shadow-study-data

name	Shadow Study Data
description	An analysis of shadows cast by the proposed development on surrounding properties, streets, parks, and other sensitive areas.

9. Shadow Study Data

What It Is

An analysis of shadows cast by the proposed development on surrounding properties, streets, parks, and other sensitive areas.

Why It Matters

• Official Plan policies protect sunlight access, especially for parks, schools, and residential properties
• Required for most applications involving increased height
• Committee of Adjustment and OLT consider shadow impact when evaluating the "desirable development" test

Governing Law

• Official Plan policies on sun/shadow (e.g., Toronto OP Section 3.1.2(b)(iv) — "adequate light")
• Urban Design Guidelines — specific shadow requirements
• Zoning by-law angular plane provisions — partly designed to limit shadows
• Provincial Planning Statement — general livability principles

How to Build It

Shadow analysis is typically performed at specific dates and times
prescribed by the municipality.

Toronto standard test dates and times:
  - March 21 / September 21 (equinoxes): 9:18 AM, 12:18 PM, 3:18 PM, 6:18 PM
  - June 21 (summer solstice): 9:18 AM, 12:18 PM, 3:18 PM, 6:18 PM
  - December 21 (winter solstice): 9:18 AM, 12:18 PM, 3:18 PM (sunset ~4:44 PM)

Note: Times are Eastern Standard Time (EST); some municipalities use
Eastern Daylight Time (EDT) for spring/summer dates.

Process:
1. Model the proposed building and surrounding buildings in 3D
2. Set the geographic coordinates (latitude/longitude)
3. For each test date/time, calculate sun position
   (azimuth and altitude angles)
4. Project shadows from the building onto the ground plane
   and adjacent buildings
5. Identify impacts on:
   - Public parks and open spaces (especially concerning)
   - Residential rear yards and windows
   - School yards
   - Sidewalks and public realm
   - Heritage properties

Output:
SHADOW STUDY SUMMARY

Test Results:
| Date | Time | Shadow Length | Key Impacts |
|------|------|-------------|-------------|
| Mar 21 | 9:18 AM | Xm NW | Shadow reaches [location] |
| Mar 21 | 12:18 PM | Xm N | No impact on park |
| Mar 21 | 3:18 PM | Xm NE | Shadow reaches [location] |

Net New Shadow:
[Difference between existing condition shadow and proposed condition shadow]

Impact Assessment:
- Parks: [X hours of sunlight maintained? / Y hours of new shadow]
  Toronto standard: minimum 5 hours of sunlight on parks
  between 10 AM and 4 PM on September 21
- Residential properties: [description of impact]
- Streetscape: [description of impact]

Mitigation (if needed):
- Height reduction at [location]
- Stepback at [level]
- Building orientation adjustment

Computational Approach

For basic shadow analysis without full 3D modeling:
1. Sun position: Calculate solar azimuth and altitude for
   latitude 43.65°N (Toronto) at each test time
2. Shadow length = Building height / tan(solar altitude)
3. Shadow direction = opposite of solar azimuth
4. Shadow footprint = project building outline using
   shadow vector
5. Compare footprint to sensitive receptor locations

For accurate analysis:
  - Use 3D modeling software (Rhino, SketchUp, Revit)
  - Import surrounding context buildings
  - Run shadow simulation at specified dates/times
  - Generate shadow diagrams (plan view)