[Equest-users] Wall insulation in multifamily buildings

[David Eldridge via Equest-users]

R-19 is not the worst starting point, I’d expect diminishing returns going from good insulation to great insulation, but a much bigger jump in efficiency from poor to good insulation levels.

Make sure you are modeling the cavity insulation accurately including any equivalent assembly resistance due to the studs. i.e. continuous insulation requirements are there because the cavity insulation is de-rated quite a bit from the studs and which can be important in colder climates.

In terms of an overall percentage difference due to envelope changes you may also see that window performance dominates if the WWR is relatively high.

David



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



From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nathan Miller via Equest-users
Sent: Thursday, March 09, 2017 2:52 PM
To: Michael Campbell <mcamp1206 at gmail.com>
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Wall insulation in multifamily buildings

Don’t know where your building is located, but on the Seattle area multifamily projects we routinely model, envelope has very little impact on building energy use. DHW and ventilation seem to be the items we have the most influence over that really can change the energy consumption.

FWIW, many of us in the Seattle market are starting to believe the standard plug/misc load assumptions from the Energy Star MF High Rise Sim Guidelines (if you are using them) overestimate that energy use, and result in more “free heat” in the building and thus less sensitivity to envelope changes (among other implications).


Nathan Miller, PE, LEED AP BD+C – Mechanical Engineer/Senior Energy Analyst
RUSHING | O 206-285-7100 | C 207-650-3942
www.rushingco.com<http://www.rushingco.com/>

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Michael Campbell via Equest-users
Sent: Thursday, March 09, 2017 3:44 PM
To: equest-users <equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>>
Subject: [Equest-users] Wall insulation in multifamily buildings

Hello eQUEST Users,
I've been working on a model for a multifamily building, 5 stories, approximately 300,000 square feet.  I've been running a few iterations of the model to see how changes to the wall assembly affect the model results.

What I've found is that changes in the wall assembly seem to have a minimal impact on the model results.  I just did a comparison where I took an assembly with R-19 cavity insulation and 2" rigid insulation and compared that to the same assembly but without the rigid insulation.  This was applied to the entire building.  What I found was only a 0.4% increase in total energy cost after taking out the rigid insulation.  I'm wondering if others have found similar results in multifamily buildings?
Any input is appreciated.
Thank you,
Mike Campbell
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