Green Building Design 101 – Natural Daylighting

The first thing any architect or builder should tell you is that we need to work with nature, not against it. This is the key mindset of sustainability. Every building site contains inherent natural potentials. This can mean average rainfall, prevailing winds, geothermal activity, even the ground beneath your very feet, or any number of other naturally occurring phenomena just waiting to be tapped for energy and resources. Natural daylighting has tremendous potential in the context of a net-zero house.

Natural Daylighting

Natural daylighting, whether from a ray of light reaching through the curtains, or the soft dappled light just beneath the canopy of an oak tree. It evokes in us warmth and serenity. Our sophisticated eyes function efficiently and without stress in the presence of natural light. Our moods are calmer. Our energy tends to be higher. Recent studies in architectural design have shown that natural lighting may even improve the test scores of our children upwards of 25% compared to students in classrooms with no windows and no natural lighting, leading to a revolution in the design of educational institutions. Best of all, daylight is completely free (when the sun is up). Undeniably natural lighting is the most desirable, and sustainable solution for interior lighting – provided that windows and openings do not incur excessive heat gain.

Admitting an acceptable level of life-nourishing light while managing heat gain requires a rigorous balancing act. Luckily, today’s energy-efficient windows, as well as advances in lighting design, allow efficient use of windows to reduce the need for artificial lighting during daylight hours without causing heating or cooling problems.

While the best way to incorporate daylighting in your home depends on your climate and home’s design, the sizes and locations of windows should be based on the path of the sun roughly according to the cardinal directions.

The Cardinal Directions

North-facing windows are the most advantageous for daylighting. They admit an even wash of cool natural light, producing little glare and almost no unwanted summer heat gain. High north-facing clerestory windows are an effective and energy efficient means of admitting quality light.

South-facing windows are excellent sources of natural lighting as well, and useful for moderating seasonal temperatures. They allow most winter sunlight into the home but little direct sun during the summer – provided that they are properly shaded. Generally, south-facing glazing should be sheltered from the summer sun with long, low-hanging eaves.

East- and west-facing windows are not desirable for natural lighting – they should be limited. They may cause glare, admit a lot of unwanted heat during the summer months, and contribute little to no solar heating during the winter. If eat-west facing windows are a must for other reasons, they should be heavily shaded with vertical louvers or vegetation.

Of course site constraints and design concerns will generally preclude a house from being built entirely oriented to the cardinal directions. Nonetheless, best practices entail that all windows, skylights, and other openings are as strategically placed as possible with the angle and position of the sun in mind. For homebuyers looking at finished or older housing stock, the same rules apply. Generally houses with most of their long faces facing east/west will suffer from undue glare and heat gain and should be avoided. For those looking to build, eco-conscious eco-builders, such as Native, make it a priority to focus heavily on the design and orientation of the building and the placement of windows. Surprisingly, this may be the most important step in the design of any eco-friendly house. A house that leverages the inherent conditions to its advantage will be profoundly more sustainable than any house that does not. It would also be profoundly less expensive.

Build to your climate. Build Native.