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Recent research into emissions of (semi-)volatile organic compounds [(S)VOC] from solid materials has focused on the development of suitable reference materials for quality assurance/quality control of emission test chamber measurements, which fulfill requirements such as homogenous and reproducible (S)VOC release. The approach of this study was to find a method for preparation of a material with predictable (S)VOC emission rates. AVOC (styrene) and an SVOC (2,6-diisopropylnaphthalene, DIPN), loaded into either vacuum grease or a 1:1 mixture of paraffin/squalane, have been tested. For the prediction of the emission rates, a model using the finite element method (FEM) was created to simulate the (S)VOC emission profiles. Theoretical and experimental results obtained in a Micro-Chamber/Thermal Extractor (μ-CTE™) and in 24 L emission test chamber measurements were in good agreement. Further properties were investigated concerning the material applicability, such as shelf life and inter-laboratory comparability. The maximum relative standard deviation in the inter-laboratory study was found to be 20%.
Emission testing of products is currently a rapidly increasing field of measurement activity. Labelling procedures for construction products are based on such emission test chamber measurements and hence measurement performance should be verified. A suited procedure for this purpose is the testing of one unique homogenous material in different laboratories within a Round Robin Test (RRT). Therefore, it is useful to have a reference material which can be used within inter-laboratory studies or as part of the quality management system to ensure comparable results. Several approaches on the development of reproducibly emitting materials have been published. These have in common only to emit a single VOC – toluene. Two further research studies carried out by BAM aimed to develop reference material for emissions testing containing one or more VOC in a single material. The first approach was a doped lacquer with Volatile and Semi-Volatile Organic Compounds (VOC/SVOC) and the second was Thermoplastic Polyurethane (TPU) or a Squalane/Paraffin mixture. Results received with the lacquer based material were presented in more detail.
Earth, timber, fibre boards and insulation materials based on wooden and other natural fibres offer a variety of properties beneficial for eco innovative constructions that are able to improve the energy and resource efficiency of buildings.
Due to their porosity, natural building materials are vapour active and are able to buffer moisture. In combination with highly insulated and airtight but vapour permeable building envelopes, modern earth-timber constructions provide stable indoor humidity levels and can therefore be naturally ventilated while achieving highest energy efficiency standards. Experimental evidence suggests that monitored pilot buildings in Berlin do show healthy indoor air humidity levels (around 50%) in wintertime, while mechanically ventilated buildings demonstrate significantly lower values (around 25%), which have to be considered as uncomfortable and unhealthy.
The application of building materials being poor in chemical emissions, particularly volatile organic compounds (VOC) and radon, improves the indoor air quality further, so that intermittent ventilation twice a day will be sufficient to provide healthy indoor air quality. The air quality in critical rooms (e.g. small bedrooms), demonstrating a smaller air volume, should be monitored if appropriate ratios of room size to occupancy level cannot be realised.
Through night time ventilation in summer, vapour active earth-timber constructions provide evaporative cooling (humidity adsorption at night time and desorption during the day). As a result, indoor temperatures of earth-timber buildings range around 8 °C below the outside temperature peak, when an appropriate glazing ratio is reflected. The EU funded research project H-house is investigating various construction materials regarding water vapour adsorption as well as emission and absorption of harmful substances. Based on this investigation new wall constructions are designed to provide a healthier indoor environment.
Multi residential buildings, developed as highly energy-efficient and airtight are nowadays often fitted with mechanical Ventilation Systems as a way to overcome shortcomings and even defects tinked to indoor climate. The presented study investigates the potential of low-emitting. natural building materials with hygroscopic properties to contribute to a healthy and comfortable indoor environment, while reducing the need for mechanical Ventilation.
A selection of natural building materials suitable for application as internal partition walls has been investigated with regards to their water vapour adsorption capacity.
Special emphasis was placed on the investigation of modified earth plasters as well as wood-based materials, used as wall lining to provide increased adsorption capacities.
In addition, tests on materials emissions (formaldehyde, VOCs, SVOCs and radon) as well as adsorption tests of airborne pollutants have been conducted in specially-designed fest chambers. All tests were performed at either the material or the component tevel.
