power from your DOAS system as well as all the terminal units?  If so, would you only include the fan power for the supply fan in the DOAS system?


See some excerpts from the 2015 NECB pasted below.



Aaron Where the proposed building's secondary system does not meet the requirements of Clause, the reference building's secondary system shall be modeled as having an identical fan power demand. Application 

1) Except tor equipment covered by Article and whose minimum performance includes fan energy, this Subsection applies to all fan systems 

a) that are used for comfort heating, ventilating or air-conditioning, or any combination thereof, and

b) for which the total of all fan motor nameplate ratings is 10 kW or more (see Note A-

2) For the purposes of this Subsection, the power demand of a fan system shall be the sum of the demand of all tans required to operate at design conditions to supply air to the conditioned space. (See Note A-


A- .(2) Fan System Design. Although the allowed maximum power demand of a fan system based solely on the supply airflow, the calculation of actual power demand includes supply fans, return fans, relief fans, and fans for series fan-powered boxes, but not parallel-powered boxes or exhaust fans such as bathroom or laboratory exhausts.


A- Constant-Volume Fan Systems. This type of system includes bypass variable-air-volume systems in which the airflow through the tan is not varied. Both supply and return fans must be accounted for, but not exhaust fans. The power demand of the motors refers to the power drawn by the motors and not their nameplate rating.




     Aaron Smith, 




    Principal, Mechanical Engineer 






     t: (902) 422-7393 


     f: (902) 423-4945 


     e: asmith at mreng.ca <mailto:asmith at mreng.ca> 

      <http://www.mreng.ca/> www.mreng.ca 


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