Resumo

RORIZ, Victor Figueiredo; CARAM, Rosana Maria  e  RORIZ, Maurício. Effective surface absorbtances and emittances: an estimating method, an experimental model, and examples of their importance. Ambient. constr. [online]. 2012, vol.12, n.2, pp. 7-22. ISSN 1678-8621.  http://dx.doi.org/10.1590/S1678-86212012000200002.

Building surfaces usually have bumps and hollows that can significantly change their behaviour in relation to radiant flow. Therefore, the usual calculation procedures, instead of adopting the simplification that all surfaces of a construction are perfect plans, should apply corrections in the radiative properties of those surfaces. The effective absorptances and emittances resulting from those surface irregularities should be considered. This paper presents a simple method to evaluate those influences and exemplifies the importance of such aspects, presenting results of simulations developed in EnergyPlus for a simple geometry building, over a one-year period, in the city of Brasilia. Adopting effective absorptances and emittances, simulation results show differences of up to 2.8 ºC in the internal air temperature, compared to those obtained ignoring the influences that the ripples of the tiles have on radiant flows. Considering the use of air conditioners, this could represent up to 30% variation in the energy consumption estimate.

Palavras-chave : Absorptivity; Emissivity; Effective emittances; Effective absorptances.