HAP-Unconditioned space temp.pdf

Partition Tab / Space Form

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Partition Tab / Space Form About Partitions. The Partitions tab on the Space Form contains information about heat transfer through walls and ceilings which are adjacent to unconditioned or partially conditioned regions, or adjacent to regions at significantly different temperatures. Examples: A wall adjacent to an unconditioned warehouse, a refrigerated storeroom, or an unconditioned mechanical room. Heat flow through these walls and ceilings depends upon the heat transmission properties of the wall or ceiling and the temperature behavior in the adjacent region which are both specified by the user.

The Partitions Tab. Each space can contain up to two partition elements. The Partitions tab divided into two panels which allow the characteristics of each wall or ceiling partition to be defined: Partition Type Area U-Value Unconditioned Space Maximum Temperature Ambient at Space Maximum Temperature Unconditioned Space Minimum Temperature Ambient at Space Minimum Temperature

Partition Type This item defines whether partition data is for a ceiling or a wall adjacent to an unconditioned region. This input determines how loads for the partition are reported on design load calculation reports. These reports contain separate line items for ceilings and partitions (walls). Readers should note that the same procedure is used to calculate loads whether it is designated as a ceiling partition or a wall partition. This input only affects where the load is reported.

Partition Area

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8/6/2013

Partition Tab / Space Form

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Specify the gross surface area of the wall or ceiling partition which is adjacent to the unconditioned region. Gross area is used when computing the heat gain or loss through the partition.

Partition U-Value Specify the overall U-value for the wall or ceiling partition. This U-value is used when computing heat transfer through the ceiling or wall partition.

Partition Unconditioned Space Temperatures When calculating transmission loads for wall or ceiling partitions adjacent to unconditioned regions, the temperature of the unconditioned region must be known. Temperature behavior in the unconditioned region is estimated with a simple linear model which defines the unconditioned space temperature as a function of the outdoor air temperature. The model is defined by specifying two pairs of temperatures: 1. The Unconditioned Space Maximum Temperature and the corresponding Ambient Temperature at Maximum Space Temperature. 2. The Unconditioned Space Minimum Temperature and the corresponding Ambient Temperature at Minimum Space Temperature. Together these four temperature inputs define the three sections of the space temperature profile: 1. When the outdoor air temperature is warmer than the "Ambient at Maximum Space Temperature", the unconditioned space temperature is equal to the "Unconditioned Space Maximum Temperature." 2. When the outdoor air temperature is between the "Ambient at Maximum Space Temperature" and "Ambient at Minimum Space Temperature", the unconditioned space temperature varies linearly with outdoor temperature. 3. When the outdoor air temperature is colder than the "Ambient at Minimum Space Temperature", the unconditioned space temperature is equal to the "Unconditioned Space Minimum Temperature."

Example: A partially conditioned warehouse is adjacent to the conditioned space. The warehouse is heated to maintain a 50 F air temperature in winter and is cooled to maintain a 95 F air temperature in the summer. Otherwise, the warehouse temperature floats between 95 F and 50 F. Based on engineering judgment, it is assumed the warehouse reaches 50 F when it is 30 F outdoors. The warehouse reaches 95 F when it is 90 F outdoors. Inputs used to model such a situation are as follows: Unconditioned Space Maximum Temperature = 95 F.

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Partition Tab / Space Form

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Ambient at Maximum Space Temperature = 90 F. Unconditioned Space Minimum Temperature = 50 F Ambient at Minimum Space Temperature = 30 F The figure above shows the unconditioned space temperature profile resulting from these inputs. When the outdoor temperature is above 90 F, the space temperature remains constant at 95 F. Between outdoor temperatures of 90 F and 30 F, the unconditioned space temperature varies linearly as a function of outdoor temperature. Below 30 F, the unconditioned space temperature remains constant at 50 F.

file://C:\Documents and Settings\thomask6\Local Settings\temp\~hhD0EA.htm

8/6/2013