[Equest-users] Slab on Grade Floor Heat Loss

Sun Feb 4 10:06:34 PST 2018

Maria:
Yes, sometimes I model an entire floor as having roofconstruction if some of the floor is exposed to outdoor conditions.  If part of this floor is under a conditionedspace, it is possible to delete the roof constructions under the conditionedarea.  If it is possible, I model severalshells per floor in order to more accurately define which areas are exposed tooutdoor conditions and which areas are adjacent to a condition space.  Often this is not possible since multiplezones span the condition-unconditioned area of the shell above and we run intothe problem of these zones having external walls down the middle of them.
The same follows for underground floors.  In the model I referenced, about 1/2 of thefirst floor is over a conditioned space and one half is slab on grade.  So I defined this floor as over anunconditioned space in the DD wizard as this should result in a reasonable average.
If I remove the first floor external slab on grade floors asI have stated, it is interesting that before and after the removal of thefloors, the slab on grade floor conductance is 0 in both cases.  By removal of the floor, the conductanceremains 0 but the infiltration changes based on the LS-B reports.
I have spent time experimenting and have found that deletingthe roof constructions in zones adjacent to conditioned areas in both thebaseline and proposed models results in approximately a 1/10 of one percentchange in the annual MBTU consumption.
For example, when removing a roof construction in a zonewith a plenum under a conditioned zone, the wall conductance increases and the infiltrationincreases.  Looking at the unconditioned plenumfor this zone, when removing the roof construction, the wall conduction increases,the roof conduction decreases and the infiltration decreases.
It is my expectation that the utility reviewer is at leastas competent as I am in eQuest.  And eventhough I have been submitting models over 10 years, I have a lot to learn.  

Going in circles to correct a 1/10 of one percent differenceis unreasonable.  I have gone back on unpaidtime to calibrate models based on the annual energy consumption post model and postproject completion.  The annual utilitycost of the model is often 30-50% greater than the actual cost since thebuilding is not operated per the requirements of Appendix G, 90.1.  For example, in a residential high-rise, theapartment fans do not run whenever the zone is occupied, and this makes a hugedifference in the annual energy consumption. Per 90.1, the model is not intended to predict actual energy consumption,but is just a comparison between a code compliant model vs. the proposed modeloperated to the requirements of the standard.
Sure, anyone can nitpick any one of the several hundredassumptions used in models, but a competent reviewer should know which will affectthe model significantly and would need to be revised.  Modeling is not a science, it is an art.  Thank you,
 Paul Diglio

      From: Maria Karpman <maria.karpman at karpmanconsulting.net>
 To: Paul Diglio <paul.diglio at sbcglobal.net>; "Bishop, Bill" <bbishop at pathfinder-ea.com>; Nathan Miller <nathanm at rushingco.com>; equest-users at onebuilding.org 
 Sent: Friday, February 2, 2018 4:34 PM
 Subject: RE: [Equest-users] Slab on Grade Floor Heat Loss

