Re: [EnergyPlus_Support] U values and SHGC of air filled and argon filled double glazing

It's been a while but from memory it uses the algorithms used by ISO 15099. You can use the WINDOW software from lbnl to check (it also outputs the idf text you need, the way you need it). they should be pretty close.

I think your problem may be to confusing "rating" values with current simulation values. For example, the conditions of two different environments may produce diffent actual u-values than the rating u-value which is at a predifined test condition which "rates" the glazing.

I'm trying to think of a situation which could occur so that the net heat gain (SHGC) is more with the argon fill than the air fill.

at the same time
I'm trying to think of a situation which could occur so that the non-solar transmission (conduction+convection+surface radiation)Â is more with the argon fill than the air fill.

I can't come up with anything. Have you checked your edge parameters and frame parameters?

2017-05-22 11:06 GMT+02:00 Amrita Ghosh amritaghosh1986@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:

Â

I have not used the simple glazing method. I have provided the optical properties of glass in "WindowMaterial:Glazing" and selected the gas type in "WindowMaterial:Gas". Then I have provided the three layers (glass, gas, glass) in "Construction".
When I am comparing the results, the total heat gain through the window is higher for Argon DGU (though the U-value is lower). That's why I wanted the equation/ method that EnergyPlus follows for calculating SHGC.

Thank you,
Amrita

On Thursday, 18 May 2017 4:00 AM, "rahul a rahula7@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@yahoogroups.com> wrote:

Â

Are you using the simple glazing method or layer-by-layer method to describe the glazing? As Jean mentions, the simple glazing method can give unpredictable results sometimes. If you used the layer-by-layer method, what are your glass layers?

From the Output Details document, for the construction object-related output in the .eio file:
"This is the center-of-glass Solar Heat Gain Coefficient for summer conditions (indoor air temperature = 24C (75.2F), outdoor air temperature = 32C (89.6F), windspeed = 2.8 m/s (6.2 mph), 783 W/m2 (248 Btu/h-ft2) incident beam solar radiation normal to glazing."

On Tue, May 16, 2017 at 12:54 PM, Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroups.com> wrote:

Â

it depends. I assume the differences are small? when you input simple model inputs, e+ has a complicated method of looking up the best fitting complex fenestration equivalent and simulates with that. It could be that it just happened to select a combination of glass and frame that fit most of the criteria INCLUDING VLT.

Am 15.05.2017 09:23 schrieb "Amrita Ghosh amritaghosh1986@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@ yahoogroups.com>:

Â

Hi,

I have modelled a simple building with a single window using double glazing unit. I have used air filled and argon filled DGU in the window for two different cases. When I am running the program for warm and humid weather condition, the argon filled DGU is giving a lower U-value than the air filled one. But the SHGC as well as the cooling energy consumption are lower for the air filled DGU. Can anyone please justify this result? How is the SHGC being calculated in Energy Plus?

Thank you,
Amrita