Norhayati Mahyuddin

A Review of CO2 Measurement Procedures in Ventilation Research

Abstract It is widely recognised that the carbon dioxide (CO2) concentration level inside a building is a reflection of the indoor air quality in that building. In most buildings, occupants are a major source of CO2 through exhalation. It is generally accepted that the concentration of CO2 varies with location (horizontal and vertical) within an enclosed space and this can impact on the variation of indoor air quality within the space. Hence, measurement errors related to CO2 sampling strategies in a space are important as they can lead to uncertainties in the mean concentration for the space. The aim of this paper is to investigate existing measurement practices and sampling locations and how these influence the CO2 concentrations monitored in buildings. To identify the work done in CO2 measurement practice and determine the current limitations in establishing representative locations for CO2 concentration in buildings, two main approaches were used: (i) an extensive literature review of existing knowledge from peer reviewed articles and other relevant documents (database); (ii) the use of questionnaires to identify reported measurements with CO2 sensors as representation of research methods applied by professionals and research organisations. The findings show that most researchers (based on the database and questionnaires analysed) prefer heights between 1.0 m to 1.2 m in the middle of an occupied zone as a representative location. This compares to the recognised breathing zone height of between 0.75 m to 1.8 given in the literature surveyed.

Particulate Matter Mass Concentration (PM10) under Different Ventilation Methods in Classrooms

Abstract Recently, studies have shown that the classroom environment is very important for students’ health and performance. Thus, the evaluation of indoor air quality (IAQ) in a classroom is necessary to ensure students’ well-being. In this paper the emphasis is on airborne concentration of particulate matter (PM) in adult education rooms. The mass concentration of PM10 particulates was measured in two classrooms under different ventilation methods in the University of Reading, UK, during the winter period of 2008. In another study the measurement of the concentration of particles was accompanied with measurements of CO2 concentration in these classrooms but this study is the subject of another publication. The ambient PM10, temperature, relative humidity, wind speed and direction, and rainfall events were monitored as well. In general, this study showed that outdoor particle concentrations and outdoor meteorological parameters were identified as significant factors influencing indoor particle concentration levels. Ventilation methods showed significant effects on air change rate and on indoor/outdoor (I/O) concentration ratios. Higher levels of indoor particulates were seen during occupancy periods. I/O ratios were significantly higher when classrooms were occupied than when they were unoccupied, indicating the effect of both people presence and outdoor particle concentration levels. The concentrations of PM10 indoors and outdoors did not meet the requirements of WHO standards for PM10 annual average.

Computational fluid dynamics modelling of the air movement in an environmental test chamber with a respiring manikin

In recent years, computational fluid dynamics (CFD) has been widely used as a method of simulating airflow and addressing indoor environment problems. The complexity of airflows within the indoor environment would make experimental investigation difficult to undertake and also imposes significant challenges on turbulence modelling for flow prediction. This research examines through CFD visualization how air is distributed within a room. Measurements of air temperature and air velocity have been performed at a number of points in an environmental test chamber with a human occupant. To complement the experimental results, CFD simulations were carried out and the results enabled detailed analysis and visualization of spatial distribution of airflow patterns and the effect of different parameters to be predicted. The results demonstrate the complexity of modelling human exhalation within a ventilated enclosure and shed some light into how to achieve more realistic predictions of the airflow within an occupied enclosure.

RETHINKING CONSTRUCTION SAFETY: AN INTRODUCTION TO TOTAL SAFETY MANAGEMENT

Who is responsible for construction safety: architects, engineers, contractors, or perhaps even clients? Safety of the constructed facility is normally the responsibility of the architect and engineer, whereas safety of the construction process is conventionally considered to be the contractors responsibility. In many cases, construction accidents are, therefore, mainly considered as the contractors responsibility. In fact, many factors associated with construction accidents can be traced back to the designers responsibility as well as the clients responsibility. Under the barner of rethinking construction mainly introduced in the UK Construction industry, there is a need to include rethinking construction safety as a focus. This paper discuss a concept of rethinking construction safety. This concept contains an introduction of total safety management (TSM) in construction. The development of this concept is based on the constraint-response theory of construction accident. In this paper, the role of p...

The spatial distribution of carbon dioxide in rooms with particular application to classrooms

In most buildings, occupants are the main source of indoor carbon dioxide (CO2) due to exhalation. Although CO2 is not considered to pose serious health risks to occupants, elevated levels of CO2 may serve as an indicator of insufficient ventilation. This study examines how CO2 is distributed within a complex indoor environment of a classroom and how this distribution is affected by different parameters. Measuring CO2 concentrations at a single location or height may not act as a true representation of an entire space, unless it is measured in a very small confined space. In this study, it was observed that higher CO2 concentration values can be found at higher levels in a room and not only at a height between 1 m and 1.2 m as claimed by many researchers. Therefore, if CO2 concentration levels vary significantly, deviations from the average measured values could become large. It was also found that the CO2 concentration reflects the dynamic relationship among the occupants, their activity levels and occupancy periods. The findings present a useful contribution for future researchers to efficiently and strategically design experimental set ups with well-organised positioning of sensors for CO2 monitoring purposes.

