ASHRAE Standard 138 2021

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ASHRAE Standard 138-2021 — Method of Testing for Rating Ceiling Panels for Sensible Heating and Cooling (ANSI Approved)

Published By	Publication Date	Number of Pages
ASHRAE	2021	30

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Description

ASHRAE Standard 138 establishes uniform methods of laboratory testing for rating steady-state thermal performance of ceiling panels used in indoor spaces for sensible heating, sensible cooling, or both, with the objective of rating ceiling panels under repeatable conditions.The 2021 edition of Standard 138 includes updated references.

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1	ANSI/ASHRAE Standard 138-2021
3	CONTENTS
4	FOREWORD 1. PURPOSE 2. SCOPE 2.1 This standard specifies procedures, apparatus, and instrumentation for rating thermal performance of ceiling panels in a specific indoor configuration and thermal conditions. 2.2 Thermal performance of a ceiling panel is measured in terms of heat delivered or heat removed by the ceiling panel as a function of the average fluid temperature of the heat transfer medium in the ceiling panel and the temperatures characterizing… 2.3 This standard covers testing of ceiling panels in the following effective panel surface high and low temperature range limits: 2.4 This standard does not cover the following ceiling panels: 3. UNITS OF MEASUREMENT 3.1 System of Units. In this standard, the International System of Units (SI) is used. Inch- pound (I-P) units are shown parenthetically. Values shall be based on the National Institute of Standards and Technology (NIST) values, which, in turn, are b… 3.2 Basic Units. The unit of length is meter, designated m (foot or inch, designated ft or in.). The unit of mass is the kilogram, designated kg (pound, designated lb), and the unit of time is second or hour, designated s or h. The unit of temperatur…
5	3.3 Derived Units 4. SYMBOLS
8	5. DEFINITIONS
9	6. INSTRUMENTS AND MEASURING STANDARDS 6.1 Accuracy and Precision. Instruments and methods of measurement that are described in the following sections are subject to accuracy and precision specifications as shown in Table 1. The specified requirements correspond to two standard deviations… 6.2 Resolution. The resolution of an instrument is the smallest change in input that will result in a measurable change in output. In no case shall the resolution of the measurement device be greater than the accuracy specified for the instrument. 6.3 Standard of Fluid Temperature Measurements. Measure temperature of the heat transfer fluid in accordance with ANSI/ASHRAE Standard 41.1, Standard Method for Temperature Measurement 1. 6.4 Standard of Fluid Flow Rate Measurements. Measure the flow rate of the heat transfer fluid in accordance with ANSI/ASHRAE Standard 41.8, Standard Methods of Measurement of Flow of Liquids in Pipes Using Orifice Flowmeters 2. Flow rate measuring i… 6.5 Standard of Fluid Pressure Measurements. Measure the pressure of the heat transfer fluid in accordance with the general guidelines given in ANSI/ASHRAE Standard 41.3, Standard Method for Pressure Measurement 3.
10	6.6 Standard of Thermal Energy Measurements. Thermal energy transferred to or removed from the test panel during the measurements at a test point may be directly measured by a thermal energy measuring instrument that is calibrated according to ANSI/A… 7. STANDARD TEST SETUP AND THE EQUIPMENT 7.1 Test Room. The testing facility shall be equipped with an air-conditioned test room capable of accommodating the test chamber and carrying out the tests. The test room shall also accommodate the necessary testing, recording, and measuring instrum… 7.2 Test Chamber. Test panels shall be subjected to test in a test chamber that is located in the test room. The test chamber shall satisfy the following requirements.
13	7.3 Installation of Test Panels in the Test Chamber
15	8. METHOD OF CONDUCTING A STANDARD TEST 8.1 Test Requirements. Several conditions are required in order to start, conduct, and complete a successful test. All conditions must be satisfied to consider a test successful.
16	8.2 Starting a Test. A sensible heating test shall start from the test point with the lowest average fluid temperature determined for the given test (Section 8.1.2.1.1). A sensible cooling test shall start from the test point with the highest average… 8.3 Conducting a Test. Tests shall be conducted by taking measurements at all test points successfully. All steady-state measurements at a test point shall be completed within a time period not to exceed 300 s. The test shall proceed from the first t…
17	8.4 Ending a Test
18	9. PROCESSING TEST DATA 9.1 Heat Flux at the Thermally Effective Panel Surface(s). Heat flux at the thermally effective panel surface(s) shall be calculated at every test point.
19	9.2 Calculation of AUST in the Test Chamber. Calculate AUST by including all interior surfaces of the test chamber exposed directly to thermally effective panel surfaces. 9.3 Calculation of the Mean Radiant Temperature in the Test Chamber. Calculate tmr in terms of interior surface temperatures of the walls and the floor, portion(s) of the ceiling surfaces that are not obstructed by test panel(s), and temperatures of … 9.4 Calculation of Operative Temperature in the Test Chamber, to. Calculate to as the arithmetic average of ta and tmr. 9.5 Calculation of the Characteristic Performance Coefficients of the Test Panel. Three characteristic performance equations shall be determined for three separate definitions of the temperature difference, Dt. Negative signs designate the sensible c…
20	9.6 Pressure Drop in the Test Panel. At a given test point, pressure drop in the heat transfer fluid circulating in the test panels shall be recorded for documentation purposes only. Pressure drop is the difference between the fluid pressure measurem… 9.7 Graphical Representation of Test Results. Processed test data shall be presented on a logarithmic graph with temperature differences on the abscissa and qad on the ordinate. Information boxes shall provide information about every test point. Test… 9.8 Calculation of the Panel Thermal Resistance. Thermal resistance of a test panel between the fluid of the test panel and the indoor space shall be calculated by using Equation 20. 10. ACCEPTANCE CRITERIA FOR THE STANDARD TEST 11. REPORTING STANDARD TEST RESULTS 11.1 Standard Test Report. After the successful completion and acceptance of a test, a written test report is prepared. If the test was not successfully completed, a short report with reason(s) for terminating the test shall be prepared. If the test … 11.2 Content of the Standard Test Report. The test report for a successful test shall describe the objective, descriptions of the test panel, number of identical test panels, test data, calculations, results, uncertainty of the test results, and any … 12. REFERENCES
22	NORMATIVE ANNEX A: ADJUSTMENT OF PANEL HEAT FLUX
24	NORMATIVE ANNEX B: LINE FITTING BY THE METHOD OF LEAST SQUARES
25	INFORMATIVE ANNEX C: UNCERTAINTY ANALYSIS OF PANEL HEAT FLUX
26	INFORMATIVE ANNEX D: CALCULATING THE APPROXIMATE THERMAL EFFICIENCY OF THE TEST PANEL
27	INFORMATIVE ANNEX E: PROVISIONS FOR ELECTRIC PANELS AND CALIBRATION OF THE TEST CHAMBER E1. Evaluating Test Panels E2. Calibration Testing of the Test Chamber E3. References

Additional information

Standard Title	ASHRAE Standard 138-2021 — Method of Testing for Rating Ceiling Panels for Sensible Heating and Cooling (ANSI Approved)
Published Code	ASHRAE
Publication Date	2021
Pages Count	30

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