Chemistry and Sensory

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Material emissions and indoor air quality

People spend most of their time indoors. Buildings and construction products, despite the variety of materials used to make them, must be as environmentally friendly and as non-detrimental to health as possible. The emission characteristics of construction products are tested according to recognized methods and standards (AgBB, ISO 16000 series). If they have an adverse effect on user well-being, it is possible to perform an analysis of volatile organic compounds (VOC) and particulate (PM) emissions indoors to discover the structural causes or sources triggering the complaints. If necessary, the indoor air composition is analyzed for its odor-active compounds. In order to identify and quantify these substances, scientists use a combination of classic VOC analysis and flavour chemistry methods (gas chromatography-olfactometry, also known as GC-O or GC sniffing). The main objective is to localize the source of the emissions and to remove the cause of mostly unpleasant malodors.

The odor characteristics of construction materials, technical materials and raw materials, or of building and vehicle interiors (automobiles, airplanes) are evaluated using odor panels according to national and international standards and industrial guidelines.

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Air purification systems and functional surfaces

As part of the drive to improve energy efficiency, buildings are being made more airtight. But this compromises air exchange between the inside and the outside environments – ventilation that is necessary for hygiene reasons. In a bid to maintain good air quality, we investigate and improve the efficiency of air purification systems such as filters, absorbers and (photo-) catalytically equipped surfaces and components in order to reduce VOCs, odorants, aerosols and dusts. But air purification capabilities are not the only functional modification that can be made to surfaces and components. Super-hydrophobic and dirt-repellent surfaces with long-lasting effectiveness help protecting outside surfaces from water and dirt.

New analytical methods, failure analysis

Analysis methods are being developed for various problems, target components and environmental conditions. An internal method enables, for example, the rapid and precise identification and quantification of over 80 volatile aminoic compounds by means of high-pressure liquid chromatography, coupled to a triple quad mass spectrometer (HPLC-MS-MS). Since recognized and standardized test procedures are often too time consuming for use in examining damage cases or for product development, we develop new rapid procedures (for instance based on thermal extraction) with which emissions and material characteristic changes can be quickly determined. Currently we are aiming to develop new analysis and evaluation processes for water leachable substances.

Often the causes for damage to buildings are not to be found in the buildings themselves. Thanks to the testing of faulty construction products in the laboratory, causes of building damage can be determined and recommendations for how best to avoid such problems in the future can be provided. The methods we use for comprehensive materials characterization include SEM-EDX, IR and UV spectroscopy, DTA, TGA and DSC.

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Sustainability and durability

Buildings should be economically and ecologically sustainable. Many construction products today contain biologically active ingredients that prevent or delay microbial growth. The extent and effects of the release of such agents and additives on the environment can be examined in field tests under real climatic conditions or by means of laboratory experiments according to DIN EN 16105 and FprCEN/TS 16637-2 (DSLT). The results are used by manufacturers for product development and for setting national and European standards. In addition to the durability of construction materials, the energy efficiency of buildings is also an important criterion. Fraunhofer IBP provides support in this complex area through developing both public and privately-funded organized certification systems.

Odor and taste analysis

New materials and construction products may release unpleasant odors. Scientists can get to the bottom of any such malodors from technical materials and construction products using molecular sensory technologies. The odor-active compounds contained in and emitted by the product are extracted via solvent extraction or gas phase extraction, and are analyzed via gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS). A weighting is then carried out via dilution experiments and their chemical structure elucidated. Based on this, it is possible to determine the origin of odorous substances from raw materials during production, allowing optimization of the manufacturing processes.

The structure of taste-active substances such as those found in drinking water transported in plastic pipes or stored in plastic bottles is identified. These substances either migrate from the synthetic matrix or are first created upon contact with water. The influence of environmental conditions such as atmospheric pressure on odor and taste perception is examined.

Air quality monitoring, sensor systems

Appropriate sensors are being developed, based on scientific understanding of the composition of emissions (VOCs and odor-active compounds) indoors, that can detect and quantify certain air contaminants. The aim is for these sensors to be able to detect such compounds that go hand in hand with the human perception of poor air quality (indicator compounds). The resulting signals can be selectively used to display air quality and to intervene in the control of ventilation systems (demand-controlled ventilation).

As it stands, the fermentation process in conventional biogas plants is largely unregulated. In the future, scientists will be able to monitor and evaluate this process using data from detectable indicator compounds created during anaerobic fermentation. Sensors are being developed that can detect specific target gases in order to use these signals for better controlling the fermentation process.