[Bldg-sim] Building envelope average energy demands

John Eurek redmodeler at yahoo.com
Fri Aug 26 14:33:53 PDT 2011

As an engineer reading that article I chuckled thinking "Do they realize 'energy loss' isn't always a bad thing?"
In your house, most of the time it is a bad thing.  In an office building it can be a good thing.  I think the answer you are looking for will be difficult to find.  If you make a good energy model you can site yourself.  And you get something like David talked about
From: Giulio Castorina <artitecture at gmail.com>
To: "Goldwasser, David" <David.Goldwasser at nrel.gov>
Cc: John Eurek <redmodeler at yahoo.com>; "bldg-sim at lists.onebuilding.org" <bldg-sim at lists.onebuilding.org>
Sent: Friday, August 26, 2011 4:17 PM
Subject: Re: [Bldg-sim] Building envelope average energy demands

Hi All,

thank you all for your quick response. Actually I don't want to calculate that value, but just need to cite/reference a source that gives information about this data. 

I found this http://www.sustainablefacility.com/articles/print/86593 where a graph is shown...but not really references fully. It says about ASHRAE Std 90 - I dont have access to this. Is this a chart inside the Do you know if it is inside the ASHRAE standards? 

In particular I'm looking at expenditure through external vertical walls/windows - hence facades especially in office buildings.



Il 26/08/2011 23:06, Goldwasser, David ha scritto: 
Maybe not quite what you are looking for, but we have a video  tutorial showing an envelope elimination parametric. In this example we used a full service restaurant but you can do this with any model. The approach is to run a baseline simulation and then to switch all exterior and ground exposed surfaces to an adiabatic boundary condition. Next remove all fenestration surfaces. Then re-run the model. Due to the load driven nature of this project the maximum savings through envelope improvements was just over 3%, but maybe would be 15-20% for an office. Of course it depends where the project is located; the harsher the climate, the more potential savings through envelope improvements. And it depends on the quality of the envelope that you use as a starting point; building activity, and mechanical system efficiency. 
>Here is a link to the video.
>And here is a link to COP adjusted end use graphs in Google Documents
>This doesn’t mean that only 3% of the energy is due to the envelope, but it does show potential savings for retrofits on various elements. You could get more specific and just isolate the roof, or even solar gain from the windows. Or run create an elimination run for plug loads where you set loads to nothing.
>David Goldwasser, LEED AP
>National Renewable Energy Laboratory
>From:bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of John Eurek
>Sent: Friday, August 26, 2011 2:36 PM
>To: Giulio Castorina; bldg-sim at lists.onebuilding.org
>Subject: Re: [Bldg-sim] Building envelope average energy demands
>I don't know if this answers your question, but I have tried to determine the % of energy use due to the envelope on a recent building by running multiple energy models.  What I found was the energy balance in complex.
>An example is a perfect balance on a cold day 
>"People" + "Lighting" + "Plug Loads" - "Loss through Wall" = 0
>So if the insulation was higher, your loss though the wall would be less and the A/C power usage would be increased.
>You could hand calculate the envelope energy demand for an empty unoccupied building, but with internal loads it gets foggy.
>The energy model will show you what you can expect from various R-values, but I have not found a way to say x% of energy is due to the envelope.
>From:Giulio Castorina <artitecture at gmail.com>
>To: bldg-sim at lists.onebuilding.org
>Sent: Friday, August 26, 2011 2:52 PM
>Subject: [Bldg-sim] Building envelope average energy demands
>Hi All,
>Can anyone advise a good resource (article, webpage, book, etc..) which states what is the average energy demands (construction+running costs) due to Envelopes only in buildings? I would need just a figure in percentage over the whole energy demands of a typical office building. Is this data somehow available?
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