Appendix 1 : Example of Use of Table 6 to Relate Plot Ratio and Population Capacity

Table 6 can be used to solve the three types of problem set out below:

[ Simple Table Format ]

Item Problem type
 1  2  3
GFA per flat Assumed

Assumed

Assumed
Persons per flat Assumed Assumed Assumed
Plot Ratio given (HKPSG) given (HKPSG) ?
Gross Site Area given ? given
Population ? given given



The following examples illustrate how the graphs in Table 6 are used for each of the three types of problem (see Figure A1). It is assumed in these examples that an allowance will need to be made for the provision of LOS within the DSA but outside the NSA (see section 6.5).


Problem type 1 : How much population can a given site area accommodate at a given plot ratio (PR)?

Example:

Given :

Site Area     14ha
Ppf     3.5
GFApf     50m2
PR     6.5
therefore  m2 GFApp = 50÷3.5
=

14.3

and  NSApp = 14.3÷6.5
=

2.2


Strike a vertical line on the graph from 14ha on the X-axis. This meets the 2m2 NSApp curve at population 32 000 and the 3m2 NSApp curve at 25 000. The required population is therefore about 30 600.



Problem type 2 : What site area is required for a fixed population at a given plot ratio?

Example:

Given :

Population     20 000
Ppf     2.8
GFApf     60m2
PR     5

therefore 

GFApp = 60÷2.8
=

21.4m2

and 

NSApp = 4.3

 

 

Strike a horizontal line on the graph from 20 000 population on the Y-axis. This meets the 4m2 NSApp curve at 13.4ha, and the 5.0m2 NSApp curve at 15.7ha. The required area is therefore around 14.1ha.



Problem type 3 : What Plot Ratio is required to accommodate a fixed population on a fixed site area?

Example:

Given :

Population 10 000
Site Area 7ha
Ppf 3.0
GFApf 60m2

therefore 

GFApp

20m2

 

Strike a horizontal line on the graph, from 10 000 population on the Y axis to meet a vertical line from 7ha on the X axis. These meet on the between the 4 and 5m2 NSApp curves, say NSApp is 4.3m2.

 


NSApp   =
GFApp÷PR
i.e. 4.3   =
20÷PR
therefore PR  

=

4.65

It should be noted when interpolating between the curves for NSApp that some allowance may need to be made for the fact that the intervals between curves are not regular. Otherwise minor discrepancies may result, compared with the correct values.

 

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   Last revision date : July 2016