Overall results to date suggest that natural materials contribute to an improved indoor environment quality through an increased moisture-buffering capacity, low emissions and the potential to adsorb airborne pollutants, therefore reducing the need for mechanical Ventilation.
The inhalation of radon (222Rn) decay products is the leading cause of lung cancer apart from tobacco smoking. Besides the permeation of radon from the subsoil through the basement as main source of radon in indoor air, also building materials have to be taken into consideration, especially at low air change rates in buildings. The Construction Products Regulation (EC, 2010) gives essential requirements for construction works regarding the release of dangerous substances such as toxic gases and radiation to which radon can be assigned. The recently adopted Basic Safety Standards Directive (EC, 2013), which has to be ratified by each European member state in between the next three years sets reference levels for indoor radon concentrations for the first time. In research project financed by the German Ministry for the Environment, Nature Conservation, Building and Nuclear Safety a practical, reliable and easily applicable test procedure for the determination of radon exhalation from building materials – based on ISO 16000-9 (ISO, 2006) and CEN/TS 16516 (CEN, 2013) – should be developed. In contrast to the static test procedure published by Richter et al. (2013), dynamically operated test chambers shall be foregrounded. First results of this study are presented, focused on the reliable measurement of radon background concentration and the selection of suitable radon test devices, representing the basic elements of the subsequent work.
Emissions of building materials might have negative impact on human health and well-being. In the EU-funded research project H-House more than 30 natural materials (earthen dry boards and plasters, bio-based insulation materials made of wood, flax, reed, straw, etc.) used for renovation and refurbishment were tested regarding emissions of VOC, formaldehyde and radon. Different to ordinary emission tests on single materials this study focuses on the emissions from complete wall assemblies. Therefore, specially designed test chambers were used allowing the compounds to release only from the surface of the material facing indoors. The testing parameters were chosen in order to simulate model room conditions. The emission results were finally evaluated using the AgBB evaluation scheme, a procedure currently applied for the approval of flooring materials in Germany.
Development of a multi-VOC reference material for quality assurance in materials emission testing
(2015)
Emission test chamber measurement is necessary to proof building materials as sources of volatile organic compounds (VOCs). The results of such measurements are used to evaluate materials and label them according to their potential to emit harmful substances, polluting indoor air. If only labelled materials were installed indoors, this would improve indoor air quality and prevent negative impacts on human health. Because of the complex testing procedure, reference materials for the quality assurance are mandatory. Currently, there is a lack of such materials because most building products show a broad variation of emissions even within one batch. A previous study indicates lacquers, mixed with volatile organic pollutants, as reproducible emission source for a wide range of substances. In the present study, the curing of the lacquer-VOC mixture inside micro-chambers was optimised. Therefore, the humidity and the chamber flow were varied. Typical indoor air pollutants with a wide range of volatilities, for example, styrene, n-hexadecane, dimethyl and dibutyl phthalate were selected. It turned out that, under optimised curing parameters inside the micro-chamber, their emission can be reproduced with variations of less than 10 %. With this, a next important step towards a reference material for emission testing was achieved.
Volatile organic compounds (VOCs) found indoors have the potential to affect human health. Typical sources include building materials, furnishings, cleaning agents, etc. To address this risk, chemical emission testing is used to assess the potential of different materials to pollute indoor air. One objective of the European Joint Research Project 'MACPoll' (Metrology for Chemical Pollutants in Air) aims at developing and testing a reference material for the quality control of the emission testing procedure. Furthermore, it would enable comparison of measurement results between test laboratories. The heterogeneity of the majority of materials makes it difficult to find a suitable reference sample.
In the present study, styrene, 2-ethyl-1-hexanol, N-methyl-α-pyrrolidone, lindane, n-hexadecane, 1,2-dimethyl- and 1,2-di-n-butyl-phthalate were added to 12 commercially available lacquers (6 alkyd and 6 acrylic polymer based lacquers) serving as carrier substrate. After homogenization, the mixtures were loaded into a Markes Micro-Chamber/Thermal Extractor (µ-CTE) for curing and investigation of the emission behavior for each compound. For almost all of the investigated chemicals, the preferred glossy acrylic lacquer showed emissions that were reproducible with a variation of less than 20% RSD. Such lacquer systems have therefore been shown to be good candidates for use as reference materials in inter-laboratory studies.
