English Glossary


02.06.2017

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Z

Z

impedance

zenith angle

Angle measured from directly overhead to the geometric centre of the sun's disc, as described using a horizontal coordinate system. The solar elevation angle is the altitude of the sun, the angle between the horizon and the centre of the sun's disc. If θs is the solar zenith angle, then the solar elevation angle αs = 90° – θs.

zero loss efficiency

Efficiency of a collector when there are no thermal losses

zone of theoretical visibility

ZTV - Maps produced are theoretical because they estimate exposure of proposed development based upon landform data only, and take no account of intermittent screening by vegetation or structures. ZTV maps estimate visibility of the proposed development in the surrounding landscape and not its 'visual influence'.

zone of visual influence

ZVI - Provides a visual representation, usually presented as a map with markings or colourings, of the area over which a site and/or a proposed development may be visible.

ZTV

zone of theoretical visibility

ZVI

zone of visual influence