Indoor Environmental Quality Assessment Research Articles

Multitrait-multimethod analysis of subjective and objective methods of indoor environmental quality assessment in buildings

Indoor environmental quality (IEQ) refers to the condition of a building’s internal environment that is related to the occupants’ health, comfort, and wellbeing. The assessment and improvement of IEQ in buildings are based on either subjective or objective assessment or the use of both measures, and in recent times, have been attracting attention due to its role in contributing to green building and sustainable environment. This study is aimed at evaluating and analysing the validity of the IEQ parameter traits as assessed using subjective and objective measures. The convergent and discriminant validity of the measured parameter traits were tested by analysing a multitrait–multimethod (MTMM) matrix using confirmatory factor analysis (CFA). The results indicated that there is no convergent validity in the IEQ parameter traits as assessed using subjective and objective methods. However, discriminant validity of the measured parameter traits was adequately supported. This clearly shows that as much as IEQ parameter traits measured through objective physical measurement and subjective occupant survey define the same concept, they cannot be taken to represent a single and same unit of measurement.

Indoor environmental quality assessment: Part 1: Choice of the indoor environmental quality sub-component models

Indoor environment quality is a relative measure of comfort perception by people exposed to the indoor conditions. It is expected that any assessment of energy performance should also include indoor comfort. This study is to review indoor environmental quality models (with respect to thermal and acoustic comfort, indoor air and lighting quality). A simplified indoor environmental quality model is also developed with consideration of EN 15251 draft ‘Guideline for using indoor environmental input parameters for the design and assessment of energy performance of buildings’. This article analyses what components should be modelled and in particular discusses the effect of different weighting schemes on the overall indoor environmental quality index. The analysis includes thermal comfort models, indoor air quality, acoustic comfort and daylight illumination versus lightning. The proposed indoor environmental quality component sub-models will give the most reliable results when the model indoor environment input data are correctly measured and disturbing influences of indoor environmental quality monitoring process are well defined and properly assessed. The final indoor environmental quality result is based on subjoining the uncertainty values achieved in panel analysis of percentage of persons dissatisfied with indoor environmental quality with corrected measurement uncertainty. All simulations for IEQindex sub-components and preliminary metrological analysis of the whole indoor environmental quality model were performed with the NIST program for Monte Carlo tests. The presented indoor environmental quality model proposal is developed to support engineers’ practice as the convenient tool for a practical assessment of building’s occupational satisfaction.

The impact of indoor environmental quality on work productivity in university open-plan research offices

Indoor environmental quality (IEQ) has significant impacts on office occupants' productivity and these impacts differ according to the type of office. The present study focuses on a special type of open-plan offices, university open-plan research offices (UOROs), and aims to study how the IEQ of this type of offices affects the occupants' productivity. A four-part IEQ assessment framework for the University Open-plan Research Office (UORO) is first proposed. Then the investigation is conducted based on survey responses collected from 231 people who are working in UOROs from 19 universities in China. The analysis results show a clear picture of (1) how the office productivity is affected by the five key IEQ aspects (layout, air quality, thermal comfort, lighting and acoustic environment), (2) how these five key IEQ aspects are affected by their corresponding sub-factors, such as conversation noise, and (3) how occupants' perception of sub-factors are affected by individual factors, such as occupant demographics and work activity. The results also emphasize the quality of acoustic environment has the greatest influence on the occupants' productivity in UOROs and imply occupants working in UOROs have higher requirements for acoustic environment than in other common types of open-plan offices. Based on the analysis, a decision-making strategy is also presented for the evaluation and improvement of the IEQ of UOROs.

