Design Parameters

There are two given conditions in any design—the climate and the building type (or space types within a building). Once these are established, questions about window orientation, daylight controls, window size, shading systems, and window type can be addressed. The Facade Design Tool can assist in determining performance outcomes from a given set of design parametrics.

These design parametrics affect decision-making at several scales in the building design process. The larger scale issues of placement on the site, building configuration, and overall layout come first. Even in the early design phase, the orientation, size, and shape of individual spaces and whether they have windows are being established. The refinement of individual spaces and systems follows, which involves window size and shape as well as the use of shading devices and daylight control systems. Finally, glazing and frame type are specified with the desired properties.

As a designer proceeds from larger to smaller scale decisions, discoveries are made later in the design process that may raise questions about earlier assumptions. This dialogue between scales is a normal part of the design process and the impacts of all these design parameters working in an integrated fashion ensures building design and performance goals are achieved.

Designers can enter at any parametric to make a decision within a given context. For example, the site may dictate that windows can only be oriented to the west, so the designer can assess the optimal window area and other choices within the context of west-facing windows. In another case, costs or aesthetics may rule out external shading devices, so the designer can determine the best glazing type for the unshaded condition. Use the Facade Design Tool to understand and see outcomes of design decisions.

Design parametrics used in the Facade Design Tool:

Performance Outcomes

Windows can have a significant impact on building operating costs, health, productivity and occupant well-being. Windows have a dominant influence on a building's appearance and interior environment, yet windows can be one of the most important components impacting its energy use, peak electricity demand, and environmental consequences. Heat gain and heat loss through windows can represent a significant portion of a building's heating and cooling loads. By providing natural light, windows can reduce electric lighting loads by using design strategies such as dimming controls, automated shading, and light redirection.

The traditional purpose of windows was to provide light, view, and fresh air for the building's occupants. As completely sealed, mechanically ventilated, and electrically lit commercial buildings have become the norm in the last half of the twentieth century, the role of the window in addressing occupant needs has declined. There is a growing recognition that the benefits of windows are valuable and contribute to the satisfaction, health, and productivity of building occupants. Use the Facade Design Tool to understand the environmental and human-centered outcomes of design decisions.

Outcomes from the Facade Design Tool:


Design Guidance

To provide guidance to designers, these guides examine the energy use impacts for perimeter zones for offices and schools in hot, mixed and cold climates. The energy use has been calculated for many window design variations including 4 orientations, 6 glazing areas, 12 glazing types, 9 shading conditions, and 2 light control options. Also included in the design guides is how the Facade Design Tool was used to determine the outcomes.


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