10-1 Pencahayaan Alami Siang Hari: Deskripsi PASH

Summary

In this 10th week of the TF-3200 Building Physics course, Dr. Rizky Armanto discusses natural lighting in buildings, focusing on two main categories: direct sunlight and diffuse daylight. Direct sunlight, although crucial, often causes glare and heat, making it less desirable in design. Diffuse daylight, from the sky, is preferred for its soft, glare-free light. The course also covers key factors like sun position, solar luminance, and sky models (uniform, cloudy, and clear) to predict natural lighting performance in building design, emphasizing the importance of understanding sun angles and atmospheric conditions for optimal lighting design.

Takeaways

• 😀 Natural lighting in buildings can be categorized into two groups: direct sunlight and diffuse daylight.
• 😀 Direct sunlight can cause glare and heat in the room, making it generally less preferred in building design.
• 😀 Diffuse daylight, which comes from the sky, clouds, or atmospheric particles, is preferred for building design as it generally does not cause glare.
• 😀 The position of the sun, with its elevation (0° to 90°) and azimuth (0° to 360°), plays a key role in determining natural lighting in a building.
• 😀 Solar luminance and the luminance of the sky depend on factors like the sun’s position, water vapor, clouds, dust, and atmospheric components.
• 😀 A sky model can help predict natural lighting performance in buildings by considering factors like the sun’s position and sky conditions.
• 😀 Sky models can be mathematical or conceptual and are based on factors such as sun position, cloud density, and atmospheric turbidity.
• 😀 Empirical sky models are built using measurements of solar irradiance and sky luminance over a full year.
• 😀 Several standardized sky models exist, including the uniform sky model, completely cloudy sky model, partially cloudy sky model, and clear sky model.
• 😀 The uniform sky model assumes the same luminance across the sky, while the completely cloudy sky model involves no direct sun, but varied luminance in the sky.
• 😀 The clear sky model allows for direct sun observation without any cloud interference, offering the most straightforward sky condition.

Q & A

What are the two major categories of natural light sources in building physics?

The two major categories are direct sunlight and natural daylight (diffuse natural light).

What is the primary characteristic of direct sunlight in building design?

Direct sunlight is associated with glare and heat in the room, which is why it is often avoided in building design.

Why is natural daylight preferred in building design?

Natural daylight, coming from the sky or clouds, generally does not cause glare and is more desirable in building design for its softer, diffuse light.

What two factors are important for describing the position of the sun in relation to building design?

The position of the sun is described by its elevation (0 to 90°) and azimuth (0 to 360°), which indicates the direction of the sun from different points like north, south, east, and west.

What are some components of the atmosphere that influence the luminance of the sky?

The luminance of the sky is influenced by water vapor, clouds, dust, and other components in the atmosphere.

What is a sky model, and why is it important in predicting natural lighting performance?

A sky model is a representation of sky conditions based on factors such as the position of the sun, cloud density, and atmospheric turbidity. It helps predict natural lighting performance in a building more accurately.

What are some ways to construct a sky model?

A sky model can be constructed mathematically, conceptually, or empirically based on measurements of solar irradiance, sky luminance, and atmospheric conditions over a year.

What is a uniform sky model?

A uniform sky model assumes that sky luminance is the same at all angles, regardless of elevation or azimuth.

How does a completely cloudy sky model differ from a clear sky model?

In a completely cloudy sky model, the sun is not visible, and there is a gradation of luminance across the sky. In a clear sky model, the sun is visible without any clouds, allowing for direct sunlight.

What is the key difference between a partially cloudy sky model and a completely cloudy sky model?

A partially cloudy sky model combines the characteristics of a cloudy sky with the direct visibility of the sun, while a completely cloudy sky model does not allow for direct sunlight visibility.