TRIPLESAVE – THE INVESTIGATION AND MONITORING OF A COMBINED NATURAL DAYLIGHTING AND STACK VENTILATION SYSTEM

摘要

Increasing the use of natural daylight for lighting purposes in buildings may offer savings in total buildingrnenergy consumption. One technique is the use of lightpipes that can not only bring light into otherwiserninaccessible or dimly lit places, but also improve the internal environment without generating excessive heat.rnThis investigation aims to develop a unit combining light pipe technology and passive stack ventilation byrnutilising the light pipe as an exhaust stack. The performance of two light pipes have been continuouslyrnmonitored in two separate environmental chambers situated outdoors. Measurement of low velocity airflowrnrates and natural stack ventilation through the test chambers has been carried out using the constant injectionrntracer-gas method. The results show a good correlation between solar altitude/time of day, internal lux valuesrnand the external lux values. Computational Fluid Dynamics (CFD) has been used to investigate the simulatedrnperformance of the passive stack ventilation through the integrated system. The simulation results showed thatrnCFD can be a useful tool for the design of passive stack systems. The experimental results show that lightpipesrnare proficient devices for introducing daylight into buildings and reducing energy costs. An analysis has shownrnthat the use of light pipes can lead to savings in electricity usage of up to 20 – 30 %.