How to select an exhaust fan based on room area: a simple algorithm
Online stores often receive questions in the ventilation section such as: “What room size is this fan designed for?” and “Is this fan suitable for a 7 sq. m. bathroom?”
These are the right questions to ask before purchasing a fan. To understand whether a unit will effectively remove stale air from a room, several factors need to be considered:
- the purpose of the room where the fan will be installed (residential, industrial, commercial, and so on);
- the volume of the room (width × length × height).
The next step is to refer to the code of practice for multicompartment residential buildings and determine the required ventilation rate for your room. Once you have this information, you can choose a fan. Usually, these documents provide an air exchange coefficient. You simply multiply this number by the room’s volume to get the required airflow capacity.
Let us look at the most common example. Exhaust fans are most often purchased for bathrooms or toilets. The standard areas for such rooms in apartment buildings are typically 5.5 sq. m. and 1.1 sq. m. respectively. For this example, let us also take a standard ceiling height of 2.5 m.
The air exchange rate in this case is 6–8 for a bathroom and 8–10 for a toilet. If we take the upper values of the coefficient, we get 110 m³/h for the bathroom and 30 m³/h for the toilet. However, for a toilet it is often better to install a fan with up to 80 m³/h for quick odor removal.
Thus, for a bathroom, a fan such as the FRESH 100 TURBO would be suitable, and for a toilet, the ROUND 100 would be a good option.
Household fans come with various flange connection diameters: 100 mm, 125 mm, 150 mm, and others. Fans also have typical airflow capacity ranges depending on diameter:
- 100 mm — 80–100 m³/h;
- 125 mm — 140–190 m³/h;
- 150 mm — 230–360 m³/h.