The development of a gas mixing system (GMS) that enables dynamic and retraceable production of stable long-term VOC gas mixtures within the ppb range is discussed. In this system pure liquid substances are kept separately at a constant temperature, evaporated according to their vapour pressure and removed by a small inert gas flow. A modular set-up allows flexible handling. All vapours generated are finally united in a mixing chamber. Any concentration level of the gas mixture can be produced by a suitable combination of evaporation temperature, carrier and dilution gas flows. Test results from continuous operation over six weeks are presented. The equipment was tested on seven volatile organic compounds (VOC) of different vapour pressure ranges. It was possible to establish stable operation for the equipment during the entire period and reproducible gas concentrations which were traceable to the mass as an SI unit, thus the system is suitable for long-term tests.---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Im Beitrag wird die Entwicklung eines Gasmischsystems (GMS) beschrieben, das die dynamische und rückführbare Generierung von langzeitstabilen VOC-Gasgemischen im ppb-Bereich erlaubt. Dabei werden Reinsubstanzen separat temperiert, ihrem Dampfdruck entsprechend verdampft und durch einen kleinen Inertgasstrom abgeführt. In einer Mischkammer werden sie schließlich zusammengeführt. Durch die Kombination von Verdampfungstemperatur, Träger- und Verdünnungsgasflüssen ist die Einstellung eines beliebigen Konzentrationsniveaus des Gasgemischs möglich. Aus einem Dauerbetrieb von sechs Wochen werden Untersuchungsergebnisse gezeigt. Dabei wurde die Apparatur mit insgesamt sieben flüchtigen organischen Verbindungen (VOC) unterschiedlicher Dampfdruckbereiche betrieben. Die Anlage lief über den gesamten Zeitraum stabil und lieferte reproduzierbare und auf die Masse als SI-Einheit rückführbare Gaskonzentrationen. Somit ist das Verfahren für Langzeitanwendungen geeignet.
Determination of radon exhalation rates from construction materials using VOC emission test chambers
(2013)
Determination of radon exhalation from construction materials using VOC emission test chambers
(2013)
The inhalation of 222Rn (radon) decay products is one of the most important reasons for lung cancer after smoking. Stony building materials are an important source of indoor radon. This article describes the determination of the exhalation rate of stony construction materials by the use of commercially available measuring devices in combination with VOC emission test chambers. Five materials – two types of clay brick, clinker brick, light-weight concrete brick, and honeycomb brick – generally used for wall constructions were used for the experiments. Their contribution to real room concentrations was estimated by applying room model parameters given in ISO 16000-9, RP 112, and AgBB. This knowledge can be relevant, if for instance indoor radon concentration is limited by law. The test set-up used here is well suited for application in test laboratories dealing with VOC emission testing.
The inhalation of 222Rn (radon) is one of the most important reasons for lung cancer, after smoking. Usually, the geological subsoil and the building ground are the dominant sources for enhanced indoor radon levels. Additionally, building materials can increase indoor radon concentrations when these materials contain higher contents of 226Ra (radium), especially in combination with low air exchange rates. For a realistic estimation of indoor radon
concentrations, it is helpful to carry out measurements of radon exhalation rates from relevant materials using emission test chambers. In Germany, it is aspired to limit the total indoor radon concentration to 100 Bq/m3, whereby building materials should contribute at most 20 Bq/m3. Within a project financed by the German Institute for Construction Technology (DIBt), a practical oriented measurement procedure of the radon exhalation of building materials in accordance to ISO 16000-9 was developed to have a means for the assessment of these materials with respect to their indoor use. Test chambers with different volumes were used. The tested materials were mainly used for wall constructions (e.g., bricks, light-weight concrete) and have known specific radium activities and radon exhalation rates.
With a gas mixing system (GMS) developed in our laboratory we created a gas mixture of
four substances. Adsorptive wall materials of four different compositions were exposed to this
gas mixture, consisting of 1-pentanol, hexanal, butyl acetate and n-decane. Aim of this study
was to scrutinize the ability of these samples to reduce the concentration of the supplied gas.
This capacity is expressed in the sorption flux F or area specific adsorption rate respectively.
The test was performed referring to a draft of ISO 16000-24.