A semi-centralized, valveless and demand controlled ventilation system in comparison to other concepts in field tests

Publication date: November 2015
Source:Building and Environment, Volume 93, Part 2
Author(s): Alexander Merzkirch, Stefan Maas, Frank Scholzen, Daniele Waldmann
The idea of adapting the air supply rate to the actual demand in a building is not a new one. In commercial buildings it is already state-of-the-art to establish a demand controlled ventilation, where the level of air flow is based on sensors or time control. In residential buildings however, mechanical ventilation systems, whether centralized or decentralized, are in most cases operated in a constant modus, providing fresh air regardless if the fresh air is needed or not, even though the technology and the components needed for demand controlled ventilation exist and can be purchased at reasonable prices. In this article, results of field tests with a semi-centralized demand feedback-controlled ventilation system are shown and compared to outcomes with other demand controlled systems. The semi-centralized prototype includes decentralized fans per ventilation zone, making a room-wise ventilation possible and valves to balance the system hydraulically unnecessary. It is shown that each presented concept of demand controlled ventilation can save energy by decreasing the operational time or the mean air flow rate without compromising air quality. Concepts which make a zone- or even a room-wise control of air flow possible, showed the highest energy saving potential of up to two-thirds compared to a system operating at constant flow rates. In addition to the energy savings due to decreased operational time, the maintenance and filter costs are decreased while the user comfort is increased, as natural ventilation in spring, summer and autumn may easily be added when ΔT between inside and outside is small.