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Mechanical ventilation systems - what are they, what types are they, how do they work and which one have we selected for MarPlus.

The Technical Building Code, in its basic document relating to health, the DB-HS, and specifically in chapter HS3 dedicated to air quality, in its latest revision of December 2019, establishes the need to use these systems to maintain adequate air quality in the interior of dwellings.

What must be complied with?

Thus, according to this DB, in new dwellings such as the Residencial MarPlus in Gandia, the habitable rooms of the dwellings must have a sufficient flow of outside air so that the average annual concentration ofCO2 inside the dwelling is less than 900 ppm (parts per million air volume units). In older dwellings, this air renewal could only be achieved by traditional ventilation, i.e. by sporadically opening doors and/or windows. This, as we will see, is very inefficient:

  • Firstly, it does not allow a continuous and adequate renewal of the air in the home. We only ventilate when we open the doors and/ or windows to the outside. This is usually done for short periods of time which, in addition, require our interaction (opening and then closing) to produce this ventilation, which is why, for example, we can never ventilate while we are sleeping.
  • Every time we open to ventilate, we let the energy we have used to acclimatise our home escape . Thus, we lose the energy we have used to heat or cool the house (depending on the time of year). Natural ventilation is therefore not very energy efficient.
  • In addition, the air we let in may not be in optimal conditions, depending on where we live, it may be polluted and require prior filtering.
  • Finally, opening up also exposes us to noise pollution and noise from the outside environment, which is particularly inappropriate in urban areas.

For this reason, the current CTE does not accept natural ventilation as a method for renewing the air in the living areas of dwellings. In order to achieve this indoor air renewal, one of these types of ventilation systems could be considered inside the building or dwelling:

  1. Hybrid system of mechanical ventilation in intake: As the name suggests, a mechanical forced ventilation system is used to supply fresh air to the rooms and extract it naturally with simple grilles.
  2. Hybrid mechanical exhaust ventilationsystem : Contrary to the previous case, it requires louvres and natural ventilation for intake and uses fan(s) for exhaust, i.e. controlled mechanical ventilation (CMV) for exhaust to allow air renewal. This system requires that dry rooms that are in contact with the external envelope of the building have ventilation grilles that are open to the outside.
  3. Double-flow mechanical ventilation system: In these systems, both air intake and air extraction are carried out by means of a mechanical ventilation system controlled by fans. In other words, they allow stale air to be extracted from the damp areas of the house (bathrooms and kitchen) and fresh outdoor air to be introduced into the dry rooms (bedrooms and living rooms).

The CTE itself, in its DB-HE, the basic document relating to energy saving, indicates the keys to an efficient home: it is essential to work on the airtightness of its envelope. The more airtight the dwelling is, the less the energy stored inside it will escape and the less energy will be needed to maintain a comfortable temperature inside. But this airtightness is at odds with the natural renewal of indoor air, so the most recent DB HS3 requires the use of a system (VMC) such as system 2 in the previous list (hybrid extraction), or 3 (double-flow mechanical ventilation). It is easy to see that, of the two systems validated by HS3, the most efficient is the double-flow system.

Dual flow system with heat recovery and 100% automatic bypass Siber DF EVO

Residencial MARPLUS new build location in Gandia Why a dual flow system for your home at MarPlus?

At our new development in Gandia, the Residencial MarPlus with energy rating A, we have selected as a ventilation system, a dual-flow VMC system. This is because it controls both the inflow of fresh air and the outflow of stale air from damp rooms. In addition to this, at no time are there open louvres exposed directly from the rooms to the exteriorwhich makes it possible to ensuring the tightness of the enclosure of housing y therefore maintain energy efficiency. The fresh air inlet is always filtered, guaranteeing maximum air quality. to the VMC system and from there it is blown into the dry rooms. In fact, thanks to this filteringIndoor air quality is higher than outdoor air quality.. For example, thanks to the filters included in the system, pollen and most of the allergens present in the air can be filtered out. Indoor air quality is one of the fundamental parameters for ensuring the healthiness and sense of well-being inside your home.
Similarly, the extraction is connected from the wet rooms to the VMC and from there to the outside.

Example double flow Siber.co.uk
Example double flow © Siber.co.uk

What is a heat recovery unit?

A good double-flow controlled mechanical ventilation system must also have a heat recovery unit to ensure maximum efficiency, but what is a heat recovery unit and how does it work? The aim is to ensure that the energy contained in the indoor air is not wasted during the air renewal process before it is extracted. The heat recovery unit is nothing more than a heat exchanger consisting of a structure of very thin conductive sheets through which both the air coming from the street and the air coming out of the interior circulate separately, but without mixing, thus producing a heat exchange between the two flows, so that the incoming flow is tempered and the energy of the air being expelled is not lost.
In this way, in winter, the cold air that enters receives a high percentage of the heat from the air that is expelled, maintaining a pleasant temperature in the home. Meanwhile, in summer, the hot air filtered from outside is cooled by the recuperator thanks to the lower temperature air that is expelled from the house.

What is Bypass and why 100% automatic?

In addition, the VMC selected for our new project in Gandia, the MarPlus Residential, has a double flow system with heat recovery and 100% automatic Bypass. This ByPass consists of equipping the system with interior and exterior temperature probes so that it can control and automate when the two flows must exchange heat and when not, in order to be tremendously efficient as it does not require any human intervention, thus guaranteeing maximum energy efficiency at all times. For example, in the summer, in the early morning if it cools down, it may be of interest to introduce filtered air without passing it through the exchanger if it happens to be at a lower temperature than the indoor air.

The VMC selected for the new development in Gandia has a heat recovery unit with an efficiency of 95%, specifically the premium model of the Siber brand , the highest range, the so-called DF EVO, which will be installed as standard in all the homes of the MarPlus Residential. This model is also certified by the renowned and prestigious Passive House Institute.

Dual-flow SVC heat recovery unit
Example of bypass © Siber.es
Residential MARPLUS full logo

Visit the home page of our website https://ganditec.es to have access to all the documentation of our new development in Gandia. New housing in Gandia, in la Safor, the Residencial MarPlus.

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