[Hap-users] HAP Cooling Load Calculation.

Tue Dec 18 11:19:08 PST 2012

>From th e Cooling Load Calculations andPrinciples

"Thermal Zoning
Thermal zoning is a method of designing and controlling the HVAC system so that occupied areas can bemaintained at a different temperature than unoccupied areas using independent setback thermostats. A zone is defined as a space or group of spaces in a building having similar heating and cooling requirementsthroughout its occupied area so that comfort conditions may be controlled by a single thermostat.When doing the cooling load calculations, always divide the building into zones. Always estimate the buildingpeak load and individual zones airflow rate. The building peak load is used for sizing the refrigeration capacityand the individual zone loads are helpful in estimating the airflow rates (air-handling unit capacity).In practice the corner rooms and the perimetric spaces of the building have variations in load as compared tothe interior core areas. The following facts may be noted:

a) The buildings are usually divided into two major zones.
*
Exterior Zone: The area inward from the outside wall (usually 12 to 18 feet, if rooms do not line theoutside wall). The exterior zone is directly affected by outdoor conditions during summer and winter.
*
Interior Zone: The area contained by the external zone. The interior zone is only slightly affected byoutdoor conditions and usually has a uniform cooling.

b) Single-zone models shall be limited to open floor plans with perimeter walls not exceeding 40 feet inlength.

c) For large building footprints, assume a minimum of five zones per floor: one zone for each exposure(north, south, east & west) and an interior zone"

Hector Lampra, P. Eng, LEED AP, CEM

From: Doddi, Sai K [mailto:Sai.Doddi at hatchmott.com]
Sent: Tuesday, December 18, 2012 3:10 PM
To: Hector Lamprea
Subject: RE: HAP Cooling Load Calculation.

Hector ,
                Thanks so much for helping. If you don't mind, I have another question.

How do the zones work? Is zone like a block that is a group of spaces? Why would I want any more than 1 zone?
In the classroom example in HAP, a few spaces are categorized into a zone. Why is it necessary? Couldn't they have been just defined as separate spaces?

I know these are too many questions.

Any suggestions would be great.

Thanks,
Sai.

From: Hector Lamprea [mailto:hector.lamprea at fundyeng.com]<mailto:[mailto:hector.lamprea at fundyeng.com]>
Sent: Tuesday, December 18, 2012 10:16 AM
To: Doddi, Sai K
Subject: RE: HAP Cooling Load Calculation.

There is a tab in the room called partitio, use this to recreate diffence in room temperarutes.

Hector Lampra, P. Eng, LEED AP, CEM

From: hap-users-bounces at lists.onebuilding.org<mailto:hap-users-bounces at lists.onebuilding.org> [mailto:hap-users-bounces at lists.onebuilding.org]<mailto:[mailto:hap-users-bounces at lists.onebuilding.org]> On Behalf Of Doddi, Sai K
Sent: Tuesday, December 18, 2012 2:09 PM
To: hap-users at lists.onebuilding.org<mailto:hap-users at lists.onebuilding.org>
Subject: [Hap-users] HAP Cooling Load Calculation.

Hello there,
                I am a new HAP user currently using HAP to assess the cooling load for a train station. I am having trouble understanding conceptually how HAP handles certain cooling loads.

In my case, I have two adjacent rooms, one of which is air conditioned to 68 deg F and 50% RH, and the other does not need any A/C, just ventilation. There are a few set of rooms at one end of the station and another set of rooms at the other end of the station. Some of the rooms need A/C whereas some others don't.

In HAP, I haven't been able to figure out, how to assign an order to the rooms. I would think this order is important to assess the heat transfer between the rooms correctly and correspondingly calculate the overall heat load.

In order to estimate the heat load, I would like to have an independent a/c system for each room that needs to be airconditioned. Hence, I am using 5 CAV's to air condition 5 spaces (rooms) and I am also using 4 CAV's to ventilation ( not A/C) to ventilate the 4 non-A/C rooms. Also, there are corridors and windows.

As mentioned earlier, I haven't been able to figure out how to arrange the rooms in an order and how to group them. In the space properties, I see a tab for Partitions. But, it allows for a maximum of 2 partitions only. I am not sure if this is the way to specify internal walls.

The tutorial only comes with 2 examples, that does not consider a case where the rooms are conditioned differently.

Any suggestions would be greatly appreciated.

Thanks much,
Sai.

Sai Doddi | sai.doddi at hatchmott.com<mailto:sai.doddi at hatchmott.com>
Hatch Mott MacDonald
111 Universal Hollywood Drive, Suite 2100,
Los Angeles, CA 91436
Tel: 818-736-4314  Fax: 818-506-8044
http://www.hatchmott.com

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Sai Doddi | sai.doddi at hatchmott.com<mailto:sai.doddi at hatchmott.com>
Hatch Mott MacDonald
111 Universal Hollywood Drive, Suite 2100,
Los Angeles, CA 91436
Tel: 818-736-4314  Fax: 818-506-8044
http://www.hatchmott.com

[test.png]

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