Air Enthalpy as an IAQ Indicator in Hot and Humid Environment—Experimental Evaluation

The authors studied the impact of indoor air humidity in the range of 60% to 90% on building user perception in the temperature range of 26 to 28 °C. The research thesis was put forward that the impact of humidity on indoor air quality dissatisfaction of building users in a warm and humid indoor environment is greater than that indicated in thermal comfort models. The presented experiment examined the indoor air quality perception of n = 28 subjects in the test chamber of a nearly zero energy building under ten environmental conditions, together with a thermal comfort assessment. The authors developed an experimental relation for predicting building users’ satisfaction based on the Weber–Fechner law, where the predicted percentage of dissatisfied users (PD) is determined by means of air enthalpy (h), PD = f(h). The obtained results confirmed the sated thesis. Additionally, the intersection points of the experimental function and isotherms resulting from the Fanger model are presented, where the thermal comfort assessment starts to indicate lower user dissatisfaction results than experimental values. The authors recommend the experimental equation for humid air enthalpies in the range of 50 to 90 kJ/kg. The indoor air quality assessment based on the enthalpy value is simple and can be used to determine the overall Indoor Environmental Quality index of a building (IEQindex).

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Effects of Climatic Conditions, Season and Environmental Factors on CO2 Concentrations in Naturally Ventilated Primary Schools in Chile

Sustainability ◽

10.3390/su13084139 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4139

Author(s):

Muriel Diaz ◽

Mario Cools ◽

Maureen Trebilcock ◽

Beatriz Piderit-Moreno ◽

Shady Attia

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Primary Schools ◽

Co2 Concentration ◽

Building Design ◽

Climatic Conditions ◽

Indoor Environmental Quality ◽

Co2 Concentrations ◽

The Impact

Between the ages of 6 and 18, children spend between 30 and 42 h a week at school, mostly indoors, where indoor environmental quality is usually deficient and does not favor learning. The difficulty of delivering indoor air quality (IAQ) in learning facilities is related to high occupancy rates and low interaction levels with windows. In non-industrialized countries, as in the cases presented, most classrooms have no mechanical ventilation, due to energy poverty and lack of normative requirements. This fact heavily impacts the indoor air quality and students’ learning outcomes. The aim of the paper is to identify the factors that determine acceptable CO2 concentrations. Therefore, it studies air quality in free-running and naturally ventilated primary schools in Chile, aiming to identify the impact of contextual, occupant, and building design factors, using CO2 concentration as a proxy for IAQ. The monitoring of CO2, temperature, and humidity revealed that indoor air CO2 concentration is above 1400 ppm most of the time, with peaks of 5000 ppm during the day, especially in winter. The statistical analysis indicates that CO2 is dependent on climate, seasonality, and indoor temperature, while it is independent of outside temperature in heated classrooms. The odds of having acceptable concentrations of CO2 are bigger when indoor temperatures are high, and there is a need to ventilate for cooling.

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HVAC Ventilation Strategies: The Contribution for Thermal Comfort, Energy Efficiency, and Indoor Air Quality

Journal of Green Building ◽

10.3992/jgb.2.2.131 ◽

2007 ◽

Vol 2 (2) ◽

pp. 131-150 ◽

Cited By ~ 7

Author(s):

