# The Ability to Control VOC Emissions from Multilayer Building Materials
## 1 Introduction  
### General Overview of the Research Problem  
Indoor air quality (IAQ) continues to be a major environmental problem due to the presence of indoor pollutants and their health hazards, irritation and discomfort to occupants. Volatile organic compounds (VOCs) are one of the main indoor air pollutants [1], and their excessively high concentration in rooms affects the well-being and health of users, which can cause Sick Building Syndrome (SBS) [2], defined as a complex of disease symptoms occurring in a building. The source of volatile organic compounds is, among others, construction products containing organic solvents or polymers. Often, their presence in the room is indicated by a chemical smell, which can be irritating. An unpleasant odour's perception increases with the increase in temperature caused by solar radiation or during the heating season when ventilation in the rooms is limited [3, 4]. In the flooring systems used in apartment construction and offices, numerous construction products are used, often characterised by significant VOC emissions, e.g., adhesives or primers. The indoor air pollution level related to VOC's air concentration, apart from the emissionsfrom products, depends on many factors such as air humidity, number of air changes and temperature [4]. Heated floors, covered by the authors' current research interest, are a special case, where higher temperatures may significantly increase emissions, especially in the first few days after installation. The authors discovered also that the assessment of the VOC emission level from multilayer systems in the context of the variability of environmental parameters is a seldom-described issue in the literature. In the case of many layers of products in the floor system, diffusion resistance causes emission delay in time and non-obvious waveforms. Our research consideration is that the models used to determine the air pollutant concentration from a product with a single layer can only partially be used to assess complex product systems, e.g., floors. Standardised test methods for VOC emissions from construction products do not consider temperature effects from underfloor heating systems [5]. An example of this is the horizontal research standard EN 16516, which assumes standard conditions for testing products at a temperature of 23 \({}^{\circ}\)C \(\pm\) 1 \({}^{\circ}\)C.  
Typical VOC emission testing is based on assessing the concentration of chemical compounds emitted from the building material in the test chamber based on a European model room's assumption reflected in the standardised test chamber [5]. The test conditions are specified in the standards EN ISO 16000-9: 2006 [6], including test temperature, minimum chamber area, its tightness, airflow range, chamber structure andthe number of air changes per hour. For example, in the literature data, [PERSON] [7] and [PERSON] [8] present experiments completed at one temperature, 23 \({}^{\circ}\)C. The dominating research work in literature is focused on the evaluation of formaldehyde determined by the HPLC method and the assessment of the total volatile organic compounds, TVOC (Total Volatile Organic Compounds), by the GC/MS (Gas Chromatography with Mass Spectrometry) method and less frequently, the measurements of the concentrations of individual compounds in the C\({}_{6}\)-C\({}_{16}\) range. Considering the lack of published research on the emissions from multi-product systems (as in our case-the electrically heated floors) considering the variability of the environmental conditions with increased temperature and humidity, the authors planned, developed and provided a series of laboratory experiments where such dependence is investigated using a modified chamber method based on the standard approach [5]. A large number of construction and finishing materials have emerged that emit volatile substances as organic compounds (VOCs) are commonly used in buildings, including adhesives [9], carpets [10], floorings [11], ceiling tiles, paints and furniture [12; 13; 14].