| 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)
