Wall insulation in multifamily buildings

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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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Reputation: 200

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

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Two cents from the Old Guy..
I did an eQuest model for a house in Southern California for the gas Company. Changed lighting wall R-value and window treatment. Wall impact was much as Michael found it. Biggest impact was window treatment..and that was in the 2-4% range.
Insulation has its greatest impact on heating. Window treatment on cooling. It also depends on how much outside surface touches the building. Interior rooms never see the sun (or the Moon).
Michael's results are not a mystery in most places in the contiguous US. Northern Canada or Finland, maybe more.
John R. Aulbach, PE

#yiv6968246943 #yiv6968246943 -- _filtered #yiv6968246943 {panose-1:2 4 5 3 5 4 6 3 2 4;} _filtered #yiv6968246943 {font-family:Calibri;panose-1:2 15 5 2 2 2 4 3 2 4;} _filtered #yiv6968246943 {font-family:Verdana;panose-1:2 11 6 4 3 5 4 4 2 4;}#yiv6968246943 #yiv6968246943 p.yiv6968246943MsoNormal, #yiv6968246943 li.yiv6968246943MsoNormal, #yiv6968246943 div.yiv6968246943MsoNormal {margin:0in;margin-bottom:.0001pt;font-size:12.0pt;}#yiv6968246943 a:link, #yiv6968246943 span.yiv6968246943MsoHyperlink {color:#0563C1;text-decoration:underline;}#yiv6968246943 a:visited, #yiv6968246943 span.yiv6968246943MsoHyperlinkFollowed {color:#954F72;text-decoration:underline;}#yiv6968246943 span.yiv6968246943EmailStyle17 {color:#1F497D;}#yiv6968246943 span.yiv6968246943EmailStyle18 {color:windowtext;}#yiv6968246943 .yiv6968246943MsoChpDefault {} _filtered #yiv6968246943 {margin:1.0in 1.0in 1.0in 1.0in;}#yiv6968246943 div.yiv6968246943WordSection1 {}#yiv6968246943 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|O206-285-7100 |C207-650-3942 www.rushingco.com ?

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Mike,

We see similar results for wall insulation in climates colder than Seattle, unless the internal loads are insignificant like in a warehouse.

You are accounting for the thermal bridging of the studs, aren?t you? There are tables in Appendix A of ASHRAE 90.1 that give assembly U-factors for various framed assemblies.

Keith Swartz, PE | Senior Energy Engineer
Seventhwave
608.210.7123 seventhwave.org

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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

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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 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

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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.

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Joined: 2016-07-15
Reputation: 200

Few more thoughts on this:

1) I agree with Joe and David that R-19 ??has already captured most of
the energy losses (or savings) for the wall?. R-19 is better than 90.1 2016
requirements for steel-framed wall in climate zone 4A, and since 90.1
requirements are set taking into account cost effectiveness, it is not
surprising that further improvement does not often pay off.

2) Overwhelming majority of high performance multifamily projects have
efficient heating systems, often condensing boilers or VRF HPs, which
lowers heating costs and potential savings from envelope improvements.

3) Most multifamily projects in North East have gas heating, and gas is
cheap compared to electricity. For example EPA EStar MFHR projects in NY
typically use $0.15/kWh and $1/Therm in performance rating calculations,
which effectively makes BTU of electricity ~4.4 times more expensive than
BTU of gas. This further shrinks contribution of heating toward the total
building energy $, and reduces potential savings from envelope
improvements. (Using source energy instead of $ in performance rating
calculations makes envelope improvements more appealing, because with EPA
PM site-to-source conversions BTU of electricity has only ~ 3 times greater
weight than BTU of gas.)

4) I am curious about the reasoning behind Nathan?s comment that ??
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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Michael Campbell via Equest-users
*Sent:* Thursday, March 09, 2017 9:55 PM
*To:* Joe Huang
*Cc:* equest-users
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

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.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

I thought I might chime in on this discussion as well to drive a few points home.

I have attached a file illustrating a graph to explain Joe?s comment below. It shows diminishing returns from increased insulation. When it comes to effective envelope ECMs for projects. I focus on two very important things:

1) Lower infiltration will save you more energy than any other envelope ECM. However, it is hard to get an owner to buy off on this and enforce the requirement with the contractor. Typically, an envelope consultant will be brought in to assist the architect with details, supervise the contractor during construction, and test the building (or a portion thereof) to verify performance. You can see how something like this is hard sell to an owner because it can be a costly process, and if the building fails the blower door test, the contractor has a $$ issue and the a lot of rework.

2) Window-to-Wall Ratio (WWR) reduction is great. On the curve illustrated in the attached file, you essentially replace an expensive window with a cheaper wall assembly and saving more energy! It?s a true win-win-win. However, windows exist for more reasons than daylight controls. Comfort and views are essential for occupants. Some architects may also argue they are essential for aesthetics as well, so you have to have a target in mind for the project you are willing to negotiate. On commercial projects, I generally shoot for 25% WWR.

3) Window upgrades are next since they have the most potential to save energy on the illustrated curve. Since you tried to minimize the WWR on #2, this ECM will be cheaper than it would have been otherwise ? always saving the client $$ ? This includes glazing and frames.

4) After all three of the above items are addressed, I start to talk about added insulation in the walls, roof, etc.
Anyway, this is my approach on new construction. Is this what you guys see, or am I missing something?

Let me know.

[ARCH | NEXUS]
DAVID W. GRIFFIN II
BEMP
ENERGY ANALYST
2505 E Parleys Way
Salt Lake City, UT 84109
Office 801.924.5028
archnexus.com
[Twitter][Facebook][Youtube][LinkedIn]

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Joined: 2016-07-15
Reputation: 200

My only comment is that developers and contractors like curtain wall (window wall for high rise MURBS) because it is less expensive to install and can be installed in any weather. This may be the main reason we see glass towers north of the 49th.

[Title: RWDI - Description: RWDI logo]

Christopher Jones, P.Eng. | Senior Energy Analyst
RWDI
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

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Reputation: 200

I can?t think of the last high-rise project I worked on that stayed anywhere near 25% WWR. 40-50% is very much the norm in Seattle (climate where I do most of my modeling work). Owners want 60%+. Mid-rise resi (and mixed use), I do tend to see 25-35% WWR as typical.

When we do the envelope sensitivity analysis on high rise multifamily projects, honestly the glazing percentage isn?t as bad a penalty as you?d think. Like on the order of 0.1-0.25% energy penalty for each 1% increase in glazing when we are already in the 40%+ glazing band, meaning we are comparing extra glazing to opaque wall. This is with a WSHP system serving residences. If it is more of a traditional hydronic job, that penalty seems to go up a little, but still isn?t a killer.

Using standard ESMFHRSG plug loads we see the conditioning load of the buildings driven by internal loads, ventilation, and infiltration, not envelope. Related to the previous comment in this thread from Maria:

?I am curious about the reasoning behind Nathan?s comment that ?? 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 overestimate that energy use?. EPA?s plug loads are 4 times lower than COMNET?s for Multifamily/Residential, and are also lower than the loads in PNNL High Rise Apartment prototype. Passive house protocols are the only two sources that I know off that prescribe lower in-unit loads - Passivehaus Institute (PHI) loads are less than half of EPA?s, and US passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general, in-unit electricity consumption can vary significantly depending on occupant demographics (by factor of 10 based on some papers), so both COMNET and PHI may be correct for some apartments. We compared EPA assumptions to the in-unit electricity usage in several apartment complexes in NJ, and the numbers were in the right ballpark, so appear to represent reasonable averages.?

