The MathsDensity
F.A.R is a measure of density, and is found by dividing the
total areas of all the floors by the area of the ground occupied (including the
building plots, gardens and streets.) The higher the F.A.R, the higher the
density.
Assuming that each resident requires 40m² of living space at a
F.A.R of 0.75, then the ground space required per person for housing
is given by:
|
Ground per person (residential) |
= floor area / F.A.R
|
| |
= 40 / 0.75 |
| |
= 53.33m² |
And assuming each resident requires 30m² for
non-residential uses at a F.A.R of 1.5, then the ground space
required per person for non-residential uses is given by:
|
Ground per person (non-res) |
= floor area / F.A.R
|
| |
= 30 / 1.5 |
| |
= 20m² |
Now we can calculate the average F.A.R:
|
Average F.A.R |
= floor area per person/ total ground area
per person
|
| |
= ( 40 + 30 ) / ( 53.33 + 20 ) |
| |
= 0.9545 |
Town for 24,000
The area of the town is given by
∏r² where r, the
radius, is 750m.
|
Area of town |
= ∏ × 750² |
| |
=
1,767,145m² |
With an average F.A.R of 0.9545 and allowing 70m² per capita (40m² for housing, 30m²
for work, services etc.) this gives a population of:
|
Population |
= building
area × F.A.R / floor space per capita |
| |
= 1,767,145 × 0.9545 /
70 |
| |
= 24,097 |
Or over 24,000 people.
Assuming a walking speed of 75 metres per minute,
the walk from the edge of the town to its centre is given by:
|
Walk to centre |
= radius of town / walking speed |
| |
= 750 / 75 |
| |
= 10 minutes |
Town for 35,000
The area of the town is given by
∏r² where r, the
radius, is 900m.
|
Area of town |
= ∏ × 900² |
| |
=
2,544,690m² |
This gives a population of:
|
Population |
= building
area × F.A.R / floor space per capita |
| |
= 2,544,690 × 0.9545 /
70 |
| |
= 34,700 |
Or just under 35,000 people.
And the walk to the centre is given by:
|
Walk to centre |
= radius of town / walking speed |
| |
= 900 / 75 |
| |
= 12 minutes |
Sample Blocks2.5 Storey Row Housing

|
Total floor
area |
= floor area × number
of storeys |
| |
= (2 × 84 × 10) ×
2.5 |
| |
=
4200m² |
|
Ground area |
= (8 + 84) × (8 + 10
+ 12 + 8 +12 + 10) |
| |
=
5520m² |
|
F.A.R |
= total floor area /
ground area |
| |
= 4200 / 5520 |
| |
= 0.76 |
4 Storey Block

|
Total floor
area |
= floor area × number
of storeys |
| |
= (4 × 48 × 10) ×
4 |
| |
=
7680m² |
|
Ground area |
= (10 + 48 + 2 + 10) ×
(10 + 48 + 2 + 10) |
| |
=
4900m² |
|
F.A.R |
= total floor area /
ground area |
| |
= 7680 / 4900 |
| |
= 1.567 |
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