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2014-03-10 06:45 PM - last edited on 2023-05-11 10:22 AM by Noemi Balogh
2014-03-14 09:45 PM
EcoBoger wrote:
As it stands today (March 2014, AC17 build 5019), both, standard EcoDesigner and a commercial version of EcoDesigner STAR have a fundamental flaw in a calculation of solar gain causing these add-ons to overestimate needed cooling by a huge margin, basically rendering these programs unusable for sustainable architectural design.
Moreover, this is not a new issue. It goes back for more than a year and started when AC17 was released in summer 2013.
I, personally, made this issue public back in summer 2013, shortly after the initial release of AC17, and brought it to Graphisoft's attention in this thread: Solar Analysis is not accounted in Energy Simulation (AC17).
However the issue is not resolved after 6(!) updates to the main program.
The root of this problem is very simple:
One of widely advertised features of AC17 is a, so called, concept of "model-based shading". The idea behind this concept is that a shaded opening (glass door or window) will not add to the solar gain calculations, thus providing architects with fundamental tool of sustainable architectural design.
In other words, if the window facing the sun in your project is shaded by model geometry (overhangs, adjacent walls or buildings, trees, etc.), EcoDesigner and EcoDesigner STAR are marketed as being able to account for that and subtract appropriate amount from total solar gain calculations.In reality - they do not.
Both, EcoDesigner built into AC17 and an expensive add-on EcoDesigner STAR, fail to calculate this issue properly, subsequently, grossly overestimating needed cooling equipment.
I did see a few threads in this forum asking questions about overinflated energy readings for buildings designed, but it appears people do not realize where these miscalculations come from.
Let me explain.
If you haveanywindows in your project receiving direct sunlight (How many of us have windows in our projects? All of us?) these windows will always be shown as unshaded no matter how you cover them up with model geometry.
Even a solid wall placed right in front of these windows will not prevent EcoDesigner or EcoDesigner STAR from showing these windows as beingconstantlyexposed to direct sunlight throughout a year.
This basically means that EVERY AC17 project that uses EcoDesigner or EcoDesigner STAR (which is worse, as EcoDesigner STAR is a paid add-on, is expensive to own and supposed to be "Standard Compliant") will giveerroneous results.
Interestingly, all windows in question are properly calculated and shown as shaded under EcoDesigner's or EcoDesigner STAR's "solar analysis" dialog accessible from "Openings" tab in "Energy Model Review" dialog box.
Moreover, kWh redings for any window shaded by model geometry is also properly reduced.
However, this reduction in kWh never makes it to the Energy Evaluation Report and every window is assumed to be unshaded there, thusALWAYSshowing exaggerated solar gain for any thermal block with windows oriented toward the sun, even if they are completely shaded by a solid wall built wight on top of them.
I am curious. This issue is around since AC17 came out, but I constantly see published success stories of architectural buildings being designed with AC17 and EcoDesigner and supposedly properly calculated in relation to sustainable design.
I wish I knew how they did it. Am I the only one here with this issue?
It is very easily reproduced and ANY project relying on EcoDesigner and model-based shading will ALWAYS give erroneous results.
Basically, until this issue is fixed, AC17 and EcoDesigner or EcoDesigner STAR are a dead weight in sustainable design.
Thoughts?
2014-03-17 04:57 PM
2014-03-18 05:08 PM
2014-03-18 06:38 PM
EcoBoger wrote:
As it stands today (March 2014, AC17 build 5019), both, standard EcoDesigner and a commercial version of EcoDesigner STAR have a fundamental flaw in a calculation of solar gain causing these add-ons to overestimate needed cooling by a huge margin, basically rendering these programs unusable for sustainable architectural design.
Moreover, this is not a new issue. It goes back for more than a year and started when AC17 was released in summer 2013.
I, personally, made this issue public back in summer 2013, shortly after the initial release of AC17, and brought it to Graphisoft's attention in this thread: Solar Analysis is not accounted in Energy Simulation (AC17).
However the issue is not resolved after 6(!) updates to the main program.
The root of this problem is very simple:
One of widely advertised features of AC17 is a, so called, concept of "model-based shading". The idea behind this concept is that a shaded opening (glass door or window) will not add to the solar gain calculations, thus providing architects with fundamental tool of sustainable architectural design.
In other words, if the window facing the sun in your project is shaded by model geometry (overhangs, adjacent walls or buildings, trees, etc.), EcoDesigner and EcoDesigner STAR are marketed as being able to account for that and subtract appropriate amount from total solar gain calculations.In reality - they do not.
Both, EcoDesigner built into AC17 and an expensive add-on EcoDesigner STAR, fail to calculate this issue properly, subsequently, grossly overestimating needed cooling equipment.
I did see a few threads in this forum asking questions about overinflated energy readings for buildings designed, but it appears people do not realize where these miscalculations come from.
Let me explain.
If you haveanywindows in your project receiving direct sunlight (How many of us have windows in our projects? All of us?) these windows will always be shown as unshaded no matter how you cover them up with model geometry.
Even a solid wall placed right in front of these windows will not prevent EcoDesigner or EcoDesigner STAR from showing these windows as beingconstantlyexposed to direct sunlight throughout a year.
This basically means that EVERY AC17 project that uses EcoDesigner or EcoDesigner STAR (which is worse, as EcoDesigner STAR is a paid add-on, is expensive to own and supposed to be "Standard Compliant") will giveerroneous results.
Interestingly, all windows in question are properly calculated and shown as shaded under EcoDesigner's or EcoDesigner STAR's "solar analysis" dialog accessible from "Openings" tab in "Energy Model Review" dialog box.
Moreover, kWh redings for any window shaded by model geometry is also properly reduced.
However, this reduction in kWh never makes it to the Energy Evaluation Report and every window is assumed to be unshaded there, thusALWAYSshowing exaggerated solar gain for any thermal block with windows oriented toward the sun, even if they are completely shaded by a solid wall built wight on top of them.
I am curious. This issue is around since AC17 came out, but I constantly see published success stories of architectural buildings being designed with AC17 and EcoDesigner and supposedly properly calculated in relation to sustainable design.
I wish I knew how they did it. Am I the only one here with this issue?
It is very easily reproduced and ANY project relying on EcoDesigner and model-based shading will ALWAYS give erroneous results.
Basically, until this issue is fixed, AC17 and EcoDesigner or EcoDesigner STAR are a dead weight in sustainable design.
Thoughts?
2014-03-27 04:56 PM
2014-05-15 04:07 PM
Miklos wrote:I am not sure who provided you with the information about cases listed above to be properly calculated, but none of them (i.e. 610, 910 etc.) that have to do with solar shading are.
We used the relevant ASHRAE 140 Standard Test cases (Case600, Case610, Case620, Case630, Case900, Case910, Case920, Case930) to check the accuracy of our solar study, which - interestingly - all give correct results. Please download the PLNs of these test cases from here if you wish to try running them yourself:
https://graphisoft.sharefile.com/d/sa7f66eab4454d558
Miklos wrote:Actually, it is the same exact issue I detailed in my thread related to this issue as far back as June 2013. You can read my initial post here:
The issue detailed above is quite similar to the one you reported in the summer of 2013. Still, they are two completely separate issues. The one you reported in the summer of 2013 was corrected in ArchiCAD 17 Hotfix 3.
2014-05-26 12:11 PM
2014-07-29 01:07 AM
2014-07-30 04:46 PM