We all know the importance of the quality of the air we breathe, and we know that pollution caused by industry and cars is present in the streets. But do we know if the air in our house is healthy?
Outside, the concentration of CO2 in the air is below 0.04% (400ppm) with small variations due to the effect of the season, the time of day and localized pollution points.
We need air to live. Every day we breathe many liters of air that go directly to our lungs, and the concentration of CO2 directly affects people’s respiratory rhythm. It is considered that from 1,000 ppm people will endure negative health effects. A resting person breathes about 12 breaths per minute which results in moving about 360 liters / hour. If we analyze a two person room, all night they “breathe” thousands of liters of air and the CO2 increases rapidly (graph attached), arriving at values of 2,000ppm and up to of 2,500ppm, this has very little health value. In the mornings, we usually ventilate our rooms. By doing this we get the concentration down to correct values of 400ppm, but it is clear that we have been breathing unhealthy air for many hours, and do so every night. Therefore, throughout our life we will be breathing this air for many years.
A possible solution is to leave the windows open or use windows that have ventilation systems, but it is evident that, regardless of whether we are talking about prefabricated houses or not, energy losses from the hot air coming out of the house goes against the objectives of energy efficiency and economic logic. The option provided in passive houses is to integrate a dual flow ventilation system with heat recovery. In winter, the equipment draws the hot and used air from the inside to the outside, while it takes clean cold air from the outside, and uses a heat exchanger to avoid losing energy, recovering 90-95% of the heat, so we end up with air that is clean and warm inside. Therefore, with a reasonable investment, we obtain a house with optimal levels of CO2 every day of the year and without energy losses.
