Until recently, renderings were the architect’s primary tool for understanding daylight in their designs—renderings, and a healthy dose of intuition. But a new generation of daylighting analysis tools, which is emerging alongside a new generation of daylighting metrics, are enabling architects to look at daylight in new ways—with important implications for design.
Business as usual, when it comes to daylight, is to use rules of thumb to design, then use renderings to check the design and communicate the intent. Rendering has fast become an art form: the creation of exquisite, evocative, often atmospheric imagery that communicates the mood, the experience, the visceral feel of the design. This is no accident: daylighting is a magic ingredient in architecture, bringing dynamism to static structure, imbuing buildings with a sense of time, and renderings are a powerful way to capture and communicate these ideas—a necessary complement to the hard line plans and sections that comprise much of the architect’s lexicon. Renderings have expanded our ability to communicate designs. They have also expanded our ability to conceptualize designs—and especially to conceptualize the daylight in our designs.
But there’s something missing: there are important daylight-related questions that renderings simply can’t answer. Even if they can be made reasonably accurate, they’re still incomplete: depicting a moment in time, but not providing an indication of whether that moment is unique or typical.
That’s a problem, because daylight is not just poetic—it’s also practical. Most spaces have lighting requirements tied to the functions we perform in them. Is there enough light in my classroom for reading and writing? Is there enough light in my office to work—but not so much that my computer screen is washed out? And how much of these lighting requirements can be met through daylighting alone?
These questions are increasingly important for myriad reasons. New benefits of daylight are constantly being uncovered: daylight improves learning in school, improves recovery rates in hospitals, improves productivity in workplaces, and improves psychological wellbeing nearly everywhere. And there are energy benefits as well: when daylight can replace electric lighting, we can save the energy consumed by the electric lights; but we also eliminate the heat emitted by those lights and therefore reduce the need for cooling. It’s not enough for daylight to be poetic—it also needs to work. And this is where daylight analysis comes in.
Daylight analysis used to be a cumbersome process, requiring new 3D models, extensive inputs, and significant technical expertise. But new tools are far faster, more intuitive, and integrated into the designer’s modeling environment—making this analysis accessible to every designer, and for every type of decision. This is happening at the same time that new metrics are being developed to evaluate daylight; therefore our ways of measuring are changing at the same time as they’re becoming dramatically more accessible.
If current practice is shaped in part by the advantages and limitations of rendering tools, what will be the effect of these new tools and metrics? What possibilities do they open up—What new ways of conceptualizing design? There are different types of daylight metrics, which allow architects to understand daylighting in different ways, and are therefore useful for answering different types of design questions. I’ll consider three types here: whole-building annualized metrics, annualized daylight visualizations, and time-of-day visualizations.
Annualized Metrics & Objective Comparisons
Annual daylight metrics summarize the daylight performance of a building throughout an entire year, taking into account design, location, and weather. These metrics help to answer the question: “Where does my design stand, relative to best practice, to specific daylight targets, or to another design?” Terms like Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE) are simply summaries of how frequently the space gets adequate daylight (sDA) or whether there’s risk of too much light (ASE).
The results are more powerful than you might expect. A recent example is Ashjar at Al Barari, a residential complex designed by 10 DESIGN, in which the design team used annual metrics to understand the daylighting potential and glare risk of overall building form, glazing ratios, and shading strategies. “Each residential type features a unique and variable aesthetic,” says Sean Quinn, Head of Sustainable Design. “The goal was a responsive design approach not a repetitive solution.” Shading in particular became a key element of the design’s aesthetic. These annual daylight metrics were used alongside annual energy metrics in order to draw out the tradeoffs and synergies between the two results. In this way, these metrics open the possibility of actually designing daylight—of crafting strategies that shape daylight, just as an architect shapes program relationships, views, or formal composition.
Annualized Visualizations & Decision-Making
The weakness of annual metrics is that they don’t help architects understand why a design is performing in a certain way. The high-level numbers are opaque: where are the dark spots and where are the bright spots? This information is critical in shaping daylight in an intentional way. This is where annualized daylighting visualizations come in: they show how the daylight is spatially distributed throughout the year, allowing detailed investigation into the lighting levels of each space. These images help answer the questions: “Am I comfortable with these light levels and patterns? Where are the problem areas? How can I improve the design?”
An example is a residential project in Iowa designed by my own firm, Sterner Design. A partially underground house with an aggressive energy target, it was critical to use glazing carefully, for both passive solar heating and to get quality daylight into the space. Early on I used daylighting visualizations to compare options and understand the depth of daylight penetration given the different floorplans. Later analysis focused on the quality of daylight in the main living areas, where good daylight is most important, and allowed me to quickly test strategies for improvement, such as taller windows, strategically placed skylights, or strategies for “borrowing” light from the well-lit upper story. The analysis allowed me to tune the building form, space layout, and glazing according to the sun in a way that simply would not have been possible before.
Time-of-Day Visualizations & Communication
While annual metrics and visualizations are effective diagnostic and design tools, they don’t always provide the most intuitive understanding of lighting conditions. What does the space feel like? How does the experience change over time? What is the light like in the middle of winter or the height of summer?
These are questions for which time-of-day visualizations are well-suited. Whereas the other metrics speak to macro-level comparisons—attainment of goals, annual averages—these speak to the experience of the space, yet quantify that experience in a way that renderings cannot.
This was what led Allan Joyce Architects to use a combination of interior renderings and point-in-time analyses to design a Tearoom retrofit in Harrowgate, UK. The client wanted to understand whether the design “worked”—what the space would actually feel like given the proposed changes. The architects paired renderings and time-of-day visuals to communicate the experience in a way that was both intuitive and verifiable. “Our client was delighted,” said Toby Evison, Architect at Allan Joyce. “They could easily comprehend the effect of the design proposals, and this directly informed their decision making.”
As these new possibilities reach more designers—the ability to shape daylight, to interrogate it objectively, to define targets and evaluate outcomes—it becomes possible to shape a building according to daylight. This enables architects to work on the poetic and the pragmatic simultaneously: to understand with equal ease the aesthetic and pragmatic implications of design decisions. By rendering visible daylighting data, architects can interact with it, form it, mold it to purpose, and ultimately achieve better designs—designs that both work and inspire.
Carl S. Sterner, Assoc. AIA, LEED AP, is the Owner of Sterner Design and Senior Product Marketing Manager at Sefaira, a software company specializing in performance-based design. Visit Sefaira at the AIA Convention in Atlanta at booth 2874.
