4 research outputs found
Development of low-cost indoor air quality monitoring devices: Recent advancements
The use of low-cost sensor technology to monitor air pollution has made remarkable strides in the last decade. The development of low-cost devices to monitor air quality in indoor environments can be used to understand the behaviour of indoor air pollutants and potentially impact on the reduction of related health impacts. These user-friendly devices are portable, require low-maintenance, and can enable near real-time, continuous monitoring. They can also contribute to citizen science projects and community-driven science. However, low-cost sensors have often been associated with design compromises that hamper data reliability. Moreover, with the rapidly increasing number of studies, projects, and grey literature based on low-cost sensors, information got scattered. Intending to identify and review scientifically validated literature on this topic, this study critically summarizes the recent research pertinent to the development of indoor air quality monitoring devices using low-cost sensors. The method employed for this review was a thorough search of three scientific databases, namely: ScienceDirect, IEEE, and Scopus. A total of 891 titles published since 2012 were found and scanned for relevance. Finally, 41 research articles consisting of 35 unique device development projects were reviewed with a particular emphasis on device development: calibration and performance of sensors, the processor used, data storage and communication, and the availability of real-time remote access of sensor data. The most prominent finding of the study showed a lack of studies consisting of sensor performance as only 16 out of 35 projects performed calibration/validation of sensors. An even fewer number of studies conducted these tests with a reference instrument. Hence, a need for more studies with calibration, credible validation, and standardization of sensor performance and assessment is recommended for subsequent research
Generic wireless sensor network for dynamic monitoring of a new generation of building material
Existing testing methods for building materials before deployment include a series of
procedures as stipulated in British Standards, and most tests are performed in a controlled
laboratory environment. Types of equipment used for measurements, data logging, and
visualisation are commonly bulky, hard-wired, and consume a significant amount of
power. Most of the off-the-shelf sensing nodes have been designed for a few specific
applications and cannot be used for general purpose applications. This makes it difficult
to modify or extend the sensing features when needed. This thesis takes the initiative of
designing and implementing a low-powered, open-source, flexible, and small-sized
Generic wireless sensor network (GWSN) that can continuously monitor the building
materials and building environment, to address the limitations of the conventional
measurement methods and the technological gap.
The designed system is comprised of two custom-made sensor nodes and a gateway, as
well as purpose designed firmware for data collection and processing. For the proof of
concept and experimental studies, several measurement strategies were designed, to
demonstrate, evaluate, and validate the effectiveness of the system. The data was
collected from selected case study areas in the School of Energy, Geoscience,
Infrastructure and Society (EGIS) laboratories by measuring and monitoring building
structures and indoor environment quality parameters using the designed GWSN. The
measured data includes heat flux through the material, surface and air temperatures on
both sides of the material/structure, moisture variation, ambient temperature, relative
humidity, carbon dioxide, volatile organic compounds, particulate matter, and
sound/acoustic levels.
The initial results show the potential of the designed system to become the new
benchmark for tracking the variation of building materials with the environment and
investigating the impact of variation of building materials on indoor environment quality.
Based on the estimates of the thermal performance data, the sample used in the
experiment had a typical U-value between 4.8 and 5.8 W/m2K and a thermal resistance
value of 0.025m2
·K/W[1][2]. Thermal resistance values from the GWSN real-time
measurement were between 0.025 and 0.03 m2K/W, with an average of 0.025 m2K/W,
and thermal transmission values varied between 4.55 and 5.11 W/m2K. Based on the data
obtained, the results are within the range of typical values[3]. For thermal comfort measurements, the results of humidity and temperature from GWSN
were compared to values in the Kambic climatic chamber in the EGIS laboratory, and the
accuracies were 99 % and 98 % respectively. For the IAQ measurements, the values of
CO2 and TVOCs were compared to the commercial off-the-shelf measuring system, and
the accuracies were 98 %, and 97 %. Finally, the GWSN was tested for acoustic
measurements in the range of 55 dB to 106 dB. The results were compared to class one
Bruel & Kjaer SLM. The accuracy of GWSN was 97 %. The GWSN can be used for in lab and in-situ applications, to measure and analyse the thermal physical properties of
building materials/building structures (thermal transmittance, thermal conductivity, and
thermal resistance). The system can also measure indoor air quality, thermal comfort, and
airborne sound insulation of the building envelope. The key point here is to establish a
direct link between how building materials vary with the environment and how this
impacts indoor environment quality. Such a link is essential for long-term analysis of
building materials, which cannot be achieved using current methods.
Regarding increasing the power efficient of the implemented GWSN as well as its
performance and functionality, a new sensing platforms using backscatter technology
have been introduced. The theory of modulation and spread spectrum technique used in
backscattering has been explored. The trade-off between hardware complexity/power
consumption and link performance has been investigated.
Theoretical analysis and simulation validation of the new sensing technique, using
backscatter communication, has been performed. A novel multicarrier backscatter tag
compatible with Wireless Fidelity has been implemented and an IEEE 802.11g OFDM
preamble was synthesized by simulation. The tag consists of only two transistors with
current consumption no larger than 0.2 μA at voltage of less than 0.6 V.
Novel harmonic suppression approaches for frequency-shifted backscatter
communication has been proposed and demonstrated. The proposed approaches
independently manipulate mirror harmonics and higher order harmonics whereby;
specified higher order harmonics can be removed by carefully designing the real-valued
(continuous and discrete) reflection coefficients-based backscatter tags.
When successfully implemented, the backscatter system will reduce sensor node power
consumption by shifting the power-consuming radio frequency carrier synthesis functions
to carrier emitters.Engineering and Physical Sciences Research
Council (EPSRC) Funding EP/H009612/
Estudio de sistemas pasivos para evitar problemas respiratorios en interiores de vivienda ubicados en lugares de clima húmedo y ventoso
[Resumen] El siguiente trabajo indagará sobre las influencias de diversos agentes a la hora de realizar una
construcción y cómo esta relación puede afectar a la salud de las personas que la habitan.
La calidad del aire interior se puede ver alterada por numerosos parámetros por las
características climáticas, las condiciones del entorno y por las concentraciones de
contaminantes que, cada vez son mayores en ambientes interiores.
Además de considerar las herramientas legislativas y guías para identificar las situaciones de
riesgo en cuanto a calidad de aire interior, se investigarán los recursos y conocimientos
necesarios que pueden regular esta situación de malestar.
En concreto, el estudio buscará una zona de costa con clima húmedo y ventoso para analizar la
influencia de la humedad en afecciones respiratorias como el asma y la rinitis alérgica; las
soluciones constructivas pasivas que pueden ser óptimas para disminuir los agentes físicos,
biológicos y químicos que puedan contaminar el ambiente interior de las viviendas, así como
las mejoras que se puedan realizar para mitigar este tipo de situaciones de una forma
sostenible.[Abstract] This research will investigate the influence of various agents when making a housing
construction and how this relation can affect the health of its inhabitants.
Indoor air quality can be altered by many parameters such as climate characteristics,
surrounding conditions and pollutant concentration, which are on the rise in indoor
environments.
In addition to considering legislative tools and guidelines to identify potential indoor air quality
hazards, it will also research the resources and the competences to mitigate this discomfort.
Specifically, this paper will take a coastal area with a humid and windy climate to analyze the
influence of humidity on respiratory diseases such as asthma or allergic rhinitis, the passive
construction solutions that can reduce the physical, biological and chemical agents that
contaminate the home indoor environments and the improvements that can be made to
mitigate this hazards in a sustainable way.Traballo fin de mestrado (UDC.EUAT). Edificación sostenible. Curso 2018/201