Design Ratios

Question 1

What is net to gross ratio and what is the optimal ratio?

Answer 1

The ratio of useable space against total space. An optimal ratio would be 75-80%

Question 2

What is wall to floor ratio and what is the optimal ratio?

Answer 2

A measure of the proportion of external wall required to enclose a given floor are. Optimal ratio for commercial offices is around 40% - 60%

Question 3

How do you calculate wall to floor ratio?

Answer 3

Divide the gross internal floor area by the external wall area.

Question 4

On Helix, you say you identified an inefficient unit. Can you give some more details on this?

Answer 4

Yes, this units wall to floor ratio was 1.17, or 117% which is above optimum for an industrial unit. To make it more efficient they could either change the shape of the unit from a rectangle to a square, which would improve the ratio to 0.82, or 82%, I also looked at adding a FF office, which further improved the ratio to 0.67, or 67%.

Question 5

How can you improve the net to gross ratio?

Answer 5

• Reduce service and mechanical space
• Use open plan designs
• Centralise common areas to service multiple areas

Question 6

How can you improve wall to floor ratio?

Answer 6

• Optimise the building shape
• Add more floors where possible
• Reduce ceiling heights
• Utilise efficient structural systems to reduce the need or internal walls