Architecture and daylight: planning strategies for energy-efficient buildings
Energy efficient, healthy, and affordable: the predictable nature of seasonal daylight geometry makes it one of the first topics to be considered when undergoing any design project.
In the decades since the 1970s, we’ve learned a great deal about how to take advantage of the sun to not only reduce building energy consumption, but also to shrink operational expenses. Recent years have seen an upswing in the use of solar technologies ranging from photovoltaic panels to solar thermal energy collection. The question that immediately comes up among building owners is, of course, “What’s it going to cost?”
However, before building owners intent on harnessing the sun’s energy start making decisions about specific technologies, they should consider two aspects of architectural design that can maximize the delivery of daylight and views to the outdoors with no real cost impact: building orientation and massing—in other words, the building’s placement on the site and the building’s form in three dimensions. In a moderate/cool climate, the largest contributors to a building’s annual energy use are heating and lighting sources. Our planet happens to be circling a free source of heating and lighting—we just have to plan and design appropriate solutions to capture it.
Daylight coming directly from the east and west when the sun is low in the sky causes glare, which can lead to eye pain and distract people from their work or studies. Additionally, this direct daylight is less consistent throughout the day and leads to potentially excessive heat loads that force air conditioning systems to work harder. South daylight is far more easily controlled with sun shading devices, while windows facing north provide diffuse, gentle daylight due to access to the skyline without direct sunlight.
Proper orientation is a way to set the project on a path for success when it comes to energy use and human health and performance. For additional resources, check out this tool for calculating solar position by location and this Whole Building Design Guide.
“Our planet happens to be circling a free source of heating and lighting—we just have to plan and design appropriate solutions to capture it.”
The following diagrams illustrate three types of massing and their impact on daylighting. The illustrations can be applied to any building type. Note the diagrams assume Chicagoland as the facility location; results will vary based on location. Also, up indicates north for each diagram.
The purple portions of the diagrams signify solar positioning. The top border of the purple area indicates the sun’s path through the sky at the summer solstice, while the bottom border shows the path at the winter solstice. The shaded area represents the months between the extremes. The orange lines within that area are sunrise and sunset during the winter solstice. More generally, the graphs are abstractions of the tool that designers use to calculate the sun’s horizontal angle from any point at any time of the day during any day of the year.
You might notice that the diagrams show both angled and rectilinear massing. This shows a “zone of flexibility” built into the diagrams. Walls do not need to face directly south for optimal daylight delivery—they can be up to ten degrees off and still perform well.
When it comes to maximizing daylight to outdoor spaces, the simplest massing proves the most effective. An east/west orientation of a linear mass maximizes daylight from the south (direct sunlight) and the north (indirect sunlight). This building type works better with smaller, less complex buildings; conversely, I recommend avoiding it for larger buildings that might be more complicated.
This type of massing involves two basically parallel volumes connected by a smaller volume. During all seasons except winter, daylight touches about 50% of the outdoor spaces. The strategy works particularly well for larger building types that function well with “wings” or departments. Examples include schools, hospitals, and office buildings. The massing can also be improved if the northmost wing is taller in elevation than the southmost one, and vice versa (though conditions would be worse if the south bar is taller).
In this scenario, the facility encloses a courtyard. A downside is that it limits daylight to the courtyard. Conversely, O massing helps block east and west winds, providing more comfort for those in the courtyard. I suggest using this for building types that require more flexible circulation patterns, since there is not a single pinch point for travel between the parts, like in H massing. Additionally, it works well for building owners who prefer a completely enclosed outdoor space. O massing also creates more opportunities for viewing the outdoors from the interior.
Early Decisions and Their Consequences
Choices about massing and orientation made early in the design process have huge impacts down the line. The wrong choices can lead to many complaints—just ask building occupants who have to deal with views of mechanical equipment, glare from low winter sun, or overheated or underlit rooms.
Next time you start planning a building project, make sure to ask your architect about massing and solar orientation. Ask for early energy models as soon as preliminary massing options are available.
The diagrams above are a start. None of them is always the correct solution. It all depends on the scale of the project, site conditions, and owner preferences about how the building relates to exterior spaces.
Keep in mind that some massing strategies may result in higher upfront costs, but can have a desirable return on investment due to energy savings and reduced operations and maintenance costs. Additionally, building owners should discuss with their architects how occupant access to nature and daylight can create greater engagement, wellness, and happiness among regular occupants or visitors.
If all this points to anything, it’s this: architects need time and space to think about the consequences of early decisions. Thus, I encourage building owners to resist the temptation to rush the early part of the design process to get to the “real” part of the project. Aristotle said it best: “Well begun is half done.”
1. Heating, Cooling, Lighting: Sustainable Methods for Architects, 3rd Edition. Lechner, 2008.
2. ArchDaily, How to Implement Passive Solar Design in Your Architecture Projects.
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