Developing early design stages tools for windows considering sky conditions, solar radiation, and shading control

This paper presents two innovative design tools—the Sky-Type Calculator and the Iterative Shading-Mask-Protractor for Sun Control—to enhance early-stage window design in building projects. Windows are crucial in connecting indoor and outdoor environments, significantly affecting energy efficiency, daylight quality, and occupant well-being. Despite the availability of various simulation tools for assessing lighting and energy performance, there is a lack of tools that can guide designers on the window size, orientation, and shading devices based on dynamic sky conditions. These new tools provide comprehensive data and visualizations, enabling designers to conduct thorough analyses of window designs tailored to specific locations and varying sky types, offering more detailed insights than traditional metrics and simulation outputs.

The tools were developed using Rhino 7’s Grasshopper platform, Ladybug plugin and GHPython. The process involved importing EPW files, linking Rhino models, processing data, and generating visual outputs. These tools were designed to enhance sun control in window design for professionals and serve as educational aids for students learning about solar control. The main features of the tools include:

Sky-Type Calculator: This tool extracts data from EPW files to determine the ratio of diffuse to global horizontal illuminance, providing detailed information on daily, monthly, and yearly predominant sky types. Users can analyze either hourly results or predominant daily sky types. The tool generates diagrams to visualize monthly and yearly sky type patterns and includes spreadsheet outputs for further analysis, such as generating histograms of sky types for different cities. It provides data on the number of overcast hours or days per year, which is useful for daylighting and PV design.

Iterative Shading-Mask-Protractor: This tool generates a 3D shading mask visualization based on a Rhino model, incorporating sun path and solar radiation data on a monthly or yearly display. It visualizes the solar geometry and radiation for the target window, illustrating the relationship between shading device efficiency and exposure to the sky. The tool features real-time adaptive visualization, dynamically updating diagrams in response to model changes, allowing for immediate assessment and implementation of sun control strategies.

In summary, these tools enable designers to understand the sky conditions of a location and make informed decisions of window placement, orientation, and size, along with the appropriate dimensions and forms of shading devices under dynamic sky conditions. The tools have been tested in several projects, providing valuable insights that enhance window design and contribute to evidence-based design practice and research.