This contribution reports on ongoing efforts exploring the potential of aerogel-based plasters on historical façades. As a case study, aerogel-based plaster was applied without reinforcement meshes to a small area in the historical main building of the Vienna University of Technology. The objective is to examine the long-term behavior of the plastered surfaces. For this, a monitoring infrastructure has been implemented, which enables the in-situ measurement of temperature, humidity, and heat flux within different layers of the construction using a wireless sensor system. These measurements are intended to offer a before- after comparison of the thermal behavior of the treated components

This article addresses the discrepancies between projected and actual energy performance of thermally retrofitted buildings. Toward this end, we use detailed data and observations pertaining to seven residential buildings in Austria that were thermally retrofitted recently. These include five multifamily residences in Vorarlberg, the upper level of a duplex house in Lower-Austria, and a residential complex for the elderly in Styria. During the heating season 2009–2010 (1st October–30th April), indoor temperature and relative humidity levels were measured and logged in these buildings. For each building, the actual energy use during this period was derived based on bills for gas and electrical power. Additionally, we obtained and examined existing energy calculations (energy certificates) for these buildings. In six cases out of seven, we found a large discrepancy between projected and actual space heating demand. To explore possible reasons for this discrepancy, we generated for each of the buildings an energy certificate and performed detailed thermal simulations. Thereby, we took the main input parameters for energy calculations into consideration (air change rate, indoor air temperature, outside air temperature, and internal gains). If we use standard (default) values as suggested by Austrian standards for these parameters, the above-mentioned discrepancy cannot be explained. Measurements in the buildings, as well as interviews with the building’s inhabitants implied that standard-based input data assumptions were not reliable. A subsequent multi-factor study suggested that specifically the assumptions regarding air change rates might be responsible for the large deviations of the calculated values from the actual heating demand.

The research suggests a production method of insulating composites created from lignocellulosic agricultural biomass with fungal mycelium as a binder agent and offers a deeper investigation of their thermophysical properties. Particularly, the samples were meticulously evaluated for density and thermal conductivity. The function was built on the suggestion by the authors regarding the thermal conductivity-weight ratio indicator. The metric was initially introduced to assess the correlation between these parameters and was also applied to qualitatively evaluate the biocomposite among other commonly used natural insulations. An applied polynomial trend analysis indicated that the most effective densities for the wheat, hemp, and flax, which were 60, 85, and 105 kg·m⁻³ respectively. It was determined that the optimal density for wheat and hemp composites corresponded to values of 0.28 and 0.20 W⁻¹·kg⁻¹·m⁴·K of the coefficient, respectively. These values were superior to those revealed in other common natural insulating materials, such as cork, cotton stalks, hempcrete, timber, etc. As a result, the proposed insulating material may offer numerous opportunities for application in industrial settings of civil engineering.

This contribution reports on recent advances in the utilization of vacuum glass in contemporary window construction. Generally speaking, vacuum glazing consists of two glass panes with an evacuated interstitial space. To maintain the functionality of the glazing, a vacuum-tight edge seal and a grid of distance-holding pillars are required. Vacuum glazing features a first-rate thermal performance as it significantly reduces conductive and convective heat transport rates. In comparison to multi-pane insulation glasses of comparable thermal performance, vacuum glass products feature a reduced weight and construction depth. However, the application of vacuum glass in windows requires a critical rethinking of the current practice of window construction, especially with regard to thermal bridges and the related surface condensation risk at the glass/frame-construction joints. Specifically, the glass edge seal, which can be considered to be the weak spot of vacuum glass in terms of heat transfer, requires an insulating cover that is not provided in typical insulation glass frame configurations. Further relevant aspects to be considered include the structural stability of window constructions with vacuum glass, the acoustical performance, and issues regarding usability. In this context, the present contribution highlights the methodology and findings of two recent research projects (MOTIVE, FIVA) that addressed window construction requirements with regard to vacuum glazing deployment.