Improving Occupants’ Satisfaction with Mechanical Ventilation using Technical and Non-Technical Solutions: Slutrapport til højnelse af tilfredsheden med mekanisk ventilation i renoverede etageboliger

This project focuses on evaluating occupants' and building management staff's experiences with mechanical
ventilation in renovated residential buildings in Denmark. It proposes technical and non-technical solutions to
increase satisfaction levels among occupants and staff. The project is divided into two phases: Phase 1
studies the impact of new mechanical ventilation systems on occupant satisfaction with indoor climate,
ventilation system, annoyance, and functionality. Phase 2 investigates the impacts of faults in a CAV AHU
system on thermal and electrical energy use, thermal comfort, and indoor air quality. The study develops
fault models, defines KPIs, and evaluates how faults can affect energy use and indoor climate conditions.
The conclusions of each phase are as follows:

Phase 1: Tenants experience more noise, draughts, and dry conditions after the renovation and installation of a new decentralized ventilation system, which may be the reason why fewer people are satisfied with the ventilation system. Conversely, there are also fewer people who are dissatisfied with the new ventilation system than with the old central ventilation system. The perceived indoor air quality has not improved after the renovation, which may be due to increased experience of dry air in winter and drafts and noise from the ventilation system. An important conclusion, however, is that there is a correlation between satisfaction with the decentralized ventilation system and satisfaction with the indoor climate. Furthermore, satisfaction with the decentralized ventilation system is closely linked to having received written instructions for use in connection with the installation and to the fact that the residents have dared to adjust the system and feel that they can adjust it as they wish. In order for the residents to be satisfied with the system, is it required that they are introduced to the system and that they gain confidence and experience in using the system.

Phase 2: Fault impact detection
The presence of faults in a typical Danish ventilation system can lead to increased energy use. Poor bypass damper operation is the main cause of thermal energy increase, followed by poor insulation of ducts and
sensor faults. Fans' efficiency degradation may lead to increased electric energy use. The results obtained can be useful for producers and manufacturers of these systems, as they give awareness of the impact that poor design and operations can have on systems' energy use