Our Primary source of natural light is the Sun. Providing maximum daylight penetration in the interior spaces is one of the principal determinants for any project. It not only increases occupant comfort and productivity, satisfaction but also lowers electricity bills. Day lighting acts as an essential factor in considering about global warming, carbon emissions and sustainable design, influencing human behavior, health and productivity.
Designing with daylight refers to design with proper control of natural light into the interior. Whether in the initial concept of planning for the buildings/providing energy-efficient systems, natural light plays a primary role in the productivity of workable areas.
Benefits of Day lighting:
- A Primary source of heating and lighting.
- Improves Aesthetics of the interiors.
- Daylight produces light without the need for electricity or any fossil fuels.
- Visual comfort and provides psychological needs.
- Connects humans to the natural world and be in close contact with natural serene.
- Deeply relaxes our mind.
- Natural source of vitamin-D and increases energy levels.
- Stimulating effect both mentally and emotionally.
- Comfort and energy efficiency
Components of Daylight:
- Direct Sunlight-Light received directly from Sun.
- Excessively bright, produces glare and contrast, introduce heat and UV radiation.
- Skylight – Sunlight diffusing and scattering through various states of our atmosphere.
- different qualities depending on time of day, time of year, weather and atmospheric conditions.
- Diffused Sunlight -Sunlight after its interaction with some sort of diffusing materials.
- manageable source of light.
- To Increase Productivity and satisfaction while working for Human comfort.
- Windows and Views that connect to nature and outside environment.
- Optimized and controlled daylight in the Interior spaces.
- Minimizing glare while working with computer screens.
1.Understanding Solar Principles and Directions
- High Latitudes – High Sun angles and short shadows.
- Low Latitudes – Low Sun angles and long shadows.
- Tropical Region – Using shading devices to prevent heat from direct Sunlight.
- Arid Region – Providing Courtyards and windows.
- Change of Seasons
- Factors relating to natural changes from day to night until the daylight fades. Weather from bright sunny days to cloudy and rainy days. Changes of season from summer to winter, autumn, etc.
- Sky conditions
- Standard overcast sky
- Clear sky with and without sun
- Partly cloudy sky.
- Location and Orientation of building
- North light is generally cool and consistent light casting moderate shadows.
- East light is strong and bright in the morning but fades away as the day progresses.
- West light is generally strong with intense heat in the late afternoons.
- South light is generally comfortable in terms of brightness and heat.
- Building Form
- Long and narrow building footprints provide better access for daylight compared to a completely square block. Internal courtyards can be provided if the the building footprint is in square form.
Day lighting also effects from neighboring buildings, trees, and any other land forms that obstruct the building.
2.Day lighting Devices
- Window design and sizing.
- Horizontal windows provide maximum and even illumination, day lighting will penetrate well into a space.
- Large windows maximize daylight and provide uninterrupted views of the city/landscape surroundings.
- Clerestory windows allow daylight deep into space, also illuminates the roof and provide views of the sky and clouds.
- The clear glass gives importance to the view outside, especially in residential projects.
- Triple glazed windows to reduce solar internal gain and energy efficiency.
- Incorporating skylight/roof lights for a good amount of light penetration into the interior space. Domes and Glazed domes were a part of day lighting strategy in the earlier days.
- Providing light wells that penetrate from the ceiling to the inner spaces.
- Planning with central courtyards and Atrium which can be either open or covered with glazed skylights.(Covered spaces slightly reduce the amount of daylight but helps in keeping out of rain and moisture into the interiors).
- Occupant comfort
- Reduction in need for air-conditioning.
- Consider diffusing techniques such as Tinting, Frosting, and Fritting.
- Diffusing : Use of transparent acrylic, frosted glass, other slightly opaque materials.
- Tinting : Tinting films and laminates. Tints absorb a part of incident solar radiation.
- Frosting : Transparent materials with lines etched or embedded.
- Clear glass gives importance to the view outside, allows maximum transmission of daylight.
- Tinted glass reduces the transmission of solar radiation.
- Other types of glazing such as laminated glass, patterned glass, glass blocks, etc., modifies the amount of light transmission.
- Single glazing, Double glazing, Triple glazing – prevents heat loss from inside. The space between them is filled with air or gas fill (usually krypton or argon) which is sealed tightly.
- Maintain proper Glazing ratios and specifications.
- Reflective coatings (Low – E value)
Hazards of Daylight
- Heat gains – Direct Sunlight contributes to excessive heat gain and light.
- Glare and Contrast
- Fading of Fabric and other materials : Exposure to Direct sunlight – UV radiation results in fading of fabrics over time.
Shading devices/Lighting Controls – Measures to Control Glare
- Providing shading devices to control gain to reduce the effect of heat from direct sunlight.
- Louvers enable stack effect ventilation, reduce heat gain.
- Blinds control glare but the outside view is negatively effected.
- Shading fins and awnings increase comfort levels.
- Solar Control Window Films reduce the amount of harshness of the sun, thereby improving occupant comfort and saves energy. Improves the performance of the glazing.
- Light shelves increase illumination as they bounce deep into the room.
- Overhangs and Canopies outside act as shading devices.
3.Integrating with Electrical light
- Integrating and working in harmony with electrical light.
- Intensity : Reducing the intensity of complementary electrical light using technologies such as photocells, dimmers, and time clocks.
- Color : Coordinating daylight with the color temperatures of electrical light.
- Shape : Integrating daylight with the shape and electric elements together.
Day lighting acts as an essential factor in considering about global warming, carbon emissions and sustainable design, influencing human behavior, health and productivity.