Jatuwat Varodompun ◽

Mojtaba Navvab

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Cfd Simulation ◽

Indoor Environmental Quality ◽

Ventilation Strategy ◽

Jet Ventilation ◽

Advantages And Disadvantages ◽

Ventilation Strategies

In Heating Ventilating and Air Conditioning (HVAC) systems, ventilation strategies impact building energy consumption, occupants' thermal comfort and Indoor Air Quality (IAQ). Ventilation strategies such as Mixing Jet Ventilation (MJV), Displacement Ventilation (DV), and Impinging Jet Ventilation (IJV) are operated on the different principals. MJV relies on dilution, while DV and IJV rely on both dilution and stratification. Due to climatic variation, ventilation strategies must be operated under different cooling and heating load scenarios. Typically, each ventilation strategy controls the indoor environment through a single adequate flow rate with suitable supply parameters such as temperature, pollutant concentration, vapor, velocity, etc. Hence, the indoor thermal and IAQ condition are independently impacted. A room with excellent thermal condition is possible to have poor IAQ. Given this limitation, vast air flow variables, and occupants' activities, the performances evaluation of these strategies are complicated. In this study, three ventilation strategies, MJV, DV, and IJV are thoroughly investigated. The Computational Fluid Dynamics (CFD) simulation was mainly utilized to handle the complexity of this study. The parametric studies of 48 CFD simulations are presented. Referring to ASHRAE RP-1133, the experimental data from a specially built HVAC-IEQ laboratory was used to validate the CFD data. The research results indicate both advantages and disadvantages in all three strategies. In addition, there is no single strategy that can perform excellently in all indexes. Using the well-known index called ventilation effectiveness (VEF), DV performs outstandingly. However, under a newly proposed index called ventilation performances, DV fails because the stratification discomfort exceeds 36% of room area. MJV suffers from low VEF and excessive draft. However, the IAQ of MJV is not as poor as expected. IJV can be an alternative especially for space where sleeping and sitting activities dominate. IJV can conserve HVAC energy, while maintaining good IAQ. Compared to DV, although VEF is lower, stratification discomfort is minimized to 24%–12% (depending on supply velocity). Overall, this study demonstrates that ventilation strategies are the key to enhance IAQ. Therefore, the utilization of an appropriate ventilation strategy might increase, Leadership in Energy and Environmental Design (LEED) score, particularly for Indoor Environmental Quality, Innovation and Design Process, and Energy and Atmospheric categories.

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AN EVALUATION OF INDOOR ENVIRONMENTAL QUALITY AND OCCUPANT WELL-BEING IN MANITOBA SCHOOL BUILDINGS

Journal of Green Building ◽

10.3992/1552-6100.12.1.123 ◽

2017 ◽

Vol 12 (1) ◽

pp. 123-141 ◽

Cited By ~ 1

Author(s):

Ahmed Radwan ◽

Mohamed H. Issa

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Environmental Quality ◽

Indoor Air ◽

Well Being ◽

School Buildings ◽

Indoor Environmental Quality ◽

Middle Aged ◽

Green School

This exploratory research aims to evaluate indoor environmental quality in the classrooms of three school buildings in Southern Manitoba, Canada, and to evaluate the well-being of these schools' teachers as it pertains to their perception of their classrooms' indoor environment. The schools include a middle-aged, conventional school; a new, non-green school; and a new, green school certified using the Leadership in Energy and Environmental Design rating system. The methodology involved using a mobile instrument cart to conduct snapshot measurements of thermal comfort, indoor air quality, lighting and acoustics in classrooms and an occupant survey to evaluate teachers' long-term satisfaction with their classrooms' indoor environmental quality. The results showed that the new, green and new, non-green schools' classrooms performed better than the conventional, middle-aged school's classrooms with respect to some aspects of thermal comfort and indoor air quality only. Teachers in the new, green school and in the new, non-green school were more satisfied than teachers in the conventional, middle-aged school with their classrooms' overall indoor environmental quality, lighting quality and indoor air quality. Surprisingly, the new, green and new-non green school classrooms' performance were very comparable with the new, green school's classrooms performing statistically significantly better with respect to relative humidity. Similarly, none of the differences in teachers' satisfaction ratings between the new, green and new, non-green school were statistically significant.