Her comment made me realize I?m suffering a bit from selection-bias. The projects I tend to model are the newest multifamily projects to hit the market. These projects in Seattle are almost all studios and 1 BR, with a few 2 BR and penthouses sprinkled in. They aren?t serving as housing for families, but more professionally-employed individuals, who don?t cook much, who probably concentrate their electronics (laptop plus maybe a flat screen) more than the typical American family, and certainly do less laundry. Some of the trend on housing design seems to be minimal living space and more amenities. That is probably why the national averages for dwelling unit plug loads seem high for THE TYPE OF PROJECTS I WORK ON.

Hope that makes more sense (given some reflection).

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

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Joined: 2016-07-15
Reputation: 200

To David?s comment about infiltration (?Lower infiltration will save you
more energy than any other envelope ECM.?), there are a few caveats.

a) To document infiltration-related savings in App G models (e.g. for
LEED), the baseline air leakage would be modeled as 0.4 CFM/SF *@ 75Pa*
(90.1 2013 G3.1.1.4). 90.1 2013 Table G further requires that infiltration
inputs in the simulation tool are adjusted to account for factors such as
weather and ??. HVAC system operation?.?. 90.1 leaves these adjustments to
the modeler, but PNNL?s Infiltration Modeling Guidelines for Commercial
Building Energy Analysis

mentions in passing (Note 2 on p.6) that ?The total building infiltration
schedule fraction will be 1.0 when all heating, ventilation and air
conditioning (HVAC) systems are off and 0.25 when the HVAC systems are in
operation.? (It?s good that they used Energy Plus for the study, so results
must still be accurate in spite of this seemingly arbitrary assumption
J.) Since
HVAC systems are operating 24/7 in multifamily, infiltration schedule in
the baseline and proposed design would have to be set to 0.25 of the peak
if we follow the PNNL study, which very significantly reduces
infiltration-related heating load in the model. (The infiltration load is
shown in LS-F report.) As a side note, with LEED v3 and v4,
infiltration-reduction credit can be claimed via exceptional calculation
methods, or by using LEED pilot credit

which is based on 90.1 2016 Appendix G modeling rules with the appropriate
adjustment to performance targets and point scale. (I recommend that you
check out this credit, as it simplifies the baseline model.)

b) Potential savings from infiltration reduction should be considered
in conjunction with the specified ventilation strategy. In North East, it
is overwhelmingly common to have 100% OA units serving multifamily
corridors with no exhaust, and continuously running rooftop exhaust fans
serving kitchens and bathrooms in apartments on one vertical stack with no
make-up. Both supply and exhaust rates are often grossly oversized compared
to the minimum CFM required by code, and since the relevant code
(summarized here
)
requires that apartments are compartmentalized and envelope is air-tight,
it creates an interesting conundrum for air J. Balanced ventilation is
still a rarity in NE even in high performance buildings. Old editions of
ASHRAE Fundamentals had a way of taking into account this dynamics (see
below), which was crude but better than ?one size fits all? approach in the
PNNL study. So I?d use ASHRAE?s method in lieu of PNNL?s to model
infiltration savings for LEED, and to decide whether tighter envelope
should be pursued for a given project.

Nathan, thanks for clarifying your plug load observations. Your explanation
makes total sense. On the related note, the latest LEED EAc1 template
includes the following info (based on ASHRAE Applications handbook) for the
impact of occupant demographics on HW usage. Perhaps you can reference this
data (also used in EPA HRMF program) to justify modeling lower plug loads
for certain projects. But I can also see that rating authorities may reject
this logic and insist on using ?typical? plug loads in the model,
recognizing that occupant demographics may change over the life of the
building.

*From:* Nathan Miller [mailto:nathanm at rushingco.com]
*Sent:* Tuesday, March 14, 2017 9:38 AM
*To:* Chris Jones ; David Griffin II <
DGriffin at archnexus.com>; Maria Karpman ;
Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org
*Subject:* RE: [Equest-users] Wall insulation in multifamily buildings

I can?t think of the last high-rise project I worked on that stayed
anywhere near 25% WWR. 40-50% is very much the norm in Seattle (climate
where I do most of my modeling work). Owners want 60%+. Mid-rise resi (and
mixed use), I do tend to see 25-35% WWR as typical.

When we do the envelope sensitivity analysis on high rise multifamily
projects, honestly the glazing percentage isn?t as bad a penalty as you?d
think. Like on the order of 0.1-0.25% energy penalty for each 1% increase
in glazing when we are already in the 40%+ glazing band, meaning we are
comparing extra glazing to opaque wall. This is with a WSHP system serving
residences. If it is more of a traditional hydronic job, that penalty seems
to go up a little, but still isn?t a killer.

Using standard ESMFHRSG plug loads we see the conditioning load of the
buildings driven by internal loads, ventilation, and infiltration, not
envelope. Related to the previous comment in this thread from Maria:

?I am curious about the reasoning behind Nathan?s comment that ?? 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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.?

Her comment made me realize I?m suffering a bit from selection-bias. The
projects I tend to model are the newest multifamily projects to hit the
market. These projects in Seattle are almost all studios and 1 BR, with a
few 2 BR and penthouses sprinkled in. They aren?t serving as housing for
families, but more professionally-employed individuals, who don?t cook
much, who probably concentrate their electronics (laptop plus maybe a flat
screen) more than the typical American family, and certainly do less
laundry. Some of the trend on housing design seems to be minimal living
space and more amenities. That is probably why the national averages for
dwelling unit plug loads seem high for THE TYPE OF PROJECTS I WORK ON.

Hope that makes more sense (given some reflection).

*Nathan Miller, PE, LEED AP BD+C** ? **Mechanical Engineer/Senior Energy
Analyst*

*RUSHING* | *O* 206-285-7100 | *C* 207-650-3942

*www.rushingco.com *

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Chris Jones via Equest-users
*Sent:* Tuesday, March 14, 2017 7:46 AM
*To:* David Griffin II ; Maria Karpman <
maria.karpman at karpmanconsulting.net>; Michael Campbell ;
Joe Huang
*Cc:* equest-users at onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

My only comment is that developers and contractors like curtain wall
(window wall for high rise MURBS) because it is less expensive to install
and can be installed in any weather. This may be the main reason we see
glass towers north of the 49th.

[image: Title: RWDI - Description: RWDI logo]

*Christopher Jones, **P.Eng. *| Senior Energy Analyst
*RWDI*
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *David Griffin
II via Equest-users
*Sent:* Monday, March 13, 2017 7:46 PM
*To:* Maria Karpman; Michael Campbell; Joe Huang
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

I thought I might chime in on this discussion as well to drive a few points
home.

I have attached a file illustrating a graph to explain Joe?s comment below.
It shows diminishing returns from increased insulation. When it comes to
effective envelope ECMs for projects. I focus on two very important things:

1) Lower infiltration will save you more energy than any other
envelope ECM. However, it is hard to get an owner to buy off on this and
enforce the requirement with the contractor. Typically, an envelope
consultant will be brought in to assist the architect with details,
supervise the contractor during construction, and test the building (or a
portion thereof) to verify performance. You can see how something like this
is hard sell to an owner because it can be a costly process, and if the
building fails the blower door test, the contractor has a $$ issue and the
a lot of rework.

