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Energy savings with controlled ventilation systems: Passive Houses

Is it complying with the European legislation? What energy-saving measures will you have to take?

  • November 22, 2022
CMV - Controlled Mechanical Ventilation


One of the major challenges and themes that dominate today is concern for the environment, climate change, sustainability and energy efficiency. Most countries are involved in reversing the damage that has been done to the planet, and the consequences that, in one way or another, we are all feeling.

To ensure that sustainability goals are guaranteed, in accordance with European legislation 2010/31/EU, from the year 2018 for public buildings and 2020 for other new construction buildings, these must have an energy consumption of almost null (nZEB-nearly Zero Energy Buildings).
To meet this objective, we know that different protocols and project strategies have been implemented that aim at high energy efficiency. Within these new ways of approaching new constructions, there is an important method to highlight: passive houses.

In this article developed by Selectra, an energy market consultant, and by Tecofix, it is shown the importance of these buildings in terms of energy savings and the importance of controlled ventilation systems in these houses.

This type of construction focuses mainly on offering high levels of comfort inside the houses, offering conditions that require the minimum use of air conditioning. This results in considerable energy savings, ranging between 70% and 90%, when compared to a traditional house. Saving energy in this type of construction is a fundamental concept, which is why it is important to implement measures to save energy, such as reducing the consumption of air conditioning systems.

Selectra also recommends that if you don't live in a passive house, you adopt new energy consumption habits that go beyond just choosing the cheapest light company.

What energy saving measures can be adopted?

- Use of appliances classified with energy label A, are those that consume less energy and perform exactly the same functions;

- Installation of LED lamps. They may be more expensive, but they consume less energy and last even longer;

- Use of dryers, dishwashers and heating at times when electricity is cheaper. Electricity traders have available bi-hourly tariffs that allow you to pay less for kWH at night, for example:

     -->  Use of thermostats to control energy consumption;

     -->  Do not leave devices on standby;

     -->  Cooking for several days, as it avoids turning on appliances, such as stove and oven, so many times.

What characteristics should a passive house have?

A passive house must meet these elements:

     - Thermal insulation;

     - High efficiency windows;

     - Ventilation with heat recovery;

     - Hermeticity;

     - Extreme care with thermal bridges.

These constructions must include optimal and continuous thermal insulation throughout their surroundings, windows with a high insulating capacity (as they are part of the envelope) and with ruptures of thermal bridges to avoid heat loss.

The combination of all these elements makes the interior space very hermetic, hence the need to include a mechanical ventilation system.

The importance of controlled ventilation systems

The great tightness of the interior of passive houses means that losses are very low and their interior conditions very stable, so that the need to air-condition the environments is minimized.

However, the great tightness must be complemented with excellent ventilation, as the space can suffer from problems with humidity and condensation, creating an unhealthy and unsuitable environment for living. However, as already mentioned, the passive house places the comfort of the inhabitants at the center of its strategy, in a healthy and safe environment. To achieve this, you need an adequate temperature and good indoor air quality, so it is important to have permanent ventilation that does not alter the two previous factors.

Traditional ventilation through open windows is not prohibited in passive houses, however, it is important to do so ensuring that it does not cause energy losses, which is more difficult. In any case, opening the windows, despite being somewhat unintuitive for a domestic user of a traditional house, is not necessary for a passive house to be well ventilated.

This is because there is a controlled mechanical ventilation system that ensures that the air conditions breathed in the house are optimal. Air renewal is established through what we call a Controlled Mechanical Ventilation (VMC) system. This method makes it possible to maintain a constant air flow adapted to the indoor conditions, with a minimum expenditure of energy, which makes this system highly efficient.

What is the best VMC system?

Among the systems that we can consider in a house, the most efficient Controlled Mechanical Ventilation system is the so-called extract and intake mechanical ventilation or dual-flow mechanical ventilation systems.

For the system, the heat exchanger is essential, where the thermal exchange of hot air to cold air takes place, both in winter and in summer. In this exchange, it is important that both air flows exchange energy in a sealed way, to avoid contamination of the clean air with the extracted air. In addition, there is also filtering of the air that is captured from the outside, which guarantees the best possible conditions with regard to indoor air quality, lowering the initial levels of pollen, bacteria, dust, among others.

Controlled Mechanical Ventilation systems significantly improve key issues. On the one hand, it is a system that guarantees the best comfort and health conditions inside homes. On the other hand, the commitment to energy efficiency makes it a strategy that goes beyond the individual benefit, to have a definitive impact on a more sustainable construction for all.

Author: Dep. Marketing Tecofix