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Detailed Analysis of Thermal Comfort and Indoor Air Quality Using Real-Time Multiple Environmental Monitoring Data for a Childcare Center

Energies ◽

10.3390/en14030643 ◽

2021 ◽

Vol 14 (3) ◽

pp. 643

Author(s):

Sukjoon Oh ◽

Suwon Song

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Real Time ◽

Indoor Air ◽

Energy Use ◽

Environmental Data ◽

Monitoring Data ◽

Indoor Environmental Quality ◽

Childcare Center

Thermal comfort, indoor air quality (IAQ), and energy use are closely related, even though these have different aspects with respect to building performance. We analyzed thermal comfort and IAQ using real-time multiple environmental data, which include indoor air temperature, relative humidity, carbon dioxide (CO2), and particulate matter (e.g., PM10 and PM2.5), as well as electricity use from an energy recovery ventilation (ERV) system for a childcare center. Thermal comfort frequency and time-series analyses were conducted in detail to thoroughly observe real-time thermal comfort and IAQ conditions with and without ERV operation, and to identify energy savings opportunities during occupied and unoccupied hours. The results show that the highest CO2 and PM10 concentrations were reduced by 51.4% and 29.5%, respectively, during the occupied hours when the ERV system was operating. However, it was also identified that comfort frequencies occurred during unoccupied hours and discomfort frequencies during occupied hours. By analyzing and communicating the three different types of real-time monitoring data, it is concluded that the ERV system should be controlled by considering not only IAQ (e.g., CO2 and PM2.5) but also thermal comfort and energy use to enhance indoor environmental quality and save energy based on real-time multiple monitoring data.

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Effects of the COVID-19 Pandemic on Indoor Air Quality and Thermal Comfort of Primary Schools in Winter in a Mediterranean Climate

Sustainability ◽

10.3390/su13052699 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2699

Author(s):

Alicia Alonso ◽

Jesús Llanos ◽

Rocío Escandón ◽

Juan J. Sendra

Keyword(s):

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Primary Schools ◽

Indoor Environmental Quality ◽

Indoor Environments ◽

Thermal Discomfort ◽

Air Supply ◽

Hybrid Ventilation

Research studies have shown the potential effects of indoor environmental quality (IEQ) on pupils’ health and academic performance. The COVID-19 pandemic has prompted renewed interest in the assessment of deficient indoor air quality (IAQ) conditions in schools and has become a priority over achieving adequate comfort conditions. Scientific studies confirm aerosols as one of the transmission routes of SARS-CoV-2 so that the possibility of airborne transmission increases in indoor environments with high occupancy, such as classrooms. As a result, international protocols and guidelines have established a requirement for educational buildings to over-ventilate with a fresh outdoor air supply. The main object of this work is to analyse the effects of the COVID-19 pandemic on thermal comfort and indoor air quality, in winter, in two classrooms of southern Spain. Thus, onsite measurements of environmental variables were conducted before and during the pandemic. Both classrooms have mechanical ventilation systems as they are within a recently built primary school (2018). Results shows a decrease of 300 ppm in CO2 weekly average values during the pandemic, when hybrid ventilation is used, and a decrease of 400 ppm when schools are naturally ventilated during all teaching hours. However, the analysis of standards shows that over 60% of hours are thermal discomfort conditions.

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Numerical analysis of the impact of natural ventilation on the Indoor Air Quality and Thermal Comfort in a classroom

E3S Web of Conferences ◽

10.1051/e3sconf/201911101023 ◽

2019 ◽

Vol 111 ◽

pp. 01023 ◽

Cited By ~ 1

Author(s):

George-Mãdãlin Chitaru ◽

Andrei Istrate ◽

Tiberiu Catalina

Keyword(s):

Numerical Simulation ◽

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Indoor Air ◽

Natural Ventilation ◽

Simulation Software ◽

Educational Institutions ◽

Research School ◽

The Impact

Indoor air quality (IAQ) inside educational institutions is an important topic in the field of building and health research. School absenteeism and educational performance have been linked to poor air quality inside classrooms. A numerical simulation software has been used to test 5 different scenarios of natural ventilation during summer and winter. CO2 levels, air relative humidity, operative temperature and PMV were used as indoor air quality and thermal comfort indicators. Results have shown high CO2 and humidity levels when all windows are closed, and a variable improvement when different natural ventilations strategies are employed. A detailed procedure for the numerical simulation has been presented.

