Advanced ventilation systems – more than just air changes
Advanced ventilation systems safeguard regular air changes without wasting valuable energy. Subject to model, they can even provide DHW and central heating.
The increasing impermeability of new buildings and modernised residential dwellings in particular, calls for a continuous air change, for example, in order to avoid the growth of mould fungus and damage to the building. However, ventilation via windows is not very practicable as the sole means of ventilation. To ensure an energy efficient and hygienic minimum air change, ventilation via windows would have to occur four to six times a day for approx. 5 minutes each time. Heating would have to be turned off and windows fully open, making this virtually impossible. Mechanical ventilation systems reliably safeguard the necessary supply of fresh air, as well as energy efficient central heating and DHW.
The various ventilation systems
Decentralised ventilation: Accurate and energy efficient
In the case of decentralised mechanical ventilation, a distinction is drawn between systems with and without heat recovery: Decentralised systems with heat recovery have an individual appliance installed in the external wall in every room to be ventilated. For this, there are systems with two fans and heat recovery via a countercurrent heat exchanger for example. When choosing suitable decentralised appliances, it is also important to look for the lowest possible sound emissions and at ease of cleaning and maintenance. It should be possible to control the individual fans so that the air flow rate can be matched to demand.
A decentralised ventilation solution is the number one choice, particularly for modernisation projects or specific moisture problems. Little installation effort is generally required. Individual appliances work separately to ensure that air is extracted in moisture-critical rooms such as bathrooms and kitchens. In conjunction with a second appliance, they ensure good ventilation throughout the living space. Separate sensors control the appliances subject to the indoor air humidity level.
Centralised ventilation: Pleasant fresh air everywhere
With centralised ventilation units, a distinction is drawn between extract air systems and supply/extract air systems: The simplest and most cost effective system for centralised mechanical ventilation is an extract air system. Stale air is extracted via ductwork from the extract air areas such as the kitchen, bathroom and toilet. At the same time, the resulting negative pressure causes fresh air to be drawn through outdoor air apertures directly into the supply air areas (living room, play room, bedrooms). The air volume extracted from the extract air areas is determined by the fan capacity. Occupants can match the air flow rate to their demand via a simple step switch. With a small heat pump, the extract air can be utilised for DHW heating and, if required, central heating. Using extract air at relatively high temperatures as a heat source ensures excellent levels of efficiency.
The ventilation ducts required for this can be routed in walls, concrete or intermediate ceilings, in the floor, in the screed below or even uncovered. This solution is therefore used primarily in new build or for extensive modernisations. The major benefit: A consistent level of comfort with fresh air throughout the entire living space. The energy recovered from extract air can be used to heat the supply air.
Unlike an extract air system, a supply/extract air system draws the outdoor air from a central point and distributes it by means of pipework throughout the supply air areas. Heat is recovered in a countercurrent heat exchanger, transferring up to around 90 % of the latent heat in the extract air to the supply air. The outdoor air is filtered to prevent contamination of the unit and ductwork, and to protect allergy sufferers against the effects of dust and pollen. Various filter qualities are available. Centralised supply/extract air systems ensure excellent levels of comfort in the home.