ASHRAE 90.1-App G: Site Shading

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Hello,

ASHRAE 90.1-2004 Appendix G has a clause pertaining to self-shading of the
baseline building, but there does not seem to be any explicit direction
regarding shading from other objects beyond the building envelope (trees,
buildings, etc). Should the base case be modeled as being impacted by
adjacent buildings or other objects? Would this be different for a new
building versus an existing building that is being gutted?

Thanks

Eric Studer, PE, LEED AP

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Eric,

My understanding is that, regardless of the fact that the building is
new or existing, there is no specific requirement regarding the modeling
of neighboring shading objects.

______________

Demba Ndiaye

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Appendix G does specifically state that for existing buildings being gutted,
the Baseline building envelope should be modeled based on the existing
conditions prior to any revisions that are part of the scope of work being
evaluated (Table G3.1(5)(f)). Therefore, if you are modeling self-shading
and adjacent buildings in the proposed case for an existing building, they
should also be modeled in the base case for existing buildings.

Best Regards,
Gail Stranske

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What if it's an existing building, but the project is going LEED-NC or Core
and Shell. Does the baseline get modeled as the existing conditions of the
building before demo? If a project is going for LEED -existing buildings,
then the baseline energy model should be with existing conditions. What
delegates whether the baseline model should be an ASHRAE perpetration or
existing conditions?

Kevin Kyte, LEED AP

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Even if it is going LEED-NC or Core & Shell, the applicable ASHRAE
Performance Rating Method (ASHRAE 90.1-2004 Appendix G Table G3.1(5)(f))
states that the baseline envelope should be modeled with existing conditions
prior to any retrofit. The envelope for additions to the existing building
should be modeled with the applicable ASHRAE Building Envelope Requirements
table and corresponding Appendix G Table G3.1(5) requirements.

LEED for existing buildings uses benchmarking for comparison, not energy
modeling.

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What if there is existing conditions and no know gives you anything and all
they keep saying to you when you ask about it repeatedly that there is 3" of
insulation?

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Thanks to all who have weighed in on the issue of site shading. Table
G3.1(5)(f) pertains to the building envelope and not the site. The
complication arises when considering the rotation of the base case building
to remove the impact of building orientation. If there are adjacent
existing buildings, then a rectangular building footprint would likely
conflict with them. It seems that this is an item that should be clarified
in 90.1-2007?

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I have been trying to set up an electrical utility rate that varies by
season and by time of day.

I keep getting this Caution message:

BLOCK-CHARGE Cust 1 Elec TOU IS USED IN A TIME-OF-USE

FORMAT, BUT IS NOT TOU-SEASON-LINKED TO ANY OTHER

BLOCK-CHARGES FOR SEASONAL CHANGES. THEREFORE, ANY

SEASONAL CHANGE MUST OCCUR ON THE BILLING DAY OR

ERRORS WILL RESULT. REFER TO REPORT ES-F.

I even tried setting up the rates using the wizard and when I run that
it still comes back with an error message.

Anyone have any luck implementing this method?

Thanks!

Timothy Howe, MS, LEED(r) AP

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SCE (SoCal Edison) rates are the most complicated one's I've modeled.
They include time of day and seasonal rates. I suggest inputting those
rates from the wizard (first screen) into the model and adjusting the
values from the library to match your rates and times. This is a "work
backwards from the answer" kind of approach. Before using this approach
and learning how to enter various types of rates, I struggled with
getting the utility rates setup in eQUEST correctly as well.

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