[Equest-users] Walls and Zones
Katie Tuttle
Katie.Tuttle at hei-eng.com
Tue Jan 12 08:07:07 PST 2010
Based on some responses I’ve received regarding walls, spaces and zones in eQuest, here’s my stab at summarizing what I’ve learned:
Walls
1. Walls have 3 functions
a) Transfer Heat
b) Store Heat
c) Reflect Daylight
2. Interior wall types
a) Standard interior
i. Transfers Heat
ii. Stores Heat
iii. Reflects Daylight
b) Air Wall
i. Transfers heat
ii. Reflects Daylight
c) Adiabatic
i. Stores Heat
ii. Reflects Daylight
d) Internal Interior
i. Stores Heat
ii. Reflects Daylight
3. For heat transfer to occur, you MUST have a wall. Deleting walls between spaces that are actually open air will cause eQuest to NOT transfer any heat between these two spaces. For example:
a) Open office space with a perimeter and core zone.
i. In order for heat transfer to occur between those two areas (as it actually would) a wall must exist between them.
ii. That “wall” would need to have a high u-value. The surface reflectance of that wall may need to be tweaked to simulate daylight passing through it and reflecting back into that area since DOE-2 treats air-walls as opaque (for all practical purposes).
iii. If the interior wall were just deleted between the perimeter zone and core zone of the open office space, no heat transfer will occur during simulation.
iv. This lack of heat transfer could affect this zone, for example, when it’s quite cold outside and that perimeter zone is losing heat – without the benefit of some of the interior zone’s heat, that perimeter zone would have to make up all of that heat loss (which wouldn’t actually occur).
Spaces
1. eQuest can only have one SPACE per ZONE.
2. When creating your spaces in the wizard (or detailed mode), make sure you zone this per thermostat, not per room.
Thanks for everyone’s responses!
KATIE L. M. TUTTLE EI, LEED® AP
Mechanical Designer
Henderson Engineers, Inc. 8325 Lenexa Drive Lenexa, KS 66214
dir 913 742 5508 tel 913 742 5000 fax 913 742 5001 www.hei-eng.com <http://www.hei-eng.com/>
From: Sara Lewis [mailto:SLewis at tesengineering.com]
Sent: Tuesday, January 12, 2010 7:55 AM
To: Katie Tuttle
Subject: RE: [Equest-users] Walls and Zones
I think (and could be wrong because I am VERY new to eQUEST) that you could assign the different spaces to the same zone on the “zone group definitions” tab of the building design wizard. You’re able to name your zone, pick the spaces that belong to that zone, and also specify the HVAC system that serves that zone.
Sara Lewis
tesengineering
providing dependable guidance since 1993
Sara Lewis
phone: (440) 614-0325
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Katie Tuttle
Sent: Tuesday, January 12, 2010 8:52 AM
To: James Hansen; omoltay at mimtarch.com; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Walls and Zones
To follow up on the previous questions, I’ve wondered the same thing – what if you want to assign multiple spaces to one zone in eQuest? For example, two rooms are being supplied by the same VAV box. They need to be created as two SPACES (on the “Building Shell” and “Internal Loads” tabs) because of different internal loads, but then on the “Air-Side HVAC” tab, both of the spaces need to be assigned to one ZONE. Is this possible?
Thanks!
KATIE L. M. TUTTLE EI, LEED® AP
Mechanical Designer
Henderson Engineers, Inc. 8325 Lenexa Drive Lenexa, KS 66214
dir 913 742 5508 tel 913 742 5000 fax 913 742 5001 www.hei-eng.com <http://www.hei-eng.com/>
-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Tuesday, January 12, 2010 6:31 AM
To: omoltay at mimtarch.com; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Walls and Zones
Instead of deleting interior walls, why not just convert them do a different type? If I have a large open office with multiple zones, I'll just set up all interior walls to be of type "Air".
Here are the available wall types from the help file:
INT-WALL-TYPE
Specifies the type of interior wall through code-words that identify the type of heat transfer that occurs across the wall.
STANDARD
The default. Designates an interior wall that separates two spaces and conducts heat between the spaces. It can be defined with a CONSTRUCTION with TYPE=U-VALUE or TYPE=LAYERS although the heat storage effects of the wall are accounted for only if TYPE=LAYERS. If you choose a CONSTRUCTION with TYPE=U-VALUE, the U-value should be less than 0.709 Btu/ft2-F-hr (4.02 W/m2-K), which is the limiting value for two air films and a very low resistance solid layer. The NEXT-TO keyword is required for this wall type. However, if the NEXT-TO space is the same as the space in which the wall was defined, the program will change INT-WALL-TYPE to ADIABATIC.
ADIABATIC
Designates an interior surface that does not conduct heat between spaces but can store heat. This type should be used to separate spaces that are considered to be identical and are, therefore, defined with MULTIPLIER or FLOOR-MULTIPLIER in the SPACE command. An example is the wall, ceiling, or floor that separates identical spaces that are side-by-side on one floor of a building or above one another in a multistory building. This type of wall should have delayed construction.
INTERNAL
Designates an interior surface that lies completely inside a space. An example is a water wall used to store solar energy in a space. Another example is a wall between two rooms that are modeled as a single space. This type of wall should have a construction with TYPE=LAYERS; in this case the thermal mass of the wall will be considered in the space's custom weighting factor calculation
AIR
Designates a non-physical interior surface with no mass (i.e., an opening between spaces) across which convection can take place. This type of wall should have a CONSTRUCTION with TYPE=U-VALUE. In this case, we recommend an approximate U-value of 2.7 Btu/ft2-hr (15.3 W/m2). The NEXT-TO keyword is required for this wall type.
If the "AIR wall" is part of a daylit space, its INSIDE-VIS-REFL values need to be specified (even though it is not a physical wall) since daylight can be reflected back across the AIR wall from the adjacent space. The values to use for INSIDE-VIS-REFL in this case are determined as follows. Assume that the AIR wall, of area A, is defined in space 1 and separates space 1 and space 2. Let the spaces have inside surface area Si (excluding the AIR wall) and area-weighted visible reflectance ri excluding the AIR wall). Then INSIDE-VIS-REFL=(R2 , R1) where Ri is the cavity reflectance of space i given by
Ri = A * ri / (Si - (Si -A)*rI)
GHT Limited
James Hansen, PE, LEED AP
Senior Associate
1010 N. Glebe Rd, Suite 200
Arlington, VA 22201-4749
703-338-5754 (Cell)
703-243-1200 (Office)
703-276-1376 (Fax)
www.ghtltd.com
-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of omoltay at mimtarch.com
Sent: Monday, January 11, 2010 6:54 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Walls and Zones
Dear all,
I have not received a reply to my previous question, so here is a
simplified version of it: I see that everytime I create a zone in the
Wizards, eQuest builds walls around these zones. Does every zone (or every
space) need to have walls around? Would it be a problem if I delete these
walls afterwards?
For example, when I have a large open office, I would like to have several
zones. So after the Wizard creates the building description, I have to
delete all the walls around these zones.
Is this normal procedure?
Thanks,
Omer Moltay, LEED AP
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