Designed for Daylight: Benefits of Passive Solar Design

Passive solar design is a sustainable, cost-effective way to save energy and conserve nonrenewable resources. This architectural concept involves designing buildings that maximize natural sources of heating, cooling, lighting and ventilation to create comfortable conditions inside. 

In most cases, a passive design relies on the sun and its energy. Ultimately, this approach will benefit both the structure's inhabitants and the planet as a whole.

1. Light

One of the biggest benefits of passive solar design is that it harnesses and maximizes natural light, especially in sunnier climates. To maximize exposure, architects orient the building so its windows face the sun for most of the day. In the Northern Hemisphere, this means the structure will face south.

Designers may also enlarge the building perimeter to allow for long, narrow forms that harvest daylight more effectively than a multiple-story design. Using matte, light colors on the interior will ensure high reflectance and further increase the daylight level. Prevent glare by locating reflector systems above eye-level and improve visual comfort by avoiding dark surfaces on the back wall.

2. Well-Being

Improving access to natural lighting will automatically reduce the need for artificial lights, which can provide significant health benefits for inhabitants. For instance, exposure to sunlight boosts vitamin D and helps prevent bone loss, weight gain, heart disease and even cancer. In an office setting, sunlight can also decrease drowsiness by 10%, boost productivity by 2%, and minimize eye strain, headaches and blurred vision by 84%.

Passive solar design will also balance users' circadian rhythms and realign their sleep schedule with the natural cycle of sunrise and sunset. Since sleep and mood are intertwined, absorbing more light will also ward off depression and seasonal affective disorder, especially as the days grow shorter. 

3. Warmth

The more sunlight a space absorbs, the warmer it will be. In colder climates, designers and architects can maximize this natural heat by properly orienting windows and using a glazing treatment to avoid heat loss and light transmission. During the spring and fall, inhabitants should use shading to prevent overheating. They should also ensure a tight building envelope and incorporate the use of insulation to improve energy efficiency. 

Most buildings will be more efficient if they incorporate thermal mass — or materials that store heat. Architects can accomplish this by using concrete, brick, stone and tile during construction. These materials will absorb heat from sunlight to warm the building during the cooler, shadier months. They'll also pull it in from the air, effectively cooling the interior in the summer 

Finally, roofing is another element of passive solar design. Commercial buildings collect much solar energy from roofing, which is exposed most directly to the sun. Opting for a reflective coating can help maintain lower temperatures without needing excessive air conditioning in hot climates. 

4. Sustainability

Since passive design relies on natural resources to heat, cool and light interiors, it is more environmentally friendly and more sustainable than electricity and gas. If architects build to meet Passive House Institute U.S. standards, inhabitants will enjoy a 40-80% reduction in energy usage and associated costs. Ultimately, this will result in fewer carbon emissions and help conserve nonrenewable resources. 

Inhabitants could further maximize their energy efficiency and sustainability by taking advantage of the sun's power. Most passive homes experience sunlight the majority of the year, making them an excellent place to install photovoltaic systems. Even a few solar panels on the roof may be enough to charge electronic devices, heat the water and allow for net-zero or even net-positive energy efficiency. 

Passive Daylighting Begins With Design

Daylight design must begin in the concept stage and include an integrated approach. Otherwise, it will be incredibly difficult — if not impossible — to achieve net-zero efficiency if that's the ultimate goal. After completing the construction process, architects can retrofit the building with some passive design elements. 

However, the post-construction design process will most likely limit them to installing light shelves, windows, window glazings and a skylight or two. That's why it's best to incorporate passive solar from the start.

Evelyn Long is the editor of Renovated, a construction and home improvement magazine. Her work focuses on better building techniques for more sustainable communities.