2) Window-to-Wall Ratio (WWR) reduction is great. On the curve
illustrated in the attached file, you essentially replace an expensive
window with a cheaper wall assembly and saving more energy! It?s a true
win-win-win. However, windows exist for more reasons than daylight
controls. Comfort and views are essential for occupants. Some architects
may also argue they are essential for aesthetics as well, so you have to
have a target in mind for the project you are willing to negotiate. On
commercial projects, I generally shoot for 25% WWR.

3) Window upgrades are next since they have the most potential to save
energy on the illustrated curve. Since you tried to minimize the WWR on #2,
this ECM will be cheaper than it would have been otherwise ? always saving
the client $$ J This includes glazing and frames.

4) After all three of the above items are addressed, I start to talk
about added insulation in the walls, roof, etc.

Anyway, this is my approach on new construction. Is this what you guys see,
or am I missing something?

Let me know.

[image: Image removed by sender. ARCH | NEXUS]

DAVID W. GRIFFIN II

BEMP
ENERGY ANALYST

2505 E Parleys Way
Salt Lake City, UT 84109

*Office* 801.924.5028

archnexus.com

[image: Image removed by sender. Twitter]
[image:
Image removed by sender. Facebook]
[image:
Image removed by sender. Youtube]
[image:
Image removed by sender. LinkedIn]

*From:* Maria Karpman via Equest-users [
mailto:equest-users at lists.onebuilding.org
]
*Sent:* Friday, March 10, 2017 9:24 PM
*To:* Michael Campbell; Joe Huang
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

Few more thoughts on this:

1) I agree with Joe and David that R-19 ??has already captured most of
the energy losses (or savings) for the wall?. R-19 is better than 90.1 2016
requirements for steel-framed wall in climate zone 4A, and since 90.1
requirements are set taking into account cost effectiveness, it is not
surprising that further improvement does not often pay off.

2) Overwhelming majority of high performance multifamily projects have
efficient heating systems, often condensing boilers or VRF HPs, which
lowers heating costs and potential savings from envelope improvements.

3) Most multifamily projects in North East have gas heating, and gas
is cheap compared to electricity. For example EPA EStar MFHR projects in NY
typically use $0.15/kWh and $1/Therm in performance rating calculations,
which effectively makes BTU of electricity ~4.4 times more expensive than
BTU of gas. This further shrinks contribution of heating toward the total
building energy $, and reduces potential savings from envelope
improvements. (Using source energy instead of $ in performance rating
calculations makes envelope improvements more appealing, because with EPA
PM site-to-source conversions BTU of electricity has only ~ 3 times greater
weight than BTU of gas.)

4) I am curious about the reasoning behind Nathan?s comment that ??
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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Michael Campbell via Equest-users
*Sent:* Thursday, March 09, 2017 9:55 PM
*To:* Joe Huang
*Cc:* equest-users
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

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.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

I feel like expanding just a little (who am I kidding?) on Maria?s quote from the PNNL guidelines? document regarding infiltration schedules:

?The total building infiltration schedule fraction will be 1.0 when all heating, ventilation and air-conditioning (HVAC) systems are off and 0.25 when the HVAC systems are in operation.?

1. For extra context: That report details an exploration of options to constructively translate 90.1 envelope subcommittee advice concerning baseline overall air infiltration quantities (1.8 CFM/ft2 @ 75Pa) into a procedure and set of inputs appropriate for usage with energyplus 3.1+. The above quote, if I am not mistaken, actually sources from the SSPC 90.1 Envelope Subcommittee? if not by direct citation. I would not aim any specific concerns about this prescriptive language at those authors.

2. The effects of such a fractional schedule (uniformly for both energyplus and in doe-2, at least) would be to:

a. reduce naturally driven infiltration (as determined each interval between wind / temperature / stack effects) by 75% when HVAC = ON

b. not modify naturally driven infiltration when HVAC = OFF

3. The purpose of such a reduction is to (in broad strokes) represent the effects of aggregate building pressurization as is typically intended with new commercial HVAC design. If my building interior is positively pressurized relative to the exterior, less air should infiltrate in.

4. This reduction as prescribed is intended to occur every hour that fans achieving building pressurization are in operation. 24/7 = correct for multifamily with centrally-driven ventilation/pressurization (typical multifamily design for some locales, but not in all markets).

5. To the best of my knowledge, 75% is a dart on the wall. I?m not aware of any study that informed this directly, but it follows logic that generally infiltration still happens with pressurized buildings, sometimes, so any aggregate reduction should remain under 100%. I?m personally convinced there is no single number that would be appropriately applied to all buildings/systems, however. Indeed situations exist where the systems in operation actually de-pressurize the building interior and would therefore amplify infiltration (by design, coincidence, or accident).

This same schedule however is also the primary vector to factor in ?higher than design state? naturally driven infiltration. This occurs for example in scenarios where buildings that have doors that could open for people to enter and exit.

So what is this ?design state?? Depends on who you ask - I?d offer 2 perspectives:

1. Open windows & doors are not normally considered by well-meaning mechanical engineers designing for building pressurization. If I may reach a bit (I?m sure I cannot speak for everyone), the broad assumption is that doors, windows, and other openings are considered in an effectively closed state most of the time, and when they are open all bets are off. While we can compartmentalize and try to mitigate the effects, we cannot generally design buildings to be effectively pressurized to combat infiltration on a macro level while many doors/windows are open, else those doors would never close and the windows would whistle all day.

2. From a prescriptive/compliance M+V perspective, leakage through windows and doors are for practical reasons deliberately excluded to ensure the air-tightness of the rest of the envelope assembly is what?s being measured in isolation (I?m sure this varies based on locally prescribed/normal protocol). Such openings are taped/sealed off to ensure they do not impact blower door testing results.

I suspect this phenomenon of building operation (operable doors/windows) was for justifications including the above also not a concern of the envelope committee when prescribing infiltration schedule factors no higher than 1.0 during occupied/unoccupied hours. ?And that?s totally fine for those interested in setting an arbitrary bar for something like compliance modeling/testing: By the book, that reality has been pushed off the table for discussion and so shouldn?t be a concern or part of the conversation (unless someone with a big stick changes their mind on the matter).

The reality of operable doors/windows can however be a meaningful thing to miss if you are trying to calibrate and/or determine realistic savings potential for directly-affected ECM scope (including adding vestibules/compartmentalization to entryways, general envelope re-sealing packages, and addressing dysfunctional/non-existent building pressurization situations).

Some suggestions for those concerned about getting infiltration schedules ?right? for reasons beyond compliance:

1. Windows/doors/and other operable envelope openings are not always in closed state. Consider increasing naturally driven infiltration rates above those expected/measured for ?fully closed? states during hours where you can expect openings. Typical elementary school should see values above 1.0 when school lets in & out (doors/vestibules are held open), and perhaps also seasonally during nice weather where windows are operable & actually used.

2. Another dart on the wall to consider: Depending on the occupancy type, eQUEST wizards seems to suggest hourly factors approaching 1.25 (25% increase in naturally driven infiltration) around hours where you?d typically expect heavier foot traffic around entries (at start/close of typical weekday occupancy patterns and around lunch hours, generally). I call it a ?dart on the wall? again because I?m not certain if this is based on any specific study.

3. Working building pressurization systems can be rendered ineffective over time due to bad pressure sensors / controls / envelope degradation: a 75% reduction may be too aggressive

4. Building pressurization systems can be TOO effective for similar causes ? ever notice doors blowing open or not shutting well? 75% may overly conservative in those cases

5. A fractional schedule appropriate for perimeter infiltration is probably not appropriate for core zones without vertical exterior exposures (if you presume any infiltration loads are seen there to begin with).

