Ventilation: a friend or a ghost?


OXYGEN @Housing Fair

Ventilation: a friend or a ghost?

Although the legislation on mechanical ventilation in Lithuania has been mandatory since 2016, there are still many myths surrounding this technical area. Newcomers are as afraid of the heat recovery unit as they are of every other innovation. We’ve dispelled your fears by presenting the main types of mechanical ventilation systems, highlighting their main features, positive and negative characteristics.
Types of ventilation systems:
1. Natural ventilation by opening the windows

Costs nothing, but is ineffective – only the “draught” created will remove the excess CO2 accumulated, which requires the opening of windows in rooms on opposite sides of the building. “Draughts will not form in calm outdoor weather – on a hot summer day or a cold winter day when the air masses are almost stationary.
Outdoor noise, dust and insects are brought indoors with the outdoor air. In winter, opening a window loses heat energy. In summer, indoor coolness is not retained.
2. Central air extraction system

A mechanical ventilation system where air circulation is provided by a central exhaust fan, usually mounted on the roof of the building. Fresh outdoor air is brought into the rooms through vents in the windows.
This system only partially prevents outdoor dust and noise from entering the living space. Thermal energy is also not conserved. In winter, colds are possible because the window vents allow extremely cold outdoor air to enter the room.
3. Ducted mini-recuperators

Easy to install, just drill a hole in the building wall. However, for this system to work well, it needs to have a high number of pairs of ventilation units, to be correctly designed and balanced, to operate synchronously, to be interconnected by electrical cables or wirelessly, and to be centrally controlled.
Complaints about insufficient energy efficiency are possible in winter. They are also disliked by some users because of the sound that is emitted directly into the living space, and are often installed before moving in and then never used because of cold or noise.
This solution does not ensure a continuous and uninterrupted flow of fresh air, as the principle of the mini-recuperator is based on the principle of reversible airflow, i.e. the contaminated air is first removed from the room, thus warming up the heat exchanger of the mini-recuperator, and then fresh outdoor air is supplied to the room, warming up the heat exchanger.
4. Ducted recuperators

These are installed quite simply by drilling one or two holes in the building wall. This solution is better than standard mini-recuperators as it ensures a continuous and uninterrupted flow of fresh air. However, more than one of these is often needed for a dwelling, with a unit in each living room and additional forced air systems for the kitchen and toilet areas.
5. Central ventilation system

This is a large and very powerful ventilation unit, capable of serving the whole apartment block. It distributes the fresh air flow to all the apartments in the building and removes the polluted air from each apartment. The system is efficient, but in the event of a unit failure, the air is immediately cut off to all apartments. It is also easy to rebalance the system – if one neighbour wants to reduce the supply or extract air flows, the supply and extract air to the other apartments is increased. As more neighbours are added, the supply air to the remaining apartments increases dramatically, causing all residents to complain about draughts or noise in the ducts.
A duct system is needed in each apartment, but the user cannot control the airflows, either up or down.
6. Individual housing recuperator

The ideal solution for every small or large dwelling. Requires ductwork but the user can individually control the ventilation of his/her dwelling by increasing, decreasing or switching off (not recommended). It is also possible to individually select the air filtration class and set a weekly ventilation programme.

(C) Žilvinas Salialionis, 2021 OXYGEN