RE: [EnergyPlus_Support] Three glass glazing with extra foward mounted glass screen

�Great minds�

My next suggestion was to combine two layers into an equivalent glass to include in a triple pane assembly. Problem then is venting the outer air space as it is likely to get too warm�

Ned Lyon, P.E. (MA, WV)
Staff Consultant

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From: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Monday, July 27, 2020 2:26 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Three glass glazing with extra foward mounted glass screen

Okay. So this is my current solution. I create the 3-Ply glazing system in WINDOW 7.7.

I don't seem to be able to get a set of spectral data for the 3-Ply system as a whole, but I do get the average data just fine. I use create a new glazing consisting of one layer in designbuilder and ascribe it the average properties of the 3-ply system. The resulting U-Value, SHGC, Tvis and Direct Solar Transmission matches almost perfectly, so that I feel it is a good Equivalent Layer.

I then create a 2 Pane system with my Equivalent Layer as inner pane and the spectral glazing layer of the protective glass screen as outer layer with the air gap as in the design at 230 mm. My shades are in between layers.

Then I use the "Airflow Window" option in designbuilder which means the WindowProperty:AirflowControl in energyplus. This creates a ventilating layer between the panes.

What do you think?

Am So., 26. Juli 2020 um 16:23 Uhr schrieb Jean Marais <jeannieboef@xxxxxxxxx>:

Yeah, I've thought of that as a possibility. The external glazing (3-ply) will be treated by the program as internal glazing. That brings some implications with it as well...for one that radiation passing through internal glazing enters the zone as fully diffuse. Then I could just as well model the external shading surface with transmission. I think the local temperature behind the protective screen might be much more than Outdoor Air temperature. I have a simulation report of someone modelling the same system with far less air gaps which apparently only came to max 53ºC. If it's a hot day 32ºC and inside is 26ºC, my 3-ply Window has U=1.0 W/m²/K that would mean 6 W/m². If the 53ºC were worst case that would mean 27 W/m²...almost 5 times as much heat as a maximum error. This speaks for your zone model idea, but I don't believe the slat model works on internal glazing.

Am Sa., 25. Juli 2020 um 15:01 Uhr schrieb 'Edward G. Lyon' eglyon@xxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

Jean,

You might try making the well-ventilated space a zone in your model with a triple glaze on one side and the single glaze on the other side. I’m not sure how to integrate the blind with a single glaze, but it should be possible to have opaque horizontal walls like light shelves even if the single glaze has to be split into segments. You don’t need to condition the zone but you can provide air exchange to simulate the well-ventilated part.

Ned Lyon, P.E. (MA, WV)
Staff Consultant

SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
617.285.2162 mobile
781.907.9009 fax
www.sgh.com

Send Files

From: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Friday, July 24, 2020 5:17 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Three glass glazing with extra foward mounted glass screen

Dear Collegues,

I would like your thoughts on how to model a 3-ply complex glazing with external slatted blind, where a forth (well ventilated) protective glass screen sit in front of it all on the very outside.

I have all the IGDB data on both the external screen as well as the 3-ply system and the slatted blinds.

As e+ doesn't handle slatted blinds well as interpane blindes regarding it's posittion in that setup and is restricted by max 3 pane systems, I'm thinking of modelling it as a normal 3 pane system with external blinds and then construction an external transparent surface in front of the window.

I remember that one can set the transmission and relection properties of such an external surface. On the one hand only diffuse radiation will hit my window as expected, but on the other hand I will probably loose any spectral effects and cancle direct beam completely.

Perhaps I should adjust the properties of my slatted blind to incorporated the extra blocking effect of the external glass screen?

I'm sure you all have some ideas...

Kind regards,

Jean

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Posted by: "Edward G. Lyon" <EGLyon@xxxxxxx>

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