6. Accounting for the effects of adding vestibules, rotating doors, and similar compartmentalization ECM?s requires at least acknowledging naturally driven infiltration floats above ?everything closed? or ?design? levels of infiltration, so that you can make appropriate relative reductions.

In closing, I guess I want to emphasis for tone: this is mostly just my opinion, man! I am not a certified blower door technician, nor an energyplus developer, nor a standard/compliance language-crafter? Just a fellow with a few thoughts I feel others could benefit from considering. My sincere hope is someone out there can benefit/grow from some of these perspectives and/or return the favor someday by setting me straight if/when I?m going down the wrong path.

~Nick

[cid:image001.png at 01D29D6B.F3900850]
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

[cid:image002.png at 01D29D6B.F3900850]

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Here I am trying to keep the "chain letter" going :-)

Nick has hit upon something that's a bit of a sore spot for me, i.e., modeling buildings
by the intent or rationalization of a building policy, rather than documentation of how
buildings actually behave. I've always been skeptical of this "pressurization == no
infiltration" claim that I've heard going all the way back to the early 1980s. I can see
how pressurization might keep out infiltration, but wouldn't it then result in
exfiltration, which would be a net loss of conditioned air that needs to be made up by the
air handler?

The most rigid application of what I call "modeling by intent" was when I introduced the
use of DOE-2 for a new residential building energy standard in China. When the topic got
to be infiltration, I heard that should be set at 1.0 ACH, which was mandated as the
amount of fresh air needed to an occupied space, although no equipment nor technology was
mentioned for maintaining such a steady flow of air. It must be "smart air". as one
reviewer commented at a critique in Arizona upon seeing an architect's drawing with arrows
bringing in natural ventilation horizontally into a building...

Joe

Joe Huang
White Box Technologies, Inc.
346 Rheem Blvd., Suite 205A
Moraga CA 94556
yjhuang at whiteboxtechnologies.com
http://weather.whiteboxtechnologies.com for simulation-ready weather data
(o) (925)388-0265
(c) (510)928-2683
"building energy simulations at your fingertips"

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Just like with plug loads that were discussed in this ever expanding
thread, there is clearly no one-size-fits-all infiltration schedule that
can work for all projects. Capturing interaction between infiltration and
mechanical ventilation is inherently complex, leakage testing is done at
conditions that are different from the actual operating conditions of the
building (as Nick has described), and the actual operating conditions are
in flux. So ideally the rules of the compliance modeling protocol should?.

(a) Incentivize tighter envelop

(b) Limit performance credit from infiltration reduction, to reflect
uncertainty of the realized savings

(c) Account for the aspects of the project that are likely to have high
impact on savings

Arguably equations from the old ASHRAE Fundamentals that I included in the
email below did a better job with addressing these than the infiltration
schedule in the PNNL paper. For example, they recognized difference in
savings from tighter envelope in projects with balanced versus exhaust-only
ventilation. Even if the new mechanical code does not allow certain
configuration of ventilation systems, common scenarios should still be
accounted for in post - 90.1 2016 App G, to support its application to
existing buildings and buildings designed to meet earlier versions of 90.1.
For example LEED pilot credit uses 90.1 2016 App G to calculate improvement
over 90.1 2010.

Maria

*From:* Krishnan Gowri [mailto:krishnan.gowri at autodesk.com]
*Sent:* Wednesday, March 15, 2017 7:38 PM
*To:* Nicholas Caton ; Maria Karpman
; Nathan Miller ;
Chris Jones ; David Griffin II <
DGriffin at archnexus.com>; Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org
*Subject:* RE: [Equest-users] Wall insulation in multifamily buildings

Nick:

Thanks for adding me to this discussion. As one of the primary authors of
the PNNL infiltration report and current ECB member (which has an addendum
in the works), I can provide the following background information:

1. The schedule fractions modify the infiltration input in E+. These
fractions are applied to infiltration rates calculated based on the design
flow rate, wind velocity (a linear coefficient is used) and zone altitude.

2. These fractions and the design flow rate in the report are provided
by the 90.1 Envelope subcommittee.

3. When HVAC systems are off, these equations work as expected.
However, when HVAC systems are operating, the assumption is that building
pressurization will decrease the infiltration (ECB is considering changes
to this based on outdoor air damper state).

All the assumptions and guidelines in the PNNL report were based on
extensive analysis of medium/large office buildings, though much of this
has been used for all building types. The primary intent is to determine
savings for air barrier requirements, by appropriately modeling envelope
air leakage rates.

Hope this helps, -krishnan

*From:* Nicholas Caton [mailto:Nicholas.Caton at schneider-electric.com
]
*Sent:* Wednesday, March 15, 2017 3:23 PM
*To:* Maria Karpman ; Nathan Miller <
nathanm at rushingco.com>; Chris Jones ; David
Griffin II ; Michael Campbell ;
Joe Huang
*Cc:* equest-users at onebuilding.org; Krishnan Gowri <
krishnan.gowri at autodesk.com>
*Subject:* RE: [Equest-users] Wall insulation in multifamily buildings

I feel like expanding just a little (*who am I kidding?*) on Maria?s quote
from the PNNL guidelines? document regarding infiltration schedules:

*?**The total building infiltration schedule fraction will be 1.0 when all
heating, ventilation and air-conditioning (HVAC) systems are off and 0.25
when the HVAC systems are in operation.?*

1. For extra context: That report details an exploration of options
to constructively translate 90.1 envelope subcommittee advice concerning
baseline overall air infiltration quantities (1.8 CFM/ft2 @ 75Pa) into a
procedure and set of inputs appropriate for usage with energyplus 3.1+.
The above quote, if I am not mistaken, actually sources from the SSPC 90.1
Envelope Subcommittee? if not by direct citation. I would not aim any
specific concerns about this prescriptive language at those authors.

2. The *effects* of such a fractional schedule (uniformly for both
energyplus and in doe-2, at least) would be to:

a. reduce naturally driven infiltration (as determined each interval
between wind / temperature / stack effects) by 75% when HVAC = ON

b. not modify naturally driven infiltration when HVAC = OFF

3. The *purpose* of such a reduction is to (in broad strokes)
represent the effects of aggregate building pressurization as is typically
intended with new commercial HVAC design. If my building interior is
positively pressurized relative to the exterior, less air should infiltrate
in.

4. This reduction as prescribed is intended to occur every hour that
fans achieving building pressurization are in operation. 24/7 = correct
for multifamily with centrally-driven ventilation/pressurization (typical
multifamily design for some locales, but not in all markets).

5. To the best of my knowledge, 75% *is a dart on the wall*. I?m not
aware of any study that informed this directly, but it follows logic that
generally infiltration still happens with pressurized buildings, sometimes,
so any aggregate reduction should remain under 100%. I?m personally
convinced there is no single number that would be appropriately applied to
all buildings/systems, however. Indeed situations exist where the systems
in operation actually de-pressurize the building interior and would
therefore *amplify* infiltration (by design, coincidence, or accident).

This same schedule however is *also* the primary vector to factor in
?higher than design state? naturally driven infiltration. This occurs for
example in scenarios where buildings that have doors that could open for
people to enter and exit.

