Cooling load temperature difference calculation method: Difference between revisions

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The '''cooling load temperature difference (CLTD)''' '''calculation method''', also called the '''cooling load factor''' '''(CLF)''' or '''solar cooling load factor''' '''(SCL) method''', is a method of estimating the [[cooling load]] or [[heating load]] of a building. It was introduced in the 1979 [[ASHRAE]] handbook.

==CLTD/CLF/SCL cooling load calculation method==

The CLTD/CLF/SCL (cooling load temperature difference/cooling load factor/solar cooling load factor) [[Cooling load|cooling load]] calculation method was first introduced in the 1979 [[ASHRAE]] Cooling and Heating Load Manual (GRP-158) <ref name=SML>Spitler, J.D., F.C. McQuiston, K. Lindsey. 1993. The CLTD/SCL/CLF Cooling Load

Calculation Method, ASHRAE Transactions. 99(1): 183–192.</ref> The CLTD/CLF/SCL Method is regarded as a reasonably accurate approximation of the total heat gains through a building envelope for the purposes of sizing [[HVAC]] equipment. This method was developed as a simpler calculation alternative to difficult and unwieldy calculation methods such as the transfer function method and the [[Sol-air temperature]] method.<ref name=MS>McQuiston, F.C., and J.D. Spitler. 1992. Cooling and heating load calculation manual. Atlanta: ASHRAE</ref> Error when using the CLTD/CLF/SCL method tends to be less than twenty percent over and less than ten percent under.<ref name=SML/>

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Q = U*A*CLTD <ref name=SML/><ref name=Textbook/>

Q = U*A*(T2-T1)

Where Q = Overall heat transfer in Btu per hour

U = Overall heat transfer coefficient in Btu/(ft2-hr-deg F)

A = Area in square feet

T1 = outdoor temperature in degrees F

T2 = indoor temperature in degrees F

===For heat gains due to people, equipment (hooded and unhooded), and lighting===

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===Data tables===

In addition to tables published by [[ASHRAE]] for select latitudes, a computer program called CLTDTAB, availablereleased sincein 1993 and no longer available, cancould behave been used to generate custom CLTD/CLF/SCL tables for a specific zone type for any [[latitude]] and month. This allowsused to allow the use of this method, without interpolation, for any area in the world.<ref name=SML/>

If thea program similar CLTDTAB is used, the results obtained using this method will tend to be very close to the more rigorous TFM Method mentioned earlier.<ref name=SML/> CLTDTAB is no longer available, similar software can be purchased and downloaded.

==References==

{{reflist}}

[[Category:Heating, ventilatingventilation, and air conditioning]]