Design Ratios Flashcards
What is net to gross ratio and what is the optimal ratio?
The ratio of useable space against total space. An optimal ratio would be 75-80%
What is wall to floor ratio and what is the optimal ratio?
A measure of the proportion of external wall required to enclose a given floor are. Optimal ratio for commercial offices is around 40% - 60%
How do you calculate wall to floor ratio?
Divide the gross internal floor area by the external wall area.
On Helix, you say you identified an inefficient unit. Can you give some more details on this?
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%.
How can you improve the net to gross ratio?
- Reduce service and mechanical space
- Use open plan designs
- Centralise common areas to service multiple areas
How can you improve wall to floor ratio?
- Optimise the building shape
- Add more floors where possible
- Reduce ceiling heights
- Utilise efficient structural systems to reduce the need or internal walls
On Redhill, what advise did you provide based on the sensitivity analysis you carried out?
On Helix, explain how you identified a unit with an inefficient wall/floor ratio.
How would adding a first floor office increase the efficiency?
Why did you use wall/floor ratio and not NIA/GIA ratio?
Explain how you would adjust benchmark rates to suit the current date.
In your cost plans, what exclusions do you typically make?
Why use wall/floor ratio, and not net/gross ratio?
They show different things:
- wall/floor indicates the proportion of external wall needed to enclose a given floor area.
- net/gross indicates the proportion of a total floor or building that is useable.
What is the typical net to gross for offices?
To the building usually between 75-85% because of reception areas etc
To the floorplates usually between 70-75%
