Fast estimation of thermal transmittance based on temperature measurements is uncertain, and the obtained results can be burdened with a large error. Nevertheless, such attempts should be undertaken merely due to the fact that a precise measurement by means of heat flux measurements is not always possible in field conditions (resentment of the residents during the measurements carried out inside their living quarters), and the calculation methods do not allow for the nonlinearity of thermal insulation, heat bridges or other fragments of building envelope of diversified thermal conductivity. The present paper offers the estimation of thermal transmittance and internal surface resistance with the use of temperature measurements (in particular with the use of thermovision). The proposed method has been verified through tests carried out on a laboratory test stand built in the open space, subjected to the influence of real meteorological conditions. The present elaboration involves the estimation of thermal transmittance by means of temperature measurements. Basing on the mentioned estimation, the authors present correction coefficients which have impact on the estimation accuracy. Furthermore, in the final part of the paper, various types of disturbance were allowed for using perturbation numbers, and the introduced by the authors “credibility area of thermal transmittance estimation” was determined.

The laboratory testing of the construction materials and elements is a subset of activities inherent in sustainable building materials engineering. Two questions arise regarding test methods used: the relation between test results and material behavior in actual conditions on the one hand, and the variability of results related to uncertainty on the other. The paper presents the analysis of the results and uncertainties of the simple two independent test examples (bond strength and tensile strength) in order to demonstrate discrepancies related to the ambiguous methods of estimating uncertainty and the consequences of using test methods when method suitability for conformity assessment has not been properly verified. Examples are the basis for opening discussion on the test methods development direction, which makes possible to consider them as ‘sustainable’. The authors address the negative impact of the lack of a complete test models taking into account proceeding with an uncertainty on erroneous assessment risks. Adverse effects can be minimized by creating test methods appropriate for the test’s purpose (e.g., initial or routine tests) and handling with uncontrolled uncertainty components. Sustainable test methods should ensure a balance between widely defined tests and evaluation costs and the material’s or building’s safety, reliability, and stability.

This paper describes the issue of unidirectional temperature distribution in a plate with the assumption of perturbations in the problem parameters. The new algebraic perturbation system is proposed as a possible alternative to the traditional I-order perturbation methods. A calculation example is presented to compare the classical solution of a problem with that using perturbation numbers. The investigation of a possibility to apply the new algebraic system using a simple example represents an introduction to the further development of the proposed methodology which can be used to solve more complicated problems, taking into account among other properties, inhomogeneity of material, its porosity or the occurrence of thermal bridges.

The paper analyses the loss mechanism of roof insulation kits’ performance due to dampness increase in the insulation layers. The analyzed structures were used in standard conditions for ten years and had thermal insulation made of expanded polystyrene with a hydrophobized surface. The dampness of the thermal insulation materials was determined after the referenced period for their future fitness as roof insulation, based on laboratory tests of material samples collected from the structures. They were completed with a computer simulation of heat transfer and dampness in the partition for working conditions specified for ten years, assuming the thermal conductivity was determined for the materials collected from the analyzed roofs. It was discovered that simulation-based calculation dampness values are much lower than those observed after ten years of roof utilization. Additionally, the authors attempted to determine the correlations between the period of thermal insulation materials used in real conditions and the selected properties of the products determined in laboratory tests. To that end, the collected material was dried to constant weight and then subjected to accelerated aging through total immersion in water at room temperature, for twenty-eight days, followed by 300 freeze-thaw cycles at –20°C and +20°C. The results helped conclude that the abovementioned laboratory testing cycle does not allow for assessing the fitness for the use of the referenced products for ten years. The directions of future laboratory tests were set, suggesting extending the testing cycle at least twice.