#yiv0810656751 #yiv0810656751 -- _filtered #yiv0810656751 {font-family:Helvetica;panose-1:2 11 6 4 2 2 2 2 2 4;} _filtered #yiv0810656751 {font-family:Wingdings;panose-1:5 0 0 0 0 0 0 0 0 0;} _filtered #yiv0810656751 {panose-1:2 4 5 3 5 4 6 3 2 4;} _filtered #yiv0810656751 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;} _filtered #yiv0810656751 {font-family:Verdana;panose-1:2 11 6 4 3 5 4 4 2 4;}#yiv0810656751 #yiv0810656751 p.yiv0810656751MsoNormal, #yiv0810656751 li.yiv0810656751MsoNormal, #yiv0810656751 div.yiv0810656751MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:11.0pt;}#yiv0810656751 a:link, #yiv0810656751 span.yiv0810656751MsoHyperlink {color:blue;text-decoration:underline;}#yiv0810656751 a:visited, #yiv0810656751 span.yiv0810656751MsoHyperlinkFollowed {color:purple;text-decoration:underline;}#yiv0810656751 p.yiv0810656751msonormal0, #yiv0810656751 li.yiv0810656751msonormal0, #yiv0810656751 div.yiv0810656751msonormal0 {margin-right:0in;margin-left:0in;font-size:11.0pt;}#yiv0810656751 p.yiv0810656751msonormal0, #yiv0810656751 li.yiv0810656751msonormal0, #yiv0810656751 div.yiv0810656751msonormal0 {margin-right:0in;margin-left:0in;font-size:11.0pt;}#yiv0810656751 p.yiv0810656751msonormal, #yiv0810656751 li.yiv0810656751msonormal, #yiv0810656751 div.yiv0810656751msonormal {margin-right:0in;margin-left:0in;font-size:11.0pt;}#yiv0810656751 p.yiv0810656751msochpdefault, #yiv0810656751 li.yiv0810656751msochpdefault, #yiv0810656751 div.yiv0810656751msochpdefault {margin-right:0in;margin-left:0in;font-size:11.0pt;}#yiv0810656751 span.yiv0810656751msohyperlink {}#yiv0810656751 span.yiv0810656751msohyperlinkfollowed {}#yiv0810656751 span.yiv0810656751emailstyle18 {}#yiv0810656751 span.yiv0810656751emailstyle19 {}#yiv0810656751 span.yiv0810656751emailstyle20 {}#yiv0810656751 p.yiv0810656751msonormal1, #yiv0810656751 li.yiv0810656751msonormal1, #yiv0810656751 div.yiv0810656751msonormal1 {margin:0in;margin-bottom:.0001pt;font-size:11.0pt;}#yiv0810656751 span.yiv0810656751msohyperlink1 {color:#0563C1;text-decoration:underline;}#yiv0810656751 span.yiv0810656751msohyperlinkfollowed1 {color:#954F72;text-decoration:underline;}#yiv0810656751 p.yiv0810656751msonormal01, #yiv0810656751 li.yiv0810656751msonormal01, #yiv0810656751 div.yiv0810656751msonormal01 {margin-right:0in;margin-left:0in;font-size:11.0pt;}#yiv0810656751 span.yiv0810656751emailstyle181 {color:windowtext;}#yiv0810656751 span.yiv0810656751emailstyle191 {color:windowtext;}#yiv0810656751 span.yiv0810656751emailstyle201 {color:#1F497D;}#yiv0810656751 p.yiv0810656751msochpdefault1, #yiv0810656751 li.yiv0810656751msochpdefault1, #yiv0810656751 div.yiv0810656751msochpdefault1 {margin-right:0in;margin-left:0in;font-size:10.0pt;}#yiv0810656751 span.yiv0810656751EmailStyle35 {color:windowtext;}#yiv0810656751 .yiv0810656751MsoChpDefault {font-size:10.0pt;} _filtered #yiv0810656751 {margin:1.0in 1.0in 1.0in 1.0in;}#yiv0810656751 div.yiv0810656751WordSection1 {}#yiv0810656751 Some eQUEST models do have redundant roofs, exterior or underground floors sandwiched between the Shells created in DD Wizard. These can be easily identified by hiding some exterior and interior surfaces from 3D view,  to look “inside” the building, like in the screenshots below. There is also a nice summary of surface areas at the end of LV-D report, which can be used to check that the modeled “UNDERGROUND” and “ROOF” areas are as expected for the projects. That said, reviewers too make mistakes. We all know that sometimes they are hands full J.    Maria Karpman LEED AP, BEMP, CEM________________Karpman Consultingwww.karpmanconsulting.net Phone 860.430.1909 41C New London TurnpikeGlastonbury, CT 06033  From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Diglio via Equest-users
Sent: Friday, February 02, 2018 3:27 PM
To: Bishop, Bill <bbishop at pathfinder-ea.com>; Nathan Miller <nathanm at rushingco.com>; equest-users at onebuilding.org
Subject: Re: [Equest-users] Slab on Grade Floor Heat Loss Thanks Bill, you are always such a big help.  That is what I thought, but just wanted to run it by the forum. Thanks to you too Nathan. Paul Diglio From: "Bishop, Bill" <bbishop at pathfinder-ea.com>
To: Nathan Miller <nathanm at rushingco.com>; Paul Diglio <paul.diglio at sbcglobal.net>; "equest-users at onebuilding.org" <equest-users at onebuilding.org> 
Sent: Friday, February 2, 2018 3:13 PM
Subject: RE: [Equest-users] Slab on Grade Floor Heat Loss Paul,Your reviewer may have thought that if the slab was showing up as an “exterior surface” (such as on the LV-D report) than the model was simulating heat transfer between the zones and the outside air through the slab. But eQUEST/DOE-2 simulates heat transfer across underground surfaces differently, as described in the UNDERGROUND-WALL and UNDERGROUND-FLOOR section of the DOE-2 help documentation. The main difference is that ground temperature is used instead of the OA temperature as the outside temperature. The monthly ground temperature is taken from the weather file, or can be entered as SITE-PARAMETERS:GROUND-T. The eQUEST wizard creates custom constructions for each underground surface based on inputs for Exterior/Cavity Insulation and Perimeter Floor Insulation. Underground floors are given constructions with low U-factor (high R-value) consistent with the lower heat transfer that would be expected. Regards,~Bill William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
| Senior Energy Engineer |    |
|   |
| 134 South Fitzhugh Street                 Rochester, NY 14608 |
| T: (585) 698-1956                        F: (585) 325-6005 |
| bbishop at pathfinder-ea.com             www.pathfinder-ea.com |
| Carbon Fee and Dividend - simple, effective, and market-based. |

