Why Bother with Ventilation?
My 220m² home, built less than 10 years ago, features triple-glazed windows and excellent insulation. It has a ventilation system with a heat exchanger that warms fresh air using exhaust air, and a heat pump that draws energy from the ground for floor heating, controlled by Uponor wireless thermostats. During winter, the average monthly energy consumption is 1600 kWh, and 900 kWh during summer, including the 500-600 kWh used to charge my electric car. This leaves about 1000 kWh for heating and ventilation during winter. Everything seemed fine, so why bother with an upgrade?
The house was almost perfect, but "good" is never the best, and the best can become just good enough.
The Problem
Despite the advanced setup, the air quality was sometimes insufficient. The Vallox Digit 145e central ventilation unit delivered air constantly to every room, ventilating sleeping areas during the day and living spaces at night. Setting the unit to maximum speed would be too loud, over-ventilate unoccupied rooms, and increase the electricity bill. The situation worsened with guests or during workouts, as CO₂ levels rose quickly, causing fatigue. Additionally, one of my children is allergic to cats, making good ventilation crucial.
The gym room highlighted these issues. Ventilation was set for two people at rest, but it was inadequate even for one person exercising, as oxygen consumption can be up to five times higher during workouts. Opening windows during winter was not a comfortable solution. CO₂ readings of 2000 ppm with visitors or during workouts were common.
The Search for a Solution
I needed a dynamic system that could deliver fresh air where needed, closing grilles and valves in unoccupied rooms. Typically, only one-third of the rooms are occupied at any time, so redirecting airflow could meet the required capacity without a larger, more expensive unit.
After evaluating options, Aerefy.com valves emerged as the ideal retrofit solution. These valves have built-in sensors to detect presence and measure air quality, replacing existing valves without needing duct access. Moreover, they are battery-powered, solving the power supply issue for exhaust valves in the ceiling.
Installation and Results
Installing the Aerefy valves took just two hours. I also automated the central unit to adjust air supply based on valve status, maintaining a 100 Pa pressure difference in the exhaust duct.
The results are impressive:
- CO₂ levels never exceed 900 ppm, even with 10 guests.
- The average ventilation unit's electricity consumption is about 50% lower.
- Furthermore, as in total 2x less air is ventilated out of the building, it has also lowered the heating bill.
- Humidity levels are in the normal range.
While I work for Aerefy, this doesn't change the fact that the problem was solved cost-effectively, with no comparable solution from competitors.