Brick Walls of Buildings of the Historical Heritage. Comparative Analysis of the Thermal Conductivity in Dry and Saturated State

Abstract

In the energy efficiency restoration, one of the most important aspects to consider is the loss of heat through the enclosing walls, for which constructive solutions are sought to improve their thermal performance, being usual to place a sheet of insulating material on the inner side of the facade, avoiding intervening on the outside, so as not to alter the appearance of the buildings. This fact is aggravated in the buildings built with brick factory, especially in those belonging to the Historical Heritage whose walls are raised with handmade bricks joined by mortar joints. This type of wall has a high porosity, whose immediate consequence is the absorption of a large amount of water, which is a good conductor of heat, which means that a wall saturated with water has a higher thermal conductance than being dry, increasing the consumption of energy needed to thermally condition the interior. Applying the current regulations, in order to determine the thermal conductivity of the mentioned walls, laboratory tests have been carried out on dry and saturated specimens and also on similar materials. The analytical study of the values obtained from the thermal conductance of the brick factory wall in wet state and in dry state offers data with important variations. The most immediate conclusions are two, firstly that it is necessary to know the state of humidity of the facades to determine the insulating behavior of the same and that to save energy and achieve an effective intervention, it is necessary to act on the outside of the walls, keeping it dry by applying treatments on the facades.