[Equest-users] Wall insulation in multifamily buildings
Michael Campbell via Equest-users
equest-users at lists.onebuilding.org
Thu Mar 9 18:54:58 PST 2017
Wow, thank you everyone for the extremely helpful responses.
To answer a few of the questions... the project is in NJ, Climate Zone 4A.
I did account for the thermal bridging of the walls studs. This project
has some metals studs and some wood studs and I accounted for both using
Appendix A of ASHRAE 90.1-2013.
Nathan, thanks for the input specifically regarding the Energy Star
Multifamily High Rise inputs values. This particular project is
participating in the ESMFHR Program so I am using their guidelines for
equipment/plug loads.
On Thu, Mar 9, 2017 at 6:32 PM, Joe Huang via Equest-users <
equest-users at lists.onebuilding.org> wrote:
> I'd say the message is that R-19 wall insulation has already "captured"
> most of the energy losses (or savings) for the wall.
>
> (leaning heavily on my cane...) Back in 1986, I did a project in support
> of ASHRAE and DOE residential energy standards where I did what then seemed
> an endless number of DOE-2 simulations (~ 20,000) for five prototypical
> residences in 45 US climates, from which using regression analyses I came
> up with the component loads (KBtu/ft2) for various components of the
> building (walls, roofs, internal loads, windows, etc.). Just picking out
> the wall component loads for an apartment in Seattle, Miami, and DC, I get
> the following:
> Seattle Miami Washington DC
> HL CL HL CL HL CL
> R-0 28.8 0.8 1.1 4.7 23.1 1.5
> R-11 10.9 0.4 0.3 1.5 8.9 0.8
> R-19 7.1 0.3 0.2 0.9 5.9 0.5
> R-34 3.9 0.2 0.1 0.5 3.2 0.3
>
> So, by R-19, you're already on the flat part of the curve and more
> insulation buys you very little.
>
> Incidentally, this data base of component loads was then turned into a PC
> program called PEAR (Program for Energy Analysis of Residences) that then
> multiplied the regression curves by the component scalar (ft2 of wall,
> e.g.), and added them up to derive the heating and cooling energy use of a
> house.
> PEAR is now so out-of-date technologically that the display no longer
> functions, but I still think there's some good basic information contained
> in the data base. David - maybe something that could be updated and
> maintained by IBPSA? Or better yet, put it on the Web ?
>
> source: "Technical documentation for a Residential Energy Use Data Base
> Developed in Support of ASHRAE Special Project 53", Huang, Ritschard, and
> Bull,
> LBL-24306, November 1987.
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 205A
> Moraga CA 94556yjhuang at whiteboxtechnologies.comhttp://weather.whiteboxtechnologies.com for simulation-ready weather data
> (o) (925)388-0265 <(925)%20388-0265>
> (c) (510)928-2683 <(510)%20928-2683>
> "building energy simulations at your fingertips"
>
> On 3/9/2017 2:07 PM, David Eldridge via Equest-users wrote:
>
> 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
> <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> <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 <(206)%20285-7100> |*C* 207-650-3942
> <(207)%20650-3942>
>
> *www.rushingco.com <http://www.rushingco.com/>*
>
>
>
> *From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
> <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>
> *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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