 From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nathan Miller via Equest-users
Sent: Friday, February 02, 2018 2:35 PM
To: Nathan Miller <nathanm at rushingco.com>; Paul Diglio <paul.diglio at sbcglobal.net>; equest-users at onebuilding.org
Subject: Re: [Equest-users] Slab on Grade Floor Heat Loss Fixed my typo in the F-factor heat loss calc (should have read 50 ft of perimeter)… See below.  Nathan Miller, PE, LEED AP BD+C – Mechanical Engineer/Senior Energy AnalystRUSHING | O 206-285-7100 | C 207-650-3942www.rushingco.com From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nathan Miller via Equest-users
Sent: Friday, February 2, 2018 2:33 PM
To: Paul Diglio <paul.diglio at sbcglobal.net>; equest-users at onebuilding.org
Subject: Re: [Equest-users] Slab on Grade Floor Heat Loss In the past I’ve done a conversion of F-factor (perimeter based) slab-on-grade heat loss to U-factor (area) and input that in on a zone-by-zone basis if I really wanted to nail down SOG heat loss.  Example- Space is 20’ x 30’, but the exposed perimeter is only two of the faces (20’ + 30’). Lets say it is uninsulated SOG.  F-factor from 90.1: F = 0.73 Btu/(hr*ft*F)

Perimeter based heat loss: 0.73 Btu/(hr*ft*F) * 50 ft = 36.5 BTU/(hr *F) Then we can back-calculate the U-factor to assume for the whole floor to equate to that heat loss: 36.5 BTU/(hr *F) = 600 SF * X BTU/(hr*SF*F) -> U = 0.0608 BTU/(hr*SF*F) You can create a custom floor construction for each space to provide the U-factor to produce equivalent heat loss that the F-factor calcs are telling you lose. For purely core zones (no exposed perimeter), I guess the F-factor calcs are telling us were not really losing heat through that slab (doesn’t’ seem right, but it probably is relatively small)  Nathan Miller, PE, LEED AP BD+C – Mechanical Engineer/Senior Energy AnalystRUSHING | O 206-285-7100 | C 207-650-3942www.rushingco.com From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Diglio via Equest-users
Sent: Friday, February 2, 2018 2:19 PM
To: equest-users at onebuilding.org
Subject: [Equest-users] Slab on Grade Floor Heat Loss I recently submitted a model to the local utility company for an incentive.  Part of the buildings' first floor is slab on grade. One of the comments I received back is that this erroneously shows up as an exterior surface and I should delete all the slab on grade floors in the component tree.  Doesn't seem right to me. I did a few and it does reduce the overall energy consumption.  In the 3D model, no floors show, just open to the interior of the zone. So is eQuest assuming that without this floor, there is no heat loss out the bottom of the zone?  Is this reasonable? Thank you, Paul Diglio 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20180204/aa7dbe00/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image008.jpg
Type: image/jpeg
Size: 39580 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20180204/aa7dbe00/attachment-0016.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image009.jpg
Type: image/jpeg
Size: 43067 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20180204/aa7dbe00/attachment-0017.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image010.jpg
Type: image/jpeg
Size: 1479 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20180204/aa7dbe00/attachment-0018.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image011.jpg
Type: image/jpeg
Size: 1610 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20180204/aa7dbe00/attachment-0019.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image015.png
Type: image/png
Size: 4098 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20180204/aa7dbe00/attachment-0004.png>