Conference Agenda

Hygrothermal calculation tools have become more frequently used as an instrument in the moisture safety design process. Although there are blind verified hydrothermal calculation tool to be used for those purposes there is a lack of knowledge how to make realistic assembled calculation models which provides reliable results for the moisture safety design. During the on-going work inventing realistic levels of different parameters and reliable assembled calculation models to be used in the moisture safety design process a failure linked to time shifts between measured and calculated values which cause deviations was noticed. This study aims to identify possible deviations caused by time shifts when comparing measured and calculated values using a metric method for evaluation of hygrothermal calculation models which diagnose differences. The study is needed as a part of the on-going work to invent realistic levels of parameters and reasonable assembled calculation models for reliable moisture safety designs. The levels of different parameters and reasonable assembled calculation models is also needed in order to be able to make proper comparisons of measured and calculated values in damage investigations when measured climate data is used as boundary conditions.

This study evaluated the impact of the applied and incidental moisture management strategies of two CLT buildings. It involved analysing project specifications, technical drawings, and procurement documents, along with data collection from field studies. To validate its accuracy, the hygrothermal simulation was tested against on-site moisture measurements. The model was then utilised to predict moisture safety outcomes for different strategies. In the first building, measured moisture content (MC) ranged from 9% to 18% in areas where the CLT panels' end-grain protection remained intact. In the second building, MC varied from 12% to 18% in first-floor panels with functional end-grain protection, while second-floor panels without such protection reached up to 40%. Localised damage to end-grain protection and a poorly designed floor panel connection joint caused moisture issues in the first building where material replacement was necessary. In the second building elevated MC in the second-floor panels warranted mechanically aided moisture dry-out. Readiness to mitigate moisture problems was deemed necessary regardless of the protection method used against water ingress. Prolonged exposure to outdoor air, even when under temporary weather protection increased MC in the case of the first building, however the temporary weather protection proved effective in protecting against rain. Undamaged end-grain protection was also deemed effective. The predictive analyses of moisture safety strategies indicated that in 6 of 10 cases for the first building and in all cases for the first-floor panels of the second building a moisture safe outcome was expected. However, no moisture-safe outcomes were indicated for the second-floor panels of the second building. The results demonstrate the benefits of predictive analyses which likely could have prevented the selection of a solution without end-grain protection in the second-floor panels in the second building, as evidenced by measurable data. The outcomes rely on design and planning quality, so including specific moisture safety drawings and a moisture safety strategy analysis within the building design documentation is recommended.

In the context of global climate change driven by greenhouse gas emissions, the construction sector within the European Union (EU) is responsible for approximately 40% of final energy consumption. This significant contribution highlights the urgent need for effective measures to mitigate the sector’s carbon footprint and accelerate the transition to climate neutrality. Among the various strategies aimed at improving energy efficiency in buildings, the thermal rehabilitation of existing structures is of paramount importance, as older buildings typically exhibit poor thermal performance and significantly higher energy demands for heating and cooling.

One of the main challenges in retrofitting older buildings is that external thermal insulation is not always possible due to architectural, structural, or heritage preservation limitations. Consequently, internal insulation emerges as a viable alternative for enhancing energy efficiency in such cases. This study investigates the hygrothermal behaviour of internally insulated external walls to evaluate their effectiveness in improving thermal performance while maintaining indoor comfort conditions.

For this research, a representative wall from an old building was monitored over an extended period using advanced heat flux and temperature sensors provided by Hukseflux Thermal Sensors. These instruments enabled the precise measurement of thermal resistance in two distinct scenarios: one with internal insulation applied and another without insulation. The acquired empirical data were systematically compared with theoretically calculated values to assess the accuracy of predictive models and the real-world impact of insulation.

Additionally, the study examined the transient heat and moisture transport at the interface between the insulation and the existing substrate wall. To achieve this, LogTag humidity and temperature recorders were deployed to capture long-term fluctuations in environmental conditions. The recorded data were subsequently analyzed and cross-referenced with dynamic hygrothermal simulations conducted using WUFI® Pro software.

The findings indicate that applying internal insulation to external walls is a technically feasible and effective approach to thermal rehabilitation. The study highlights the importance of controlling moisture transport at the insulation-substrate interface to prevent potential issues such as interstitial condensation, which could compromise long-term durability. Internal insulation presents a promising solution for enhancing the energy efficiency of older buildings where external insulation is not a viable option. Careful selection of materials, proper installation techniques, and thorough hygrothermal analysis are essential to ensure optimal performance and longevity. Further research and field studies are recommended to refine predictive models and develop best practices for building renovation projects.

Growing interest in reducing the carbon footprint of new buildings has led to the increased use of cross-laminated timber (CLT) in construction. Despite its environmental benefits, the hygrothermal performance of CLT structures remains a critical issue, particularly during the construction phase, when the wood's sensitivity to moisture becomes paramount. While existing research has addressed the mechanical properties of CLT constructions, there is a no-ticeable gap in the investigation of their building physics performance. This study presents an in-depth analysis of the hygrothermal behavior of a CLT residential building in central Germany, with a particular focus on the exteri-or walls. To capture real-time data, extensive wireless RFID sensors were strategically placed within the component structures to monitor temperature and relative humidity. The analysis focuses on two consecutive winter peri-ods during which the building is (1) under construction and (2) occupied and examines the moisture behavior of the CLT construction during these peri-ods. The results emphasize that moisture levels within the CLT wall assembly are significantly affected by construction-related moisture content and the building's operational environment.

Time-domain reflectometry (TDR) can be utilized to assess the moisture content of building materials. However, hard building materials always have poor contact with TDR probes, which can impair the accuracy of TDR test results. In addition, in-situ factors (e.g., insertion location, insertion depth, and ambient temperature) may negatively affect the TDR test results. In order to improve the accuracy of TDR test results, this study examines the influence of the aforementioned in-situ factors on the TDR test results of moisture contents over five common building materials (i.e., concrete, cement mortar, insulation mortar, gypsum, and autoclaved aerated concrete). At first, the moisture content of these five materials is determined via the gravimetric method as the reference. Next, these materials with different moisture contents are tested through TDR, with both the presence and absence of kaolin as the lubricating layer, from two insertion locations (front and side), at three insertion depths (1.6 cm, 2.5 cm, and 5 cm), and under three ambient temperatures (5°C, 23°C, and 40°C), respectively. Test results indicate that the presence of kaolin is beneficial to improving the accuracy of TDR test results, and the influence of insertion location and ambient temperature can be neglected. In contrast, the insertion depth has a noticeable impact on the TDR test results, which can be corrected using the TDR depth factor under a critical moisture content.

This study employs the statistical inverse uncertainty analysis method to identify uncertain parameters based on comprehensive measurement data. The research procedure involves measuring deterministic design parameters such as lighting, equipment, hot water boiler, and air-conditioning system using energy meters. A building energy model representing the studied house is validated and calibrated against the measured data. Ranges of indeterministic design parameters of envelope performance, coefficient of performance of the air conditioners, setpoints, and infiltration rate (ACH) are defined. Then, the statistically significant indeterministic design parameters are identified using regression analysis. The analysis indicated that the coefficient of performance is the most substantial parameter, followed by the air infiltration and envelope performance (thermal bridges of wall, roof, and fenestration). Then, occupant behavior (setpoint) came as the last design parameter. The inverse uncertainty analysis provides COP from 2 to 2.5, ACH between 1.5 and 2, setpoint between 22 and 23°C, and the wall and roof insulation of 5 cm.