nZEB (Nearly Zero Energy Building) buildings are designed to have near-zero energy consumption, as the name suggests. This means they have an extremely low energy requirement, achieved through the use of renewable energy sources and the implementation of new technologies.
Characteristics of nZEB buildings
nZEB buildings do not have zero energy consumption – a target that is impossible to achieve – but their energy requirements are very low. The key features relate to the building envelope, insulation, airtightness and the use of renewable energy sources. Insulation and airtightness are essential for preventing excessive heat transfer – outwards in winter and inwards in summer. Preventing heat loss helps to maintain a constant temperature inside the building without the need for intervention to adjust it.
However, a very high level of airtightness does affect air exchange, which is essential for ensuring indoor conditions that are as close as possible to ideal. In an enclosed space, humidity levels rise, increasing the risk of mould or fungi developing. In this regard, controlled mechanical ventilation plays a vital role.
The importance of mechanical ventilation
Air exchange is essential for ensuring a high standard of indoor air quality. Opening windows, however, is not the most efficient solution. To prevent unnecessary heat loss and air contamination from smog or harmful substances, the use of a mechanical ventilation unit is the best choice. A mechanical ventilation system allows you to control air exchange, maintaining conditions close to the optimum. Thanks to the implementation of new technologies, such as heat bypass devices, it is possible to recover heat only when it is actually needed.
nZEB buildings should be viewed and analysed as a system comprising multiple parameters, rather than as a single component. Insulation, airtightness, controlled ventilation and renewable energy are just some of the many parameters that come into play to ensure the lowest possible energy consumption. Considering them all as a whole makes it possible to design and develop buildings with ever-lower energy requirements.
