Jiangtao Du

Assessing the daylight and sunlight availability in high-density residential areas: a case in North-east China

This study investigated the impact of building orientations, typical layouts and positions at facades on daylight and sunlight availability in high-density residential areas in North-east China. Vertical daylight factor (including sky component and reflected component) and sunlight hours along the centre building facades in three typical models were calculated using Radiance and Autodesk Ecotect Analysis. From the results the attenuation of the vertical daylight factor on the facade of each building model is explained and some empirical functions are derived. In addition, the results of sunlight analysis show the relationships between the sunlight hours, building orientations and layouts. The achieved results could be developed into design guidelines for the earlier urban planning.

The assessment of vertical daylight factors across the walls of atrium buildings, Part 1: Square atria

This study investigated the impact of well geometry and surface reflectance on the vertical daylight factors of walls in atria with square plan forms under a CIE standard overcast sky. Artificial sky scale model measurements were used to validate predicted values of vertical daylight factors using the software package Radiance. More simulated vertical daylight factors data for a much wider range of square atrium geometries and surface reflectances were then produced. From the results the variations of the vertical daylight factor on the walls of square atria were assessed and explained and some empirical functions derived. Some guidelines for supporting design are presented.

Daylight in atrium buildings: Geometric shape and vertical sky components:

This study investigated the impact of well geometry on vertical sky components in atria with square and rectangular forms under a CIE standard overcast sky. By comparing scale model measurements and analytical theory the vertical sky components, calculated using Radiance, were validated. More simulated data of vertical sky components for a very wide range of atrium geometries are given. From the results the attenuation of the vertical sky component on the wall of a square atrium is explained and some empirical functions are derived. In addition, the results from atrium models with rectangular floor plans show the relationships between the vertical sky component and the plan aspect ratio. Some guidelines for design are presented.

A novel coupling control with decision-maker and PID controller for minimizing heating energy consumption and ensuring indoor environmental quality

Due to climate change, global energy crisis, and high-quality life requirement for people, decreasing building energy consumption and enhancing indoor environment quality through control of heating, ventilation, and air conditioning systems tend to be increasingly important. Therefore, favorable control methods for heating and ventilation systems are urgently necessary. In this work, a new coupling control with decision-maker was proposed, developed, and investigated; meanwhile, several demand controlled ventilation strategies combined with heating control method was compared considering heating energy consumption, thermal comfort, and indoor air quality. In order to properly model the service systems, the air change rates and thermal time constants have been first measured in a reference office installed with commonly applied bottom-hinged tilted windows in our low-energy building supplied by geothermal district heating. Then, simulations have been carried out across two typical winter days in the reference office. The results illustrate that the proposed combination of suitable heating and demand controlled ventilation coupling control methods with decision-maker and proportional-integral-derivative (PID) controller could greatly reduce heating consumption in the reference room during the office time: around 52.4% (4.4 kW h energy saving) per day in winter in comparison to a commonly suggested method of intensive and brief airing. At the same time, it could ensure indoor CO2 concentration to keep within the pre-set ranges (Pettenkofer limit: 1000 ppm) as well as low variations of indoor temperature (standard deviation (SD): 0.1°C).

A model study of the daylight and energy performance of rooms adjoining an atrium well

The performances of light shelf systems are evaluated in the context of various interior configurations typical of multistory office buildings by using CBDM (climate-based daylight modeling). A physical scale model of one of the light shelf systems is tested in the first phase under real sky conditions in Raleigh, North Carolina, USA. The data collected from the experiments are used to validate the simulations by a computer-based dynamic daylighting research tool - DAYSIM which is based on the concept of CBDM (Radiance + Perez Sky Luminance Model + Daylight Coefficient). In the second phase, additional simulations utilizing the validated tool are conducted to study the effects of system geometries and interior space characteristics. Specifically, the following parameters are identified and assessed: light shelf length, ceiling height, and interior configurations typical of North American office building settings. The findings have displayed the impact of various system parameters and interior design approaches on daylighting performances. The limitations of the study include possible errors in both computational simulations and the physical testing, and errors caused by the process of generating the sky models from solar radiation data for DAYSIM.