1. Home
  2. Ventilation
  3. Advantages of demand controlled ventilation

The most efficient way to balance indoor air quality and energy savings.

 

It is commonly accepted that most water distribution facilities work on demand, and not permanently. Thus why should it be different for ventilation, with each cubic meter of fresh air to warm during all the heating season having a significant economic and environmental cost?

The concept of demand controlled ventilation rests on the principle of providing occupants with the right amount of fresh air, when they need it, where this is useful. With intelligent airflow management (included demand controlled ventilation), energy savings are made on every occasion that the need for ventilation is low or null, which can represent more than half the time. Conversely, an activity which emits indoor air pollution such as preparation in a kitchen, a shower, or even the release of odorous metabolic compounds, generates a need for a greater ventilation to remove the pollution quickly.

At every moment, demand controlled ventilation offers an optimization of heating consumption and indoor air quality, on a fully automated basis. Every Aereco ventilation system is designed on this concept of demand controlled ventilation, which beyond being particularly effective for the comfort of the occupant, has many other benefits on the working of the demand controlled ventilation system.

Better air renewal for greater comfort

By providing the most ventilation for the places that need it most, Aereco’s demand controlled ventilation systems largely contribute to improving air quality in dwellings. When a main room is occupied, its relative humidity increases; the air inlets then open more to increase airflow and better evacuate stale air. Activity in wet rooms (kitchen, bathroom, toilets, etc.) is accompanied by water vapour emissions; the opening of the exhaust units increases with the relative humidity, increasing the airflow and so evacuating polluted air more rapidly.

Protection against moisture

The higher relative humidity generated by breathing and human activity in the kitchen or shower, for example, can lead to destructive condensation, in which moulds can grow. When the relative humidity increases dangerously, humidity sensitive exhaust units open quickly to evacuate excess moisture and eliminate the risk of condensation.

Reduced and controlled heating consumption

Ventilation is often held responsible for a large share of the thermal losses in a dwelling, sometimes as much as 50 %. While this is true of the majority of traditional ventilation processes, Aereco systems preserve heat in less occupied rooms and dwellings by automatically reducing the airflow.

Additional benefits

In addition to combining indoor air quality and energy savings optimisation, demand controlled ventilation demonstrates many indirect benefits resulting from the reduction of average airflow:

• Reduced average power consumption of the demand controlled exhaust fan

By reducing the average airflow rate, demand controlled ventilation systems allow the exhaust fan to work well below the maximum airflow, thus at a very low power.

• Less clogging of filters, air ducts and terminals

The inherently reduced airflow of demand controlled ventilation leads to the reduction of the total amount of particles that can clog the components that make up the demand controlled ventilation system, which is directly proportional to the total volume of air introduced by the ventilation system in any given period. Thus, maintenance of air ductwork and filters (where these have been used), can be reduced with the power consumption of the demand controlled exhaust fan (when presence of filters).

• Increased life of demand controlled exhaust fans

By reducing average airflow over the year, demand controlled ventilation permits a reduction of the demands placed on the exhaust fan, and thereby increases its longevity. This is because the longevity of the exhaust fan depends in particular upon the power at which it works, and that power is directly related to the request of average airflow through the ventilation system.

• Greater availability of pressure and airflow for terminals

In a collective air ductwork system, serving either an individual home or collective dwellings, the airflow modulation at the various vents permits the avoidance of overloading the air ducts with unnecessary airflow rates, as would be the case with a constant airflow ventilation system. Thus, the rooms or dwellings with a low airflow requirement release the air duct space for the rooms or dwellings with a higher need for ventilation. These can then benefit from the demand controlled ventilation, from all the pressure and flow potential of the air ductwork, with losses in the air ducts being optimized and reduced.

• Reduced size of air ductwork to gain on valuable floor space

In demand controlled ventilation, airflow modulation permits a reduction in the size of the ventilation ductwork, exploiting the advantage presented by the fact that in a collective system, not all of the exhaust vents are working at the maximum level simultaneously. This phenomenon, called airflow time-dispatching, has been verified during numerous in-situ experiments carried out by Aereco. The air ductwork can therefore be sized for a total airflow lower than the sum of the maximum airflows, unlike that of a constant airflow ventilation system where the size of ducting corresponds to the strict sum of airflow. This use of smaller air ducts, can thereby allow a reduction in the total floor space required for ducting.

How does it works?

By offering airflow adapted moment-by-moment to occupants’ needs, Aereco demand controlled ventilation systems reduce thermal losses due to ventilation, improve indoor air quality and limit moisture problems, to answer the following questions:

Intelligent airflow distribution inside the dwelling

The Aereco demand controlled ventilation system optimises air distribution within the dwelling: thanks to the humidity sensitive air inlets, it directs the most air to the rooms that need it most. In this way, the system limits heat losses in unoccupied rooms and provides good ventilation where it is needed. The same principle is used at the exhaust through demand controlled exhaust units.

Because the number and activity of occupants in dwellings vary from moment to moment, so does the need for air renewal

To meet this variable need, Aereco demand controlled ventilation systems provide an airflow directly determined by the level of pollution inside each dwelling. An increase of indoor pollution is usually accompanied by an increase of relative humidity, which causes the opening of humidity sensitive air inlets and demand controlled exhaust units. In residences where occupancy is lower, the terminals open less, saving energy.

Pressures and airflows are balanced

In apartment blocks using using passive stack ventilation or hybrid ventilation, the stack effect naturally favours the lower floors over the higher floors, giving more pressure to the first floors. The humidity controlled ventilation system compensates for the lack of pressure at the upper floors by opening more (for a given humidity), balancing the airflows along the duct column.