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Comfort IAQ – a new tool to simulate the indoor particulate matter pollution in relation to the chosen supply air filter quality

E3S Web of Conferences ◽

10.1051/e3sconf/201911102024 ◽

2019 ◽

Vol 111 ◽

pp. 02024

Author(s):

Tobias Zimmer

Keyword(s):

Particulate Matter ◽

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Test Chamber ◽

Building Envelope ◽

Outdoor Air ◽

Good Tool ◽

Air Filter ◽

The Impact

Many factors are rather well known for their ability to create a good indoor air climate, but when it comes to airborne particles, there is no great deal of documentation to consult and set requirements. Nor are there much of other specific guidelines. The new, product-neutral and free online calculation tool Comfort IAQ helps to understand the mechanisms behind IAQ and gives a good indication on what would be the impact on indoor air quality (IAQ) due to air exchange, outdoor air environment, air filter selection and building envelope characteristics. Comfort IAQ allows to simulate the concentrations of Particulate Matter (PM1, PM2.5, PM10) in a specific ventilated room, depending on the chosen supply air filter quality. To model the room and the supply air conditions in a realistic way, Comfort IAQ allows to define besides outdoor air conditions (ODA) also the room dimensions, the air changes, the recirculation air rate as well as the supply air filter quality (based on ISO 16890, EN779 or ASHRAE 52.2). Based on these values, the Comfort IAQ tool provides an estimation of the indoor particle concentration and gives engineers and planers a good tool to optimize the Indoor Air Quality, by choosing the best combinations of supply air filter qualities and ventilation rates for a specific application. The algorithms in the online tool Comfort IAQ have been developed by Lars Ekberg, (Docent-installallationsteknik, Chalmers Tekniska Högskola) and the accuracy of the calculations was verified by comparing them with measurements in a full-scale test chamber.

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Occupants’ Interaction With an Occupant Voting System for Thermal and Indoor Air Quality Feedback – Case Studies in Office Spaces

Frontiers in Built Environment ◽

10.3389/fbuil.2021.643630 ◽

2021 ◽

Vol 7 ◽

Author(s):

Donya Sheikh Khan ◽

Jakub Kolarik ◽

Peter Weitzmann

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Case Studies ◽

Indoor Air ◽

Thermal Environment ◽

Office Buildings ◽

Indoor Environmental Quality ◽

Quality Feedback ◽

The Impact

Occupants can provide valuable feedback on the indoor environmental quality of buildings. Research on occupant voting systems (OVS) has demonstrated that apps or electronic devices can act as viable tools for collecting long-term feedback from occupants. However, previous research has only to a limited extent explored occupants’ interaction with OVS and the impact it might have on the reliability of the collected feedback. The present paper presents three case studies on applying a tangible OVS, denoted TiAQ, to collect feedback on thermal and indoor air quality (IAQ) in office spaces. The main objective of the present study was first to explore occupants’ interaction with TiAQ and their motivation. Second, identifying whether feedback collected with TiAQ could represent occupants’ comfort and discomfort with the thermal environment and IAQ. Thirdly, identifying challenges related to occupants’ interaction with TiAQ that might affect the representativeness of collected feedback. The present study was conducted at three office buildings in up to 7 months and demonstrated that TiAQ was suitable for collecting long-term feedback on occupants’ comfort and discomfort with the thermal environment. On average, one vote was cast per day per occupant. Additionally, in one of the office buildings, 60% of occupants reported to have interacted with TiAQ daily or weekly when, e.g., passing the device going to/from the office spaces. Occupants’ expectations of TiAQ and getting “feedback on feedback” need to be further addressed to identify ways to sustain occupants’ long-term use of the device and reduce “ill-willed” interactions.

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Building Performance Evaluation of a New Hospital Building in the UK: Balancing Indoor Environmental Quality and Energy Performance

Atmosphere ◽

10.3390/atmos12010115 ◽

2021 ◽

Vol 12 (1) ◽

pp. 115

Author(s):

Nishesh Jain ◽

Esfand Burman ◽

Samuel Stamp ◽

Clive Shrubsole ◽

Roderic Bunn ◽

...

