Passive Louver Daylighting System with Compound Parabolic Concentrator
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Solution Overview
Problem
Existing daylighting systems, such as anidolic and louver systems, face challenges in efficiently redirecting light deep into buildings while preventing glare and maintaining a compact design, often requiring additional shading systems and being costly or ineffective under varying sunlight conditions.
Innovation Solution
A new louver system incorporating a compound parabolic concentrator (CPC) profile that redirects both direct sunlight and diffuse skylight at an angle near horizontal, preventing direct sun penetration and using refractive rods and a reflective ceiling to mitigate glare, while being simple, maintenance-free, and suitable for both sunny and cloudy conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a zenithal anidolic collector is used to redirect light, then light can be concentrated and redirected into controlled angular ranges, but the system requires large physical dimensions (1-2m long, 0.5-1m tall) that reduce ceiling height and create integration challenges
Solution Approach 1:
The patent divides the large zenithal anidolic collector into multiple smaller louver elements arranged in an array. Each louver is a simplified version of the CPC geometry, processing a portion of the incoming light. This segmentation allows the system to achieve the same overall light redirection function while reducing the scale of individual components and facilitating easier integration into building facades.
Solution Approach 2:
The patent transitions from a three-dimensional volumetric collector to a two-dimensional louver array system. By arranging flat louver elements in a planar array on the facade, the system achieves light redirection without requiring the depth and volume of a traditional anidolic collector, thus preserving ceiling height and simplifying integration.
2Object-affected harmful factors
If blinds are shut to control glare from anidolic systems, then direct sunlight is blocked, but the blinds remain shut for long periods reducing natural light and requiring automation
Solution Approach 1:
The patent converts the harmful direct sunlight that causes glare into beneficial diffuse light by using reflective louver surfaces to redirect sunlight onto the ceiling. The ceiling then acts as a secondary light source, distributing soft, glare-free illumination throughout the space. This eliminates the need for glare-controlling blinds while maintaining comfortable lighting conditions.
Solution Approach 2:
The patent introduces the ceiling as an intermediary element between the louver system and the occupied space. The ceiling receives redirected sunlight and redistributes it diffusely, acting as a mediator that transforms direct harsh light into soft ambient light, thereby eliminating glare without requiring operational controls.
3Illumination intensity
If louver systems are designed to redirect light onto the ceiling, then direct sunlight is blocked, but the systems either reject too much light above certain angles or allow light below horizontal causing glare
Solution Approach 1:
The patent applies different surface properties to different parts of the louver structure. The outer surfaces are designed with specific reflectivity characteristics to redirect light at controlled angles, while the inner surfaces have different properties to manage light distribution. This local differentiation allows the system to accept a broad angular range of incoming light while maintaining precise control over the redirected output angles.
Solution Approach 2:
The patent optimizes the geometric parameters of the louver profiles, including the angles and curvature of the reflective surfaces, to achieve the desired light redirection pattern. By carefully selecting and adjusting these parameters, the system can accept light from a wide angular range while redirecting it onto the ceiling at angles that prevent glare, eliminating the trade-off between angular acceptance and glare control.
4Object-affected harmful factors
If automated shading systems are used to protect from glare, then glare control is improved, but the system becomes expensive and requires maintenance
Solution Approach 1:
The patent creates a self-regulating optical system that automatically redirects sunlight based on its geometry, without requiring external control mechanisms. The louver profiles are designed to passively respond to incoming light angles, automatically redirecting sunlight onto the ceiling when needed and allowing other light to pass through when appropriate. This self-service approach eliminates expensive automated shading systems while maintaining effective glare protection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively penetrates light deep into spaces, reducing glare and maintenance needs, and bridges the gap between expensive automated systems and ineffective passive systems, providing consistent performance across different lighting conditions without reconfiguration.
Implementation Method 1
A new louver system incorporating a compound parabolic concentrator (CPC) profile that redirects both direct sunlight and diffuse skylight at an angle near horizontal
Implementation Method 2
using refractive rods and a reflective ceiling to mitigate glare
Implementation Method 3
using refractive rods and a reflective ceiling to mitigate glare
Data Source
AI summary
A daylighting system for use in a building including a louver array having a first longitudinal element, and a second longitudinal element spaced therefrom. At least one of the first and second elements has an asymmetrical profile, each of the first and second longitudinal elements has a bottom profile including a parabolic surface, portions of opposing surfaces of the first and second longitudinal elements define a compound parabolic concentrator profile having a non-horizontal centerline that is tilted upwards, and the array prevents line of sight therethrough. A louver for a daylighting system includes (i) a leading edge defined by a leading connecting surface disposed between a parabolic concentrator surface and a flat surface; and (ii) a trailing edge defined by a trailing connecting surface disposed between a lower compound parabolic concentrator profile, and an upper compound parabolic concentrator profile. A method for designing a louver profile is provided.