[Equest-users] Adding Insulation to existingbuilding(UNCLASSIFIED)

[Nick Caton]

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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