Keyword(s):

Performance Evaluation ◽

Air Quality ◽

Thermal Comfort ◽

Indoor Air Quality ◽

Environmental Quality ◽

Indoor Air ◽

Building Design ◽

Energy Performance ◽

Building Performance ◽

Indoor Environmental Quality

Hospitals are controlled yet complex ecosystems which provide a therapeutic environment that promotes healing, wellbeing and work efficiency for patients and staff. As these buildings accommodate the sick and vulnerable, occupant wellbeing and good indoor environmental quality (IEQ) that deals with indoor air quality (IAQ), thermal comfort, lighting and acoustics are important objectives. As the specialist nature of hospital function demands highly controlled indoor environments, this makes them energy intensive buildings due to the complex and varying specifications for their functions and operations. This paper reports on a holistic building performance evaluation covering aspects of indoor air quality, thermal comfort, lighting, acoustics, and energy use. It assesses the performance issues and inter-relationships between IEQ and energy in a new building on a hospital campus in the city of Bristol, United Kingdom. The empirical evidence collated from this case study and the feedback received from the hospital staff help identify the endemic issues and constraints related to hospital buildings, such as the need for robust ventilation strategies in hospitals in urban areas that mitigate the effect of indoor and outdoor air pollution and ensuring the use of planned new low-carbon technologies. Whilst the existing guidelines for building design provide useful instructions for the protection of hospital buildings against ingress of particulate matter from outdoors, more advanced filtration strategies may be required to enact chemical reactions required to control the concentration levels of pollutants such as nitrogen dioxide and benzene. Further lessons for improved performance in operation and maintenance of hospitals are highlighted. These include ensuring that the increasingly available metering and monitoring data in new buildings, through building management systems, is used for efficient and optimal building operations for better IEQ and energy management. Overall, the study highlights the need for an integrated and holistic approach to building performance to ensure that healthy environments are provided while energy efficiency targets are met.

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Window operation behaviour and indoor air quality during lockdown: A monitoring-based simulation-assisted study in London

Building Services Engineering Research and Technology ◽

10.1177/01436244211017786 ◽

2021 ◽

pp. 014362442110177

Author(s):

Farhang Tahmasebi ◽

Yan Wang ◽

Elizabeth Cooper ◽

Daniel Godoy Shimizu ◽

Samuel Stamp ◽

...

Keyword(s):

Air Quality ◽

Indoor Air Quality ◽

Indoor Air ◽

Energy Demand ◽

Natural Ventilation ◽

Probabilistic Models ◽

Performance Model ◽

Outdoor Environment ◽

Ventilation Strategies ◽

The Impact

The Covid-19 outbreak has resulted in new patterns of home occupancy, the implications of which for indoor air quality (IAQ) and energy use are not well-known. In this context, the present study investigates 8 flats in London to uncover if during a lockdown, (a) IAQ in the monitored flats deteriorated, (b) the patterns of window operation by occupants changed, and (c) more effective ventilation patterns could enhance IAQ without significant increases in heating energy demand. To this end, one-year’s worth of monitored data on indoor and outdoor environment along with occupant use of windows has been used to analyse the impact of lockdown on IAQ and infer probabilistic models of window operation behaviour. Moreover, using on-site CO2 data, monitored occupancy and operation of windows, the team has calibrated a thermal performance model of one of the flats to investigate the implications of alternative ventilation strategies. The results suggest that despite the extended occupancy during lockdown, occupants relied less on natural ventilation, which led to an increase of median CO2 concentration by up to 300 ppm. However, simple natural ventilation patterns or use of mechanical ventilation with heat recovery proves to be very effective to maintain acceptable IAQ. Practical application: This study provides evidence on the deterioration of indoor air quality resulting from homeworking during imposed lockdowns. It also tests and recommends specific ventilation strategies to maintain acceptable indoor air quality at home despite the extended occupancy hours.

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