## 1 Introduction
The effects of hysteresis on the sorption and moisture capacity--the key physical phenomena--need to be included in the mathematical model of transfer. Accordingly, the reliability of the measured material properties, which serve as the input for the HAM models, remains very uncertain. A round-robin test was performed within IEA/ECBCS 41 to determine the hygro properties of porous building materials in order to generate a data set for comparison of the numerical models [16]. As a result, recent studies experimented with quantification of the hygro properties from different aspects by applying different measurement techniques [17; 18; 19]. An important factor to consider is the specific technology and composition of the investigated porous material, which may differ significantly depending on the region as well as the manufacturer. The energy performance of buildings has undergone major developments in recent years. In the framework of the current trends and global development, new technologies and structural solutions aim to increase the energy efficiency of buildings. AAC is a building material commonly used in Europe but also in other regions of the world [20; 21]. Its preference stems from particularly advantageous thermal insulation properties and lightweight construction principles. Currently, its expansion is also extensive in regions of Asia and especially China [22], which operates several hundred production plants [23]. This proves that it is of interest all around the world. However, its use often confronted with other more natural forms of sustainable materials, due to the group of recent trends in the contemporary construction industry [24]. One of the key characteristics of AAC is its hygric properties [25]; they are highly dependent on the water content of the porous material [26]. As a result, high values of water content can significantly reduce the thermal performance of AAC, which may affect why its utilization is accompanied with various levels of application around the world. The composition of the material is a basic structure of Portland cement, lime, sand or fly ash and aluminum powder. Bulk densities of AAC range from 400 kg\(\cdot\)m\({}^{-3}\) to 800 kg\(\cdot\)m\({}^{-3}\) and predisposes its building application according to the requirements and demands of incorporation into the structure in terms of purpose and function. Recently, these types of material have seen rapid progress in development, focusing mainly on their pore structure [27] and the impact of the filler by reusing industrial waste [28] or other recyclates [29; 30]. Under similar conditions, ash-based AAC was found to exhibit a slightly higher moisture sorption compared to sand-based concrete. Improving the thermal insulation properties and the utilization of plastic waste can also be a promising solution for lightweight concrete [31]. There are also current efforts to improve AAC with the integration or incorporation of a high latent heat capacity [32; 33]. This paper analyses the equilibrium moisture content levels of three types of commercially produced AACs with different bulk density and compressive strengths, along with their basic physical properties by applying different measurement methods. Though there are some studies comparing conventional static methods and automated dynamic vapor sorption (DVS) methods [34; 35], its application is still not widely used in relation to building materials. In addition, as the DVS method represents an effective method, it is considered suitable to be used for sorption isotherms determination of AAC up to about 80% relative humidity [35]. This represents an important limitation that needs further investigation. Thus, the data obtained by this research will make it possible to carefully reconsider this research finding, aiming to identify the suitability of the compared methods for measuring sorption/desorption properties. The methodology used is expected to provide the reference for measuring the sorption/desorption isotherms of AAC with both static and automated techniques.