So what is this ?design state?? Depends on who you ask - I?d offer 2
perspectives:

1. Open windows & doors are not normally considered by well-meaning
mechanical engineers designing for building pressurization. If I may reach
a bit (I?m sure I cannot speak for everyone), the broad assumption is that
doors, windows, and other openings are considered in an effectively closed
state *most* of the time, and when they are open all bets are off. While
we can compartmentalize and try to mitigate the effects, we cannot
generally design buildings to be effectively pressurized to combat
infiltration on a macro level while many doors/windows are open, else those
doors would never close and the windows would whistle all day.

2. From a prescriptive/compliance M+V perspective, leakage through
windows and doors are for practical reasons deliberately excluded to ensure
the air-tightness of the rest of the envelope assembly is what?s being
measured in isolation (I?m sure this varies based on locally
prescribed/normal protocol). Such openings are taped/sealed off to ensure
they do not impact blower door testing results.

I suspect this phenomenon of building operation (operable doors/windows)
was for justifications including the above *also* not a concern of the
envelope committee when prescribing infiltration schedule factors no higher
than 1.0 during occupied/unoccupied hours. ?And that?s *totally fine* for
those interested in setting an arbitrary bar for something like compliance
modeling/testing: By the book, that reality has been pushed off the table
for discussion and so shouldn?t be a concern or part of the conversation
(unless someone with a big stick changes their mind on the matter).

The reality of operable doors/windows *can* however be a meaningful thing
to miss if you are trying to calibrate and/or determine realistic savings
potential for directly-affected ECM scope (including adding
vestibules/compartmentalization to entryways, general envelope re-sealing
packages, and addressing dysfunctional/non-existent building pressurization
situations).

Some suggestions for those concerned about getting infiltration schedules
?right? for reasons beyond compliance:

1. Windows/doors/and other operable envelope openings are not always
in closed state. Consider increasing naturally driven infiltration rates
above those expected/measured for ?fully closed? states during hours where
you can expect openings. Typical elementary school should see values above
1.0 when school lets in & out (doors/vestibules are held open), and perhaps
also seasonally during nice weather where windows are operable & actually
used.

2. Another dart on the wall to consider: Depending on the occupancy
type, eQUEST wizards seems to suggest hourly factors approaching 1.25 (25%
increase in naturally driven infiltration) around hours where you?d
typically expect heavier foot traffic around entries (at start/close of
typical weekday occupancy patterns and around lunch hours, generally). I
call it a ?dart on the wall? again because I?m not certain if this is based
on any specific study.

3. Working building pressurization systems can be rendered ineffective
over time due to bad pressure sensors / controls / envelope degradation: a
75% reduction may be too aggressive

4. Building pressurization systems can be TOO effective for similar
causes ? ever notice doors blowing open or not shutting well? 75% may
overly conservative in those cases

5. A fractional schedule appropriate for perimeter infiltration is
probably not appropriate for core zones without vertical exterior exposures
(if you presume any infiltration loads are seen there to begin with).

6. Accounting for the effects of adding vestibules, rotating doors,
and similar compartmentalization ECM?s requires at least acknowledging
naturally driven infiltration floats above ?everything closed? or ?design?
levels of infiltration, so that you can make appropriate relative
reductions.

In closing, I guess I want to emphasis for tone: this is mostly just my
opinion, man! I am not a certified blower door technician, nor an
energyplus developer, nor a standard/compliance language-crafter? Just a
fellow with a few thoughts I feel others could benefit from considering.
My sincere hope is someone out there can benefit/grow from some of these
perspectives and/or return the favor someday by setting me straight if/when
I?m going down the wrong path.

~Nick

*Nick Caton, P.E., BEMP*

Senior Energy Engineer
Regional Energy Engineering Manager

Energy and Sustainability Services
Schneider Electric

D 913.564.6361
M 785.410.3317
F 913.564.6380
E nicholas.caton at schneider-electric.com

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *Maria Karpman
via Equest-users
*Sent:* Tuesday, March 14, 2017 11:53 AM
*To:* Nathan Miller ; Chris Jones <
Christopher.Jones at rwdi.com>; David Griffin II ;
Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

To David?s comment about infiltration (?Lower infiltration will save you
more energy than any other envelope ECM.?), there are a few caveats.

a) To document infiltration-related savings in App G models (e.g. for
LEED), the baseline air leakage would be modeled as 0.4 CFM/SF *@ 75Pa*
(90.1 2013 G3.1.1.4). 90.1 2013 Table G further requires that infiltration
inputs in the simulation tool are adjusted to account for factors such as
weather and ??. HVAC system operation?.?. 90.1 leaves these adjustments to
the modeler, but PNNL?s Infiltration Modeling Guidelines for Commercial
Building Energy Analysis

mentions in passing (Note 2 on p.6) that ?The total building infiltration
schedule fraction will be 1.0 when all heating, ventilation and air
conditioning (HVAC) systems are off and 0.25 when the HVAC systems are in
operation.? (It?s good that they used Energy Plus for the study, so results
must still be accurate in spite of this seemingly arbitrary assumption
J.) Since
HVAC systems are operating 24/7 in multifamily, infiltration schedule in
the baseline and proposed design would have to be set to 0.25 of the peak
if we follow the PNNL study, which very significantly reduces
infiltration-related heating load in the model. (The infiltration load is
shown in LS-F report.) As a side note, with LEED v3 and v4,
infiltration-reduction credit can be claimed via exceptional calculation
methods, or by using LEED pilot credit

which is based on 90.1 2016 Appendix G modeling rules with the appropriate
adjustment to performance targets and point scale. (I recommend that you
check out this credit, as it simplifies the baseline model.)

b) Potential savings from infiltration reduction should be considered
in conjunction with the specified ventilation strategy. In North East, it
is overwhelmingly common to have 100% OA units serving multifamily
corridors with no exhaust, and continuously running rooftop exhaust fans
serving kitchens and bathrooms in apartments on one vertical stack with no
make-up. Both supply and exhaust rates are often grossly oversized compared
to the minimum CFM required by code, and since the relevant code
(summarized here
)
requires that apartments are compartmentalized and envelope is air-tight,
it creates an interesting conundrum for air J. Balanced ventilation is
still a rarity in NE even in high performance buildings. Old editions of
ASHRAE Fundamentals had a way of taking into account this dynamics (see
below), which was crude but better than ?one size fits all? approach in the
PNNL study. So I?d use ASHRAE?s method in lieu of PNNL?s to model
infiltration savings for LEED, and to decide whether tighter envelope
should be pursued for a given project.

Nathan, thanks for clarifying your plug load observations. Your explanation
makes total sense. On the related note, the latest LEED EAc1 template
includes the following info (based on ASHRAE Applications handbook) for the
impact of occupant demographics on HW usage. Perhaps you can reference this
data (also used in EPA HRMF program) to justify modeling lower plug loads
for certain projects. But I can also see that rating authorities may reject
this logic and insist on using ?typical? plug loads in the model,
recognizing that occupant demographics may change over the life of the
building.

*From:* Nathan Miller [mailto:nathanm at rushingco.com]
*Sent:* Tuesday, March 14, 2017 9:38 AM
*To:* Chris Jones ; David Griffin II <
DGriffin at archnexus.com>; Maria Karpman ;
Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org
*Subject:* RE: [Equest-users] Wall insulation in multifamily buildings

I can?t think of the last high-rise project I worked on that stayed
anywhere near 25% WWR. 40-50% is very much the norm in Seattle (climate
where I do most of my modeling work). Owners want 60%+. Mid-rise resi (and
mixed use), I do tend to see 25-35% WWR as typical.

