| 1. Scope
1.1 This test method, known as the calibrated hot box method, provides for the laboratory measurement of heat transfer through a specimen under controlled air temperature, air velocity, and radiation conditions established in a metering chamber on one side and in a climatic chamber on the other side. It is primarily intended for measurements under steady-state conditions and at temperatures typical of normal building applications. Heat transfer through the specimen is determined from net measured heat input to the metering chamber, corrected for the estimated loss through the chamber walls and estimated loss flanking the specimen at its perimeter, both estimates being based upon calibrations using specimens of known thermal properties. Heat loss through the metering chamber walls is limited by highly insulated walls, and, when necessary, by control of the surrounding ambient temperature, or by use of a partial guard. In the normal configuration, the metered area of the specimen is surrounded by perimeter insulation rather than by additional specimen area as is used in the guarded hot box Test Method C236.
1.2 The calibrated hot box method is specially suited for large nonhomogeneous specimens such as building structures and composite assemblies of building elements. It can be used for measurements of individual building elements such as windows and doors. Recommended practices for measurement of window and door thermal performance are being developed in Committees C-16 and E-6. The calibrated hot box method may also be used to investigate the effect of structural members, piping, electrical outlets, or construction defects, such as insulation voids, on the performance of a building section. The calibrated hot box may also be used for nonhomogeneous specimens not necessarily related to buildings, or for homogeneous specimens. Examples of the design, construction, calibration, operation, and use of calibrated hot boxes are given in the References (1-13). |
