Transmission and storage characteristics of walls experiencing sinusoidal excitation

The design procedure used in the UK to estimate the thermal response of a building for design purposes refers internal temperatures to environmental temperature tei, which is a linear combination of space averaged air and radiant temperatures. All internal heat inputs can be taken to be input at tei. The fluctuating component of heat gain due to solar radiation on the outside of a wall and transmitted to the interior can be expressed as qei = utsa where u is the alternating transmittance and tsa is the sol-air temperature. The fluctuating component of heat absorbed by the solid surfaces present in the room can be expressed as qei = ytei, where y is the admittance. This article is concerned with the behaviour of u and y. For an infinitely thick slab, the surface admittance(qsi/tsi) = a = (2[pi]k[varrho]c/P)1/2. For an infinitely thick slab, the thickness [tau] = ([pi][varrho]cX2/Pk)1/2 can be defined: a and [tau] then completely determine the conduction properties of the slab. The effects of inner and outer films to link the slab with tei and tsa are discussed and non-dimensional values are tabulated. An example of finding u and y for a multilayer slab is presented. Any multilayer slab can be described exactly by three complex elements in T or [pi] formation, and approximately by a three-section ladder formation. The response of an enclosure is discussed in matrix and circuit terms and the relations between heat flows and temperatures are described by vector diagrams.