[Equest-users] Baseline Rotations as per ASHRAE 90.1

[Sami, Vikram]

Interesting hypthesis.

I think it depends. Longer, thinner footprints work better if you are trying to daylight you building. They also wotk better with other passive strategies and natural ventilation. In terms of heat balance, high internal load buildings sometimes shed loads better with more skin.

That being said - it really depends on climate and usage. Balanve point temperature is a good way of studying this.


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From: equest-users-bounces at lists.onebuilding.org [equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton [ncaton at smithboucher.com]
Sent: Friday, July 02, 2010 10:52 AM
To: Soham Babu; Omar Katanani; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Baseline Rotations as per ASHRAE 90.1

Small rotational differences are typical of buildings with similar surface areas on the east, west, north, and south elevations.  I would only expect a significant difference if you have a very “long” footprint, or one side of your building is largely unconditioned along the perimeter.  Conceptually, I suppose we’re being “rewarded” for choosing an optimal orientation rotation on the building site – but if anything we’re really being rewarded for designing “long” building footprints as they can have a larger difference against the averaged baseline…

That said, if an architect asks me at a conceptual design stage, the most thermally efficient building shape considering exterior surface area is theoretically a hemisphere - barring that a “cubic,” compact 3D shape is better than any “long” shape with larger surface area for the given volume/footprint.  If the goal is to maximize LEED points (relative baseline performance), you might suggest a thermally inefficient, but optimally-oriented “long” shape that will do better than it’s averaged baseline… (I wouldn’t!)  If the goal is to reduce energy consumption/utilities however for the end-users, reduce the building shape surface area.

~Nick

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Soham Babu
Sent: Friday, July 02, 2010 2:29 AM
To: Omar Katanani; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Baseline Rotations as per ASHRAE 90.1

Omar,

 Simulation for 4 rotations value will be small difference only, in some of the cases it will be same also. it all depends upon the building location & orientation.

Regards
Soham

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Omar Katanani
Sent: Friday, July 02, 2010 12:48 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Baseline Rotations as per ASHRAE 90.1

Dear all,

I performed a simulation of my baseline building over the 4 rotations. The difference between the lowest consumption and the highest one out of the 4 runs was only 1.33% (1,312,500 to 1,329,200 kWh).

Is this a normal value? This is my first project but I thought I would have a bigger number.

Any advice out of your experience is greatly appreciated.

Many thanks,
Omar
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Omar Katanani
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