[Equest-users] Adding Insulation to existing building(UNCLASSIFIED)

[David Eldridge]

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