An integrative approach for indoor environment quality assessment of large glazed air-conditioned airport terminal in the tropics

The indoor environment quality in large glazed space such as airport terminals affects its users in many ways. The indoor environment quality assessment of such a building was typically conducted objective measurement using measurement and subjective assessment using questionnaire survey. However, limited resources and measurement period imply that would be incomplete and cannot provide accurate results. Computer modelling is thus an additional tool in the integrative approach for indoor environment quality assessment and analysis to improve its comfort and energy performance.Field measurement on the objective variables defined the environment quality and energy consumption, as well as questionnaire survey on the subjective judgment defined the indoor comfort. While the computer modelling was assessed across the air temperature, indoor glazed roof surface temperatures, mean radiant temperatures, operative temperatures and illuminance, to examine the building energy performance across the annual cooling load in 2010.The inner surface temperature over glazed roof were recorded as 56°C due to high level solar penetration, even when the indoor air temperatures over the floor level remain stable within the standard comfort zone. This rose the mean radiant temperature and was considered as main cause for indoor discomfort revealed by the survey. The survey found the employees to be slightly uncomfortable and dissatisfied, particularly in summer. The total energy consumption in 2010 was very high compared against the energy benchmarking. This study confirms that the large proportion of glazed roof is the cause for both overheating and thermal discomfort even with excessive use of the cooling system. In addition, recommendation was made to improve the thermal comfort condition in the large glazed air-conditioned terminal.

An integrated approach on energy consumption and indoor environmental quality performance in six Portuguese secondary schools

A major rehabilitation programme of secondary school buildings has been carried out in the last few years in Portugal. With the introduction of HVAC systems in buildings that were previously naturally ventilated, an increase on energy consumption has been verified. During the first occupancy periods of new and refurbished buildings, energy and indoor climate quality audits are important strategies to improve the buildings’ energy use. In this context, this paper aims at showing the relations between the energy consumption and indoor environment quality (IEQ) parameters, obtained from the energy and IEQ audit in six representative modernised secondary schools – part of a larger R&D project untitled 3Es – geographically and climatically distributed in Portugal mainland.The monitoring period during the mid-season 2013 varied between schools, between two and three weeks. Air exchange rates, more specifically infiltration rates, were quantified aiming at determining the current airtightness condition of the refurbished schools. A subjective IEQ assessment was also performed, focusing on occupants' feedback, providing insight on the potential linkages between energy use and occupants’ comfort.A reflection on the energy consumption indicators and the indoor conditions obtained in the classrooms was proposed, and some suggestions were anticipated.

Development of a new methodology to optimize building life cycle cost, environmental impacts, and occupant satisfaction

Thermal comfort and occupant thermal satisfaction are critical aspects in the indoor environment quality assessment and have received considerable attention by designers and building occupants. Improper indoor temperature not only decreases the level of occupant thermal satisfaction, but also has serious health related consequences. Despite the importance of occupant thermal satisfaction that has been vastly emphasized, studies incorporating occupants' satisfaction during the design process are very limited. Therefore, this study aims to develop a multi-objective design optimization model to minimize life cycle cost and life cycle emission, and maximize occupant satisfaction level in a typical commercial building. To solve the multi-objective optimization problem, a Harmony Search based algorithm is developed and employed. Moreover, to identify the level of design thermal satisfaction, a novel utility-theory based thermal comfort index is defined and calculated. A small office building is selected as a case study to analyze four different designs which are identified as optimum solutions. To determine the optimum designs, the satisfaction level of all the design combinations having cost and emissions similar to previously distinguished optimum solutions are compared and best designs are identified.

Assessment and improvement of indoor environmental quality in a primary school

This study reports levels of indoor environmental quality variables before and after installation of heat recovery ventilation in a primary school located in an urban area in Izmir, Turkey. A CO2-based modeling was performed to determine the required flow rates that would comply with an international ventilation standard, followed by computational fluid dynamics modeling for best airflow distribution in a classroom. Temperature, CO2, PM2.5, and total volatile organic compounds were found at undesired levels, among which relative humidity, CO2, and PM2.5 were improved after the intervention. Reductions in the mean and maximum concentrations were 29% and 68% for CO2 and 29% and 46% for PM2.5. This intervention study was a part of the city-wide main project that aimed to increase awareness of the students and their families, teachers, and staff regarding importance of indoor environmental quality in both at school and home due to its possible effects on children's health and academic performance, one of the major challenges of today's societies all around the globe.

