[Equest-users] [Bldg-sim] Expert advice on Wall Insulation study in eQuest

Tue Apr 28 12:39:41 PDT 2015

Great discussion!

Since this thread has clearly gathered attentions of the right individuals,
I’d like to layer on a query which may further inform Mayank’s efforts:

Is the “law of diminishing returns” as you improve envelope insulation
universal to ALL climates, in practice or in theory?  While I have reliably
observed such behavior exploring comparable ECM’s in temperate climates, I
am curious whether tropical or arctic climates should expect (all else
being equal) a relatively “flatter” curve when plotting R-value against
annual energy savings?

My gut tells me the reduced opportunity to leverage airside economizer
function or operable windows would make incremental insulation increases
more attractive for annual energy consumption, but experience has taught me
to question my gut on such matters (…Thanks Joe!).

Regards,

~Nick

*NICK CATON, P.E.*
*Owner*

*Caton Energy Consulting*
  1150 N. 192nd St., #4-202

  Shoreline, WA 98133
  office:  785.410.3317

www.catonenergy.com

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Joe Huang
*Sent:* Tuesday, April 28, 2015 11:56 AM
*To:* Daniel Knapp; Mayank Bhatnagar
*Cc:* eQUEST Users List
*Subject:* Re: [Equest-users] [Bldg-sim] Expert advice on Wall Insulation
study in eQuest

Dan,

Very good point!   I didn't even think about this, i.e., that the plot was
against conductance and not resistance.
Therefore, I would conclude that eQUEST is behaving properly.

Joe

Joe Huang

White Box Technologies, Inc.

346 Rheem Blvd., Suite 205A

Moraga CA 94556

yjhuang at whiteboxtechnologies.com

http://weather.whiteboxtechnologies.com for simulation-ready weather data

(o) (925)388-0265

(c) (510)928-2683

"building energy simulations at your fingertips"

On 4/27/2015 11:12 AM, Daniel Knapp wrote:

Hi Mayank,

I think on further reflection you are seeing exactly what you should be
seeing. The energy consumption should go down linearly with the U-value.
What does saturate is the energy savings compared to insulation thickness
or R-value which is plotted as 1/U. Here is a graph of energy vs. U and
energy vs R for your building:

All the best,

Dan

—
Daniel Knapp, PhD, PPhys, LEED® AP O+M
danielk at arborus.ca

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca
76 Chamberlain Avenue
Ottawa, ON, K1S 1V9
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740

On Apr 27, 2015, at 6:15 AM, Mayank Bhatnagar <mayank.23aug at gmail.com>
wrote:

Thank you Joe and Daniel for your response.

As you suggested, I checked LS-C report for wall conduction variation
w.r.t. U-value. It is also giving linear trend for wall conduction.
Additionally, I have done same analysis for without internal loads
(occupancy, lighting and equipment load) as Joe indicated about the
compounding effect. I still get linear trend between the energy consumption
and U-value.

For your reference, I am attaching inp, pd2 and weather file.

On Thu, Apr 23, 2015 at 8:10 PM, Joe Huang <yjhuang at whiteboxtechnologies.com
> wrote:
Mayank, Daniel,

I think it's a good idea to look at the component loads in the LS-C
reports, but I want to add some words of caution.
The loads (actually heat flows) shown in those reports are calculated at
the constant Reference Temperature, and categorized as either heating
or cooling if the total load of the building that hour is negative or
positive. These loads are corrected when DOE-2 solves for the actual
room temperature based on simple UA-deltaT principles.  If you want the
corrected wall loads, you need to get an hourly report of the wall loads
and then correct for the temperature difference Troom - Treference.

I'm not sure if this level of detail is warranted, though.  I also suspect
there's some other compounding effect that's giving you the results that
you report.

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
http://www.whiteboxtechnologies.com
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

On 4/23/2015 6:18 AM, Daniel Knapp wrote:
Hi Mayank,

I recommend opening up the SIM file (you can do this by going to Tools ->
View Simulation Output) and looking at the LS-C and LV-D reports. In the
LS-C report you can find the contribution to the peak heating and cooling
loads that come from the walls. From this you should be able to figure out
how the wall conduction is changing as a fraction of the peak loads as you
decrease the wall U-value. In the LV-D report (scroll to the very end of
it) there is a summary of the U-values for each exterior surface. This
might be a good place to look to make sure that the effective U-values that
eQUEST is simulating are matching up with your expectations of what the
U-values should be.

I would agree that the energy savings should saturate at some point.

All the best,
Dan

—
Daniel Knapp, PhD, PPhys, LEED® AP O+M
danielk at arborus.ca

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca
76 Chamberlain Avenue
Ottawa, ON, K1S 1V9
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740

On Apr 23, 2015, at 5:00 AM, Mayank Bhatnagar <mayank.23aug at gmail.com>
<mayank.23aug at gmail.com> wrote:

Hi Claire,

Thanks for your response.

The analysis has been done on an 8 hour operating office building in New
Delhi. The mechanical system is packaged single zone system with electric
resistance heating.

Please let me know if you need more information.

Thanks

Regards,
Mayank

On Thu, Apr 23, 2015 at 2:25 PM, Claire Das Bhaumik <claire at inklingllp.com>
<claire at inklingllp.com> wrote:
Mayank,

I think we need to know a bit more about the building:
- Location (some parts of India are cool, others hot!)
- Building usage - office, domestic, retail? Hours of use?
- Servicing - heating and cooling? Mechanical or natural vent?

Regards,

Dr Claire Das Bhaumik CEng FCIBSE

Partner - Inkling LLP

e: claire at inklingllp.com

t:  07950 282800

w: www.inklingllp.com

Follow us on Twitter: @DasInkling

Partnership No. OC367619

On Thu, Apr 23, 2015 at 9:51 AM, Mayank Bhatnagar <mayank.23aug at gmail.com>
<mayank.23aug at gmail.com> wrote:
Dear All,

We are working on a national level research project in India. A building
envelope analysis is a part of this project. By doing analysis, we
have found a vague results in trend (linearly downward) of reduction in
energy consumption with reducing wall U-value in eQUEST.

Theoretically, the energy consumption should approach to stagnant with
reduction in wall U-value.

Please refer figure.

Appreciate if anyone put light on this.

Thank you.

Regards,

Mayank Bhatnagar

Theoretical should come like this.
<image.png>

In eQuest the trend is-
<image.png>

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<Small Office Bldg_v5_4.pd2><Small Office
Bldg_v5_4.inp><IND_New.Delhi.421820_ISHRAE.BIN>
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