Indoor and Built Environment

The current review creates, for the first time, a comprehensive dataset of ventilation rates measured in European office buildings. This dataset can provide input to modelling studies. A review of the current status of ventilation standards and regulations for office buildings is also presented, as a reference. The review shows that the availability of measurements of ventilation rates in European offices is limited. Measurements have been carried out mainly in the Nordic and Western European countries and recently in Southern Europe. The limited data on a country level present variability and hence cannot be considered as representative, given the small number of measurements. Furthermore, due to the various measurement techniques that are used, it is not always possible to compare the results from the measurements with the existing regulations. In the case that a comparison is allowed, the mechanically ventilated (MV) buildings are over-ventilated (mean: 18 L s⁻¹ person⁻¹, range: 4.5–55 L s⁻¹ person⁻¹), compared with the national regulations and the value of 10 L s⁻¹ person⁻¹, which several studies propose to decrease the prevalence of symptoms of sick building syndrome. However, when compared against the same metrics, naturally ventilated (NV) offices are under-ventilated (NV range: 0.1–1.8 ach; MV range: 0.5–5 ach).

This paper describes a method for dynamic modelling of the interactions of semivolatile organic compounds (SVOCs) with airborne and settled particulate matter in the indoor environment. As part of the framework for dynamic modelling of indoor SVOCs recently proposed by this author, this method is fully compatible with the other components in the framework. With reduced computational complexity, the method is more flexible than the existing dynamic models. Despite the uncertainties in some of the key parameters, the simulation results have revealed important information regarding the general behaviour of SVOC-particle interactions and the role of particulate matter in human exposure to indoor SVOCs.

The purpose of this paper is to review the types of building materials that could present a hazardous risk to health of building occupants. The review is necessary as many countries including Korea and the UK have a policy target to make building sustainable and air-tight; therefore a strategy and guide is needed to address the possible hazards that could be found in existing structures of many buildings. For new buildings, the assessment should be at the beginning of building conception, which should be extended to all stages of construction, and the potential hazard should be registered in record to inform the future refurbishment procedures and end-of-life management of the building, for disposal and re-use of materials. The assessment of hazardous materials should be an important aspect of the green building certification such as those being developed in Korea. Various types of hazardous building materials are described. Guidance is provided to encourage precaution and remediation of risks when handling these materials during construction or refurbishment or with materials already in place in existing buildings. The good practice should include a checklist procedure including: survey, assess condition, assess presence, identify and analyse, record, evaluate, and finally develop a plan strategy for prevention and possible remediation.

The anthropogenic developments have been causing a warming phenomenon of city centres called urban heat islands (UHI). The effect is made worse by the urban canopy characteristics of concrete, façade glazing and asphalt surfaces of building and road structures. Buildings would absorb shortwave radiation and store heat during daytime, and release heat into atmosphere at night, thus increasing the ambient temperature. The wide spread use of HVAC air-conditioners in the densely urbanised areas, as well as increasing commercial developments and massive rise in automobile traffics are also important contributing factors, which can lead to formation of ozone and smog. Urban temperatures can be up to 5–12℃ warmer than the surrounding countryside under extreme meteorological conditions of calm and clear anticyclonic weather. High temperatures in cities can exacerbate energy demand for building air conditioning, therefore higher emission of CO₂ contributing further to green house warming. There are a number of UHI mitigation strategies including increasing the surface reflectivity and vegetation density in urban areas. This can be achieved by greening the urban environment by planting trees and vegetation; incorporating better roof designs such as cool roofs, greenroofs, reflective roofs and cool pavements. The purpose of this paper is to provide a review of UHI effects in city centres and examine the mitigation strategies and the thermal benefits of greenroofs.

The objective of this article is to provide a methodology for optimizing the envelope of a building with respect to the triple objective of heating load, cooling load and daylight. The variables to optimize are the window to wall area ratio (WWR) and the window type characterized by its visual and thermal characteristics (visual and solar transmittance, and U-value). Energy load is computed using building performance simulation software (TRNSYS). A criterion of daylight is defined as the integrated time when the illuminance is below a threshold and artificial light is required. This criterion was calculated using the software Daysim. The variables have antagonistic effects on the objectives: WWR and window type may have opposite effects by increasing solar gain and daylight duration during winter, which would be beneficial, but could lead to overheating during summer. Therefore, an easy-to-set up methodology is proposed to find the optimal solutions of such a problem. A multi-objective optimization was performed in order to find the optimal variables leading to the minimization of the energy load and the maximization of the indoor daylight duration. The method was applied to a dormitory retrofitting. Optimal solutions are the best compromise among antagonistic objectives and would offer guidance to designers in making construction decisions.

