Daylight and Buildings : Strategies for Sustainable Interior Spaces

In our modern society, we spend an average of 90% of our time indoors, which equates to over 21 hours per day. However, this reality is largely misunderstood by many; studies reveal that people often underestimate the amount of time they spend indoors.

This misconception highlights the importance of redesigning our living and working spaces to better incorporate daylight. Natural lighting plays a crucial role in our health, well-being, and energy efficiency. This blog post explores the benefits of daylight, strategies to integrate it into our buildings, and the challenges and innovations associated with this integration.

Benefits and Importance of Daylight in Indoor Environments

Health and Well-being

Natural light significantly reduces stress and enhances mood. Studies show that well-lit environments can lower cortisol levels, the stress hormone, among occupants. A survey conducted by Future Workplace found that 78% of employees say that access to natural light and views improves their well-being, and 70% reported an improvement in their work performance due to better access to natural light . [t ]

Natural light also influences our sleep-wake cycles, regulating our circadian rhythm. Adequate exposure to daylight helps synchronize our internal biological clock, which improves sleep quality and daytime alertness. Workers with good access to natural light slept an average of 46 minutes more per night than those without it.

Energy Efficiency

Utilizing natural light significantly reduces the need for artificial lighting, leading to notable reductions in energy consumption and associated costs. According to Facilities Net, a well-designed natural lighting system can save up to 75% of the energy used for electric lighting in a building .

In addition to energy savings, integrating natural light contributes to sustainability by reducing carbon emissions and supporting environmental goals.

Comfort and Aesthetics

Natural light creates more pleasant and visually appealing spaces. By integrating daylight into interiors, architectural details and design elements are accentuated, making spaces more vibrant and inviting. According to a survey by Future Workplace, 73% of employees say that access to natural light improves the ambiance of their workspace, enhancing the attractiveness and usability of the spaces.

Moreover, 47% of employees feel fatigued or very tired due to the lack of natural light at work, underscoring the importance of natural lighting for occupant well-being.

Solutions and Strategies for Integrating Daylight

Orientation and Design

Optimal building orientation and thoughtful design maximize exposure to natural light. Strategically orienting buildings, such as placing primary windows to the south in the northern hemisphere, can capture more daylight throughout the day. Open floor plans and transparent partitions also allow natural light to penetrate deeper into interior spaces, reducing the need for artificial lighting and creating a brighter, more welcoming environment. The design phase is crucial for a project and requires multiple studies and simulations to maximize the use of daylight as a natural resource. The principles of passive design and bioclimatic architecture are essential; for more on this topic, see our dedicated blog post.

Windows and Openings

Choosing the right windows to optimize daylighting involves considering two key factors: the light transmission coefficient (Tw) and the solar factor (Sw). The light transmission coefficient measures the amount of visible light passing through a window, with typical values ranging from 0.3 to 0.8. A higher Tw means more natural light entering the building. The solar factor indicates the proportion of total solar energy passing through the window, affecting solar heat gains. A lower Sw is preferable in hot climates to reduce heat gains, while a higher Sw is beneficial in cold climates to maximize solar heat intake.

Skylights

Solar tunnels (Sun Tunnels) and skylights are effective solutions for bringing natural light into interior spaces distant from windows or located in dark areas of the building. Solar tunnels, such as those offered by VELUX or SOLATUBE, use reflective tubes to direct light from the roof to the interior. SOLATUBE's solar tunnels have the highest light reflection rate in Europe, with 99.7% of sunlight transmitted through the conduit . Skylights can be installed on any type of roof and come in various sizes and styles, making them adaptable to different architectural applications while providing abundant natural light.

Atriums

Creating atriums at the heart of buildings allows natural light to penetrate the interior, providing a plentiful source of light while serving as architectural focal points. In addition to enhancing aesthetics, atriums contribute to better natural ventilation. Interior courtyards work similarly by bringing natural light to surrounding spaces and offering a sheltered outdoor area for occupants.

Optical Fiber

Fiber optic systems for daylight capture daylight on the roof and transport it to remote or poorly lit interior spaces. This innovative technology provides natural light in areas where windows and skylights are impractical or impossible. Fiber optic systems are particularly useful for interiors with specific architectural constraints. However, it is important to note that the farther the light travels from the collector to the luminaire, the less intense it becomes. For example, a 10-meter cable delivers about 64% of the initial light, while a 20-meter cable delivers only 40% .

Reflective and Translucent Materials

Using reflective materials, such as light-colored paints and glossy surfaces, maximizes the diffusion of natural light inside buildings. An important factor to consider for these materials is the Light Reflectance Value (LRV). LRV measures the percentage of visible light reflected by a surface. Higher LRV values mean more light is reflected, increasing the brightness of the space. For instance, white paint can have an LRV of 80 to 90%, while darker colors have much lower LRV values. Additionally, using translucent materials, such as frosted glass or polycarbonate panels, allows light to pass through while providing privacy. These materials can be used for interior partitions, facades, and roofs, evenly diffusing natural light into interior spaces and enhancing comfort and aesthetics.

Challenges and Innovations

Challenges

Glare can cause visual discomfort and reduce occupant comfort. To minimize glare while maximizing daylight intake, strategies such as using blinds, shutters, solar films, and sun shading systems are essential. Window orientation, specific glass types, and dynamic shading systems can also help reduce glare while allowing optimal daylight penetration.

Similarly, solar heat gains associated with natural lighting can cause overheating in interior spaces, especially in summer. Moreover, a high proportion of glazing or openings in a building can reduce thermal performance by increasing thermal bridges. It is essential to find the right balance between integrating natural light and maintaining thermal comfort to optimize resource use.

Integration with Light Controls

Advanced technologies for optimizing natural and artificial lighting are essential for improving energy efficiency and occupant comfort. Light control systems include light sensors, motorized blinds, and automated shading devices that adjust lighting based on available natural light. Incorporating automated control systems, such as LED lighting connected to light sensors and centralized management systems, maximizes energy efficiency. These systems can adjust the intensity of artificial lighting based on natural light, providing consistent and pleasant lighting throughout the day. For more on this topic, read our blogpost here.

Technological Innovation - Smart Window Glass 

Electrochromic glass, also known as smart glass, can change transparency in response to an electric voltage. This technology allows controlling the amount of light and heat entering a building, improving indoor comfort and energy efficiency. The glazing can switch from clear to tinted within minutes, offering unprecedented flexibility for managing natural light and solar heat. 

Electrochromic glass is particularly useful in buildings where light and heat management are crucial, such as offices, schools, and hospitals. Visually, they are similar to standard glazing and require no special maintenance other than regular cleaning, offering an innovative alternative despite their relatively high cost. One of the market leaders is Saint-Gobain's SageGlass and their electrochromic glass can reduce overall energy use by 5-15% and lower peak summertime demand by 25% or more, helping building owners save money while achieving their sustainability targets for reducing operational carbon emissions. 

Conclusion

Daylight revitalizes our health, boosts our well-being, and enhances our energy efficiency. By applying ingenious techniques such as strategic building orientation, thoughtful window selection, and the smart integration of skylights, we can maximize these benefits. Through technological innovations like electrochromic window glass, we skillfully overcome challenges related to glare and solar heat gains, creating sustainable and comfortable indoor spaces.

Ready to integrate natural light into your project? Contact us!