When we do the envelope sensitivity analysis on high rise multifamily
projects, honestly the glazing percentage isn?t as bad a penalty as you?d
think. Like on the order of 0.1-0.25% energy penalty for each 1% increase
in glazing when we are already in the 40%+ glazing band, meaning we are
comparing extra glazing to opaque wall. This is with a WSHP system serving
residences. If it is more of a traditional hydronic job, that penalty seems
to go up a little, but still isn?t a killer.

Using standard ESMFHRSG plug loads we see the conditioning load of the
buildings driven by internal loads, ventilation, and infiltration, not
envelope. Related to the previous comment in this thread from Maria:

?I am curious about the reasoning behind Nathan?s comment that ?? 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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.?

Her comment made me realize I?m suffering a bit from selection-bias. The
projects I tend to model are the newest multifamily projects to hit the
market. These projects in Seattle are almost all studios and 1 BR, with a
few 2 BR and penthouses sprinkled in. They aren?t serving as housing for
families, but more professionally-employed individuals, who don?t cook
much, who probably concentrate their electronics (laptop plus maybe a flat
screen) more than the typical American family, and certainly do less
laundry. Some of the trend on housing design seems to be minimal living
space and more amenities. That is probably why the national averages for
dwelling unit plug loads seem high for THE TYPE OF PROJECTS I WORK ON.

Hope that makes more sense (given some reflection).

*Nathan Miller, PE, LEED AP BD+C** ? **Mechanical Engineer/Senior Energy
Analyst*

*RUSHING* | *O* 206-285-7100 | *C* 207-650-3942

*www.rushingco.com *

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Chris Jones via Equest-users
*Sent:* Tuesday, March 14, 2017 7:46 AM
*To:* David Griffin II ; Maria Karpman <
maria.karpman at karpmanconsulting.net>; Michael Campbell ;
Joe Huang
*Cc:* equest-users at onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

My only comment is that developers and contractors like curtain wall
(window wall for high rise MURBS) because it is less expensive to install
and can be installed in any weather. This may be the main reason we see
glass towers north of the 49th.

[image: Title: RWDI - Description: RWDI logo]

*Christopher Jones, **P.Eng. *| Senior Energy Analyst
*RWDI*
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *David Griffin
II via Equest-users
*Sent:* Monday, March 13, 2017 7:46 PM
*To:* Maria Karpman; Michael Campbell; Joe Huang
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

I thought I might chime in on this discussion as well to drive a few points
home.

I have attached a file illustrating a graph to explain Joe?s comment below.
It shows diminishing returns from increased insulation. When it comes to
effective envelope ECMs for projects. I focus on two very important things:

1) Lower infiltration will save you more energy than any other
envelope ECM. However, it is hard to get an owner to buy off on this and
enforce the requirement with the contractor. Typically, an envelope
consultant will be brought in to assist the architect with details,
supervise the contractor during construction, and test the building (or a
portion thereof) to verify performance. You can see how something like this
is hard sell to an owner because it can be a costly process, and if the
building fails the blower door test, the contractor has a $$ issue and the
a lot of rework.

2) Window-to-Wall Ratio (WWR) reduction is great. On the curve
illustrated in the attached file, you essentially replace an expensive
window with a cheaper wall assembly and saving more energy! It?s a true
win-win-win. However, windows exist for more reasons than daylight
controls. Comfort and views are essential for occupants. Some architects
may also argue they are essential for aesthetics as well, so you have to
have a target in mind for the project you are willing to negotiate. On
commercial projects, I generally shoot for 25% WWR.

3) Window upgrades are next since they have the most potential to save
energy on the illustrated curve. Since you tried to minimize the WWR on #2,
this ECM will be cheaper than it would have been otherwise ? always saving
the client $$ J This includes glazing and frames.

4) After all three of the above items are addressed, I start to talk
about added insulation in the walls, roof, etc.

Anyway, this is my approach on new construction. Is this what you guys see,
or am I missing something?

Let me know.

[image: Image removed by sender. ARCH | NEXUS]

DAVID W. GRIFFIN II

BEMP
ENERGY ANALYST

2505 E Parleys Way
Salt Lake City, UT 84109

*Office* 801.924.5028

archnexus.com

[image: Image removed by sender. Twitter]
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Image removed by sender. Facebook]
[image:
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[image:
Image removed by sender. LinkedIn]

*From:* Maria Karpman via Equest-users [
mailto:equest-users at lists.onebuilding.org
]
*Sent:* Friday, March 10, 2017 9:24 PM
*To:* Michael Campbell; Joe Huang
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

Few more thoughts on this:

1) I agree with Joe and David that R-19 ??has already captured most of
the energy losses (or savings) for the wall?. R-19 is better than 90.1 2016
requirements for steel-framed wall in climate zone 4A, and since 90.1
requirements are set taking into account cost effectiveness, it is not
surprising that further improvement does not often pay off.

2) Overwhelming majority of high performance multifamily projects have
efficient heating systems, often condensing boilers or VRF HPs, which
lowers heating costs and potential savings from envelope improvements.

3) Most multifamily projects in North East have gas heating, and gas
is cheap compared to electricity. For example EPA EStar MFHR projects in NY
typically use $0.15/kWh and $1/Therm in performance rating calculations,
which effectively makes BTU of electricity ~4.4 times more expensive than
BTU of gas. This further shrinks contribution of heating toward the total
building energy $, and reduces potential savings from envelope
improvements. (Using source energy instead of $ in performance rating
calculations makes envelope improvements more appealing, because with EPA
PM site-to-source conversions BTU of electricity has only ~ 3 times greater
weight than BTU of gas.)

4) I am curious about the reasoning behind Nathan?s comment that ??
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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Michael Campbell via Equest-users
*Sent:* Thursday, March 09, 2017 9:55 PM
*To:* Joe Huang
*Cc:* equest-users
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

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.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Ha, this conversation has sort of gone off the rails from the initial question being asked, but I?ll continue to pile-on as well.

Here is some anecdotal information regarding DHW demand?

Maria pasted in a table that I am familiar with which indicates some starting-point-assumptions for DHW in multifamily buildings for different occupancies. Since images don?t show up in the archives, I?ll type a summary here for posterity:

Demand: Residential Occupancy Type: Baseline Daily DHW use (gal/occ/day)- Excluding Clothes/Dishwashers
Low All occupants working, seniors, middle income, and higher population density 12 gal/day
Medium Mix of working/non-working occupants, mixture of age groups, medium pop density 25 gal/day
High High % of children, low income, public assistance, no working occupants 44 gal/day

The interesting data point I have to compare to this table is the Seattle Housing Authority has provided guidance to design teams working on their projects (low-income, subsidized, affordable housing multifamily projects) that the actual metered DHW demand from their current generation of buildings is only about 12-15 gal/occ/day. And that includes laundry and dishwashing (often done by hand, not dishwashers). Compare that to the 44 gal/occ/day you might otherwise assume for this project type per the table.

They have been pretty aggressive in making sure low-flow fixtures are specified, but other than that it again indicates that any of this national guidance should be taken with a grain of salt. Their projects do tend to be very high occupant density, so it suggests that the density variable might be more important than the occupancy type?

Sincerely,

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

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

Good point Nathan ? it makes sense that population density should trump
other factors. Even if low flow showers and faucets run 24/7, they can only
deliver so much hot water. It?s a good idea to check equivalent full load
hours (EFLH) of water heaters on projects with high usage and savings
associated with that end use (e.g. multifamily, gyms, dormitories). We
sometimes see models with EFLH way over 8760 hrs/yr based on the capacity
of the specified units J. I do think operating assumptions should be
prescribed for the compliance modeling to close loopholes, and also to help
modelers use inputs that are a better fit for their projects, with
understanding that these are just best guess estimates, and that the actual
post-occupancy usage will be different.