Assessment of Indoor Environmental Quality (IEQ): Students Well-Being in University Classroom with the Application of Landscaping

The environmental quality (IEQ) in a building is an important element to perceive the good health and comfort level for the building occupants. However, each building contributes different environmental quality results towards the indoor spaces and the occupants. Learning environment is one of the spaces that need attention as it is related to student’s well being as well as their learning performance. Existing knowledge on IEQ is still limited concerning the desirable levels of air quality, maintenance, and other factors affecting IEQ in Malaysian educational establishment. Therefore, the study of indoor environment quality in buildings has been carried out in educational building as it acts as important place in learning process. The methodologies used to conduct this research are divided into two methods, which are classroom measurement normal condition and classroom intervention setting. This is done in order to compare and monitor the improvement of environment in the classroom. This research focuses on the comparison of IEQ in different classroom environment setting and the student satisfaction level in their normal classroom environment. Measurement of temperature (°C), relative humidity, carbon dioxide (CO 2 ), Volatile Organic Compound (VOC), dust particles (PM10), lighting (lux), and noise (decibel) in the classroom were collected and questionnaires were distributed among the students. This research found that most of the elements in the classroom was incompliance with the standard threshold limit value. The level of VOC in the classroom was noted to be significantly high (11.7ppm) compared to the standard threshold limit. An intervention on the normal condition classroom was set up with selected plant placed in the classroom. Results show a tremendous reduction in the percentage of relative humidity, level of TVOC, as well as CO 2 .

Toward the development of an in silico human model for indoor environmental design.

In modern society where people spend more than 90% of their time in indoor spaces, the indoor air quality (IAQ) created by buildings has the potential of greatly influencing quality of life. Because the time spent by workers/residents in indoor spaces has increased over time, the importance of IAQ issues in terms of public health is also increasing. Additionally, the quality of the indoor thermal environment also has great impact on human comfort and performance; hence, the development of a comprehensive prediction method integrating indoor air quality/thermal environment assessment and human physiological responses, is crucial for creating a healthy, comfortable, and productive indoor environment. Accordingly, the overarching objective of this study was to develop a comprehensive and universal computer simulated person (i.e., in silico human model), integrating computational fluid dynamics (CFD), to be used in indoor environmental design and quality assessment. This paper presents and discusses the development of this computer-simulated person and its application to indoor environmental design.

Energy Retrofits in Multi-family Buildings in North-east Europe: The Impacts on Thermal Conditions

We have conducted a project to develop a common protocol for indoor environmental quality (IEQ) assessment and to assess the effects of energy retrofits on IEQ. This paper focuses on thermal comfort, which was first assessed based on 2-month continuous monitoring in 16 multi-family buildings (94 apartments) in Finland and 20 buildings (96 apartments) in Lithuania during heating season before retrofits. In addition, corresponding data after retrofits were available from three buildings (17 apartments) from Finland and seven (30 apartments) from Lithuania. Two data loggers per apartment were placed to evaluate Tw and RHw (warm area), and Tc and RHc (coldest spot). Questionnaire data regarding housing quality and health were collected from the occupants. The results before retrofits indicated high Tw (>23°C) for a large proportion of time in Finnish apartments, whereas opposite trend was observed in Lithuania. After retrofits, proportion of time with high Tw was higher while proportion of apartments with low RHw was lower in Finland, whereas in Lithuania, about one fourth of the apartments had higher Tw and RHw, hence fulfilling the national guidelines. The average absolute humidity was higher after retrofits in both countries, especially in Lithuania (by 15%). Occupant responses indicated improved thermal comfort. Therefore, potential effects of energy retrofits on occupants’ thermal environment and satisfaction were demonstrated, and simply adjusting indoor temperature could help to save energy. Further analysis is needed to include the effects of outdoor conditions, as well as overall IEQ to the assessment.

