Rehabilitation of buildings with decentralized double flow ventilation

Starting from next year 2020, in our country the European regulations will become mandatory specifying that all new construction must be of Nearly Zero Energy Building. In this way, privately built homes will have to adapt to regulations that opt for energy efficiency and that requires, among other aspects, better air renewal. However, in Spain, the pending issue is the aging housing stock. To reform them, it will be necessary to adapt to the same regulations. And to achieve this, it is optimal to promote the rehabilitation of buildings with decentralized double flow ventilation. A simple way to adapt to the new scenario.

The mechanical ventilation is one of the requirements of the Nearly Zero Energy Building along with other aspects of energy savings, such as high airtightness and efficient management of lighting. Moreover, in ventilation, it is possible to allocate 30% of the accepted consumption, so choosing an energy-saving system is essential.

For that energy efficiency and to avoid the use of traditional air conditioning systems, double flow ventilation is the best alternative to heating and air conditioning units. Its operation is based on extracting the poor-quality air from the interiors through a network of ducts and introducing outside air, which will be filtered before entering the homes, for air renewal. If the system has a heat recovery unit, it will be able to heat the air supplied in winter and cool it in summer.

For old homes, however, the best option - or at least the simplest - is the rehabilitation of buildings with decentralized double flow ventilation. For this, we must understand what decentralization means.

1. Centralized double flow ventilation. This is the most efficient system. In it, all the air collected from outside to enter the house is done from a single point. Then, through a network of ducts, the filtered air will be efficiently and rationally propelled according to the total needs of the home.
2. Decentralized double flow ventilation. In this case, each room has a ventilation unit that operates separately. If we have three rooms, we will need to install three units, which will work completely independently.

Normally, when designing a new building, it is most common to opt for centralized ventilation. After all, from a single point, the entire air renewal is controlled more efficiently. However, in the renovation of buildings, this is very different.

Installing a centralized ventilation system in an already built building can be complex, therefore the simplest solution is to carry out the rehabilitation of buildings with decentralized double flow ventilation. The main benefits will be:

• It is not necessary to install a duct network or find space for the central control unit.
• It is only necessary to find a place that connects the exterior with the interior, such as a wall.
• The fans will be closer to the space and not in a remote area.

At the comfort level, it will be more or less the same experience. The problem that decentralized double flow ventilation may bring is that the fan will be in the same room and not in a separate area where life usually occurs. Therefore, it will be easier to hear the fan. Fortunately, today there are lower noise options, so we can worry less about it.

Other options in the rehabilitation of buildings with decentralized double flow ventilation

When carrying out an energy rehabilitation -which considers savings in supplies- we must not only take into account the installation of a mechanical ventilation system. To maximize air renewal and its possibilities as an efficient air conditioning system, we must also consider other aspects:

• It is interesting to implement measures that achieve greater protection against the climate indoors. For example, it is possible to install ventilated façades and roofs.
• The ceiling is very important, especially in houses or attics. Floating blinds can protect us from the sun's rays in summer, and for winter it is necessary to implement materials that insulate us from the cold.
• Doors and windows must be tightly sealed. In windows we can use double glazing.
• Thermal insulation is essential: walls and ceilings must have specific materials that protect against the entry of cold in winter and heat in summer.
• Natural lighting must be implemented, and bulbs can be replaced with LED models.

If we combine these solutions in the rehabilitation of buildings with decentralized double flow ventilation, we will achieve homes that can eliminate most of the energy consumption.