What are the most influential factors in measuring the functional efficiency of the building plans?

The efficiency of the plan is measured as-

1. For utility buildings -

Minimum circulation area. Lower the percentage of circulation area higher is the efficiency. It can be expressed in ratio of Total Carpet area: circulation area like corridors, passages etc. (Balconies, verandas and lounge etc etc if meant for particular use should be included in Usable areas, or other wise in circulation area. A space though meant for an activity but if surrounded by other spaces having movement through the space, it ceases to be activity area and so practically becomes circulation area, and so should be included in circulation area. All spaces should be defined in any one category and then the ratio should be found to determine the efficiency.

2. For building having movement as main function (Viz. Shopping Centers, Museums, Art galleries etc.)

The rational percentage should be achieved. The area should not named as circulation or link areas but as MOVEMENT AREA. It is usable area. The efficiency of such plans is to be measured by provision of the movement area per person at peak hours. For its optimization the movement area per person at peak hours (No of hours? Can peak hours be staggered?) and movement area per person at approximately Zero Hrs. should be compared. A proportionate average (Depending upon duration of Peak and Zero Hours) should be taken up for optimization.. In general 4 Sq. Meter per person at peak hours can be taken up as efficiency factor and so should be corrected against zero hours @ 1 Sq. m. per person. So as optimum efficiency value for Building with Movement as main function can be taken up as (assuming Peak Hours as 4 hrs per day) 2.5 to 3.0 sq. m. per person. Of course this cannot be generalized and should be decided logically specific to situation and location.

3. For institutional buildings

Availability of optimum usable space and linkage based on the interlink between them decides the efficiency. Draw the interrelation diagram. Lesser the crossing between the lines of interrelation more is the efficiency. In physical plan measure the total length of the lines interlinking various activity spaces. Lesser the total length more is the efficiency.

In General efficiency of plan can also be measured by ratio between available carpet area in functionally usable spaces and total plinth area (Or floor area on each floor). Higher the ratio more is the efficiency.

I hope this is enough though some more considerations can be put forth. If you like it and would like to know more, put your questions in the comment box along with your details.