The design of the shower area and the location of the ventilation system play a major role in shower comfort, bathroom climate and, not least, energy efficiency.
An "open" shower area can result in power losses as high as 5000 W to the environment, corresponding to about 25 % of the total shower power, resulting in both low comfort and limited opportunities for efficient energy recovery. A well-designed shower area instead provides high comfort and good conditions for efficient energy recovery with power losses as low as 500 W, corresponding to <3 % of the total shower power.
In an open shower area - that lack at least one shower wall in one direction, or have the ventilation outlet above the shower space - shower water evaporates into the ambient air to an extent that causes a strong cooling effect on both the shower water and the body. This cooling effect obviously reduces comfort and increases energy losses when showering - both with and without energy recovery technology installed.
The cooling effect from shower water and the body can be as high as 5 000 W, which corresponds to the part of the shower flow power available for heating the human body (only water warmer than the human skin provides a heating effect). This cooling effect can be compared with the heat output of a human being of just over 1 W per kg of body weight (at rest), which means that a person weighing, for example, 70 kg develops a heat output of the order of about 100 W. It is therefore not surprising that open shower areas such as in swimming pools and gyms can feel freezing cold when the body is wet, even though the shower water is quite warm.
The evaporated water from the open shower area carries the energy to room temperature surfaces such as walls, floors, bathroom fixtures and ventilation systems, where the water condenses and makes surfaces wet and mirrors foggy, resulting in increased soiling and possible mould growth. After the shower is finished, the moisture slowly evaporates from the surfaces again, and the energy carried to the surfaces during showering turns into ventilation losses that are difficult to recover.
An "optimized" shower area restricts air and energy exchange in all directions - greatly limiting evaporation losses from the body and shower space (from as much as 5000 W down to around 500 W), leading to a very comfortable and energy-efficient shower, with less moisture load on the bathroom and ventilation system, as well as good conditions for an efficient energy recovery in an energy recovery floor drain.
In an efficient shower area, the available heating power from the shower water to the human body is about 10 times higher than the heat losses from the body and the shower area, which explains the comfortable and energy-efficient showering.
A 'traditional' shower area we define as a middle ground between the open energy consuming and uncomfortable shower area and the "optimized" one. Depending on the exact design and placement and dimensioning of the ventilation in the room, the power losses from the traditional shower area and body typically vary around 2500 W.