Design Workshop: How to Borrow Light from Outside
You can save energy by using glass walls, windows and skylights to bring sunlight into dark areas of your home
Eric Reinholdt
12 April 2017
Houzz Contributor
In 1915 the 38-story Equitable Building in New York City was the largest office building in the world. Containing 1.2 million square feet of office space, it consumed nearly every available square foot of its diminutive lot and cast an equally large shadow on its neighbourhood in lower Manhattan. Its construction inspired the enactment of the city’s 1916 Zoning Resolution, which was designed to preserve access to light and air at the street level. The resolution prescribed specific limitations for a building’s envelope — its outer walls — and would go on to shape the stepped forms that you see today on many of the iconic towers in the city.
This underscores the importance that access to daylight had in shaping even the largest of cities, the individual buildings that make up those cities and, more broadly, sensible building design. With an increasing focus on sustainable design practices, the smart use of natural daylight in our homes is no longer a luxury — it has become a necessity. At the heart of any good daylighting strategy is a concept of “borrowed” light: The capture of light falling on the exterior of a home and transporting it to the spaces where it’s needed.
This underscores the importance that access to daylight had in shaping even the largest of cities, the individual buildings that make up those cities and, more broadly, sensible building design. With an increasing focus on sustainable design practices, the smart use of natural daylight in our homes is no longer a luxury — it has become a necessity. At the heart of any good daylighting strategy is a concept of “borrowed” light: The capture of light falling on the exterior of a home and transporting it to the spaces where it’s needed.
The sun delivers an incredible amount of light energy to us each day. To get an idea of just how much, it helps to understand the standard by which we use to measure light intensity: The foot-candle. The light from a full moon is roughly 1 foot-candle, while the sun’s illuminance on a cloudless day is roughly 10,000 foot-candles. Of course, clouds and the filtering effects of glass can reduce the actual amount of light that reaches the interiors of our homes by 50 to 90 percent. But 1,000 to 5,000 foot-candles is still an amazing amount of light, given that we need only around 35 foot-candles to comfortably read.
Harnessing this light energy isn’t as simple as placing a window on an exterior wall. Interior rooms without access to an exterior wall or spaces oriented in a way that restricts access to adequate daylight are common problems, each with a unique solution. Here’s a look at some solutions.
Walls
Interior walls built to collect and disperse light rather than restrict it are one solution. The wall shown here gathers indirect light from an adjacent light-filled bathroom and capitalises on the reflective nature of the bath’s wall surfaces to diffuse it into the bedroom. Clear glass will transmit the greatest amount of light into adjacent spaces. And because the glass here is positioned above eye level, the bath remains private and sound-isolated.
Walls
Interior walls built to collect and disperse light rather than restrict it are one solution. The wall shown here gathers indirect light from an adjacent light-filled bathroom and capitalises on the reflective nature of the bath’s wall surfaces to diffuse it into the bedroom. Clear glass will transmit the greatest amount of light into adjacent spaces. And because the glass here is positioned above eye level, the bath remains private and sound-isolated.
The white walls of the same bathroom act as the indirect light source for the nearby bedroom. Bright, neutral colours work well for an indirect borrowed-lighting strategy.
Good solar exposure is borrowed by the bedroom simply via the glazed upper wall.
Good solar exposure is borrowed by the bedroom simply via the glazed upper wall.
Because translucent materials reflect, absorb and scatter light, they make great walls for borrowing light. The degree of translucency will affect just how much light is scattered. The effect is similar to obscuring direct sight but preserving the passage of daylight. Diffused light is comfortable and limits eyestrain.
Translucency can be achieved in a variety of ways. Glass can be sandblasted or acid etched. It can also be textured or laminated. With laminated glass, a plastic interlayer lends a translucent effect similar to that created by sandblasting but without the marking characteristics. There are applied films to consider too.
Full-height glass walls offer auditory but not visual privacy. When there’s limited access to exterior window space, they’re an obvious choice.
The perceived dimensions of our rooms are naturally increased when we use the borrowed-light concept too. This means it works particularly well for spaces with floor-area constraints.
In this project the concept of borrowed light has been applied to the overall ordering system in place. There’s a logic to the order of solid and void, and it offers plenty of light to the bedroom space. The pattern on the glazed wall has been achieved with a custom film; the design was created from a sketch by the architect.
The vaulted ceiling and clerestory take advantage of reflected light from the entire volume of space.
The vaulted ceiling and clerestory take advantage of reflected light from the entire volume of space.
Stairs
Another option and an efficient vehicle for borrowing light in a home is the stairway. It’s a natural conduit for illuminating an often light-starved lower level. If the stairs can be positioned to capture and reflect light from above by either fully glazing it or using a skylight, it’s even more effective.
Another option and an efficient vehicle for borrowing light in a home is the stairway. It’s a natural conduit for illuminating an often light-starved lower level. If the stairs can be positioned to capture and reflect light from above by either fully glazing it or using a skylight, it’s even more effective.
The combination of glass guard and white walls has made this stairway a light source for the surrounding rooms. A solid wall used here would have changed this space dramatically.
Gorgeous Lights Bring a Shine to These Staircases
Gorgeous Lights Bring a Shine to These Staircases
Interior windows
Whether they’re clear or frosted, there are plenty of functional incentives to borrow light using interior windows. The ones here bring in light from the adjacent living area while preserving the nursery’s acoustical privacy.
