Controlled Mechanical Ventilation (VMC)

Controlled Mechanical VentilationControlled Mechanical Ventilation (VMC) is a technology point recently, When you started to think about how to build homes that consumed less power to be heated.

With the introduction of ’ insulation material in the walls and the Windows installation ’ tight, It was quietly excellent reduction of energy consumption, going to affect negatively on the healthiness of the building.

Sealing every draught possible, came clearly failed that continuous and constant air replacement at ’ in ’ housing and the resulting (and necessary) expulsion of polluting domestic components.
Start to create problems of:
condensation and mold on the walls
– accumulation of gas and unpleasant odours caused by cooking
– formaldehyde and other chemicals emitted by furniture, furniture or building materials
– carbon dioxide emitted from individuals and from the plants staying in it.

These conditions led to what is today called sick building syndrome (Sick Building Syndrome) already discussed previously in this space.

Open the Windows of Home to ensure air, not always can be enough, because not always the air that comes from outside can be considered clean (especially in the Metropolitan residences).
In addition, being forced to open the window, In addition to be extremely uncomfortable, go to affect the internal temperature conditioning, unnecessary waste of energy implies and undermines the good thermal efficiency of the building ’ (they sought under construction).

In light of all this it is thought such a forced air exchange system that was active 24 hours on 24 throughout the’ARC of the year, a system that would replace the manual opening ’ Windows with the ability to control exactly d ’ air flow moment by moment and limiting to a minimum the ventilation and waste of energy.

The next step in this choice was controlled mechanical ventilation which is based on a fan at a low power consumption and low noise controlled by special units that picks up the air cycle by moister environments home (such as bathrooms, rooms and kitchens), and enter the same clean and properly heated from outside ’.

The air flow rate is controllable through vents installed specific and may vary depending on the greater or lesser moisture  internal or the presence or absence of persons and / or allergens. In this way the replacement will be more or less depending on the actual ’ indoor air quality, and then the actual replacement needs.

This can be done directly from the outside, Thanks to special transit or grids, in heat recovery systems, through a distribution network and suppy. In this case you retrieve part of the thermal energy of the exhaust air to the incoming back.

In general, the operating principle is based on a few simple steps:
– the VMC, using fans, aspires clean and oxygenated air, but cold and pushes her heated environments
– at the same time, using a parallel pipe, stale indoor air is sucked, but warm.
– heat exchanger removes heat from the hot interior air and restores incoming air cooler, before it is released into the environment
– a high-performance pollen filter prevents the entrance to most of dust, pollen and other particles and pollutants in the air.

The best trading systems, currently I am able to recover heat up to a good 92%, obviously more efficient, most are bulky, more cost and more are subject to periodic maintenance… but this is the cost that you should consider if you want to have a house in shape and very efficient.


As time goes by, These systems, with the continuous input of ’ humidity and dust in the pipes of an Exchange, they tend to lose their great features, It filters and occlude the heat exchange tends to cancel. The ’ system therefore requires constant maintenance becoming more frequent and not always convenient nor inexpensive. Often, exceeded the 6-10 years of life (Depending on where you put the ’ estate), It goes inexorably to evaluate the costs and benefits are not all ’ height of the costs for the entire plant ’.

Now this device, If all ’ start contributed to the maintenance of ’ efficiently building protecting structures from damage caused by mold and excessive humidity, then remains an almost useless that Exchange little air and does not retrieve the heat expelled. The humidity so ’ back to her by Mistress and moulds ramp again.


bricksIn essence we always say the same: the humidity must be answered ’ to the root, the wall must be healthy, breathable and built with healthy and efficient policy because it is the only real ’ interface that we have with the external ’. And’ the unique ’ active device that must be functional in an inhabited environment, the unique ’ capable of adjusting efficiently and completely natural, moisture, absorption of CO2 and temperature without any other additional mechanical means.
And’ the simplest philosophy that gave us our ancestors with a baggage of centuries of constructive experience which today we perhaps forget showing a bulwark of thermal efficiency that, at the end, not always leads to benefit that promises, nor in economic terms, neither in terms of health.

Elvio Rossi