Opening the window: The best way to ventilate your home?

“Controlled mechanical ventilation is essential to optimise the efficiency of the home and keep it healthier,” explains Paul Mathis, engineer and head of R&D for ventilation and air conditioning at Viessmann. It is one of the principles of “passivhaus”: avoidance of thermal bridges. 

Mathis has devoted much of his professional life to research. He worked for 10 years at the Technical University of Aachen. He talks about the advantages of projects such as Urban Energy Lab 4.0: “It is very helpful because the knowledge and talent of researchers on projects of this kind can then be applied to product development in the business“. 

But let’s start at the beginning: How do you usually ventilate your homes? The answer is probably: by opening the windows. Mathis explains that the energy loss from this type of ventilation is enormous, and that it takes a lot of energy to reheat the house. 

What’s more, he says, buildings are increasingly better insulated and more airtight, with fewer thermal bridges, so if they are not properly ventilated, fungi or bacteria can develop. 

What is the most efficient form of ventilation? One of the major benefits of ventilation systems is heat recovery, as opposed to traditional ventilation, which simply expels the used air outside. These systems allow residual heat to be transferred to the fresh air entering the building. 

“This means that 80-90% of the energy that would normally be lost by opening a window is reused inside the home, significantly reducing energy consumption,” explains Mathis.

Mechanical ventilation ensures a healthier and more comfortable environment and is a key factor in the transition to more sustainable and energy-efficient buildings.