Daylight and energy performances of a new type of light pipe

摘要

Daylight represents a free source of illumination of building's internal spaces. For the right and optimal use of this resource, in addition to the resort to some simple designing expedients that can be brought back to the practice of "building in a workmanlike manner", it is possible to adopt specific devices able to improve the sunlight captation. Among these devices a class that presents a very interesting compromise between simplicity of realization, costs and daylighting performances is represented by the so-called "light pipes". Light pipes usually work by means of a device placed on an external closing element which attends to collect, redirect and in some cases, concentrate or collimate the incident luminous flux, and a device situated inside the environments able to transport the daylight inwards the building and distribute it into the deep zone of the rooms so as to obtain a better illuminance distribution. In this work, we propose a light pipe equipped with a flat captation system suitable to be integrated in a building's facade, without any protrusion as to the architectural envelope. This system includes: a planar closing element, a sunlight's collecting and deflecting device that optimizes the direction of the incoming solar rays as the solar position varies, a rectilinear duct with optical properties suitable for the transport of the sunlight and for its introduction into the room that has to be illuminated. The daylighting performances are simulated in different conditions of external illuminance and it is done an assessment of the lighting energy savings in a test room simulating a class room. At the end, some considerations and applying indications useful for the designer are presented.