I missed Joe?s post from yesterday - it's funny that Chinese want 1 ACH of
their famously fresh outdoor air inside residential units J. And I like
your "modeling by intent" term. It will come handy when discussing
ventilation/infiltration matters, because between mechanical and energy
code, US air is regulated to the teeth, and modeling by intent is the
standard practice J.

Nathan, you wrote ?When we do the envelope sensitivity analysis on high
rise multifamily projects ? the glazing percentage isn?t as bad a penalty
?. with a WSHP system serving residences. If it is more of a traditional
hydronic job, that penalty seems to go up a little?.? I would normally
expect an opposite trend. There was a nice article on that in ASHRAE
Journal (HVAC Selection for Envelope-Dominated Buildings
).
The outcome for a particular project would depend on the units used to
express the penalty (site energy, source energy, or energy cost), and
efficiencies of WSHPs, boilers, pumps, fans, etc. But since the original
question in this thread was for a project in NJ that may be participating
in EPA HRMF EStar program, we commonly see a lower $ penalty from high WWR
for hydronic system (w/condensing boiler and HW baseboards) versus WSHP. Or
to rephrase, the hydronic system is typically more efficient than WSHP, and
is thus more forgiving to envelope deficiencies.

*From:* Nathan Miller [mailto:nathanm at rushingco.com]
*Sent:* Thursday, March 16, 2017 9:24 AM
*To:* Nicholas Caton ; Maria Karpman
; Chris Jones <
Christopher.Jones at rwdi.com>; David Griffin II ;
Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org; Krishnan.gowri at autodesk.com
*Subject:* RE: [Equest-users] Wall insulation in multifamily buildings

Ha, this conversation has sort of gone off the rails from the initial
question being asked, but I?ll continue to pile-on as well.

Here is some anecdotal information regarding DHW demand?

Maria pasted in a table that I am familiar with which indicates some
starting-point-assumptions for DHW in multifamily buildings for different
occupancies. Since images don?t show up in the archives, I?ll type a
summary here for posterity:

Demand: Residential Occupancy Type:

Baseline Daily DHW use (gal/occ/day)- Excluding
Clothes/Dishwashers

Low All occupants working, seniors, middle income,
and higher population density 12 gal/day

Medium Mix of working/non-working occupants, mixture of age
groups, medium pop density 25 gal/day

High High % of children, low income, public
assistance, no working
occupants 44 gal/day

The interesting data point I have to compare to this table is the *Seattle
Housing Authority* has provided guidance to design teams working on their
projects (low-income, subsidized, affordable housing multifamily
projects) *that
the actual metered DHW demand from their current generation of buildings is
only about 12-15 gal/occ/day*. And that includes laundry and dishwashing
(often done by hand, not dishwashers). Compare that to the 44 gal/occ/day
you might otherwise assume for this project type per the table.

They have been pretty aggressive in making sure low-flow fixtures are
specified, but other than that it again indicates that any of this national
guidance should be taken with a grain of salt. Their projects do tend to be
very high occupant density, so it suggests that the density variable might
be more important than the occupancy type?

Sincerely,

*Nathan Miller, PE, LEED AP BD+C** ? **Mechanical Engineer/Senior Energy
Analyst*

*RUSHING* | *O* 206-285-7100 | *C* 207-650-3942

*www.rushingco.com *

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *Maria Karpman
via Equest-users
*Sent:* Tuesday, March 14, 2017 11:53 AM
*To:* Nathan Miller ; Chris Jones <
Christopher.Jones at rwdi.com>; David Griffin II ;
Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

To David?s comment about infiltration (?Lower infiltration will save you
more energy than any other envelope ECM.?), there are a few caveats.

a) To document infiltration-related savings in App G models (e.g. for
LEED), the baseline air leakage would be modeled as 0.4 CFM/SF *@ 75Pa*
(90.1 2013 G3.1.1.4). 90.1 2013 Table G further requires that infiltration
inputs in the simulation tool are adjusted to account for factors such as
weather and ??. HVAC system operation?.?. 90.1 leaves these adjustments to
the modeler, but PNNL?s Infiltration Modeling Guidelines for Commercial
Building Energy Analysis

mentions in passing (Note 2 on p.6) that ?The total building infiltration
schedule fraction will be 1.0 when all heating, ventilation and air
conditioning (HVAC) systems are off and 0.25 when the HVAC systems are in
operation.? (It?s good that they used Energy Plus for the study, so results
must still be accurate in spite of this seemingly arbitrary assumption
J.) Since
HVAC systems are operating 24/7 in multifamily, infiltration schedule in
the baseline and proposed design would have to be set to 0.25 of the peak
if we follow the PNNL study, which very significantly reduces
infiltration-related heating load in the model. (The infiltration load is
shown in LS-F report.) As a side note, with LEED v3 and v4,
infiltration-reduction credit can be claimed via exceptional calculation
methods, or by using LEED pilot credit

which is based on 90.1 2016 Appendix G modeling rules with the appropriate
adjustment to performance targets and point scale. (I recommend that you
check out this credit, as it simplifies the baseline model.)

b) Potential savings from infiltration reduction should be considered
in conjunction with the specified ventilation strategy. In North East, it
is overwhelmingly common to have 100% OA units serving multifamily
corridors with no exhaust, and continuously running rooftop exhaust fans
serving kitchens and bathrooms in apartments on one vertical stack with no
make-up. Both supply and exhaust rates are often grossly oversized compared
to the minimum CFM required by code, and since the relevant code
(summarized here
)
requires that apartments are compartmentalized and envelope is air-tight,
it creates an interesting conundrum for air J. Balanced ventilation is
still a rarity in NE even in high performance buildings. Old editions of
ASHRAE Fundamentals had a way of taking into account this dynamics (see
below), which was crude but better than ?one size fits all? approach in the
PNNL study. So I?d use ASHRAE?s method in lieu of PNNL?s to model
infiltration savings for LEED, and to decide whether tighter envelope
should be pursued for a given project.

Nathan, thanks for clarifying your plug load observations. Your explanation
makes total sense. On the related note, the latest LEED EAc1 template
includes the following info (based on ASHRAE Applications handbook) for the
impact of occupant demographics on HW usage. Perhaps you can reference this
data (also used in EPA HRMF program) to justify modeling lower plug loads
for certain projects. But I can also see that rating authorities may reject
this logic and insist on using ?typical? plug loads in the model,
recognizing that occupant demographics may change over the life of the
building.

*From:* Nathan Miller [mailto:nathanm at rushingco.com]
*Sent:* Tuesday, March 14, 2017 9:38 AM
*To:* Chris Jones ; David Griffin II <
DGriffin at archnexus.com>; Maria Karpman ;
Michael Campbell ; Joe Huang <
yjhuang at whiteboxtechnologies.com>
*Cc:* equest-users at onebuilding.org
*Subject:* RE: [Equest-users] Wall insulation in multifamily buildings

I can?t think of the last high-rise project I worked on that stayed
anywhere near 25% WWR. 40-50% is very much the norm in Seattle (climate
where I do most of my modeling work). Owners want 60%+. Mid-rise resi (and
mixed use), I do tend to see 25-35% WWR as typical.