Assessment of indoor environmental quality in existing multi-family buildings in North–East Europe

Sixteen existing multi-family buildings (94 apartments) in Finland and 20 (96 apartments) in Lithuania were investigated prior to their renovation in order to develop and test out a common protocol for the indoor environmental quality (IEQ) assessment, and to assess the potential for improving IEQ along with energy efficiency. Baseline data on buildings, as well as data on temperature (T), relative humidity (RH), carbon dioxide (CO2), carbon monoxide (CO), particulate matter (PM), nitrogen dioxide (NO2), formaldehyde, volatile organic compounds (VOCs), radon, and microbial content in settled dust were collected from each apartment. In addition, questionnaire data regarding housing quality and health were collected from the occupants. The results indicated that most measured IEQ parameters were within recommended limits. However, different baselines in each country were observed especially for parameters related to thermal conditions and ventilation. Different baselines were also observed for the respondents' satisfaction with their residence and indoor air quality, as well as their behavior related to indoor environment. In this paper, we present some evidence for the potential in improving IEQ along with energy efficiency in the current building stock, followed by discussion of possible IEQ indicators and development of the assessment protocol.

An assessment of indoor environmental quality in schools and its association with health and performance

In order to examine the associations between different indoor environmental quality (IEQ) indicators and students' performance, absenteeism and health data were collected, and sampling and monitoring were conducted in a 70 school district in the Southwestern United States during two academic years. These included measurements of temperature (T), relative humidity (RH), carbon dioxide (CO2), and settled dust. A standardized cleaning protocol was employed for surface sampling and cleaning effectiveness evaluation utilizing adenosine triphosphate (ATP) monitoring systems to detect biological contamination, and contact agar (RODAC) plates to detect culturable bacteria. In addition, student data related to socioeconomic background, absenteeism, performance, and number of visits to school nurse was retrieved anonymously from the school district. Significant associations were observed between percentages of students scoring satisfactory in mathematics and reading tests and both indoor T (r = −.353 and r = −.311 respectively) and ventilation rate (r = .417 and r = .479 respectively), which was estimated based on CO2 levels. In addition, ventilation rate was associated with mean number of visits to school nurse due to respiratory symptoms, and culturable bacteria with mean number of visits due to gastrointestinal symptoms; but there were no significant correlations between absenteeism and IEQ parameters in these school-level analyses. In conclusion, classroom ventilation rate, temperature, and hygiene of high contact surfaces appear to be important IEQ parameters, potentially related to student health and/or performance.

Energy efficiency versus indoor environmental quality in different Romanian countryside schools

The current research study, aims to couple the indoor environmental quality (IEQ) in countryside schools with energy efficiency. A detailed investigation took place on three different types of rural schools (old, new, and renovated) conveniently located for comparison purposes within a radius of 2.5km from each other. The IEQ assessment covered the period autumn 2013–spring 2014 and included both long term measurements and spot recordings. In terms of indoor air quality all three buildings performed poorly, registering average CO2 concentrations in excess of 2000–3000ppm and even approaching the health hazard level of 5000ppm. Based on these concentrations, the corresponding ventilation rates have been calculated at 2.4L/s/person (renovated school), 2.25L/s/person (new school) and 0.7L/s/person (old school). The IEQ index was calculated using the experimental data allowing the three analyzed schools to be better rated. The new and renovated buildings rank class C on the IEQ index scale and class A from an energy consumption standpoint, whereas the old building is rated D class (IEQ) and C class (energy efficiency). This shows that high energy consumption, as is the case for the old school, does not necessarily result in better comfort conditions despite their inverse correlation.

