Gated Community & Roof reflectivity

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Hello Group

I have just started working on my first energy modeling
project. I have two questions:

- How do I model roof reflectivity. I want to model a roof of 4 inch
concrete with 1 inch stucco at the bottom and top and cover the roof with
cool roof tiles. I am not sure how I can account for the energy efficiency
gains compared to base case through a high SRI roof.
- I am trying to model a large gated community with 330 villas and 7
other common buildings. As someone suggested on this group I am modeling
each building type separately and using excel to come up with a total
energy usage. But I am not sure how to model the street lighting and
landscape lighting at the exteriors. We plan to use solar street lights and
I want to demonstrate the savings through use of solar energy.

Many Thanks

Yusuf Turab

On 10 April 2012 00:32, nirupama lakshminarasimhan <

Yusuf Turab
Managing Director
IGBC Accredited Professional & LEED Green Associate
Y T Enterprises
18 A, Hamsa Layout ¦ R.S Puram ¦ Coimbatore - 641002

Tel: +91 936 310 2703
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Hello Group

- Why do I get unmet hours even when I select the auto size option in
the HVAC system? What is the point of auto sizing?
- Is there a way to simulate all 4 orientations and get an average
result for the base case?

Thanks
Yusuf Turab

Yusuf Turab
Managing Director
IGBC Accredited Professional & LEED Green Associate
Y T Enterprises
18 A, Hamsa Layout ¦ R.S Puram ¦ Coimbatore - 641002

Tel: +91 936 310 2703
Fax:<

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Classification: UNCLASSIFIED
Caveats: NONE

Consider you have 2 rooms, 1 room has 20 people for 1 hour a day, the other room has 1 person all day. If you select 1 piece of equipment using auto sizing, the equipment will make the 21 people comfortable for the one hour. The autosizing sizing is for the design condition.

Since the auto sizing balances for the case of 20 in one room and 1 in the other. When there are 0 people in 1 room and 1 in the other, you will likely get unmet load hours.

This is one of the many many many cases that cause unmet load hours, but a quick explanation of why you get unmet load hours using autosizing.

Autosizing = design case for the worst hour
Unmet load hours = does it work for the rest of the 8759 hours

John Eurek

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Thank you. I guess I have someway to go before I have system sizing and
unmet hours fully figured out. One more question:

- If I want to create multiple buildings of similar type, built up area
and construction but different conditioned spaces, interior layouts and
orientations. Can I simply make a copy of the old pd2 file and simply
change the footprint zone and orientation in the new file? I tried to do
this but I cannot see the 3D model of the new building.

Does this mean every model has to be created from scratch?

Many Thanks

Yusuf

Yusuf Turab
Managing Director
IGBC Accredited Professional & LEED Green Associate
Y T Enterprises
18 A, Hamsa Layout ¦ R.S Puram ¦ Coimbatore - 641002

Tel: +91 936 310 2703
Fax:<

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Yusuf,

Also check your thermostat throttling ranges and whether the unmet hours are
occuring at system startup.

Shaun Martin LEED AP

sm
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To Yusuf's more recent question below:

What you're describing (varying the rotation/layout only with all else remaining constant) sounds most easily accomplished in a single file, within the wizard stage. Set up your first building (ideally as a single shell), then create new shells by copying the first - editing the rotation and internal layout as necessary. If/when you have everything set up, you can save multiple copies of the file and remove the shells you don't want for each case to isolate to the correct building. You shouldn't need re-enter the same information twice.

To something Yusuf mentioned earlier:

Modeling the savings of solar street/landscape lighting can be re-stated as determining the energy consumption of a "non-solar equivalent." This is a lot trickier than it may seem on the surface. Much of that complexity is tied up in what "non-solar equivalent" means in reality: Dig hard at the cutsheets of the solar equipment in question to come up with some hard numbers for photometrics and runtime realities. If you are not trained/familiar with photometric lighting design software you may want to engage someone who is to help you along the way.

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.

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Thank you Nick

I have only partially understood your response on multiple shells but I
assume what you say is possible using the DD wizard. I will dig around a
bit on that one. Creating multiple files does not seem to work. I do not
understand why.

With regards to your second suggestion, Indian Green Building Council have
asked me not to waste time modeling the street lights. They asked me to use
an excel sheet to calculate the total lighting consumption by multiplying
the base case LPD of 2.4 W/Sq Mt with total area under lighting and average
hrs of usage. In the proposed case I simply have to subtract the total
outdoor lighting consumption from the overall energy consumption since it
is powered using solar. I thought it makes sense.

Thank You very much.

Yusuf

Yusuf Turab
Managing Director
IGBC Accredited Professional & LEED Green Associate
Y T Enterprises
18 A, Hamsa Layout ¦ R.S Puram ¦ Coimbatore - 641002

Tel: +91 936 310 2703
Fax:<

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The complexity I was cautioning for a solar lighting baseline is much simpler when you're being given an installed wattage at least. Sounds like the only thing for you to nail down is operating hours of the solar lights.

Regarding the DD wizard... I'm suggesting starting with one file then later splitting into multiple files, as you suggested for use with an external spreadsheet, to appropriately multiply the results without a massive model of the entire campus. Here is a quick illustration:
[cid:image002.png at 01CD17F4.C52FDDC0]
After completely finishing "Building A," defined as a single shell, click "create new shell" and choose to copy "Building A." You can then make only the necessary edits to orientation, space layout, window layout, etc... and other inputs will be repeated from the copied shell. Repeat that procedure for as many unique buildings as you require, then when finished you can proceed with saving the project a few times and in each project removing the shells you do not need to isolate to one building.

Hope that helps get my suggestion across better!

~Nick

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.

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Oh Yes!! I get it now. Many thanks Nick.

Regards

Yusuf Turab

Yusuf Turab
Managing Director
IGBC Accredited Professional & LEED Green Associate
Y T Enterprises
18 A, Hamsa Layout ¦ R.S Puram ¦ Coimbatore - 641002

Tel: +91 936 310 2703
Fax:<

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