For building projects, the area overview (also called room list or space program) is one of the most important overviews that is available in BriefBuilder.
The overview is a compilation of all the spatial objects in your project (buildings, groups of spaces, spaces, outdoor spaces) with their quantities and their sizes. It is a crucial overview because it shows the total size of the project in terms of both usable and gross square meters.
The area overview is divided into two parts:
– Usable floor area (UFA)
– Gross floor area (GFA)
See below for a more detailed explanation of how these parts work.
Usable floor area (UFA)
This part shows all the defined requirements in your project in relation to the quantities and sizes of spaces.
It features the following columns:
- Items: the name of the spatial object (e.g. office room)
- Quantity: the number of spaces that is required (e.g. 1)
- Quantity note: a possible note regarding the quantity (e.g. “to be located on 1st floor”)
- Usable floor area: the minimum size of a space in terms of usable square meters (e.g. 10 sqm)
- Floor area note: a possible note regarding the space’s size (e.g. “cannot be smaller”)
- Total: the calculated total usable floor area (e.g. 10 sqm)
Please note that we use the term usable floor area (UFA) as a default. This term refers the amount of square meters that is directly needed by the building’s users to support their activities. It does not include areas that are needed for technical services (e.g. shafts), construction elements (e.g. walls, façade), and primary circulation (e.g. lobbies, fire escapes)
It may be, however, that you prefer to use another term (e.g. net area or net internal area). In that case, you have to go the requirement settings menu. There, you can find the standard properties of the object ‘space’, where you can make the desired changes. It is also where you can also change the unit of measure (e.g. sqft instead of sqm) or the used definition. See example below.
Gross floor area (GFA)
This part of the overview concerns the calculation of the gross floor area (GFA) of your project. The exact definition of what GFA is can differ per country, but generally it is defined as the total floor area contained within the building (or a part of it) measured to the external face of the external walls and thus including floor area used for shafts, walls etc.
The total GFA is calculated in BriefBuilder by multiplying the usable floor areas with a particular factor (called a GFA factor in BriefBuilder, also referred to as gross/net ratio or GFA/UFA ratio). A simple example: if you have 40 sqm of UFA, and the GFA factor is 1.6, you will get a total of 64 sqm GFA (see example below).
In this part of the table, you can see the following columns:
- GFA factor: the factor that you want to apply to a specific level or specific part of your project (e.g. 1.6)
- GFA added: the sqms that you are adding by applying the aforementioned GFA factor (e.g. 24 sqm)
- Total: the calculated total gross floor area. Please note that this figure is the sum of total usable floor area, plus the added GFA’s of that level, plus all the GFA’s that have been added on the underlying levels (e.g. 64 sqm)
- GFA factor (total): the overall GFA factor, which is calculated by dividing the total gross floor by the total usable floor area (e.g. 1.6)
- Note: a possible note regarding the total of GFA (e.g. “should not exceed 70 sqm”)
How to go from UFA to GFA?
It is important to know that you can work with the GFA factor in three different ways:
(1) A GFA factor on building level
This is the simplest and easiest way of working with a GFA factor: you only define the factor on building level. It is a very correct way of working in the sense that it takes into account that many (gross) areas, such plant rooms or a central lobby, can only be assigned to the building as a whole and not to parts of it.
See the simple example below where a GFA factor of 1.6 has been applied to the building as a whole.
(2) GFA factors on group level (lowest level)
In some projects — in particular mixed-use projects — it can be that you want to differentiate the GFA factor for different kinds of functions.
For example: when working on a research building, you may to use a factor of 1.5 for the office spaces and a factor of 1.7 for the lab spaces (as these need more technical services). If this is the case, we recommend that you create a group of spaces called ‘office spaces’ and one called ‘lab spaces’ and add the GFA at that level (and thus not at building level).
See below for how that looks. It is a different way of calculating gross floor area, although it can still result in the same overall factor for the building as whole (1.6).
(3) GFA factors on multiple levels
It is also possible to combine these two approaches. In that case, you are adding GFA at multiple levels. Mathematically there is nothing wrong with this, but you have to be aware of what you are doing: you are adding square meters at every level for which you have defined a GFA factor.
See the example below where the lab spaces have a factor of 1.6 and the office spaces a factor of 1.4. And then an additional factor of 1.1 has been added on building level, resulting in an overall factor of 1.6.
Note the difference in the GFA factor for building in the first column (1.1) and the GFA factor (total) in the last column (1.6). These are different because the first is only being used to add extra square meters, on top of the gross floor areas that have already been added on the levels below.