RATING OF INDOOR ENVIRONMENTAL QUALITY IN SYSTEMS OF SUSTAINABILITY ASSESSMENT OF BUILDINGS

Indoor environmental quality (IEQ) has an important impact on health and wellbeing of building users. In order to maintain an acceptable IEQ, policies, strategies and guidelines on achieving the required IEQ have been developed. Control and evaluation of indoor air factors is needed for ensuring the sufficient air quality. Impact of emmisions from building materials, furnishings and HVAC systems to indoor air quality should be included in the assessment of indoor environmental quality. In many systems for sustainability assessment of buildings is put a great emphasis on indoor environmental quality. This paper provides an overview of sustainability assessment systems for rating of indoor environmental quality. The criteria included in LEED, BREEAM and other well known systems for assessment of indoor environmental quality are presented. Building environmental assessment system (BEAS) developed for application in Slovakia is also introduced. Worldwide used rating systems were based on the development of BEAS. This is multi-criteria system contained six main fields such as site selection and project planning; building construction; indoor environment; energy performance; water and waste management. System consist from 53 indicators of assessment.

Linear, Non-Linear and Alternative Algorithms in the Correlation of IEQ Factors with Global Comfort: A Case Study

Indoor environmental quality (IEQ) factors usually considered in engineering studies, i.e., thermal, acoustical, visual comfort and indoor air quality are individually associated with the occupant satisfaction level on the basis of well-established relationships. On the other hand, the full understanding of how single IEQ factors contribute and interact to determine the overall occupant satisfaction (global comfort) is currently an open field of research. The lack of a shared approach in treating the subject depends on many aspects: absence of established protocols for the collection of subjective and objective measurements, the amount of variables to consider and in general the complexity of the technical issues involved. This case study is aimed to perform a comparison between some of the models available, studying the results of a survey conducted with objective and subjective method on a classroom within University of Roma TRE premises. Different models are fitted on the same measured values, allowing comparison between different weighting schemes between IEQ categories obtained with different methods. The critical issues, like differences in the weighting scheme obtained with different IEQ models and the variability of the weighting scheme with respect to the time of exposure of the users in the building, identified during this small scale comfort assessment study, provide the basis for a survey activity on a larger scale, basis for the development of an improved IEQ assessment method.

Productivity metrics in dynamic LCA for whole buildings: Using a post-occupancy evaluation of energy and indoor environmental quality tradeoffs

The IEQ + DLCA framework, which integrates indoor environmental quality (IEQ) and dynamic life cycle assessment (DLCA) at the whole-building level, was revised and expanded to consider non-chemical health impacts and productivity/performance impacts. The complete framework was evaluated for a case study of a LEED gold rated university building, supplemented with a post-occupancy evaluation (POE) designed to elicit qualitative feedback on IEQ and productivity impacts specific to the building. Most non-chemical health impacts (e.g. sick building syndrome (SBS), asthma) were not able to be included in the framework, due to potential overlaps with chemical-specific impacts already included in LCA. However, productivity impacts were able to be included in the framework for the purpose of comparing different design and operational choices for a given building. Occupants were also asked to evaluate the anticipated effects on their individual productivity due to IEQ changes associated with hypothetical energy-saving strategies. Results of the POE showed occupants were generally satisfied with IEQ, and considered that increasing summer cooling temperature set points would enhance productivity. Energy savings were calculated using an empirical energy and IEQ model calibrated with sensed data from the building. Evaluation of the full IEQ + DLCA framework suggested potentially significant energy savings potential and possible productivity enhancement, but indicated tradeoffs between internal chemical impact categories related to building ventilation, indoor pollutant generation and outdoor pollutant intake. The tradeoffs and overlaps between internal chemical impact categories themselves, as well as between chemical and non-chemical impact categories such as (SBS) are a challenge for LCA of whole buildings.

