Re: [EnergyPlus_Support] why blinds not reducing heat gain through window?

I can't point to a study, but the guys at trnsys have told me that studies have shown that internal blinds bring little to no positive effect on room heat gain.

However, as we're on the topic of blinds, could someone please draw up a table showing which controls are effected by which input parameters, e.g. Control type glare - does it go the the "fixed slat" position on trigger or does it change possition between min/max slat angles to maintain a setpoint?

There are a lot of control options...a table would be a great addition to the documentaion.

Jean

On 09.10.2014, at 03:04, "Joe Huang YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Hmmm, interesting. Wouldn't the blinds reflect a fair amount of the solar back out through the window? Seems counter-intuitive that deploying blinds behind a window will increase rather than decrease the mean air temperature of the space. Have we been wrong all these decades? I'd still
like to know the thermal/optical characteristics of the window and the blinds. I suppose having a black
blind behind a window with very low IR transmissivity might create problems.

Joe

On 10/8/2014 4:45 PM, 'Edward G. Lyon' eglyon@xxxxxxx [EnergyPlus_Support] wrote:
The low mass blinds will also absorb all the solar and transfer it to the interior air. Without blinds, the solar hits a more massive floor/walls with much less immediate transfer to the air. This could give you higher cooling peak demand.

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

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Wednesday, October 08, 2014 7:07 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] why blinds not reducing heat gain through window?
I suspect there's something wrong in the modeling of the blinds. The effect of night sky radiation is not so pronounced on a window, because (1) half of what it sees is ground, (2) the other half is the sky at low angles where the sky temperatures are much less depressed as they are looking straight up the sky.

Joe
Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"
On 10/7/2014 11:00 PM, 'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support] wrote:

If you have a building with lots of glass, don't forget the radiant exchange with the night sky at -60 C. The "radiant night cooling" is possibly being blocked by the blinds, if the blinds are there during the night.

Mit freundlichen Grüßen- Sent from my iPhone (excuse the brevity)

i. A.

Jean Marais

b.i.g. bechtold

Tel. +49 30 6706662-23

On 06.10.2014, at 21:53, "annavenediki@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Hello,

I've designed a south facing room with a floor- to-ceiling window and blinds covering the whole surface of the window. I run two simulations, one with no blinds on the window and one with blinds covering the window in order to compare the results. The building's location is in Eastern Europe. The run period is from July to August (sunny and hot period). Both output variables "Zone mean air temperature" and "Surface inside face temperature", have much higher values when the simulation is run with the blinds on the window. How can this be possible? Can it be explained in a way or is there something wrong with the data?

Thanks in advance,

Anna V.