Room response according to CIBS Guide procedures

Abstract

This paper starts by amplifying the discussion of the procedures for determining the steady-cyclic thermal response of rooms presented in Section A5 of the CIBS Guide 1979. Section A5 presents the basic considerations underlying this approach to the problem but their implications are worked out only for a few specific applications. It lacks a method for determining heating plant requirements net of gains and ventilation is assumed constant except for the case of unconditioned buildings. In addition some formulae presented are justified only by cross-reference to earlier published analyses based on rather different assumptions. The second part of this paper takes the basic discussion of Section A5 as a starting point and develops a general algorithm for determining the room response for an arbitrary type of heating or cooling system (radiation, convection), arbitrary gains and arbitrary variations of ventilation rate. This can provide the basis for a general-purpose computer program implementing the Section A5 model or for deriving formulae appropriate to specific applications. The final section presents such formulae for intermittent heating requirements net of gains, including consideration of excess gain conditions. Variable ventilation is allowed for on the basis of constant ‘day’ and ‘night’ rates coinciding with the heating cycle. Substantiation of the Section A5 formula for intermittent operation of cooling plant and a more manageable version of its formula for summertime temperatures are also provided.