Assessment of LEED Indoor Environmental Quality Parameters at a New Church Building In South-central Kentucky

ABSTRACT An indoor environmental quality assessment was conducted at a newly completed Catholic church building in South-central Kentucky as part of the United States Green Building Council's (USGBC's) Leadership in Energy and Environmental Design (LEED) certification requirements. From a business perspective, green building certification has become an important staple for demonstrating energy efficiency, environmental stewardship, and sustainability. The LEED certification process stipulates, among other things, that points be awarded for energy conservation as well as documentation that selected indoor air contaminant concentrations are below certain target levels. (It must be noted that any decision by a builder or architect aimed at obtaining the LEED credit point certification involves some financial commitment.) This article summarizes the results of a comprehensive indoor environmental quality assessment for four LEED chemical contaminants and selected parameters present in indoor air, with a view ...

Assessment of Indoor Environmental Quality in Open-Plan Offices

This study aims to analyze the factors of indoor environment on occupants’ health and comfort by post-occupancy evaluation (POE) and to accumulate the fundamental data of occupants’ behaviour in relation to indoor environment, in an effort to ascertain the optimal building energy management system (BEMS). For this purpose, indoor temperature, relative humidity, vertical temperature distribution, air velocity, predicted mean vote (PMV), radiant temperature, outdoor temperature, and humidity were measured for evaluating thermal environment for nearly 2 years. Indoor air contaminants, such as PM10, CO2, formaldehyde, and volatile organic compounds (VOCs) were measured in the building and at outdoor locations. Working plane illuminance, window luminance, and the equivalent continuous a-weighted sound pressure level (Leq) were also monitored. In addition, the occupants in the intelligent office building were surveyed regarding the indoor environmental quality via the intranet. Results showed that all indoor environmental factors satisfied the recommendation, except the indoor relative humidity and PMV. The physical factors of thermal environment had been stable since two months after it was built. However, it should be necessary to improve the sound privacy caused by low background noise, seasonal air-conditioning for appropriate humidity, air freshness, and Video Display Terminal (VDT) glare in order to reduce the level of occupants’ annoyance.

Developing an indoor environment quality tool for assessment of mechanically ventilated office buildings in the UK – A preliminary study

This study describes the development of a new model for rapid assessment of Indoor Environment Quality (IEQ) in air-conditioned office buildings in the UK using design, measured, calculated and surveyed input data. The novelty of this model is that it addresses the need to present indoor environment performance ratings alongside energy performance certification and help determine by how much energy efficiency imperatives sacrifice human comfort. The model is based on the IEQindex which was developed from literature. The IEQindex is an expression which was derived from four contributing factors namely Thermal Comfort, Indoor Air quality (IAQ), Acoustic Comfort and Lighting. The relative weightings of each of the contributing factors were derived by fitting a multiple regression model to questionnaire data obtained from 68 occupants of two selected case study buildings in the UK. During questionnaire administration, measurement of indoor environment variables such as air temperature, relative humidity, air velocity, illuminance, CO2 concentrations and A-weighted sound pressure level was carried out in order to validate occupant responses. An empirical expression more suited to the air-conditioned offices in the UK was developed and the end result was a computer based program called the Indoor Environment Quality Assessment Tool (IEQAT). The model was compared to the AHP developed by Chiang et al. and the models showed good agreement.

IEQ assessment on schools in the design stage

Nowadays, the indoor environment quality (IEQ) is growing as a new and very useful index of the building quality. The current literature presents the IEQ assessment based on questionnaires applied for existing building. The original approach of this study consists in the development of an IEQ index model that can be used by architects and engineers during design stage, in order to use it as an evaluation indicator or optimize the building energy consumption versus indoor environmental conditions. Based on a large database of values resulted from simulations, multiple non-linear regression models were obtained in order to predict variables such as operative temperature, indoor sound pressure level, indoor average illuminance and specific energy consumption. A predictive model for IEQ index is proposed as a function of the four quality indexes (air quality, thermal, acoustic and visual comfort). The entire approach was tested by means of a study case where the impact of windows’ size and type on the IEQ assessment is discussed for a random climate. Also, there are presented detailed results concerning the monthly variation of IEQ and its correlation with the energy consumption. The proposed method proves to be a fast and useful method to verify architectural and engineering solutions according to the IEQ estimator.