Understanding Overshadowing Requirements for Development Applications in Perth, Western Australia
When planning a new development in Perth, Western Australia, it's essential to consider the impact your building will have on the surrounding properties, particularly in terms of overshadowing. Councils requires all Planning and Development Applications to include an analysis of the overshadowing effects of a proposed development at noon on June 21st, the winter solstice. This article will guide you through the process of determining the sun's angle at this specific time and date, ensuring your application meets council requirements.
Importance of Assessing Overshadowing
Overshadowing assessments help to maintain a balance between new developments and existing structures, ensuring that natural light availability, solar access, and overall living conditions are preserved. By analyzing the shadow cast by your building, you can mitigate potential negative impacts on neighboring properties, which is a crucial consideration for approval by the council.
Calculating the Sun’s Angle at Noon on June 21st
To calculate the sun's angle at noon on June 21st in Perth, we need to understand some key astronomical and geographical concepts:
Latitude of Perth: Perth is located at approximately 31.95°S latitude.
Solar Declination on Winter Solstice: On June 21st, the solar declination (the angle between the rays of the sun and the plane of the Earth's equator) is -23.44°, as this is the date of the southern hemisphere’s winter solstice.
Using these values, we can calculate the solar altitude angle (the angle of the sun above the horizon) at noon using the following formula:
Solar Altitude Angle(𝛼)=90∘−∣Latitude−Solar Declination∣Solar Altitude Angle(α)=90∘−∣Latitude−Solar Declination∣
Step-by-Step Calculation
Determine the Absolute Difference Between Latitude and Solar Declination: ∣31.95∘−(−23.44∘)∣=∣31.95∘+23.44∘∣=55.39∘∣31.95∘−(−23.44∘)∣=∣31.95∘+23.44∘∣=55.39∘
Calculate the Solar Altitude Angle: 𝛼=90∘−55.39∘=34.61∘α=90∘−55.39∘=34.61∘
Thus, the angle of the sun above the horizon at noon on June 21st in Perth is 34.61 degrees.
Using this angle, you can determine the distance across the ground that your proposed building's shadow will extend. You can then incorporate these distances into your site plan, ensuring to account for variations in site elevations.
Practical Application
Understanding this angle allows architects and developers to predict the shadow length and direction that their buildings will cast. This can be crucial for ensuring that new developments do not unduly impact the sunlight available to neighboring properties, which is particularly significant during the shortest days of the year. Please note that if your development is in a different location, you will need to use different calculation inputs. Simply provide your specific location, time, and date to a large language model (such as ChatGPT) and request the sun angle.