Ventilation systems have two main targets:

-Maintaining clean air inside buildings to preserve the employees' health and to eliminate nasty smell's and condensation problems

- Avoiding the exaggerated increase of temperature thanks to night ventilation.

Because modern man spends more than 90% of his time in a confined space (buildings, offices, cars, home...) and because interior air seems to be responsible for the majority of health problems (headache, tiredness, eyes irritation, nausea, sore throat, infectious illness like legionnaires, asthma), the ventilation must be integrated carefully during the construction of a building.

The installation of ventilation systems also allows buildings to fall into disrepair slowly.

Indeed, condensation not evacuated generates formation of moisture, and can cause the peeling of wallpaper.

Moreover, it is better to install ventilation systems with high energy efficiency.

Aeraulic ductworks are very often used in recent buildings to furnish new air and to avoid degradation of the framework (moisture, condensation...).

They are essential for the quality of interior air and more generally for the quality of ambient. There for, quality maintenance is essential.

Clean the air filters and air duck each month and replace the filters  two times a year.  Indeed, the choking of filters has the following consequences: decrease of aeraulic performance (less debits and air change, so degradation of the building), acoustic harmful effects, increase of fan energy consumption, premature fan degradation and risk of microbiologic contamination.

Controlling air tightness when aeraulic ductworks are installed.

The speed must be limited in order not to create unpleasant feelings. Normally for offices, a speed from 0,12 to 0,15 is required. Speed must be controlled regularly to avoid a bad treatment of the ambient (see the rules of your country).

Making regularly measures of interior temperatures and air debits. (if necessary, realising a complete new balancing of the debits by a specialised company).

Verifying the correct running of scheduling clocks: stop during the night and the holidays, change of running mode depending on the occupation of the locals.

Do not forget to change the scheduling between winter and summer.

Natural ventilation

Natural ventilation is caused by the wind that creates pressure differences around the building or may result from a stack effect, owing to temperature differences.

The air penetrates through apertures situated in the low part of the façade and comes out again through others apertures situated in the high part of the façade.

Advantages

- Natural ventilation doesn't use fans, so it doesn't consume energy.

- Little investment.

- System easy to install

Drawbacks

- The major drawback of natural ventilation is the bad control of air change.

- This type of ventilation is very sensitive to wind effect. However, auto-adjustable apertures exist to limit new air inlet.

- Noise can be generated by the crossing of air through the openings. However, acoustical apertures exist that decrease these inconveniences (but they are more expensive).

- In winter, people can feel a cold air flow near the openings.

Mechanical ventilation simple flow   

In this case, the new air is introduced naturally in the offices thanks to adjustable air-vents situated on the outside walls. On the other hand, foul air is extracted mechanically (fans) in the corridor. With this extraction, the offices are on depression and this favours the infiltration of new air.

Advantages

- Simple system, inexpensive and easy to use.

- The ventilation network doesn't take much place.

- Extracted air debits are controlled.

Drawbacks

- Risk of cold air flow due to air-vents badly set.

- Introduction of non-filtered air (dirty mark).

- Air-vents are a source of noise coming from outside.

- The transfer of air from the offices to the corridors can also generate noise.

- Air debits are not really sufficient to treat summer comfort.

Mechanical ventilation double flow

In this case, there are two ductworks. New air, filtered and preheated in winter, is blown in the offices thanks to a ductwork generally situated in the coffered ceiling of the corridor.

The diffusion of air is done with adjustable air-vents (debits and orientation of the flow). Air is mechanically extracted by an other ductwork located in the corridor

Advantages

- The occupants' comfort is always ensured if the ventilation is well adjusted and the diffusers correctly chosen.

- There is no noise generated by the new air inlet through the façade.

- Debits air are controlled everywhere.

- Heat of extracted air flow can be recovered thanks to different systems (see below).

- This system permits to treat the air before sending it in the ductwork (humidification, heating...).

Drawbacks

- The realisation of this system needs to take acoustic precautions.

- It is more expensive that the system of mechanical ventilation simple flow.

- The Ductworks take more area, which makes their integration in the building much more complex.

- Maintenance is consequently more important.

Energy savings

The possible energy savings made using these systems are coming from

The recuperation of thermal energy on the extracted air.

This one can be realised thanks to the installation of a heat exchanger on the mechanical ventilation double flow.

In the case of office buildings, the static exchanger is recommended

When ventilation is controlled by a system of regulation and technical control, the occupant of an office hasn't got a special role in the use of ventilation systems.

However, one can notice that it is forbidden to obstruct the air-vents because ventilation is regulated and built to answer to exigencies of security rules.

On the other hand, when night ventilation is recommended, employees must think to clear apertures before leaving office. During winter, these openings must be well closed to avoid the increase of heating consumption.