Indoor and Built Environment

The purpose of this paper is to provide a review of the background information regarding low-carbon housings in the United Kingdom and to raise the concern of the possible high indoor pollution load due to the emissions from building materials and combustion products which would adversely affect the indoor air quality in air-tight buildings, especially homes. The standard guidelines given by the Building Regulations in the UK are reviewed especially in relation to mechanical ventilation with heat recovery systems. Also research literatures in relation to heat recovery ventilators and the use of air-cleaners from Korea, Hong Kong and China and from Europe are also included to illustrate the various possibilities to conserve energy and to achieve adequate ventilation with an improvement of indoor air quality. The effectiveness of using a heat recovery ventilator system and trickle ventilators in unoccupied super-energy-efficient test houses is illustrated by reviewing the long-term indoor volatile organic compound (VOC) concentrations in these test houses. The awareness of the issue is important for the future design and indoor air management of buildings, so as to provide adequate ventilation for living spaces without costing too much on energy efficiency.

A residential environment configured under inappropriate architectural planning could have a harmful influence on the health of users. Such an issue has led to requirements to improve and to evaluate the health performance of buildings. A proper health performance evaluation would aid tenants or purchasers to make a suitable decision, while also providing building owners and house sellers with useful information regarding the health performance of the buildings. The overall health performance of a building should not merely be a total evaluation score of factors, but a framework that reflects the characteristics and importance of each health-affecting factor. In addition, the overall health performance should include a concept that would enable the use of the tool to estimate and improve the health performance not only at the actual operational stage after completion of a building but over the entire lifecycle including planning, design and construction. To this end, a lifecycle health performance tree (LHT) for sustainable healthy buildings has been developed by this study. Unlike the existing method, which measures the indoor air quality, light and noise factors of a completed space, LHT provides an overall evaluation of the health performance of a space during planning.

A comfortable indoor environment is an essential condition for establishing a healthy housing environment. The indoor comfort is influenced by not only architectural conditions, but also residents’ psychological adaptation and behavioural adjustments. Moreover, specific information about adjusting behaviours, such as opening windows, closing blinds and adjusting clothing, is important to enhance indoor comfort effectively and reduce energy consumption at home.

The purpose of this study is to explore residents’ evaluation and adjusting behaviour related to the indoor comfort of apartments in Korea. This study collected residents’ evaluations of thermo, sound, light and air conditions through surveys on their satisfaction, and the study identified factors affecting residents’ evaluations. In addition, this study investigated adjusting behaviours that would improve levels of indoor comfort based on the unique attributes of apartments and residents’ living culture, and it analysed the relationship between such behaviour and their satisfaction. The questionnaire survey was collected from apartment residents. Frequency analyses, t-test and multiple linear regression analysis were employed.

The results of this study would contribute to developing plans and management guidelines for enhancing indoor comfort and satisfaction as specific and practical data.

Creating comfortable indoor climates is one of fundamental functions of buildings and buildings use a large amount of energy to fulfill their function. Therefore, it is important to understand how and under what thermal environments, the occupants can achieve their comfort in their normal lives. This paper reports the results from a longitudinal field investigation, which has been conducted to reveal the comfort temperatures of occupants in open plan offices in summer, autumn and winter in Seoul, Korea and to identify the environmental factors that could affect comfort temperatures. The survey results confirm that comfort temperature would vary with seasons. This research provides the evidence to link the indoor and outdoor temperatures along with past thermal experience with comfort temperatures. An adaptive comfort model has been developed by this study for building occupants in Seoul, Korea based on the field investigation. Comparisons between the new adaptive comfort model and existing models have been also made. The establishment of an adaptive thermal comfort model for Seoul would have a significant impact on energy saving and for setting of thermal comfort standard for office buildings in Korea.

This research investigated resident behaviours in relation to kitchen ventilation in residential buildings in order to improve kitchen indoor air quality (IAQ) in South Korean living spaces. The research involved a survey study of 182 households, which identified resident behaviour with respect to ventilation, their satisfaction level regarding the IAQ, and their use and maintenance of range hoods in the kitchens. This paper describes the kitchen CO₂ concentrations with both natural and mechanical ventilation. The adequacy of the ventilation behaviour was determined by monitoring the CO₂ concentration and ventilation behaviours in 10 sampled households of residential buildings. The results showed that natural ventilation was conducted for less than 20 min once a day and that 23.3% of respondents used both natural ventilation and mechanical ventilators. Moreover, the results demonstrated that mechanical ventilators were not properly maintained. In addition, the average CO₂ concentration was greater than 1000 ppm during cooking, and natural ventilation was more effective than were mechanical ventilators. Most residents performed inadequate kitchen ventilation to achieve comfortable IAQ. This study suggests ways to improve the ventilation behaviours of residents. The findings of this research should aid in the development of IAQ standards for Korean residential buildings and may contribute to the establishment of ventilation guidelines.

