TripleSave - The Investigation and Monitoring of a Combined Natural Daylighting and Stack Ventilation System
G. Oakley et al, Institutes of Building Technology, University of Nottingham, c. 2000-2001.Review by Scott Schuetter, Energy Center of Wisconsin:
In this paper, Oakley et al develop a testing method for measuring the amount of natural daylight and passive ventilation a light pipe introduces into a test chamber. Two light pipes were analyzed, both having diameters of 0.215 m and lengths of 2.2 m. Concentric cylinders let light into the chamber and ventilation air out via natural convection. Photosensors measure the illuminance levels both internal and external to the chamber, while a tracer-gas method was employed to measure the ventilation flow rate. The measured ventilation flow rate was compared to a theoretical flow rate and showed good agreement.
The results showed a ratio of internal to external illuminance of approximately 16%. The highest natural light penetration was during periods of time that the sun was overhead. However, the addition of a Laser Cut Panel to the top of the light pipe enhanced daylight penetration during periods of low angle sunlight. The natural ventilation averaged 8 air changes per hour of the 1.3 m x 1.3 m x 1.3 m test chamber during the study, with little to no effect from wind speed or direction.