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

[Rashmi Shah]

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.

Rashmi

-----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,
>
>Brian
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 >>
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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