Demand controlled ventilation


Demand controlled ventilation: the best 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 design 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.

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. This aspect clearly promotes unbalanced demand controlled ventilation systems such as those from Aereco, when compared with the standard heat recovery ventilation systems that typically have two motors operating at a higher speed (with higher average airflow), and are then particularly penalized in terms of environmental impact and consumption of electrical energy (primary notably).


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.

Airflow demand controlled ventilation parameters

Manual activation versions, such as activation by switch or remote control are also available for some demand controlled ventilation products. Modulation parameters should allow adjustment of the air change rate based on actual needs and for this reason, the choice of a parameter depends on the application (local type), its tenure and activity (type and level of pollutant emitted). The table below gives the different parameters of ventilation modulation depending on applications as a guide:


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