Definition of parameters useful to describe dynamic thermal behavior of hollow bricks

Dynamic thermal behavior of hollow bricks is attracting much interest nowadays as there is much concern on energy performance of building envelope. In fact, high thermal inertia of outer walls provides mitigation of the daily heat wave, which reduces the cooling peak load and the related energy demand. Different approaches have been used to study dynamic thermal behavior within the papers available on unsteady heat transfer through hollow bricks. Actually, the usually employed methods for calculation of unsteady heat transfer through walls are based on the hypothesis that such walls are composed by homogeneous layers, so they are not suitable for many common building components. In this framework, a study on the dynamic thermal performance of hollow bricks is brought forth in the present paper. A critical review of available data from the literature is provided. Literature data are used to propose a parameter useful to predict dynamic thermal behavior. A finite-volume method is used to solve two-dimensional unsteady thermal fields in some standard bricks with different imposed temperature solicitations, with a numerical code developed by the authors. New results are used to check the effectiveness of the proposed parameters