The impact of IEQ on occupants’ satisfaction in Malaysian buildings

This paper focuses on the importance of occupant satisfaction with indoor environmental quality in buildings as well as the effect of indoor environmental quality towards occupants’ satisfaction. This research applied post-occupancy evaluation as a method to indicate the building occupants’ needs, their satisfaction and comfort level. The research is based on a case study approach whereby a questionnaire survey was conducted among 25 organizations involved in managing office buildings. A total of 115 questionnaires were returned for evaluation of occupants’ overall satisfaction from aspects of indoor environmental quality in these buildings and to determine the occupants’ satisfaction level within these buildings. The findings revealed that indoor environment factors that could contribute to occupants’ satisfaction consists of lighting, air quality and aesthetic perception. These classifications were made based on the factor analysis done with 22 attributes of the indoor environment. The majority of occupants are satisfied with their health conditions and do not face any serious health problems. However, occupants highlighted that some environmental conditions, health effects, air movement, ventilation and air freshness are important criteria for their satisfaction and comfort. This study provides insights into how occupants perceive their indoor environment and comfort, and identify problems that could arise in buildings.

Hotel maintenance management in Sanya, China

Purpose To optimize hotel maintenance works, planned and reactive techniques are required which efficiently and effectively engage with the commercial and regulatory requirements of hotel operators and maintenance managers. The purposes of this study are to identify the constraints and challenges of hotel maintenance from the viewpoints of key stakeholders and to determine the strategies and processes employed in maintenance to overcome them. Design/methodology/approach The study focuses on five and four star hotels in Sanya of the Hainan Province. Eight face-to-face interviews were conducted in conjunction with 50 questionnaires, which were distributed to senior hotel operators and maintenance managers. Findings Maintenance management strategies are collaborative, with input from multiple stakeholders. Partial outsourcing is extremely common, being employed as a way of lowering operating costs and saving time while also meeting governmental statutory and regulatory requirements for some mechanical and electrical services. Availability of skilled workers, types of systems being serviced and the availability of specialist materials and tools were all found to influence the viability and effectiveness of in-house maintenance as discrete from outsourced maintenance. In reality, the challenges can include a lack of labor training and relatively lower quality of materials or energy efficiency requirements, especially in Sanya’s hotel industry. Originality/value The aim of this research was primarily focused on identifying the present maintenance statuses and strategies in hotels while determining the factors which result in a favorable bias toward a successful hotel maintenance management. Factors that affect hotel operators’ and maintenance managers’ decisions were identified and their influences quantified. The difficulties faced by hotels in implementing maintenance strategies were ratiocinated and stated to investigate those issues more deeply.

A comparison between atrium and courtyard cooling efficiency in hot tropical climate, implementing different passive cooling strategies

This paper identifies the most efficient passive cooling strategies implemented in atriums and courtyards in the tropics. For this purpose, a field study of a naturally ventilated atrium building in the tropics is briefly reported upon in which five different modes are defined based on changing the atriums physical behavior and hybrid evaporative cooling usage. The results are compared with the field study results of two naturally ventilated courtyard houses with the same climate. The results indicate that the highest cooling efficiency is achieved when cross ventilation is coupled with the stack effect in both the atrium and the courtyard (and with evaporative cooling in the atrium), by implementing large inlet openings in the atrium different heights and the courtyard adjacent space (preferably on two opposite sides). In these modes, although the atrium and the courtyard airflow patterns are similar, the atrium also benefits from reverse airflow in the morning. In addition, the airflow pattern has a mo...

A review on indoor environmental quality (IEQ) and energy consumption in building based on occupant behavior

Purpose The purpose of this paper is to review the concept of occupant behavior and its relation with indoor environmental quality (IEQ) and building energy consumption. The behavior is referred to any direct or indirect action, which is selected by an occupant to manage the unpleasant indoor environmental conditions. Thermal comfort, indoor air quality, aural comfort and visual comfort are the key factors of IEQ evaluation. Human behavior significantly interacts with energy consumption in buildings. Design/methodology/approach Each IEQ parameter was reviewed separately and the overall IEQ acceptance was considered. In addition, this paper reviews the methods that were used to measure and simulate the IEQ factors, energy consumption and human behavior. Finally, the lack of knowledge in this field is based on the review demonstrated. Findings Most studies considered one or two IEQ factors to evaluate IEQ acceptance in buildings. Further, weakness of simulating all IEQ factors at the same time is the deficiency of IEQ simulation, based on reviews. In the case of occupant behavior simulation, the uncertainly of human psychological parameter is a drawback to predict behavior. Originality/value Energy consumption, occupant health and productivity are related to IEQ. Human behavior affects building energy consumption directly. Simulation software and methods can predict IEQ factors and human behavior. Therefore, reviewing the existing studies is critical to find new methods for measuring and simulating IEQ, energy consumption and human behavior in buildings.