[esp-r] Re: clarification of ESP_r air gap specification in low-e glazing

[Geissler Achim]

Hi Jon

thats an interesting topic, come to think of it. An IGU will drastically lose performance when used horizontal with heat flow upward - the ESP-r logic only takes internal heat transfer coefficient into account, though. Possibly this could be changes for TMCs? As a rule of thumb, the U-value of a horizontal IGU with heat flow upward is approx. 140 - 150 % of the vertical-with-horizontal-heat-flow value. As it is now, the user must think of this and create an additional construction for horizontal glazing, even if the actual product is the same as used in a vertical position.

Best
Achim



-----Ursprüngliche Nachricht-----
Von: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] Im Auftrag von Jon Hand
Gesendet: Mittwoch, 15. Juni 2011 23:27
An: Achim Geissler; A.Sdei at brighton.ac.uk
Cc: esp-r at lists.strath.ac.uk
Betreff: [esp-r] Re: clarification of ESP_r air gap specification in low-e glazing


It seems that the ESP-r Cookbook is rather terse on this aspect of constructions and glazing.  I attach some images which clarify what is going on.

a) in the materials databases there are a number of classes of materials
    and there is a class labeled GAPS

b) looking in GAPS there are a number of items.  Although there are some
    that are labeled argon filled the best material to pick is the top one
    labeled air gap.

c) the last image is of a tripple glazed window where the standard
    air gap material (equivalent to the legacy material zero) has had
    its air gap resistance revised so that the U value matches the
    manufacturers specification for low-e coatings.

So, leave the GAP materials c/d/e/f/g (in the image) alone for now and select the GAP material a and modify its resistance once it is in the multi-layer construction.

The Cookbook should be updated to clarify air gaps.  Thanks for pointing out the current lack of documentation.

Regards, Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On Behalf Of Achim Geissler [achim.geissler at intergga.ch]
Sent: 15 June 2011 18:21
To: A.Sdei at brighton.ac.uk
Cc: esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: low with argon fill

Dear Arianna

where did you take the U-value you give from? If you see a reduction in heating load, the U-value used seems to be O.K. If you are using standard TMCs, "low e" or "argon" is only a name and does not have any real influence on the U-value. This is set by the resistance of the gap(s) between the panes of an IGU.

In the construction data base, you can see the U-value when you edit the construction, e.g. change the resistance of the gap. Also, you could check via QA report.

Best
Achim



On Jun 15, 2011, at 4:07 PM, A.Sdei at brighton.ac.uk<mailto:A.Sdei at brighton.ac.uk> wrote:

Dear All,

I am modelling some low-e + argon gas filled windows with esp-r. I change the database settings from ordinary double glazing to low-e + argon gas filled. The U-value increases from 2.8 to over 5. The results are fine (I can see a reduction of heating load) and I am curious to know what is going on there and if I can change the U-value. Does anyone know? Thank you,

Regards,
Arianna

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