Economics of Design

Question 1

What is the wall to floor ratio?

Answer 1

W/F ratio is an assessment of the design Effciency in terms of external wall area in relation to the gross floor area.

Question 2

How is the wall to floor ratio calculated and what is an efficient percentage?

Answer 2

It is calculated by dividing the total external wall area by the GIA.
40% is deemed efficient whereas 50% is not.

Question 3

What is the Net to Gross ratio?

Answer 3

The net to gross is an assessment in terms of net area (usable space) in relation to the gross area.

Typical range is 70%-85%.

Question 4

Can you give examples of what rooms are excluded from the NIA?

Answer 4

Corridors, stairs, toilets, lifts, plant rooms, cupboard, etc.

Question 5

What design, site and economic factors impact the design economics?

Answer 5

Design - shape, size, number of storeys, internal layout, grouping of buildings

Site - location, access, topography, size, existing services, adjoining properties

Economic - Interest rates, desirability of the project, current market, resource availability

Question 6

What is the most economic plan shape?

Answer 6

Square is the most economic due to its simplicity however a circle plan is the most economic but due to its circular walls this will most likely cancel this out.

Question 7

Can you name sources of cost data?

Answer 7

BCIS
Pricing books - Spons
In house data - Recent tenders
Supplier Quotes

Question 8

According to NRM1, the term tender inflation refers to?

Answer 8

An allowance in the cost plan for fluctuations in the basic prices of labour, plant, machinery during the period form the base date to the date of tender return

Question 9

What is the base date?