Environment: HDRI Sky (CineRender)

Sky Visibility: If you turn this off, the HDRI Sky parameters still affect the rendering, but you cannot see the sky itself.
Sky Luminance: You can turn on Sky Luminance with the other effects off: this will give you the light effect of the HDRI Sky without anything else.
Use the Color/Intensity controls to vary these luminance parameters for the HDRI Image.
Use the Blur Offset and Blur Scale controls to affect the blurriness of the image’s luminance effect.
Sky Reflection: If only Sky Reflection is on, then you can, for example, see the environment reflected on a glass building, without rendering the environment itself.
Sky Refraction: Turn on/off the HDRI Sky’s refraction effect.
Rotation: Use these controls to rotate the HDRI Sky image.