When we do the envelope sensitivity analysis on high rise multifamily
projects, honestly the glazing percentage isn?t as bad a penalty as you?d
think. Like on the order of 0.1-0.25% energy penalty for each 1% increase
in glazing when we are already in the 40%+ glazing band, meaning we are
comparing extra glazing to opaque wall. This is with a WSHP system serving
residences. If it is more of a traditional hydronic job, that penalty seems
to go up a little, but still isn?t a killer.

Using standard ESMFHRSG plug loads we see the conditioning load of the
buildings driven by internal loads, ventilation, and infiltration, not
envelope. Related to the previous comment in this thread from Maria:

?I am curious about the reasoning behind Nathan?s comment that ?? 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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.?

Her comment made me realize I?m suffering a bit from selection-bias. The
projects I tend to model are the newest multifamily projects to hit the
market. These projects in Seattle are almost all studios and 1 BR, with a
few 2 BR and penthouses sprinkled in. They aren?t serving as housing for
families, but more professionally-employed individuals, who don?t cook
much, who probably concentrate their electronics (laptop plus maybe a flat
screen) more than the typical American family, and certainly do less
laundry. Some of the trend on housing design seems to be minimal living
space and more amenities. That is probably why the national averages for
dwelling unit plug loads seem high for THE TYPE OF PROJECTS I WORK ON.

Hope that makes more sense (given some reflection).

*Nathan Miller, PE, LEED AP BD+C** ? **Mechanical Engineer/Senior Energy
Analyst*

*RUSHING* | *O* 206-285-7100 | *C* 207-650-3942

*www.rushingco.com *

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Chris Jones via Equest-users
*Sent:* Tuesday, March 14, 2017 7:46 AM
*To:* David Griffin II ; Maria Karpman <
maria.karpman at karpmanconsulting.net>; Michael Campbell ;
Joe Huang
*Cc:* equest-users at onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

My only comment is that developers and contractors like curtain wall
(window wall for high rise MURBS) because it is less expensive to install
and can be installed in any weather. This may be the main reason we see
glass towers north of the 49th.

[image: Title: RWDI - Description: RWDI logo]

*Christopher Jones, **P.Eng. *| Senior Energy Analyst
*RWDI*
901 King Street West, Suite 400, Toronto, ON M5V 3H5 Canada
Tel: (519) 823-1311 ext 2052
rwdi.com

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
] *On Behalf Of *David Griffin
II via Equest-users
*Sent:* Monday, March 13, 2017 7:46 PM
*To:* Maria Karpman; Michael Campbell; Joe Huang
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

I thought I might chime in on this discussion as well to drive a few points
home.

I have attached a file illustrating a graph to explain Joe?s comment below.
It shows diminishing returns from increased insulation. When it comes to
effective envelope ECMs for projects. I focus on two very important things:

1) Lower infiltration will save you more energy than any other
envelope ECM. However, it is hard to get an owner to buy off on this and
enforce the requirement with the contractor. Typically, an envelope
consultant will be brought in to assist the architect with details,
supervise the contractor during construction, and test the building (or a
portion thereof) to verify performance. You can see how something like this
is hard sell to an owner because it can be a costly process, and if the
building fails the blower door test, the contractor has a $$ issue and the
a lot of rework.

2) Window-to-Wall Ratio (WWR) reduction is great. On the curve
illustrated in the attached file, you essentially replace an expensive
window with a cheaper wall assembly and saving more energy! It?s a true
win-win-win. However, windows exist for more reasons than daylight
controls. Comfort and views are essential for occupants. Some architects
may also argue they are essential for aesthetics as well, so you have to
have a target in mind for the project you are willing to negotiate. On
commercial projects, I generally shoot for 25% WWR.

3) Window upgrades are next since they have the most potential to save
energy on the illustrated curve. Since you tried to minimize the WWR on #2,
this ECM will be cheaper than it would have been otherwise ? always saving
the client $$ J This includes glazing and frames.

4) After all three of the above items are addressed, I start to talk
about added insulation in the walls, roof, etc.

Anyway, this is my approach on new construction. Is this what you guys see,
or am I missing something?

Let me know.

[image: Image removed by sender. ARCH | NEXUS]

DAVID W. GRIFFIN II

BEMP
ENERGY ANALYST

2505 E Parleys Way
Salt Lake City, UT 84109

*Office* 801.924.5028

archnexus.com

[image: Image removed by sender. Twitter]
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Image removed by sender. Facebook]
[image:
Image removed by sender. Youtube]
[image:
Image removed by sender. LinkedIn]

*From:* Maria Karpman via Equest-users [
mailto:equest-users at lists.onebuilding.org
]
*Sent:* Friday, March 10, 2017 9:24 PM
*To:* Michael Campbell; Joe Huang
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

Few more thoughts on this:

1) I agree with Joe and David that R-19 ??has already captured most of
the energy losses (or savings) for the wall?. R-19 is better than 90.1 2016
requirements for steel-framed wall in climate zone 4A, and since 90.1
requirements are set taking into account cost effectiveness, it is not
surprising that further improvement does not often pay off.

2) Overwhelming majority of high performance multifamily projects have
efficient heating systems, often condensing boilers or VRF HPs, which
lowers heating costs and potential savings from envelope improvements.

3) Most multifamily projects in North East have gas heating, and gas
is cheap compared to electricity. For example EPA EStar MFHR projects in NY
typically use $0.15/kWh and $1/Therm in performance rating calculations,
which effectively makes BTU of electricity ~4.4 times more expensive than
BTU of gas. This further shrinks contribution of heating toward the total
building energy $, and reduces potential savings from envelope
improvements. (Using source energy instead of $ in performance rating
calculations makes envelope improvements more appealing, because with EPA
PM site-to-source conversions BTU of electricity has only ~ 3 times greater
weight than BTU of gas.)

4) I am curious about the reasoning behind Nathan?s comment that ??
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
overestimate that energy use?. EPA?s plug loads are 4 times lower than
COMNET?s for Multifamily/Residential, and are also lower than the loads in
PNNL High Rise Apartment prototype. Passive house protocols are the only
two sources that I know off that prescribe lower in-unit loads -
Passivehaus Institute (PHI) loads are less than half of EPA?s, and US
passive house off-shoot (PHIUS) loads are 15% lower than EPA?s. In general,
in-unit electricity consumption can vary significantly depending on
occupant demographics (by factor of 10 based on some papers), so both
COMNET and PHI may be correct for *some* apartments. We compared EPA
assumptions to the in-unit electricity usage in several apartment complexes
in NJ, and the numbers were in the right ballpark, so appear to represent
reasonable averages.

*From:* Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] *On
Behalf Of *Michael Campbell via Equest-users
*Sent:* Thursday, March 09, 2017 9:55 PM
*To:* Joe Huang
*Cc:* equest-users
*Subject:* Re: [Equest-users] Wall insulation in multifamily buildings

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.

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200

That schedule for modeling infiltration has always been a sore spot for me too. It could be applicable for an upper floor of a well-sealed building, but not for lower floors if the doors are open a lot. Years ago when I was working on the airport here in Madison the building simply didn?t pressurize during the day. It seemed like a door was always open somewhere.

In my opinion, vestibules and lobbies should be modeled with much higher infiltration rates than other perimeter spaces, especially if they have electric heaters while the rest of the building is heated mainly with natural gas.

Keith Swartz, PE | Senior Energy Engineer
Seventhwave
608.210.7123 seventhwave.org

via Equest-users's picture
Joined: 2016-07-15
Reputation: 200