Preparation and thermal properties of mineral-supported polyethylene glycol as form-stable composite phase change materials (CPCMs) used in asphalt pavements

Tis work was supported by the National Natural Science Foundation of China (51704040, 51778071, 51608058), the Scientifc Research Project of Hunan Provincial Department of Education for Excellent Young Scholars (16B007), Open Fund of Key Laboratory of Special Environment Road Engineering of Hunan Province (Changsha University of Science & Technology, kf160501), and Open Fund of Key Laboratory of Biohydrometallurgy, Ministry of Education (Central South University, MOEKLB1708)

Occupant productivity and office indoor environment quality : a review of the literature

The purpose of this paper is to review the existing literature to draw an understanding of the relationship between indoor environmental quality and occupant productivity in an office environment. The study reviews over 300 papers from 67 journals, conference articles and books focusing on indoor environment, occupant comfort, productivity and green buildings. It limits its focus to the physical aspects of an office environment. The literature outlines eight Indoor Environmental Quality (IEQ) factors that influence occupant productivity in an office environment. It also discusses different physical parameters under each of the IEQ factors. It proposes a conceptual model of different factors affecting occupant productivity. The study also presents a review of the data collection methods utilised by the research studies that aim to investigate the relationship between IEQ and occupant productivity. The study presents a comprehensive discussion and analysis of different IEQ factors that affect occupant productivity. The paper provides a concise starting point for future researchers interested in the area of indoor environmental quality

Passive cooling of outdoor urban spaces. The role of materials

This paper presents the results of a comparative study aiming to investigate the suitability of materials used in outdoor urban spaces in order to contribute to lower ambient temperatures and fight heat island effect. The study involved in total 93 commonly used pavement materials outdoors and was performed during the whole summer period of 2001. The thermal performance of the materials was measured in detail using mainly infrared thermography procedures. The collected data have been extensively analysed using statistical techniques. Comparative studies have been performed in order to identify the major advantages and disadvantages of the materials studied. Materials have been classified according to their thermal performance and physical properties into ‘cool’ and ‘warm’ materials. The impact of color, surface roughness and sizing has been analysed as well. The study can contribute to selection of more appropriate materials for outdoor urban applications, and thus assist to fight the heat island effect, decrease the electricity consumption of buildings and improve outdoor thermal comfort conditions. (C) 2004 Elsevier Ltd. All rights reserved

Quantifying energy savings in daylight responsive systems: The role of dimming electronic ballasts

The application of lighting control technologies with photosensors has led to an increase in public interest. Although these technologies have been promoted during the last years their successful use in buildings has been accomplished in a small percentage of new projects. One reason is the difficulty in quantifying the energy savings and thus the subsequent payback period. Daylight responsive dimming systems consist of three basic components: photosensor, controller, and dimming unit. Electronic dimming ballast (EDB) is one substantial component of these lighting control systems which can adjust the light output due to the transferred signal from the photosensor and lighting controller. The aim of this study is to quantify energy savings among different EDBs. Eighteen commercial EDBs were selected and various sets of electrical and illuminance measurements were taken for different dimming levels, in order to develop polynomial functions between light output and consumed power. Using the measured data, a set of simulations were performed for a photosensor with an ideal cosine spatial sensitivity distribution installed in a typical office room using two control algorithms, closed loop and integral reset, trying to quantify the relative differences in energy savings. (c) 2007 Elsevier B.V. All fights reserved

Simulating the impact of daytime calibration in the behavior of a closed loop proportional lighting control system

A daylighting control system that uses the closed loop proportional algorithm needs to be calibrated both during nighttime and daytime. The selection of the daytime calibration time can affect the behavior of the system and is usually performed when the ratio of the illuminance of the ceiling sensor (SD,tc ) to the illuminance at a point on the working plane (ED,tc ) is relatively large without sunlight patches in the ceiling photo-sensor’s field of view (FOV). However, this requirement is not associated with a specific value and can be achieved under a wide range of conditions related to the sky luminance distribution. In the present work, four ceiling sensors with different field of views (FOVs) were examined in a typical north-facing office space. The effect of daytime calibration on the system’s performance was estimated through the calculation of lighting energy savings and the overdimming percentage. The results show that the effect of both the FOV of the ceiling sensor and the daytime calibration period is small except for the case of the sensor without cover, especially when it is close to the opening. In an attempt to quantify the SDtc/IDtc ratio, a new magnitude (RR) is proposed by dividing the illuminance ratios of the ceiling photo-sensor by that on the working surface during daytime and nighttime calibration. Thus, the daily calibration of the sensors with cover can be performed when RR > 1. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Performance assessment of an active sunlight redirection system in areas with different climate: A comparison

The aim of this work is to assess the impacts, both in terms of daylight efficiency and energy impacts, of an advanced daylighting system that utilizes a heliostatic configuration for sunlight redirection in a deep South oriented office room in two (2) different climate conditions. Conventional daylighting systems such as windows, and clerestories placed on building facades, for a variety of reasons, have been proven ineffective in solving the problem of deep interior daylighting. This effect even with the use of modern daylighting techniques can effectively maintain the required illuminances. In such cases, systems that are designed to take advantage both the direct and diffuse natural light while maintaining and improving occupant visual comfort, particularly at greater distances from the external walls can provide higher work-plane illuminance levels deeper into the space. The results summarized here demonstrate that, if selected according to daylight climate and integrated appropriately with electric lighting controls, the system can enhance daylight in building interiors and thereby promote energy savings. It should be noted, however, that the performance of these systems is dependent on daylight availability. Nonetheless, the information presented in this paper demonstrates the potential benefits and shortcomings from the use of sunlighting technologies in different climate zones. © 2020 Published under licence by IOP Publishing Ltd

The role of spectral response of photosensors in daylight responsive systems

Lighting control technologies using photosensors have a great potential for energy savings in areas with high levels of daylight. Although the proper application of these controls can exploit this potential, unfortunately, it has been accomplished in a small percentage of new projects. One reason is the difficulty in justification of energy savings, which in turn, is directly linked with the simulation of the behaviour of these lighting controls. The core of these systems is the photosensor, which adjusts the electric light output in proportion to the amount of the daylight that detects, using its spatial and spectral response. The aim of this study is to quantify the impact of photosensor spectral response on its illuminance values, by taking into account various daylight spectra as these are modified due to various types of coloured glazing. Five commercial photosensors were selected and their spectral response was measured. In addition, spectral transmittance of 16 commercial types of glazing was measured as well. Using these data, a set of simulations were performed using three colour channels in a typical office room and the relative differences in illuminance - and thus energy savings - among the photosensors are presented. The results show that differences are significant ranging from 36 to 118%, a fact that can affect the estimated payback period of a lighting control. system. (c) 2007 Elsevier B.V. All rights reserved