A8.9 - Overshadowing

Overshadowing

Overshadowing refers to the shadows cast onto adjoining properties. It is analogous to the overshadowing effects of buildings, which are covered by the rules in district plans through daylight admission controls restricting the height and location of building development on individual sites. The overshadowing effect is also analogous to the overshadowing effects of trees on neighbours, where enjoyment of property and personal health is protected by the provisions of the Property Law Amendment Act (1984).

Impacts of overshadowing

Where a structure, such as an embankment or overhead bridge, reduces the amount of direct sunlight on an occupied property, overshadowing has a negative impact. Positive benefits due to an increase in direct sunlight on occupied properties may accrue from the removal of buildings or structures.

Measurement of overshadowing

The changes in shadows cast by a structure shall be calculated from azimuth and altitude data for the sun during the year at the site's particular location. This shall be expressed in contours of sunshine hours lost or gained per year. An adjustment would be necessary to compensate for the average amount of cloud cover in a year, which will reduce the hours of direct sunlight.

Reporting of overshadowing

The properties affected by overshadowing shall be identified, with a description of these properties and the predicted extent and effects of overshadowing.

Where projects have been modified to mitigate the effects of overshadowing, the incremental benefits and costs of these measures shall be reported.