[Equest-users] building shade effect (UNCLASSIFIED)
Bobby Sy
rsg4999 at gmail.com
Fri Jun 1 05:35:30 PDT 2012
Hello everyone,
My apologies for my vague query the last time, hope I’ll answer all your
probing questions and forgive my innocence in using eQuest.
The project will be located in South East Asia, Climate zone 1, no heating
for HVAC system. The tower has ellipse shape perimeter wrapped by the
louvers (± 80%) and every floor decreases perimeter. It is currently on
design development stage that is why we are trying some more EEM’s to
achieve at least 7 EAc1 points, not yet for LEED submission though.
It turned out that the conflict was when the HVAC capacity for models with
and without shade is the same which is based from the equipment schedule
that I got. What I was not able to do is to auto size the capacity for a
valid result.
Now, another group of simulators are trying to figure out the envelope
thermal properties improvement by having those louvers, which the HVAC
designer could use to recalculate the peak load. Then I’ll use the SC to my
next run. Improving the envelope alone may not have significant effect but
downsizing the equipment capacities will surely do.
I know I was a bit clumsy but I believe you guys would understand, working
on multiple LEED projects is risky. Lots of thanks to Nick’s insights about
energy modeling meaning and value! I shared it with my boss; my way of
saying I need extra hands.
Now that I know other possibilities, I will try to do explore more as you
guys suggested. Some questions:
1. Is there a proper way of calculating the transmittance for tubular
louvers?
2. How do I input SFF and GFF in eQuest? I am using version 3-64.
3. Is there a faster way to put each louver as a shade with its decreasing
ellipse perimeter every floor in “inp copy paste” method?
I’d like to thank all of you for sharing your thoughts and advice; it’s
very informative and helpful.
-Bob
On Fri, Jun 1, 2012 at 3:33 AM, Joe Huang
<yjhuang at whiteboxtechnologies.com>wrote:
> Bobby, others,
>
> I beg to differ, but I find it hard to believe that a louver system with
> the density shown on your picture on a building with a WWR of 60 will have
> only a 1% impact on the building energy use.
> What is the percent impact on the cooling energy use? In an office
> building in a tropical climate, as implied in your post, solar heat gain
> through windows can easily make up 30-50% of the building's cooling load,
> so if the solar is reduced by 30-50% due to louvers, I would expect a
> cooling load reduction around 10-20%, and maybe total building energy
> around 5-10%.
>
> When you interpret the results from eQUEST, remember that the program
> doesn't model at all the UV or long-wave interactions, etc., that you've
> mentioned to explain why the savings are
> so low. If you are modeling the louvers as a BUILDING-SHADE, make sure
> that the shade is positioned correctly in front of the glazing, that the
> TRANSMITTANCE and SHADE-SCHEDULE are
> appropriately defined, and that you also adjust the SKY-FORM-FACTOR and
> GND-FORM-FACTOR for the glazing, since the BUILDING-SHADE affects only the
> direct solar radiation and not the diffuse solar radiation. This is
> particularly important in a tropical location where there is a lot of
> diffuse radiation. The form factors are meant to be the amount (solid
> angle) of sky or ground
> that the glazing "sees". The defaults are 0.50 and 0.50, i.e., half sky
> and half ground. If you input only the SFF, DOE-2 would assume 1-SFF as
> the GFF. I've had trouble with that recently,
> so it's better to also input GFF at 0.50, or a little higher if you think
> there's reradiation due to the louvers.
>
> Joe
>
> Joe Huang
> White Box Technologies, Inc.
> 346 Rheem Blvd., Suite 108D
> Moraga CA 94556
> yjhuang at whiteboxtechnologies.**com <yjhuang at whiteboxtechnologies.com>
> www.whiteboxtechnologies.com
> (o) (925)388-0265
> (c) (510)928-2683
> "building energy simulations at your fingertips"
>
>
>
> On 5/31/2012 11:53 AM, Eurek, John S NWO wrote:
>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>> It is all up to interpretation. The key to interpreting the information
>> is to first know what you want the information to say, then find the data
>> to back it up.
>>
>> If you want to sell the solar shades, focus on the reduction of solar
>> radiation. (Truth: A small part of the whole)
>> If you want to talk the architect out of it, highlight that it only saves
>> 1%. (Truth: Energy savings comes from having many small energy savings
>> methods working together.)
>>
>> 1 important question - How much does the architect like the solar shade?
>>
>> If the solar shades are just an option, the next step is to do a life
>> cycle cost analysis. You already have the energy model which is the
>> hardest part. If you can find the cost of the solar shades and energy
>> costs you could do it in 20 minutes or less.
>>
>> If the solar shades are his pet, it won't be too hard to find numbers
>> telling him how wonderful they are.
>>
>> *his/hers
>> -----Original Message-----
>> From: equest-users-bounces at lists.**onebuilding.org<equest-users-bounces at lists.onebuilding.org>[mailto:
>> equest-users-bounces@**lists.onebuilding.org<equest-users-bounces at lists.onebuilding.org>]
>> On Behalf Of R B
>> Sent: Thursday, May 31, 2012 1:26 PM
>> To: eQUEST Users List
>> Subject: Re: [Equest-users] building shade effect
>>
>> Have not followed the thread in detail - but here are some things I have
>> found about windows - first off not a whole lot of saving at the
>> yearly-building level. If you look at the peak breakdown for a window - the
>> U-value related conductance is 2/3rds vs the solar radiation (1/3rd) -
>> atleast for the one model that I was looking at. As others have noted,
>> almost 40-50% of the energy consumption is from lights/plug loads.
