Indoor Environments最新文献

Indoor air quality in schools and classrooms is paramount for the health and well-being of pupils and staff. Carbon dioxide sensors offer a cost-effective way to assess and manage ventilation provision. However, often only a single point measurement is available which might not be representative of the CO₂ distribution within the room. A relatively generic UK classroom in wintertime is simulated using Computational Fluid Dynamics. The natural ventilation provision is driven by buoyancy through high- and low-level openings in both an opposite-ended or single-ended configuration, in which only the horizontal location of the high-level vent is modified. CO₂ is modelled as a passive scalar and is shown not to be ‘well-mixed’ within the space. Perhaps surprisingly, the single-ended configuration leads to a ‘more efficient’ ventilation, with lower average CO₂ concentration. Measurements taken near the walls, often the location of CO₂ sensors, are compared with those made throughout the classroom and found to be more representative of the ventilation rate if made above the breathing zone. These findings are robust with respect to ventilation flow rates and to the flow patterns observed, which were tested by varying the effective vent areas and the ratio of the vent areas.

Every year in the United States conifers are purchased to serve as Christmas trees in homes where they emit volatile organic compounds (VOCs) to the indoor environment. Although many studies have measured the ecosystem-level emissions of VOCs from conifers outdoors (characterizing monoterpene, isoprene, and aldehyde emissions), little is known about VOC emission rates once a conifer is brought indoors. Using a proton transfer reaction-mass spectrometer we characterized the VOCs emitted from a freshly cut Douglas Fir for 17 days in an environmentally controlled chamber. Ozone injections were also performed to analyze indoor chemistry that may occur. Introduction of the tree into the chamber increased the response of 52 mass spectra signals detected by the PTR-MS by at least 500 counts per second (cps) compared to background levels, with concentrations sharply decreasing after the first two days. Monoterpenes were emitted from the tree at a rate of 12.4 mg h⁻¹ the first day and fell to 1 mg h⁻¹ by day three. Overall, monoterpene emissions from this Douglas fir were initially comparable to other strong indoor monoterpene sources (fragranced products and air fresheners) but decayed quickly and, within days, were smaller than other common indoor sources. Addition of ozone to the chamber resulted in decreased monoterpene concentrations that coincided with modest increases in formaldehyde. Four other emitted VOCs were tentatively identified due to their large increase within the first few hours of the tree placed in the chamber, behavior during ozonation, or pattern of accumulation over time.

In recent years, significant progress has been made in the development of materials that selectively reflect or absorb radiation in specific wavelength ranges. Previous studies have shown that the same intensity of radiation can produce different degrees of thermal perception depending on its wavelength. This difference is thought to be the optical properties of the skin. However, these findings have not been quantitatively verified yet. The purpose of this study is to quantitatively analyze the effects of radiation of different wavelength ranges on thermal sensation. We conducted a human subject experiment and discovered that far-infrared radiation causes a warmer and more uncomfortable sensation than near-infrared radiation. To interpret these results, we developed a new mathematical model that predicts thermal perception caused by radiation of different wavelengths. The model is based on a heat diffusion equation within the skin and considers the optical properties of the skin to simulate thermoreceptor activities in response to given spectral irradiances. Our model explained the observed phenomenon in our and previous experiments, where the same intensity of radiation but at different wavelengths can produce different degrees of thermal perception, in terms of physiological mechanisms. Additionally, the model revealed a hierarchy in thermal sensation, with far-infrared radiation being perceived as the warmest, followed by mid-infrared, visible, and near-infrared radiation. These findings are crucial for designing materials that selectively reflect or absorb radiation in specific wavelength ranges, and for developing heaters that provide efficient heating with low energy consumption.

This paper reports on the findings from INDAIRPOLLNET (INDoor AIR POLLution NETwork), a recently completed European COST Action network. INDAIRPOLLNET ran from September 2018 to March 2023 with more than 200 indoor and outdoor air quality scientists from universities, large and small companies, and research institutes around Europe and beyond. The expertise of our interdisciplinary network members covered chemistry, biology, standardisation, household energy, particulate matter characterisation, toxicology, exposure assessment, air cleaning, building materials, building physics and engineering (including ventilation and energy), and building design. The aim of INDAIRPOLLNET was to design a framework for future indoor air chemistry field campaigns, building on our improved understanding of indoor air chemistry. The main focus of our network was to better understand the sources, transformations and fate of chemical pollutants found in the air in buildings. In this paper, we present the main findings from our network, which include a call for greater spatial and temporal coverage of measurements indoors, the need for standardised techniques for indoor measurements and the impact of occupants on indoor air quality. We also present a checklist of building parameters that should be measured in any future indoor air campaign. Finally, we present our new framework, focusing on 5 key research areas: reactivity in indoor environments; mapping organic constituents indoors; the role of the occupant in indoor air chemistry; indoor modelling studies and novel materials and technologies indoors. We hope this framework will be of use to the indoor air quality community, enabling healthier buildings for the future.