Although there have been continuing efforts recently for low-energy buildings as parts of the low-carbon green growth movement, particular attention has been paid to architectural design, the elective control of façades, and the efficiency of Heating, Ventilation, and Air Conditioning (HVAC) mechanical systems. To maximize the gains from these efforts, it is essential to consider the energy distribution approach and its layout during the design stage of the building. To this end, air distribution principles in HVAC have grown in popularity in buildings. The method to deliver the energy is strongly associated with increasing concerns about indoor environmental quality on occupants’ well-being, as well as rising energy costs for space heating and cooling. This paper identifies types of air distribution systems for heating and cooling in buildings and addresses the potential energy benefit of an underfloor air distribution (UFAD or UAD) system over the conventional ceiling air distribution system. A series of EnergyPlus simulations shows performance differences between the two distribution systems. One result is that the potential benefits of an UFAD are clearly demonstrated for a large space with a high ceiling.

This paper investigated the effects of an air cleaner and ventilation strategies on the removal of VOCs in an office in association with the influence of moisture on the air cleaner performance. Here, a transient three dimensional air flow field and concentration distribution of VOCs emitted from a desk were considered. Commercial software FLUENT 6 was utilised to solve the continuity and momentum equations together with the low Reynolds number k-ε turbulence model. Numerical results showed that both the moisture and ventilation strategies have notable impacts on the VOCs concentration distribution. Cases under stronger ventilation take less time for the VOCs concentration to reach the steady state. But, in the cases with the function of the air cleaner, VOCs could be removed more considerably. The combination of the use of the air cleaner and enhanced ventilation strategies could yield more desirable indoor air quality within a relatively short time. The results showed that moisture can have a slight effect on the performance of the air cleaner, but lower moisture would be helpful to the effectiveness of the air cleaner. Thus, based on this work, suitable concentrations of indoor moisture, together with appropriate ventilation strategies have been recommended for control of indoor air quality.

Drafts in high-rise buildings caused by the stack effect can cause noise and reduce the performances of ventilation, cooling and heating systems as well as the building’s energy efficiency. Revolving doors are generally used as a method to reduce drafts; however, the effect would only be limited to the main entrance on the lobby floor.

Revolving doors have two main advantages; that their opening areas are seldom changed by people passing through the doors, and the doors do not have the pressure-related functional problems. Considering these advantages, this study examined a quantitative draft reduction method using revolving doors in high-rise buildings. This method would contribute to the design process to install revolving doors to buildings and consists of 10 steps with two key steps of selecting the installation locations of revolving doors and to calculate the air leakage area of revolving doors. Verification through simulations showed that, based on this process, the use of revolving doors could reduce the drafts in buildings by a quantified target value. Furthermore, the possibility of problems due to the stack effect in the other walls of buildings would decrease due to the pressure sharing of the additional walls fitted to revolving doors.

Lighting in buildings can exert a large influence on the comfort, well-being, and health of occupants. A window plays a major role in providing both natural lighting in buildings and a view out, so that occupants can keep in touch with the external environment. Thus, it is essential to understand what the visual requirements are to meet occupants’ needs and how window views could affect those requirements. This study aims to reveal occupant perception on window views and to identify its effects on the assessment of glare from windows. This paper presents the results from the experiment conducted in a chamber with a simulated window, which can render various window views and luminance conditions. Forty-eight subjects participated in the experiment. The results show the evidence that the glare sensation of occupants could vary with the occupant’s perception on window views under the same luminous conditions. A discomfort glare index that predicts a subjective discomfort glare as a function of background and window luminances, position index, and perception on window views, has been developed by this study. A comparison between the developed and existing glare prediction models was discussed in this paper.

This study was conducted to propose a method of identifying glare sources from windows. Discomfort glare from windows of a classroom was evaluated in the experiments involving subjects, and the features that made the subjects recognize the glare sources in the windows were explored. The results of the evaluation led to the realization that the subjects regarded the patches that were causing discomfort glare as the glare sources on windows. It means that the patches having low luminance were not the causes of discomfort glare and were excluded from glare sources for the discomfort glare evaluation. There was a linear relationship between the average luminance of the visual field and the average luminance of the glare patches. The linear relationship has been expressed by a formula. The proposed formula has made it easier to identify the glare patches from windows. The approach as suggested in this study is distinctive to the others by the fact that the glare source was determined based on the average luminance of the visual field.

