[Equest-users] Exterior insulation vs Exterior with Cavity insulation

[nic]

Again thank you for the insight.  I have attached heat transfer graphs from
eQuest that demonstrate (I believe) what you were getting at between the
different constructions' rates.  As for the utility rates, I have yet to
explore anything beyond a simple structure so peak demand shaving could
come into play here.  THe peak is showing something far better than the EUI
for that run in particular, but the HVAC energy in both kWh and Total Mbtu
are even worse at ~ 18% under the baseline.

Another monkey wrench shows up when I increase the thickness of the
continuous insulation with an improved R-Value of 18 ( > 12.)  Again the
results show a decrease in savings of 1% worse than ALT 1.

On Wed, Jan 25, 2012 at 4:18 PM, Nikola Kravik <NKravik at willdan.com> wrote:

> I’m guessing that due to no fill insulation(R-0 insulation within the
> cavity 16 OC) you have large heat transfer between in/out through the studs
> and less thermal delay-more energy consumption(heat or cool). Since it’s
> school/educational I assume you don’t operate 365/24/7 but much less hours.
>
>
>
> Depending on HeatingDegreeDays, HDD or CoolingDD(Climate factor) for your
> project you may be operating mostly in heating season or mostly in cooling
> season. Rates can vary for gas and electric, so do the tier utility
> structure so you may be penalized for operating in certain season(certain
> hours of the day). I wouldn’t rely on the 0.003 U difference. Think of it
> as a distance from A to point B driving with a car. Let’s put a point C
> half way between the A and B point. If I drive 55mph from A to B, I get
> 40mpg, if I drive 85mph from A to mid point C and 20 mph from C to end
> point B I guarantee you get probably 30mpg average (25% reduction in speed
> over the same length), so same analogy on the wall.
>
>
>
> So either you’re overpaying for heating or cooling or ventilation
> (conditioning the OA). Don’t just look at the cumulative  EUI, but check
> the therms and kWh consumption between the alternatives and see the peak
> demand.
>
>
>
> Best,n
>
>
>
>
>
> *From:* nic [mailto:ffonics at gmail.com]
> *Sent:* Wednesday, January 25, 2012 1:31 PM
> *To:* Nikola Kravik
> *Subject:* Re: [Equest-users] Exterior insulation vs Exterior with Cavity
> insulation
>
>
>
> Sorry that I wasn't more clear, but I am questioning the major decrease in
> energy performance between the baseline and the ALT 1 of 8%.  The U-value
> difference is about 0.003, so I would expect a much smaller decrease around
> 0-0.5%.  THe problem I am having is with the exterior only application of
> ALT 1 vs exterior and cavity fill insulation in the baseline.
>
>
>
> ie. 90.1 Baseline is R13 fill + R7.5 continuous insulation
>
> ALT 1 is R0 fill + R12 continuous insulation. (very common installation)
>
>
>
> Thanks,
>
> nic
>
>
>
> On Wed, Jan 25, 2012 at 3:21 PM, Nikola Kravik <NKravik at willdan.com>
> wrote:
>
> I guess your “issue” or question relates to the amount of savings so
> you’re surprised how little savings you get increasing your wall insulation
> thickness?
>
>
>
> Don’t be surprised since you mentioned is internal load dominated plus
> there are other factors like climate, orientation and wall area that play a
> role so without the building description I don’t see any issue with the
> results you’re showing.
>
>
>
> Best,n
>
>
>
> Nikola Kravik, LEED AP [image: Description:
> cid:image001.gif at 01CB9AE0.30118F00]
> Project Engineer
>
> *Willdan Energy Solutions*
>
> 11875 Dublin Boulevard, Suite A-201
> Dublin, California 94568
> T. 925.556.2600 ext. 1228
>
> C. 925.719.5883
> F. 925.556.1444
>
> nkravik at willdan.com
> www.willdan.com/energy
>
>
>
> [image: WD_tagend_300rgb]
>
>
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *nic
> *Sent:* Wednesday, January 25, 2012 1:01 PM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] Exterior insulation vs Exterior with Cavity
> insulation
>
>
>
> I am attempting to establish a few alternatives compared to an ASHRAE 90.1
> Wall construction. This much seems pretty straightforward with the only
> change between alternatives being a different construction applied to the
> exterior above grade walls. All alternatives are modeled as delayed and
> with layered materials. The wall from outside to inside is stucco(finish)
> R0.08 + Cont. Insulation R-VARIES + Ext sheathing R0.56 +
> Framing/Insulation R-VARIES* + Int. Sheating R0.56 (air films do not
> change, infiltration does not change, etc.)
>
> *framing 16" Mtl OC taken into account
>
> <<< I should mention the building is very much internal load dominant as
> an education building with a lot of laboratory space >>>
>
> The problem described below has been input into eQuest using material
> properties for all continuous insulation and a representative R-value for
> framing/insulation.
>
>
>
>
> BASELINE - 90.1 - R6* + 7.5 ci na
>
> ALT1 - only ext insulation R0.9 + 12 ci -8% savings (% energy under EUI -
> kBtu/sf/yr)
>
> ALT2 - improved ext insulation R6* + 12 ci +1% savings
>
> ALT3 - improved cavity insulation R7.1* + 7.5 ci +1% savings
>
> ALT4 - all insulation improved R7.1* + 12 ci +2% savings
>
>
>
> I guess the question really is; does the issue lie within the vav systems
> or the envelope or both?
>
>
>
> As a novice, I greatly appreciate any help.
>
>
>
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