[Equest-users] U value (Building envelope Construction)

[Alex Krickx]

Hi Pranita,

U-value is the inverse of R value. A U-30 is the equivalent of R-0.03.  Likewise, if you have an R-30 roof, you would have a U-(1/30) = U-0.03. Is it possible you entered in R-value where you were meant to enter U? I would check, and maybe try to change what you've entered.

Be careful about which units you're using, though. I think the wizards use IP units, but the INP file has metric? Not sure.

Good luck!
Alex


Alex Krickx
Building Energy Specialist
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1250 Elko Dr, Sunnyvale, CA 94089
(t) 408.541.8124

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of pranita kothuru
Sent: Tuesday, October 12, 2010 11:47 AM
To: equest-users
Subject: [Equest-users] U value (Building envelope Construction)

Hello All -

I don't know whether I am understanding the R value input in eQuest in the way its supposed to be.

In the Building Envelope Constructions (3-25) in the DD Wizard:

Construction: Custom, layer by layer construction

Layer-by layer: Arena Roof (name of the roof I have created)

In the layer by layer window I use the 'Specify Resistance' (under the spec method) option and insert the overall R value of the roof directly below in the box.

When I go to the.inp file, I see the following -

"EL1 Roof Construction" = CONSTRUCTION
   TYPE             = U-VALUE
   U-VALUE          = 30
   ABSORPTANCE      = 0.6
   ROUGHNESS        = 1

It says the U -value is 30 which is really low. Am I missing something here in understanding the U-value and R value. (I have inserted the r value as 30 not the U value)

Thank you for your comments in advance.
--

Pranita.

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