Whether they’re clear or frosted, there are plenty of functional incentives to borrow light using interior windows. The ones here bring in light from the adjacent living area while preserving the nursery’s acoustical privacy.
Interior windows aren’t subject to the same weathering and insulation restrictions as exterior windows, so they’re less expensive to buy and install. Making them operable, especially in a stairwell where natural convective flow is greatest, can help to passively ventilate a space too.
Functional reasons aside, interior windows can offer unexpected delight. Why connect a bar and a powder room? I don’t have a good reason, but I don’t need one. I love the idea that the powder room will look different based on what’s on the top shelf and the time of day. In the bar too, the differences that the powder room renders to its splashback can be appreciated. It’s these connections that make architecture interesting. Linking spaces doesn’t always have to make sense, functionally or otherwise.
Skylights
Because the sky dome above is a giant light source, it’s hard to find a more efficient means for borrowing light here than the skylight. On tight urban lots, a skylight can be used in conjunction with an interior atrium or light well and be surrounded by reflective walls to increase its efficiency.
Because the sky dome above is a giant light source, it’s hard to find a more efficient means for borrowing light here than the skylight. On tight urban lots, a skylight can be used in conjunction with an interior atrium or light well and be surrounded by reflective walls to increase its efficiency.
This project utilises a light well of sorts, allowing the lower level to borrow light from the upper skylights. The second floor hovers in the space instead of being extended to the full width of the gable, and the overall effect is lighter and brighter. The more we open up our interior spaces, the easier it becomes to bounce daylight around from areas with good solar exposure to areas with poor exposure. Painting the surfaces with a higher-sheen paint further helps distribute the light.
This luminous shower is an example of how a light well and skylight can transform a tight space into a pleasant one.
Additions to existing structures often compromise the amount of daylight the original building receives. Not here, though. The skylight ensures that the existing home borrows daylight at its perimeter.
Transoms
Similar in concept to the ideas seen in the first images in this story, a glass transom extends the dimension of a space and introduces light to a room without compromising its privacy.
Similar in concept to the ideas seen in the first images in this story, a glass transom extends the dimension of a space and introduces light to a room without compromising its privacy.
Light tubes
Simple-technology solar tubes channel light to where it’s needed using highly reflective, flexible tubes. They’re especially effective in private spaces or spaces where a lot of glass isn’t desirable.
How to Add a Skylight or Light Tube
Simple-technology solar tubes channel light to where it’s needed using highly reflective, flexible tubes. They’re especially effective in private spaces or spaces where a lot of glass isn’t desirable.
How to Add a Skylight or Light Tube
Although short tubes are used in this project, the concept is similar. Six large tubes light this otherwise dark space, a bold and considered element. The choice of multiple solar tubes rather than a single one not only feels more intentional, but as you can see, it’s also exceptionally functional. A grouping of three is usually a good starting point, but the more, the better.
Read more:
5 Tips on Lighting Your House Right
10 Reasons to Say Yes to LED Lights
Tell us:
How have you designed your home to get maximum natural light in? Tell us in the Comments below.
Read more:
5 Tips on Lighting Your House Right
10 Reasons to Say Yes to LED Lights
Tell us:
How have you designed your home to get maximum natural light in? Tell us in the Comments below.
What are you working on?
Related Stories
Working with professionals
How to Find an Architect That's Right for You
Make the construction and renovation of your home a pleasant and memorable journey by selecting the right architect
Full Story
Indian Homes
11 Indian Homes That Revolve Around Courtyards
Take inspiration from these homes that make a solid case for courtyards in urban life
Full Story
Decorating Guides
Building Secrets to a Cool, Breezy Home for Hot Indian Summers
Get updated on climate-responsive design strategies for a home that stays naturally cool all year round
Full Story
Working with professionals
What's the Difference Between an Architect and a Civil Engineer?
We clear up the confusion between the professional roles and scope of work of an architect and a civil engineer
Full Story
Architecture
These Indian Homes Know How To Combat Harsh Climate
See how these homes by SPASM, Kumar Moorthy & Associates and JPLUSDARCHITECTS mitigate the ramifications of harsh climate ahead of time
Full Story
Decorating Guides
What Are the Biggest Challenges in Renovating an Old House?
Here are some common problems which may arise during the renovation of an old property
Full Story
Indian Homes
How to Beat the Summer Heat by Keeping the Roof Cool
Here are ways to cope with the high summer temperatures that heat the roof and the top floors of residential buildings
Full Story
Decorating Guides
How to Design a Home That is Not a Burden on the Environment
Incorporate smart details with simple lifestyle changes to create a home that is kind to the planet
Full Story
Architecture
What Is Kerala Architecture?
Let's explore what design elements constitute traditional Kerala house architecture
Full Story
Architecture
Expert Speak: What Are the Best Materials for Home Elevations?
Houzz checks in with an expert about the the most sturdy and adaptable materials for home facades
Full Story
@Josh Wynne Construction Isn't the daytime heating problem taken care of with double or triple glazing?
Blue Wren In part. Glass is no where near as insulated as an insulated wall and even the best glass allows 21% solar heat gain.
Clear polycarbonate whirly-bird by Edmonds, positioned just below the ridgeline and immediately above a diffused acrylic ceiling manhole, brings light into the middle of a long axial hallway.