Effects of indoor and outdoor heat-transfer coefficients and solar absorptance on heat flow through walls

Abstract

In the calculation of space heat gain or loss through walls, it is customary to use standard values of the indoor and outdoor heat-transfer coefficients and solar absorptance h int , h out and α, respectively. This practice may lead to considerable errors. In the present study, the effects of these parameters are examined by solving the transient one-dimensional heat-conduction differential equation using the finite-difference method within typical wall constructions of various orientations with periodic outdoor boundary conditions, during typical winter and summer days. Using the results obtained, correlations are developed which express the daily maximum indoor heat flow for various orientations during the typical winter and summer days and the time at which this maximum value occurs in terms of h int , h out and α. Although these correlations were developed for a typical wall construction, location and indoor air temperature, they may be used as approximations for different wall constructions, locations and indoor air temperatures after making suggested corrections.