The importance of functional units in good design can’t be under-stated. This is particular important in residential dwelling design. The way to fairly compare design options is to ensure an appropriate functional unit is chosen, and in the case of residential design this definitely should include occupancy. After all, the primary purpose of a residence is to house people.
Another way of thinking about the importance of occupancy is taking a top-down view. That is, “how many of these dwellings would be required to house our whole population”. If you have a design that requires 200m2 of floor space to house 2 people and you rolled that design out to house 100,000 people, that is a going to demand many more dwellings (and much more of the environment) than a design that houses 3 people within 200m2.
Within eToolLCD occupancy is a really key part of the LCA calculations. For example:
- It can define your impacts per functional unit (if occupants are chosen as a function unit)
- It may feed into other calculations due to expressions and variables
eTool recommend calculating occupancy in a standardised manner to ensure comparability of LCA studies. Our preferred method is to use actual statistics for occupancy per bedroom. Below is an example subset of data:
|Occupants per Dwelling||1 Bedroom||2 Bedrooms||3 Bedrooms||4 Bedrooms||5 Bedrooms||6 Bedrooms|
For multiple dwelling LCAs this information can then be multiplied by the number of dwellings and entered into the “Occupants” under the appropriate function.
If this information is unavailable, the default is to go with the local building code minimum requirements. Below is a list of typical/industry standard commercial occupancy calculations based on country.
|Country||Occupancy Rate (m2/occupant)||Reference|
|Australia||10||National Construction Code|
|United Kingdom||~5 (assuming ceiling height of 2.4m or 11m3)||Building codes|
|Germany||9||typical industry standard|
If you want to be more specific. There are some guidelines/recommendations available online depending on what kind of workspace you require. Below are some examples from Knight Frank.
Calculator for Australian Occupancy
For Australia based projects, you can download the calculator below that will give you the suburb redevelopment potential and occupancy rate far for your project based on the postcode, number of bedrooms and dwellings. It’ll also help you calculate the occupancy rate for a commercial space based on the net lettable area.
Please note that the results from the calculator is only to provide guidance and discretion must be exercised when deciding on what data to input into the LCA. This is because each project may have unique circumstances that will affect the results. For example, a mix of residential with rural farmland or industrial areas within the same postcode. Or a heritage listed building versus a modern low density building in the middle of the CBD.
> OccupancyCalc-AU <