[Equest-users] FW: eQuest question on modelling interior surface between floors

Rashmi Shah rshah at glenergys.com
Sun Sep 30 10:42:06 PDT 2012

Interior walls never have heat transfer, unless there is temperature change
more than 10 Deg  F. Normally Garage are model as outside space, unless they
are heated or cooled.


-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Chris Jones
Sent: Friday, September 28, 2012 1:57 PM
To: Brian Fountain; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] FW: eQuest question on modelling interior
surface between floors

Thanks Brian.  I assume heat transfer between plenum and space has the same
issue in LS-B, LS-C?

At 11:28 AM 28/09/2012, Brian Fountain wrote:
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>I had a question yesterday regarding heat transfer through interior 
>walls.  I think this comes up on the list fairly frequently - why is my 
>LS-C (or LS-B) report showing no heat transfer across internal surfaces 
>when I know my garage or attic is colder than the adjacent spaces.  Is 
>this heat loss really being reflected in the model - and if so, why 
>isn't it in the LOADS reports?
>Here was my answer - (corrections & clarifications are welcome):
>What you are doing to model the effect of insulating the floor between 
>the garage and the ground level is correct.  eQUEST will calculate the 
>heat loss across that interior surface floor and show the impact of the 
>insulation.  The main issue is finding it.  I imagine you are looking 
>at the LS-C or LS-B report which show no internal conduction.  The 
>issue here is how the calculations are sequenced in DOE-2.  In the 
>LOADS, we are calculating the envelope heat loss then in SYSTEMS we are 
>calculating the HVAC response.  But, until the HVAC response is 
>calculated, we don't know what the space temperature is so we can't 
>calculate the envelope heat loss as we don't know the delta-T between 
>inside and outside.  So, for LOADS, we give the space temperature an 
>initial guess - keyword Temperature in the SPACE.  By default, all 
>spaces have their temperature set to 70F - this is why you see no 
>internal heat loss in the
>LS- LOADS reports as the temperature is the same for all zones.  You 
>could set the annual average temperature down in the garage so that the 
>heat loss shows here but it is not that important.  As long as in the 
>zones, the keyword SIZING-OPTION is set to ADJUST-LOADS then in 
>SYSTEMS, the actual space temperature will be used to recalculate the 
>heat loss.
>So, the heat loss is there - you can reassure yourself of this by 
>creating an interior wall of nearly infinite resistance, apply it as a 
>parametric run, and see the space heating in the adjacent zones go 
>down.  You can also create hourly reports that look at the parameters 
>of the zones.  One of the hourly variables (23) at the zonal level is 
>"Contrib to the zone load due to conduction from adj zones (Btu/hr)"  
>-- this is where you will see the actual hourly heat loss using the 
>actual hourly space temperature for the zones.
>I hope this helps clear up what you are seeing.  Please feel free to 
>ask more if I am not being clear.
>Kind regards,
>Equest-users mailing list
>To unsubscribe from this mailing list send  a blank message to 

Christopher Jones, P.Eng.
Suite 1801, 1 Yonge Street
Toronto, ON M5E1W7
Tel. 416-203-7465
Fax. 416-946-1005
email cj at enersave.ca

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