Windows in a building is an essential element in creating comfortable, energy-efficient and healthy indoor environment. However, the actual performance of a building depends highly on the ways of using the windows by occupants. An understanding of window use patterns is thus of importance in the design and evaluation of buildings. This study aims to extend the understanding of window control behaviour by occupants in offices. A field campaign has been conducted from March 12, 2010, to January 31, 2011, in four offices, located in Suwon, South Korea, to demonstrate the close link between carbon dioxide concentrations, prevailing internal and external temperatures, occupancy schedules and window control patterns; and to predict window use as a function of thermal and non-thermal stimuli. The research reveals that there could be large and significant seasonal effects on window control patterns, which provided main stimuli for the use of windows in spring, summer, autumn and winter. Finally, the influences of different window control patterns on indoor thermal environment and air quality have been analysed in detail.

This study aims to evaluate the optimal illuminance for each lighting colour of light-emitting diode (LED) light sources among the seven major lighting colours (red, green, blue, cyan, magenta, yellow and white); the focus was on the optimal combination of these colours for enhancement of occupant comfort and communication indoors. The evaluation of optimal illuminance for LED lighting colours found that the occupants felt the cyan LED light source was similar to a white light source, and that the relative brightness of the green lighting colour was higher than that for other colours. The evaluation of the permissible range of illuminance for LED lighting colours found that occupants believed the red lighting colours to be relatively darker; again, the relative brightness of green lighting was considered to be higher. An experiment with subjects for LED lighting colours (consisting of 19 patterns of 7 colours in the living room of a house) found that the optimal illuminance for occupants’ comfort was 32[lx]–119[lx], and for occupants’ communication was 107[lx]–584[lx]. These results satisfied the illuminance criteria of Korean Standards as the optimal illuminance for occupants’ comfort and communication in the living room.

A light pipe system is a simple daylighting device that allows the natural daylight to enter into interior spaces or underground spaces where access to windows or skylights is restricted. The use of a light pipe system can enhance illuminance without the use of artificial lighting and thus would reduce energy consumption significantly. This paper presents a performance prediction method of a light pipe system based on the amount of daylight admitted and energy saved by not needing electric lighting. The newly developed model was compared with the existing prediction model under the Korean climate conditions, to illustrate the reliability and robustness of the method. Energy saving potential due to the use of a light pipe system was determined with a due consideration of the different artificial lighting control methods (on and off control, two-step control, dimming control), demonstrating a possible saving in lighting energy usage of up to 30% in average. This study should encourage a wider application of light-pipe system in Korea especially in high rise buildings where day-lighting could be limiting; thus increasing the options for architectural design for building application.

This paper discusses the emission of formaldehyde and VOCs from wood-based panel products and the effect on indoor air quality (IAQ). The formaldehyde concentration monitored in four energy efficient test houses over a 7-year period has been included to illustrate the long-term effect of emissions from E1 wood-based panels used in dwellings. Formaldehyde emissions from wood-based floorboard obtained from investigation of sick buildings are included for comparison. Also discussed was the impact of fitting of a “low formaldehyde emitting” wardrobe in an energy-efficient test house and in an apartment home. The exposure risk of an individual unpacking the packages of the flat-packed wardrobes and during assembly was illustrated by measurement made in a 22 m³ chamber and in a test house. A variety of VOCs can be released from wood-based panels and associated materials. There is also a concern about the possible emission of wood preservative residues, such as pentachlorophenol from products made from contaminated wood sources. To minimise impact of formaldehyde and VOC emissions in homes and other buildings, building developers and designers should insist on certification of products based on available labelling schemes and this is required in some countries for assessment of Green Buildings.

Over the past 30 years, Korea has adopted structural frames with bearings for apartment buildings. The unit planning flexibility of such a structural system is inadequate, when compared to the column-beam system. The system would allow renovation easily and would provide various other legal benefits to constructors in Korea. For this reason, a column-beam system, named by green frame (GF), implemented with composite precast concrete (PC) members was previously developed. However, since the scheme would require a performance improvement to increase its economic effects and constructability, a further improved system has been developed. In the case of structural construction, it is a construction process that emits the most CO₂. Along with the constructability and economic feasibility of a construction system, a reduction in CO₂ is also critical. The purpose of this paper was to analyze the CO₂-reduction effect of the improved system constructed with enhanced composite PC members. The improved system would greatly contribute to CO₂ reduction with an average of 25.0% as compared with the bearing wall structure; and 2.8% compared to the existing GF.

