Hybrid ventilation, collective treatment for apartments
A cross between natural ventilation and mechanical exhaust ventilation, hybrid ventilation is a modern concept that uses the components and dimensioning of the passive stack ventilation ducts coupled to non-permanent low-pressure mechanical assistance.
The mechanical assistance is used only when the natural forces are not sufficient to ensure the required airflow. It is started up automatically, and can be activated by a temperature sensor, a pressure controller, or even a wind gauge.
The fresh air is admitted by humidity sensitive air inlets in the main rooms (bedrooms and living rooms); the stale air is evacuated through the wet rooms (toilets, bathroom, kitchen) through demand controlled extract units. These components control the airflows according to the needs of each room.
Hybrid ventilation combines the advantages of easy maintenance, energy savings, acoustics, and reliability of passive stack ventilation with the aeraulic performance of mechanical ventilation.
Mechanical exhaust ventilation, collective treatment for apartments
In collective mechanical exhaust ventilation, the air in a building is renewed by a fan, installed in the roof or other convenient outside location.
In demand controlled ventilation, the air extracted through the extract units of the wet rooms determines the air renewal of the entire dwelling.
The humidity sensitive air inlets then distribute the new air according to the needs of each main room.
The demand controlled extract units distribute the airflow generated by the fan according to the needs of each wet room, in each dwelling.
Thus rooms, or dwellings, with high new air requirements induce more airflow than empty ones.
Mechanical exhaust ventilation, individual treatment for apartments or houses
In this case, the fan is placed inside the dwelling. This treatment is applicable to individual houses as well as apartments.
Placing the fan inside the dwelling has the advantage of making it directly accessible, a welcome advantage when it comes to maintenance.
As with collective mechanical exhaust ventilation, the air in the dwelling is renewed by a fan.
In demand controlled ventilation, the air extracted though the extract units of the wet rooms determines the renewal of air in the entire dwelling. Humidity sensitive air inlets then distribute the new air according to the needs of each main room.
The demand controlled extract units distribute the airflow generated by the fan according to the needs of each wet room.
Thus rooms with high new air requirements induce more airflow than empty rooms.
Natural ventilation, collective or individual housing
In both individual housing and collective housing, natural ventilation exploits the natural forces (wind and stack effect) to renew the air within the dwellings.
These forces create a pressure in the air duct that starts air circulation from the inside of the dwelling towards the air duct and then outside.
The air is exhausted through the wet rooms via extract units, and this induces an admission of fresh air through air inlets situated in main rooms.
Depending upon natural forces (wind and stack effect), the natural ventilation may be random: it is therefore necessary to control it.
The humidity sensitive system, while measuring the humidity rate to drive the necessary airflow, gives an appropriated answer to the variability of the natural forces as it allows to compensate automatically the variation of stack effect, especially in winter.
In addition to its energy saving attributes (no exhaust fan) the first qualities of this system are acoustics (low air speeds) and simplicity of maintenance.
The pressures available in natural ventilation are from 5 to 15 Pa at the units, depending on building height and climatic conditions.
Heat recovery ventilation, individual treatment for houses and apartments
The principle behind heat recovery ventilation is to supply fresh air and exhaust stale air by a mechanical process, using double ductwork connected to a central unit that includes a heat exchanger to pre-heat the fresh air. Aereco has implemented this principle in an innovative system that controls airflows room-by-room, according to their specific needs: the DXR.
The DXR system comprises a heat recovery unit (DXR unit) connected to exhaust units and to a distribution box (DXR hub) that controls the airflows supplied. The counter-flow heat exchanger, incorporated in the main unit, recovers most of the energy from the exhaust air and transfers it to the supply air, so less energy is needed to heat the fresh air.
Airflows are automatically controlled according to the needs of each room of the dwelling: for the supply air in the bedrooms and the living room, and for the exhaust air from the kitchen, bathroom and WC. Each supply unit is directly connected to the DXR Hub distribution box, which adjusts the airflow to all main rooms based on the level of CO2 (or on presence detection), keeping it proportional to the measured level of pollutant. On the exhaust side, the BXC units automatically adjust the airflow according to parameters determined by various sensors: humidity in the bathroom, presence in the WC, humidity and manual boost in the kitchen. Versions with CO2or VOC sensors can also be used for exhaust units.
At all times, the total supply and exhaust airflows are measured and balanced by means of two controlled compensation valves, which can be located in the living room, in the kitchen, or in a corridor. For example, when the need for ventilation is growing during meal preparation in the kitchen without being accompanied by strong demand in the main rooms, the required exhaust airflow can be achieved by opening the supply compensation valve (located in the DXR Hub).
The bypass in the heat recovery unit automatically sends exhaust air directly outdoors, without going through the exchanger, when the outdoor temperature is mild enough; it can also be used in free-cooling mode to provide night cooling in summer.
