Bauphysik最新文献

Variable Vapor Retarders: Determination of the moisture dependent vapor permeability based on cup measurements

To improve the moisture balance of lightweight structures, variable vapor retarders are increasingly being used. These membranes change their diffusion resistance depending on the relative humidity, thus improving the moisture balance by reducing moisture ingress in winter and increasing drying in summer. The first variable vapor barrier was developed over 30 years ago at the Fraunhofer IBP in collaboration with an industrial partner. There are now many competing products with different diffusion resistance spreads and different transition ranges from vapor retarding to vapor permeable. The behavior in the component depends heavily on the exact properties — it is therefore essential to measure the properties adequately in the laboratory and to evaluate them correctly. This article describes the problem and how measurement and evaluation can be carried out reliably.

More than just a parameter: The U-value in the interplay of building physics, technology, and subsidies

Thermal transmittance (U-value) is one of the established parameters in building thermal insulation. In practice, however, it has been shown that its evaluation requires much more than the application of normative calculation methods. Influencing factors such as moisture, choice of materials, or aging can significantly alter the result—with direct consequences for eligibility for subsidies, planning reliability, and energy efficiency. This article shows how the U-value should be considered in a differentiated manner during planning – especially in conjunction with other efficiency measures and supply engineering requirements. It presents typical calculation approaches, highlights special cases, and uses best practice projects to show how a well-planned building envelope affects energy consumption and system design. In addition, technical details are placed in the context of current legal requirements and embedded in the system approach of climate neutrality by 2045.

Investigation of natural flame retardants for use in insulation materials made from renewable raw materials

The use of building products made predominantly from renewable raw materials is becoming increasingly important in the construction industry. Insulation materials play a significant role in all construction projects in order to meet the thermal insulation requirements and therefore also the climate policy targets. With sustainable construction methods, such as timber construction, there is a growing desire on the part of building owners to implement this sustainability concept in the area of insulation materials as well. In order to maintain the required level of safety in the area of fire protection, various fire protection tests have been carried out into insulating materials made from renewable raw materials and possible flame retardants made from natural raw materials. In the course of this, not only the renewability is considered, but also regional availability and other ecological aspects.

Data-based numerical tool for the Life Cycle Assessment of calcium silicate products

In the present work, the development of a data-based numerical tool for the standardized life cycle assessment of calcium silicate products is described. The Calcium Silicate Sustainability Label Tool (KS-NGS Tool) implements the methodology according to DIN EN ISO 14040/44 and DIN EN 15804 and enables the calculation of 31 environmental indicators, including global warming potential and primary energy demand. It forms the methodological basis of the Calcium Silicate Sustainability Label (KS-NGS) and establishes a binding framework for integrating ecological performance parameters into declarations of performance. The numerical tool is characterized by a modular architecture, user-oriented input of material and energy flows, as well as comprehensive functions for the evaluation and clear visualization of results. Thus, the tool not only represents a key milestone on the path towards a climate-neutral calcium silicate industry but also serves as a supporting instrument for the ecological and economic optimization of calcium silicate plants. The developed numerical tool is not limited to the calcium silicate industry but can, in principle, be transferred to other areas of the construction materials industry, thereby offering broad application potential for the ecological assessment of various construction products.

Acoustics for monument preservation – Measures, planning and validation at three real-world laboratories

Heritage-listed buildings pose a unique challenge for room acoustics: preserving historic fabric while achieving low reverberation times for speech and music. To address this, three real-world laboratories (Forum Heimat, Franz-Marc Room, large conference hall at Deichmannsaue) were selected as part of a project at Fraunhofer IBP to test reversible treatments. Following a structured literature review and ten expert interviews, each space was 3D-modelled in SketchUp, simulated in ODEON, and calibrated with on-site reverberation time measurements. Iterative evaluations of niche absorbers (22 m² Reapor), transparent micro-perforated Plexiglas column claddings (5.5 m²) and mobile partitions (120 m²) reduced reverberation to meet DIN 18041 A2 criteria. On-site tests revealed significant deviations from reverberation-chamber data, highlighting the need for fine-tuning. A concise planning compendium synthesizes actionable guidance for architects and acousticians.

Quiet ventilation: Intelligent acoustic window and ventilation control: An AI-based noise detection for adaptive control

Windows in residences, hotels, and workplaces are regularly opened for natural ventilation. However, if outdoor noise levels are too high, they are usually closed again quickly. To address this problem, the control system of an automatic window has been enhanced with an acoustic function: a microphone captures the incident outdoor sound. In a first step, automatic closing is triggered as soon as a defined noise level is exceeded. This method has already been validated through subjective evaluations of noise annoyance and perceived loudness of the target sounds and has shown high acceptance among test participants. The main focus is on developing an AI system for the intelligent control of such windows or other façade openings or ventilation units based on the characteristics of outdoor sound events. An analysis method developed at the Fraunhofer Institute for Building Physics IBP enables the detection of particularly disturbing noise types, such as aircraft. This allows the closing process to be initiated at an early stage-even for initially quiet, approaching noise sources.