[Equest-users] Adding Insulation toexistingbuilding(UNCLASSIFIED)

Wolfe, Brian bwolfe at hksinc.com
Fri Sep 9 13:49:27 PDT 2011


The intent of energy modeling is to understand how to optimize a building's efficiency and this clearly shows this is not efficient.  Where's the efficiency in installing enough insulation that it drives up the loads of a system.  This would negate true optimization and efficiency.  Plus, there's a waste of material and cost by adding something that is not needed.  I agree that if you are able to optimize the outside air, that would help, but this sounds like a misunderstanding of true energy efficiency.  To play off your scenarios of examples:  2(heating and cooling loads) - 1(heating) = 1(cooling) x 3(increased cooling) = 3(the amount of load caused by super insulating)  this just isn't efficient. 

I'm on your side that super insulating is not an efficient strategy.  Increased load, excess materials and extra cost, it doesn't make sense.  I'm interested in their reasoning for this strategy being a beneficial one.
Good luck.

Brian Wolfe, CDT, LEED AP BD+C 
Sustainable Design Coordinator 
HKS  |  Enhancing the Human Experience 
If you are sending large files, please use my Thru dropbox.
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-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Eurek, John S NWO
Sent: Friday, September 09, 2011 2:29 PM
To: Nick Caton; David Eldridge; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Adding Insulation toexistingbuilding(UNCLASSIFIED)

Classification: UNCLASSIFIED
Caveats: NONE

Today I received an e-mail with recommendations from the Construction Engineering Research Laboratory (CERL) and in the recommendations was an R-50 roof (super insulation).

The recommendations were from the building I ran energy models for and my results showed that too much insulation increases energy use.  I hit 'reply all' to the e-mail and told everyone that I disagree with their research and explained what my models showed.  I received a call from a person from CERL, he was a little defensive.  We agreed with everything but the super insulation.

I know this will come up in a future meeting and before I go toe-to-toe with him and tell the guy he is wrong, I want to make sure I am right.

One of his quotes was "We want the insulation so good that you can heat the room with a single match."  I repeatedly told him that it isn't the heating, it is the cooling.  He responded with, "the building shouldn't depend on the skin to remove heat". I agreed using the skin for cooling isn't the best method, but it is what happens.

I would agree with him that super insulation would be great IF the system has the ability to bring in a lot of outside air.  The outside air will be 'free cooling' minus the fan energy.  The large amount of outside air in essence allows you to artificially make the R value zero (just like opening the
windows)  (*snicker to myself - it is fan assisted natural ventilation*)

Will the ability to draw in outside air solve the problem of increased cooling load for a super insulated building?





Also, to those who are still reading - A part of the energy modeler's job is to understand what is happening then explaining it to others. (Even
architects)
The analogies below all involve this building with massive internal loads.
The architect insisted that you can reduce energy use by optimizing the orientation.  I ran the model, it only made a 0.05% difference.

-I told him "It is like trying to get better gas mileage by turning down the radio in your car.  The skin load is tiny compared to the servers, lights and computer loads."
-Later I told somebody "It is like trying to make a bull-doze aerodynamic, this building is a work horse.  If it were an empty house I would agree rotation matters more."
-And "With this much insulation, the orientation doesn't matter as much. If you on the beach in a speedo it matters. If you are in a parka covered head to toe, not so much."


John Eurek PE, LEED AP
Mechanical Engineer,
US Army Corps of Engineers
Omaha District CENWO-ED-DA
1616 Capitol Avenue
Omaha, NE 68102
Phone: (402) 995-2134
email: john.s.eurek at usace.army.mil



-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Thursday, September 08, 2011 2:52 PM
To: David Eldridge; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Adding Insulation
toexistingbuilding(UNCLASSIFIED)

David,

Remind me never to ask you how a thermos works ^_^.

John,

I wrote most of this yesterday and David beat me to the punch... I'm echoing much of the same from his response but maybe it'll help as well??

...

Economizers work just as you describe, and are great energy savers when the OA temps are conducive to comfort... (moving air generally takes less energy than moving heat + air) 

But sometimes it's 110F+ at your RTU in the dead heat of the summer...
In our local climate and I'm sure many others, the brunt of the cooling season has OA temps well above what we want to supply to achieve comfort inside.  Economizer function isn't terribly helpful in this situation.
With too much insulation, you still run into the same fundamental problem of "too much heat inside," with no options but to reject the heat using your cooling equipment outside, even if you do have an economizer.

Your assertion holds true, that super-insulation can be a non-issue when you have an economizer, but only for specific times in the year when the outside conditions are cooperating.  Where having an economizer (or not) may have a dampening effect on the relative impact/problem of "super-insulating" on an annual basis, it could only remove the issue for the brunt of the cooling season in a specific sort of cool, temperate climate.

Even in such a climate, blasting tons of extra air into the building to "get around" someone's decision to over-insulate the envelope doesn't seem ideal... every building should have an envelope construction where "enough is enough."

There is an easy answer to your office's water query: "it depends."
(haha, I'll be here all night!)  

There unfortunately isn't a blanket rule here because the answer does depends on efficiency of the pumps (or fans), which itself is dependent on the piping (or duct) static being overcome (variability of that comes into play for some systems), and the efficiency of the cooling equipment as well - be it a chiller plant or rooftop DX refrigeration...
everything balances out and playing with different supply temps/flow rates will return a unique answer for every project if you take the time to play with it.

... 

As David concludes, this is indeed why modelers are ultimately such popular characters =)!

~Nick

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com



NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com 


-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of David Eldridge
Sent: Wednesday, September 07, 2011 3:50 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Adding Insulation to
existingbuilding(UNCLASSIFIED)

Nick, my analogy when I talk about coffee thermoses is a metal building with internal loads and varying insulation levels.

Anyway - back to the original poster, this phenomenon could more often be true where generally it is cooler outside than inside for much of the year.

To reply to John E.'s subsequent post -- there likely will still be some hours where it is cooler outside than inside (and the insulation is now a
detriment) even if there is an  economizer.  Even while the air system is providing cooling (whether compressor-based or economizer) the walls may still be conducting energy -- they don't stop based on the HVAC system status.

Certainly the availability of an economizer can mitigate this problem, but might not make it go away completely.

But that's why we have energy models -- insulation that looks great at both design days will still have some hours in the middle where it might make energy use higher -- run a model and find out what the net is.
(Unless the building is on Mercury...then always add as much as
possible.)

David



David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP Grumman/Butkus Associates




-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Wednesday, September 07, 2011 3:00 PM
To: Eurek, John S NWO; mikef at facilitymgt.com; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Adding Insulation to existing
building(UNCLASSIFIED)

Agreeing with John per usual...

Any building with internal loads will have some break-point where adding more insulation to the envelope will be detrimental to annual energy consumption.  It's a bigger deal whenever your internals are relatively high.  The behavior you're describing is fundamentally sound.

A good thermos keeps my coffee hot longer (great in the wintertime), but it's not the ideal container when my coffee is scalding-hot and I want the contents to cool down.

I've yet to settle on a favorite analogy myself... this just comes to mind because I need to make a new pot here at work...

NICK CATON, P.E.
SENIOR ENGINEER

Smith & Boucher Engineers
25501 west valley parkway, suite 200
olathe, ks 66061
direct 913.344.0036
fax 913.345.0617
www.smithboucher.com
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Classification: UNCLASSIFIED
Caveats: NONE


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