Even though the measures to minimize the stack effect in high-rise buildings were taken that include a revolving door on the lobby floor, additional barriers to the passage of air in the lower part of the building, and air-tightness reinforcement for elevator doors, the stack effect is still present during cold season in Korea. However, it is difficult to fully apply the measures for stack effect under occupied condition in high-rise buildings. In this study, as an advanced method to lower the stack effect in high-rise buildings under occupied condition, mechanical ventilation in elevator shaft space, which cools the shaft space with outdoor air and reduces the temperature or pressure differences between indoor air in shaft and outdoor air, was proposed. In this paper, the application details and performance analyses of the installed shaft cooling system in a completed building in Korea were described. Also, as a measure to improve the performance of the applied system, concentrated cooling in the lower part of the elevator shaft where there is a main air flow passage was proposed. As a result, cooling effect of mechanical ventilation system in elevator shaft was improved and the extent of stack effect in winter was decreased effectively.

Since the photovoltaic (PV) scientific community started exploring innovative ways of incorporating solar electricity into buildings, a whole new vernacular of solar electric architecture emerged. Currently, there is a growing consensus that building integrated photovoltaics (BIPV) systems will be the backbone of the zero energy building (ZEB) European target by 2020, through their widespread commercialization. BIPV systems often produce however less energy than conventional PV systems due to architectural constraints in the design of BIPV arrays. This paper presents a conceptual study regarding the energy yield and feasibility of BIPVs in several locations in Europe. Specific conclusions on the energy yield and economic feasibility of BIPVs with regard to the implemented PV module technology, the climatic zone, the orientation of the building and the mounting disposition are drawn. The findings of this work that were also validated using hourly time step computational analysis, reveal the necessary conditions under which BIPVs could have a major contribution to fulfilling the European 2020 targets by enabling the achievement of the ZEB goal.

Design of visual environment is a complex issue involving lighting sources, luminous properties of surfaces, brightness and glare. Digital image processing software can simulate lighting designs to ensure the right amount of light and luminous quality of the visual environment. Even though there are several means about how to determine the quality of the visual environment, this study adopted high dynamic range (HDR) images captured in real-life environment. The HDR imaging has been used for research purposes to analyse discomfort glare and extract luminance on the scene. However, numbers of previous researches reveal that the capacity of HDR imaging technology for luminance acquisition might be dependent upon types of camera and the exposed ranges of images. This paper aims to verify the accuracy and pragmatic reliability of HDR image tools such as LMK and Photolux. The reflectance percentages measured by LMK and Photolux were compared to the absolute values presented by Pantone hue, value and chroma. A series of Pantone colour, yellow, warm red, rubine red, rhodamine red, purple, reflex blue, process blue and green were adopted and with varying the mixture ratio of whiteness. A variation on this type of analysis can be used to validate the design and address visual problem areas such as the detection of potential glare sources.

The aim of this study was to propose a new multi-objective optimization (MOO) of a ventilation controller which finds the optimal set points for simultaneously improving the indoor air quality (IAQ) and increasing the energy efficiency in buildings under changes in outdoor air quality and climate change. The outdoor weather information, such as ambient temperature, humidity, solar radiation and wind speed, was applied and treated as external disturbances in the building system. Two control strategies including proportional-integral (PI) control and multivariate model predictive control (MPC) were implemented and compared while controlling the indoor air temperature and CO₂ concentration in the targeted building system. A control performance assessment (CPA) technique was proposed and implemented for monitoring the MPC controller performance. With the goal of determining the optimal set points for the MPC controller, the multi-objective genetic algorithm was developed to enhance the energy consumption as well as to keep the IAQ within an acceptable range. The results indicate that the performance of the MPC controller with the optimized set points is superior to that of the PI controller in indoor building systems. More specifically, the MPC controller with the optimal set points for the indoor temperature and CO₂ control could reduce energy consumption by 5.22% and CO₂ content by 13.39% in comparison to the PI controller. In addition, the MPC controller equipped with MOO could be useful for building climate control depending on the variation of the outdoor air pollutants.

Gait recognition at smart home is considered as a primary function of the smart system nowadays. The significance of gait recognition is high especially for the elderly as gait is one of the basic activities to promote and preserve their health. In this work, a novel method was proposed for human gait recognition by processing depth videos from a depth camera. The gait recognition method utilizes local directional patterns (LDPs) for local feature extraction from depth silhouettes and hidden Markov models (HMMs) for recognition. The LDP features were first extracted from the depth silhouettes of a human body from each frame of a video containing human gait. The dimension of the LDP features was reduced by principal component analysis. Then, each HMM was trained using the LDP features. Finally, the recognition was done with a maximum likelihood calculation of the trained HMMs of different gaits. We focused on training and recognizing two kinds of gaits here, namely, normal and abnormal. The proposed approach shows superior recognition performance over other traditional methods of gait recognition.

