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Sky View Factor Calculator

Work out sky view factor instantly with clear inputs, formula shown and shareable results.

About Sky View Factor Calculator

Sky view factor is the fraction of the hemisphere visible from a point, and for the centre of an infinitely long street canyon it equals the cosine of the angle from vertical to the building parapet. A low factor means less daylight during the day and, more importantly, less radiative cooling at night, which is the mechanism behind the urban heat island.

Formulas

Sky view factor

SVF = cos(arctan(H / (W/2))) at the centre of a street canyon

Aspect ratio

H/W, the height to width ratio of the canyon

Worked example

With the default values below, Sky View Factor Calculator returns Sky view factor at street level of 0.3511. Change any input above and every figure here is recalculated in your browser.

Inputs used

Street width between building facesminimum 0.5 m
15 m
Building heightminimum 0.1 m
20 m

Results

Sky view factor at street level
0.3511
Height to width aspect ratio
1.333
Angle of visible sky
41.11 °
Urban canyon classification
Deep canyon — reduced night sky cooling

Step by step

  1. 1Values used
  2. 2Sky view factor
  3. 3Aspect ratio
  4. 4Sky view factor at street level= 0.3511
  5. 5Height to width aspect ratio= 1.333
  6. 6Angle of visible sky= 41.11 °
  7. 7Urban canyon classification= Deep canyon — reduced night sky cooling

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Sky View Factor figure worked out?

SVF = cos(arctan(H / (W/2))) at the centre of a street canyon. Sky view factor is the fraction of the hemisphere visible from a point, and for the centre of an infinitely long street canyon it equals the cosine of the angle from vertical to the building parapet.

Why does sky view factor drive night temperatures?

Because surfaces cool by radiating to the cold sky. When buildings block most of the hemisphere, that heat is radiated to other warm surfaces instead and the street stays hot after dark.

What values do I need to enter?

This calculator takes 2 inputs: Street width between building faces, Building height. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

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