[Equest-users] Increased Energy for Cooling with Increasing Insulation and Decreasing Infiltration

[Christian Kaltreider]

Hi Dan,

 

This is a common result.  You may want to search the archives, as this has
been discussed in depth before.

 

Many buildings, particularly non-residential buildings, are 'internal loads
dominant' rather than 'envelope dominant'.  This means that the majority of
the cooling energy is spent removing heat from lighting, plug loads, people
and perhaps solar gains.  None of these things are dependent on outside
temperature.  So in an internal loads dominant building, there can be many
hours out of the year in which the building is in cooling mode while the
outside temperature is lower than the inside temperature.  During these
hours, heat transfer through the walls (from inside to outside) and
infiltration are beneficial from a cooling standpoint.  They act as a sort
of uncontrolled economizer, reducing the amount of cooling required by the
mechanical system.  Increasing insulation reduces this beneficial effect.

 

I hope this helps,

Christian

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Daniel
Wright
Sent: Monday, June 11, 2012 1:03 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Increased Energy for Cooling with Increasing
Insulation and Decreasing Infiltration

 

Hello all,

I am a relatively new eQuest user and am encountering some non-intuitive
results.

If I make an eQuest model for a default building using just the default
values for everything, and then use the Energy Efficiency Measurement Wizard
to increase the insulation (roof or wall) or decrease the infiltration, I
see the annual energy used for heating decrease in both cases (which I would
expect), and the cooling energy increase in both cases (which I wouldn't
expect). I've tried this for two of the default building types (Two story
office building and Mutifamily low rise) and two different climates (LA and
NYC), and get the same results. I've also seen the same behavior in other
building models that I've created that differ in many respects to these
default cases.

Can someone please explain how this is possible?

Dan

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