LOW-VELOCITY AIR INFILTRATION IN BUILDINGS, DISPLACEMENT DIFFUSION AND EFFECTS ON THERMAL EFFICIENCY AND COMFORT: A CASE STUDY

Abstract

In 1979, the Spanish government implemented the standard “Basic Building on Thermal Conditions in Buildings NBE-CT-79”. It was then that the first requirements regarding insulation and thermal properties of materials were established to reduce energy consumption. The Mediterranean climate has influenced that insufficient attention has been paid to building insulation. In dwellings before 1979, it was detected that there is a feeling of lack of comfort. However, it is not so well known that there is a lack of airtightness in these dwellings, which may contribute to discomfort. The aim of the article is to find out if the air that enters spontaneously by infiltration produces effects similar to those of a displacement diffuser and how it affects thermal comfort. Thus, cold air would flow down the walls and be evenly distributed on the floor in winter, creating a homogeneous layer and feeling discomfort. Air infiltration measurements were carried out in 5 dwellings with an anemometer and infrared thermography to support the initial hypothesis. The Fanger Method, provided by the Polytechnic University of Valencia, was used to determine the thermal sensation produced. It was found that the cold air descended slowly and continuously to the ground in a similar way to a displacement diffuser, remaining for hours and being influential in the thermal conditions of the rooms and the lack of comfort of its occupants. Keywords: air infiltration, discomfort, thermography, displacement difusión, energy efficiency.