The global trend of increasing longevity has brought an enormous challenge to develop smart technologies to preserve independence and quality of life among the elderly in their own residences. By combining smart devices, occupants’ capabilities can be extended. The concept of ‘healthy smart home’ was introduced and numerous research projects have implemented a variety of prototypes and state-of-the-art of smart systems. However, there is little research on the elderly’s interactions and experiences in smart homes using systematic methods. The interactions of the elderly with digital devices, and further, the smart space, should be intuitive; otherwise the smart space would become an uncomfortable environment, thus displeasing the elderly. The focus of this paper is on user interfaces, especially those targeted to support the elderly’s healthy home life. Through a critical review on representative design principles for the elderly, specific criteria related to usability and user experience were defined and structuralized into a framework of user interfaces. For identifying the features of the ageing-friendly interfaces, the elderly’s reduced capabilities were considered, with a focus on assistive technologies. The proposed framework could be a basis for the perspectives of future research directions on user interfaces for the elderly in smart environments.

This study evaluates the health performance of high-density, high-rise public housing in Korea to seek ways to improve their performance for the health and wellbeing of occupants. To do this, the existing ‘Health Performance Indicator for the Public Housing’ developed by a previous study in 2010 was utilized to compare and analyse the characteristic differences as evaluated by experts and the residents. The survey tool was developed to allow evaluation by the experts using pairwise comparison between components; while the residents were asked to evaluate the relative importance of the components in the survey tool. Furthermore, Analytic Hierarchy Process was applied to the evaluation given by experts and PASW statistical package was used to analyse the survey results given by the residents. The results showed that the residents do have a high awareness of the impacts of the various components in their apartments that could be seen visually, revealing a partial difference in their awareness in comparison to that given by the experts. It is therefore necessary to utilize this understanding of the experts and residents in order to meet the actual demands of the residents in accordance with their awareness. It is expected that the evaluation results of this study would be used in the construction plan of new apartments to promote healthy housing and to incorporate not just the experts’ view but also the demand of the residents.

This paper investigates the suitability and environmental friendliness of using hybrid pre-cast composite structural systems for use in apartment buildings. The hybrid pre-cast composite structural system was utilized in one apartment building. The application propriety and environmental friendliness of hybrid pre-cast composite structural systems were verified by comparison with a flat plate, reinforced concrete Rahmen frame. The hybrid pre-cast composite structural systems presented in this study can be used as a lateral Smart Frame and a gravity Smart Frame. The lateral Smart Frame with moment connections is used for dual systems, in which the moment frames should be able to resist at least 25% of the seismic design forces. Gravity Smart Frames with pin joints for building frame systems are essentially complete space frames providing supports for vertical loads. Seismic force resistance is provided by shear walls. The hybrid pre-cast composite structural system demonstrated its application propriety by its ability to reduce the quantity of construction material. According to the structural design results with hybrid pre-cast composite structural systems, less material was required per unit area compared with the flat plate and reinforced concrete Rahmen frame structures. This structural system can thus reduce CO₂ emissions and energy consumption, helping to preserve the environment.

Mould infestation problems in building are a complex phenomenon involving various causes such as environmental conditions, substrates, exposure time, and so on. The physical properties of building materials, e.g. surface structure, can be a key factor for mould germination and growth. The aim of this study is to determine the influence of the hygroscopic properties and surface structures of the wallpapers on the mould growth. An experimental study was conducted to characterize the hygroscopic properties and surface structures of the wallpapers. Four types of wallpapers with low chemical emissions were selected in order to exclude influence on chemicals on mould germination. Cross sections of the selected wallpapers were observed in order to characterize the surface structure of wallpapers using the scanning electron microscope. Three different fungi species were inoculated on the wallpapers, and mould growth on the selected wallpapers were observed for about two weeks. The results showed that the wallpapers with irregular patterns or a flat surface structure could delay mould growth. Wallpapers with higher moisture sorption capability would limit the development of mould growth under the experimental condition. Our study has shown a clear correlation between the mould growth rate and hygroscopic properties of the wallpapers.

The lightshelf system, a sort of daylighting device, has been applied to improve the visual environment by optimal light distributions and intense illumination levels of an interior. Also, the photovoltaic is one of the most important sustainable technologies applicable to architectures. The purpose of this study was to evaluate basic data to develop the photovoltaic (PV)-integrated lightshelf systems for office buildings. The performance of PV lightshelves was evaluated by using 1/5 scaled model. The scaled office models were made and the field tests were experimented under clear sky according to installation conditions. The results have illustrated that the power performance of the PV lightshelves was excellent on the horizontal plane where the sunlight incidence occurred vertically, and that the larger the installation angle, the more rapid decrease in power performance was recorded. However, if the other performance including daylight and energy of a PV-integrated lightshelf should be considered, complementary research is necessary in any future study.