A Sun-Shading Performance Retrospective

Attending next month’s ArchitectureBoston Expo (ABX)? Be sure to check out The Good, the Bad and the Shady: a sun-shading performance retrospective on Friday, 11/16.

Controlling the sun’s effect on our thermal and visual comfort in the built environment is an age-old problem, one that has infinite solutions. In recent years, architects facing the realities of the AIA 2030 challenge and LEED have designed several forms of exterior sun-shading in an attempt to reduce solar heat gain during cooling months and prevent visual glare. These shading designs vary greatly in depth, orientation, material, rhythm, and location; consequently, little is known on how well they perform. When considering light shelves, louvers, blinds, brise-soleils, baquettes, or overhangs, how do you know which is best? This seminar tackles the questions surrounding sun-shading performance by presenting an analysis of several built and unbuilt projects.

As one of the ongoing office research projects, Ranjit and Michael H. are analyzing PAYETTE’s various approaches to daylight and solar control through exterior sun-shading.

Exterior sun-shading devices are often employed in the design of contemporary buildings to reduce solar heat gain during cooling months and prevent glare from disrupting the occupants’ visual comfort. In the last several years, PAYETTE has employed numerous forms of exterior sun-shading on projects in an attempt to address these environmental factors. This research project, using Diva (an environmental simulation plug-in for Rhinoceros), will analyze specific shading strategies designed for various PAYETTE projects in an attempt to systematically define a set of metrics with which a shading device can be evaluated. Using this information, a rule set can be developed for optimizing sun-shading devices for future design projects.

Looking across multiple control types – from louvers to baguettes to frits – our research effort will model a range of systems. Projects chosen are either recently completed or under construction; they further share common use types and orientations. We begin by comparing thermal heat gain of each project with and without shading devices. We further extend the exploration to three of those projects to analyze their responsiveness to thermal radiation, useful illuminance, and glare.

Of the three advanced models, we will then take one and utilize the Grasshopper plug-in to parametrically adjust a specific dimension of the shading system, like spacing, tile angle, or length. By doing so, we can attempt to optimize the shading system to allow maximum solar exposure during the winter months and minimize exposure during summer months. As a potential tool in the design process, Diva and Grasshopper allows us to explore the effectiveness of parametric tools for evaluating and achieving optimal solar control. An eventual second phase of research will involve measuring daylight and glare levels in built examples with the model predictions.

Many design responses to solar control are intuitive. And tools such as physical models, Revit and Sketch-Up can provide interesting supplement. However this project is interesting in understanding how the subtle differences between systems can be explored with more sophisticated tools.  We’re also learning how some systems, like frit patterns and “Okawood” glazing (timber frames housed within the evacuated cavity of an insulated glazing unit), are extremely difficult to model and render.

The presentation will highlight key findings about the effectiveness of different shading devices and the best solutions for controlling solar heat gain and glare. Through the presentation, details about daylighting simulations and parametric analysis using Radiance, DaySim, and Ecotect will be discussed and steps for carrying out sun-shading investigations on other projects will be outlined.

Details
Friday, November 16, 2012
3:30 pm – 5:00 pm

Speakers
Michael Hinchcliffe, AIA, LEED AP BD+C, Associate Principal, PAYETTE
Ranjit Korah, Designer, PAYETTE