>>
>> You might want to look at just the perimeter zones and see what happens
>> to the energy consumption reduction in just those zones?
>>
>> You can also look at just the LS-D reports to see what the % savings are.
>> Sometimes it helps in saying that reductions are x% of the cooling load
>> (without considering the HVAC inefficiencies) - which will be a higher
>> number.
>>
>>
>>
>>
>> On Thu, May 31, 2012 at 9:16 AM, Nick Caton<ncaton at smithboucher.com>
>> wrote:
>>
>>
>> Feeling confident in your modeling approach is very much
>> important, but before running deep into alternate methods, I would seek
>> perspective on what % improvement is even feasible. Perhaps a 1% net
>> improvement is quite impressive, all things considered? Considering static
>> shades can be simultaneously helpful and harmful thermally over a year, a
>> few iterations exploring different transmittance values may be enlightening.
>>
>>
>>
>> Doing so, you might be able to establish a ceiling for maximum
>> possible improvement with such shades, and suggest a more optimized
>> exoskeleton spacing or similar.
>>
>>
>>
>> There may also be a lesson in here about how to present results in
>> a fashion that both informs and appeases the design team. Perhaps the
>> shades may not have an impressive net annual baseline % improvement, but
>> significant thermal comfort and glare issues are averted, and cooling plant
>> capacities can be lowered by slicing the summertime solar loads.... I would
>> also caution to check the solar loads are indeed cutting down as
>> anticipated if you aren't sure of your approach.
>>
>>
>>
>> Best of luck!
>>
>>
>>
>> ~Nick
>>
>>
>>
>> cid:489575314 at 22072009-0ABB
>>
>>
>>
>> NICK CATON, P.E.
>>
>> SENIOR ENGINEER
>>
>>
>>
>> Smith& Boucher Engineers
>>
>>
>> 25501 west valley parkway, suite 200
>>
>> olathe, ks 66061
>>
>> direct 913.344.0036
>>
>> fax 913.345.0617
>>
>> www.smithboucher.com<http://**www.smithboucher.com<http://www.smithboucher.com>
>> >
>>
>>
>>
>> From: equest-users-bounces at lists.**onebuilding.org<equest-users-bounces at lists.onebuilding.org>[mailto:
>> equest-users-bounces@**lists.onebuilding.org<equest-users-bounces at lists.onebuilding.org>]
>> On Behalf Of Umesh Atre
>> Sent: Thursday, May 31, 2012 8:30 AM
>> To: Bobby Sy; equest-users at lists.**onebuilding.org<equest-users at lists.onebuilding.org>
>> Subject: Re: [Equest-users] building shade effect
>>
>>
>>
>>
>>
>> Bob,
>>
>> What is the project location and how is the building oriented? Do
>> these louvers run across the entire height of the building?
>>
>> If you have a heavily internal load dominated (office) building,
>> the building skin effect might be minimal, but then again the shading design
>>
>> you have in this project looks pretty dense and assuming you have
>> a need for cooling, my gut feeling is that 1% is on the lower side.
>>
>>
>>
>>
>>
>>
>>
>> ______________________________**__
>>
>> From: equest-users-bounces at lists.**onebuilding.org<equest-users-bounces at lists.onebuilding.org>[mailto:
>> equest-users-bounces@**lists.onebuilding.org<equest-users-bounces at lists.onebuilding.org>]
>> On Behalf Of Bobby Sy
>> Sent: Wednesday, May 30, 2012 10:19 PM
>> To: equest-users at lists.**onebuilding.org<equest-users at lists.onebuilding.org>
>> Subject: [Equest-users] building shade effect
>>
>> Hello everyone!
>>
>>
>>
>> I am working on a project, a high rise office building. The
>> architect added louvers as part of the design which I admire for
>> sophistication. Attached is a picture that shows the louvers outside for
>> shading. But, when I did the initial run, the effect of the louvers is only
>> around 1% energy improvement from the baseline.
>>
>>
>>
>> Please let me know if there is a better way to do it in eQuest.
>> What I did was to measure the louver thickness and proportioned it to the
>> glass area that it covers. I put the fraction as "Transmittance:" in
>> Building and Fixed Shades properties. Doe 2 help says:
>>
>>
>> TRANSMITTANCE
>>
>>
>> Fraction of incident solar radiation that is transmitted by the
>> shading surface. The default value is 0.0, which means the surface is
>> opaque. A value greater than 0.0 represents a device that passes some solar
>> radiation, such as a tree, lattice, or fabric. Using SHADE-SCHEDULE allows
>> seasonal variation in transmittance. Daylighting calculation assumes
>> TRANSMITTANCE = 0.
>>
>>
>>
>> The design team quite find it hard to believe that the louvers
>> have very minimal effect. I told them to consider the window to wall ratio
>> (almost 60%) and that fact that they will be using a clear glass, even with
>> these louvers partial UV rays still pass through the gaps that spreads
>> allover the glass surface that adds to the heat load for air conditioning.
>> Ive noticed to some of my other projects in tropical countries, building
>> shades don't have much effect to energy efficiency. Did anyone encounter
>> the same result with building shades?
>>
>>
>>
>>
>>
>> Thanks,
>>
>>
>>
>> Bob
>>
>>
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>>
>>
>>
>> Classification: UNCLASSIFIED
>> Caveats: NONE
>>
>>
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