Smart ventilation – let’s have fresh air in the house at all times

All in all, if you live in a smart home, you shouldn’t just focus on comfort functions. You should also be concerned with life quality and air quality.

This topic is only partly connected to smart homes, as the air quality within the home is pretty much determined by the materials used for insulation and by the equipment operating in the home.

We used to live in a traditional house, categorised for energy efficiency as A/B. We had plastic doors and windows. Airing the rooms was a daily task all the time, because the brick walls didn’t provide adequate air circulation, and the plastic windows hermetically sealed the rooms. When the rooms were aired, the CO2 content went down and you could feel the stuffy air being replaced with fresh air. The main disadvantage of this constant window-opening practice was the temperature fluctuation. In the winter, this meant higher heating bills; in the summer, overly warm rooms.
Then we moved to the smart home I’ve been describing on this blog. This house has a continuously running ventilation machinery to always provide fresh air in the rooms. The chart below shows you the advantages of the system.

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You can tell when we moved to the new house; that’s when the relatively high and continuously changing CO2 level switched to a constant and low value. The physiological effect of this is that you no longer breath in stuffy, smelly air – whether sleeping at night or going about your business during the day, you have FRESH air. Let me describe the process without going into too much detail:

  • air keeps coming in from the outside
  • air keeps going out from the inside (the two must be balanced)
  • going through a heat exchanger, the heat of the air inside warms up/cools down the air coming in
  • the air is filtered through with 2-3 air filters. These must be replaced every 6-9 months (this costs 50-75 USD a year)

This sounds great but… sometimes what sounds good in theory, may not work well in practice. We have the misfortune of living in an area where people use solid fuel-fired boilers. So on windless days in the winter smoke settles on the street. It’s particularly bad when your neighbor uses a fireplace from the 1800s to burn every piece of trash he finds, and he has a chimney no taller than 4 m to let the smoke out. So, one day, after the wonderful ventilation system let all the smoke inside the house, we came up with a solution: we decided to add active carbon filters to better filter the air in the heating period. Unfortunately, on those days when the weather was really windless and the neighbor burnt really stinky stuff, not even this solution worked. Even though it looked like it could withstand a chemical attack… So we finally realised that the only thing we could do is to set a timer for the ventilation system, which until then worked continuously. Now we turn it off between 4 pm and 10 pm. This was the time period when the smoke was particularly unbearable. Of course this is only needed when the external temperature goes below 15 degree Celsius.

Why am I saying this? I just wanted to warn you guys that while the fresh air effect of the ventilation system is great, you always must pay attention to every factor. If you want to use something more sophisticated than your senses to measure the air quality, you’ll need smart gadgets.

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I’ve grown to like the Netatmo product family because

  • it has a clear and informative interface


  • its rain forecast is based on local air pressure data, so to me it seems more precise than anything I’ve tried
  • if you want to monitor more than one locations, you can easily do so on your phone (e.g. your vacation home)
  • it measures CO2 data
  • it stores historical data, so if you need to look something up for some reason, the data are there at your disposal
  • it checks sound volume, so it can act as a burglar alarm
  • it can be connected to external services. For help with this, check out