In this work, the energy efficiency and CO₂ emission characteristics of a pre-stressed steel-framed reinforced concrete composite beam were investigated for application in high rise apartment buildings. The beam consisted of pre-cast and cast-in-place concrete with a structural T at the end section of the pre-cast concrete. As a result, CO₂ emissions were significantly reduced by decreasing the quantity of steel. The composite beams were tested which demonstrated acceptable structural performance as flexural members. The measured flexible strengths of the pre-stressed composite beams were compared with the calculated flexural strengths based on the strain compatibility approach in the yield limit state and maximum load limit state. Good agreement between the experimental and analytical flexural capacities was observed. The application of the pre-stressed composite beams capable of enhancing energy efficiencies while decreasing CO₂ emissions could provide a safe structure for a comfortable built environment and will be of great benefits to the welfare of a community as well. This work demonstrates that reduced CO₂ emissions can be achieved by introducing pre-stressing in a concrete composite beam and by installing a structural T only at the end of the composite beam.

Columns manufactured with pre-cast concrete could reduce construction waste and CO₂ emissions by reducing the use of temporary materials such as formwork. In this paper, three types of connection methods are introduced. The structural performance of pre-cast composite columns connected to beams was investigated for the column connection. Multi-story pre-cast composite columns could significantly reduce the construction time, resulting in a decrease in CO₂ emissions. This paper reports the analysis of the compression and bending of a two-story column so as to verify the structural performances of pre-cast composite columns to provide adequate integrity to ensure a safe environment for building accommodation. In addition, a steel-framed column and a steel-framed reinforced concrete (SRC) column configured to feature the same compression performance as a pre-cast composite column were designed on the basis of the analysis results. The CO₂ emissions and energy efficiency of the composite columns were compared with those of conventional steel and SRC columns during the design and construction phases. This paper also presents new composite columns providing efficient energy consumption with reduced CO₂ emissions for a more environmentally conscientious construction of buildings.

This paper presents a novel human home activity recognition (HAR) system designed for smart homes that utilize depth silhouettes and ℜ transformation to continuously recognize the daily activities of the elderly and disabled in an indoor environment for better lifecare and e-healthcare services. Previously, ℜ transformation has been applied only on binary silhouettes that provide only the shape information of human activities. In this work, ℜ transformation was utilized on depth silhouettes such that the depth information of human body parts could be used in HAR in addition to the shape information. In ℜ transformation, 2D directional projection maps are computed via Radon transform, and then 1D feature profiles, which are translation and scaling invariants. Then, by applying the principle component analysis and linear discriminant analysis, the prominent activity features would be extracted. Finally, Hidden Markov Models would be used to train and recognize daily home activities. The results showed a mean recognition rate of 96.55% over ten typical home activities, whereas the same system utilizing binary silhouettes could achieve only 85.75%. The proposed methodology should be useful in designing and developing a compact HAR system that can be practically used in a smart environment including smart home for the care of the elderly, infirmed or disabled people.

The purpose of this study was to provide research-based argument for a better housing for the dementia elderly within the apartment complex neighbourhood. Six case study’s designs are included to illustrate the types of facilities that could be possible that would provide a better environment for the care of elderly and older people with dementia. Literature was analyzed to give the perspectives of “sustainable and aging society,” “social integration” and “natural environment that promotes health.” Small group workshop was carried out with experienced professionals to discuss the concepts and features of the developed housing alternatives plans to validate the proposal to integrate local residents and promote holistic health for the fragile aged. The findings illustrate the vision for the shared space community, a community home for the dementia elderly, with appropriate scale for easy management and being connected with local community and with affluent green environment for healing and natural environment that would ease local residents’ aversion towards elderly housing. These housing alternatives would enable the elderly to age in place and with the most natural social integration available to local people, with a proper spatial planning to promote holistic health of the fragile aged.

Indoor air quality (IAQ) is an important factor, which can influence the health and comfort of passengers in subway stations. Various types of hazardous pollutants, such as particulate matters, remain accumulated in the subway space due to overcrowding and inadequate ventilation system. Subway stations are extremely crowded during rush hours and indoor air of the subway stations could be strongly affected, which in turn, affects passengers’ respiratory system. In this study, several key air pollutants data were collected every minute by the air sampler and tele-monitoring system (TMS) to effectively monitor and control IAQ in subway stations. The quality of the online measurement could decide the failure and success in environmental process assessment. Therefore, prompt detection of the occurrence of sensor faults and identification of those locations are of primary importance for efficient monitoring and control of IAQ. In this paper, Principal components analysis based approach is used to detect, identify and reconstruct the sensor faults in monitoring IAQ. Four types of sensor failures, namely, bias, drifting, complete failure and precision degradation are tested for monitoring IAQ. Several test results of a real subway TMS showed that the developed sensor validation technique can work well for the four kinds of sensor faults.