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

Tue Apr 28 13:29:58 PDT 2015

After seeing Nick’s comment I thought I would add my 2 cents just being in Alaska and constantly dealing with insulation issues.

The winter obviously puts high demands for heating and ventilation and I think every building we’ve upgraded for energy efficiency has seen substantial improvements in energy savings.
But many of our clients insist on “more insulation is better” in arctic conditions without really understanding the effects over an entire year.

On some projects I’ve seen R-80+ systems with 18” wall buildups.  Not to mention R80-90+  roof buildups (14”-16” thick) which obviously improve the overall heating performance – especially given our heating systems are typically operating more than 6 months out of the year.

But there is a tradeoff.

We typically get around 4-1/2 months of 60-90 degree weather up here.  This puts a high demand on cooling systems during this period.  You can easily end up with a building so heavily insulated that even in the mid 60’s outside temp range the cooling system may need to operate unless all the doors and windows were opened up– which isn’t always possible because of security reasons.

The buildings become too efficient at retaining heat to the degree that the cooling demand is higher to basically fight the building during summer months to maintain temp setpoints.

Also, Many buildings in Alaska do not have cooling systems so when you increase R-value and U-value to a certain threshold you are in some ways “biting the bullet” with regard to adding appropriate ventilation and cooling systems capable of cancelling out the heat buildup in warmer weather (which offsets X dollar amount of energy savings provided during the winter months).

Fortunately, the end result in Alaska is usually a net cost savings just because heating costs in Alaska are so ridiculously high given most buildings use fuel-oil.

However, in theory, if you were to cut the cost of heating up here to a certain threshold the cost of cooling the building would eventually be higher than the cost of heating it in the winter months.  At which point I imagine someone doing the classic face-palm.

-Chris

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nicholas Caton
Sent: Tuesday, April 28, 2015 11:40 AM
To: Joe Huang; Daniel Knapp; Mayank Bhatnagar
Cc: eQUEST Users List
Subject: Re: [Equest-users] [Bldg-sim] Expert advice on Wall Insulation study in eQuest

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<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<mailto: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

[cid:image001.png at 01D081AE.2FE7D700]

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

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca<http://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<mailto: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<mailto: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<mailto: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<mailto:danielk at arborus.ca>

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca<http://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><mailto: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><mailto: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<mailto:claire at inklingllp.com>

t:  07950 282800

w: www.inklingllp.com<http://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><mailto: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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