[Equest-users] Wall insulation in multifamily buildings
Joe Huang via Equest-users
equest-users at lists.onebuilding.org
Wed Mar 15 16:28:52 PDT 2017
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"
On 3/15/2017 3:23 PM, Nicholas Caton wrote:
>
> 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 <mailto: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 <nathanm at rushingco.com>; Chris Jones <Christopher.Jones at rwdi.com>;
> David Griffin II <DGriffin at archnexus.com>; Michael Campbell <mcamp1206 at gmail.com>; 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
> <http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.510.8703&rep=rep1&type=pdf>
> 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
> <http://www.usgbc.org/credits/new-construction-core-and-shell-schools-new-construction-retail-new-construction-healthc-110>
> 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
> <https://buildingscience.com/sites/default/files/document/ba-1507_ventilation_guidance_final_measure_guideline.pdf>)
> 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 <mailto:nathanm at rushingco.com>]
> *Sent:* Tuesday, March 14, 2017 9:38 AM
> *To:* Chris Jones <Christopher.Jones at RWDI.com <mailto:Christopher.Jones at RWDI.com>>;
> David Griffin II <DGriffin at archnexus.com <mailto:DGriffin at archnexus.com>>; Maria Karpman
> <maria.karpman at karpmanconsulting.net <mailto:maria.karpman at karpmanconsulting.net>>;
> Michael Campbell <mcamp1206 at gmail.com <mailto:mcamp1206 at gmail.com>>; Joe Huang
> <yjhuang at whiteboxtechnologies.com <mailto:yjhuang at whiteboxtechnologies.com>>
> *Cc:* equest-users at onebuilding.org <mailto: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 <http://www.rushingco.com/>*
>
> *From:*Equest-users [mailto:equest-users-bounces at lists.onebuilding.org
> <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 <DGriffin at archnexus.com <mailto:DGriffin at archnexus.com>>; Maria
> Karpman <maria.karpman at karpmanconsulting.net
> <mailto:maria.karpman at karpmanconsulting.net>>; Michael Campbell <mcamp1206 at gmail.com
> <mailto:mcamp1206 at gmail.com>>; Joe Huang <yjhuang at whiteboxtechnologies.com
> <mailto:yjhuang at whiteboxtechnologies.com>>
> *Cc:* equest-users at onebuilding.org <mailto: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 49^th .
>
> **
>
> Title: RWDI - Description: RWDI logo <http://www.rwdi.com/assets/logos/RWDI-logo.gif>
>
>
>
> *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 <http://www.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 <mailto: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 $$ issue and the a lot of rework.
>
> 2)Window-to-Wall Ratio (WWR) reduction is great. On the curve illustrated in the
> attached file, you essentially replace an expensive window with a cheaper wall assembly
> and saving more energy! It’s a true win-win-win. However, windows exist for more reasons
> than daylight controls. Comfort and views are essential for occupants. Some architects
> may also argue they are essential for aesthetics as well, so you have to have a target
> in mind for the project you are willing to negotiate. On commercial projects, I
> generally shoot for 25% WWR.
>
> 3)Window upgrades are next since they have the most potential to save energy on the
> illustrated curve. Since you tried to minimize the WWR on #2, this ECM will be cheaper
> than it would have been otherwise – always saving the client $$ JThis 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 removed by sender. ARCH | NEXUS <http://www.archnexus.com>
>
>
>
>
>
> DAVID W. GRIFFIN II
>
> BEMP
> ENERGY ANALYST
>
> 2505 E Parleys Way
> Salt Lake City, UT 84109
>
> *Office* 801.924.5028
>
>
>
> archnexus.com <http://www.archnexus.com>
>
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> sender. Facebook
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> sender. LinkedIn <https://www.linkedin.com/company/architectural-nexus>
>
> *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 <mailto: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
> <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 <yjhuang at whiteboxtechnologies.com <mailto:yjhuang at whiteboxtechnologies.com>>
> *Cc:* equest-users <equest-users at lists.onebuilding.org
> <mailto:equest-users at lists.onebuilding.org>>
> *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.
>
> On Thu, Mar 9, 2017 at 6:32 PM, Joe Huang via Equest-users
> <equest-users at lists.onebuilding.org <mailto: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 94556
>
> yjhuang at whiteboxtechnologies.com <mailto:yjhuang at whiteboxtechnologies.com>
>
> http://weather.whiteboxtechnologies.com for simulation-ready weather data
>
> (o)(925)388-0265 <tel:%28925%29%20388-0265>
>
> (c)(510)928-2683 <tel:%28510%29%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] *On
> Behalf Of *Nathan Miller via Equest-users
> *Sent:* Thursday, March 09, 2017 2:52 PM
> *To:* Michael Campbell <mcamp1206 at gmail.com> <mailto:mcamp1206 at gmail.com>
> *Cc:* equest-users at lists.onebuilding.org <mailto: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 <tel:%28206%29%20285-7100> |*C*207-650-3942
> <tel:%28207%29%20650-3942>
>
> *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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