Estimation of the surface thermal resistances and heat loss by conduction using thermography

MARINO, BEATRIZ M; MUÑOZ VASQUEZ, NATALIA; THOMAS, LUIS P

Temixco, Mexico

Simposio; SIERyS Third International Symposium on Renewable Energy and Sustainability; 2015

The level of the thermal insulation of a construction is established by the resistances of the materials employed and the thermal surface resistances, which can vary significantly from one building to another. The importance of the calculation of the latter has been underestimated with respect to other effects such as, for example, that of the parasols and recesses in the facades to reduce the incidence of sun light in summer without losing it in winter. This is probably due to the complex calculation of the surface thermal resistances since they depend on the differences of temperature and humidity, the wind, the shape of the envelope, the surroundings, etc. In this work, the infrared thermography is employed to obtain the internal and external surface temperatures of the facades of a particular construction as part of a methodology to quantify the loss of heat by conduction through the building envelope, taking advantage of the transparency of the air to the infrared radiation emitted by the surfaces. The representative values of the heat flux by conduction through the vertical plane surfaces for both floors of the building evaluated are also obtained. It is found that the thermal resistance of the boundary layers on the glass areas and walls issimilar to that of the materials, thus significantly reducing the effective thermal conductivity of the envelope. The findings show how important it is to determine the heat flux quantitatively on site. The methodology is applied to an edifice recently built under the standard characteristics of constructions in the centre of Buenos Aires province (Argentina).