Field tests of centralized and decentralized ventilation units in residential buildings – Specific fan power, heat recovery efficiency, shortcuts and volume flow unbalances

Abstract

The main objective in terms of energy efficiency of a ventilation system with heat recovery is to reduce the primary energy consumption of the building. Hence, the ratio between between saved and consumed energy should be greater than one and depends on various parameters. Fresh air supply can be decreased because of shortcuts within the system and unbalanced air flows, possibly resulting in lower heat recovery rates and unwanted ventilation losses. On the other hand, the energy consumption is often increased due to inefficient fan components or high pressure drops of inadequate components or design. These parameters among others were measured at 20 centralized and 10 to 67 (depending on the measured parameter) decentralized devices in field tests, with the goal of providing an overview of the performance of state-of-the-art ventilation systems in residential buildings. Nearly all devices showed shortcomings at one or more parameters. The values for shortcuts, heat recovery rates, sensitivity to pressure differences between in and outside and specific fan power in most cases differed from values provided by the manufacturers.

Low Polluting Building Materials and Ventilation for Good Air Quality in Residential Buildings: A Cost–Benefit Study

“…This was calculated considering a centralized mechanical ventilation system only, since a decentralized system would not deliver adequate airflow rates. For centralized systems, the specific fan power increases from 0.3 to 0.8 Wh/m 3 [22]. Hence, in this study, three values were used, namely 0.4, 0.6, and 0.8 Wh/m 3 .…”

Design criteria for outdoor air intakes and exhaust air outlets located on an external wall

“…Ventilation exhaust air re-entrainment is an episodic air pollution event which occurs when the discharged exhaust air is transported back into the building through ventilation air intakes or other openings in the building enclosure [3] and it can potentially induce indoor air quality problems from comfort issues like nuisance due to odors to re-entry of pollutants that are harmful to health [4]. The issue of contaminant transfer from an exhaust outlet to the outdoor air intake in different building types with mechanical ventilation has been reported in several studies, including single-family and multifamily residential buildings [5][6][7][8][9][10][11][12] and nonresidential buildings [13][14][15][16]. In addition, re-entrainment has been extensively studied in buildings with singlesided natural ventilation where airborne transmission of infectious biological aerosols [17,18], particulate matter [19] and gaseous contaminants [20,21] route has been shown from one dwelling unit to another through open windows via outdoor air along the external wall due to the effect of wind and buoyancy.…”

1. Experimental Research of Mitigation Systems for Controlling and Reducing Radon Exposure in Residential Buildings

“…An experimental study on ventilation system in suburban buildings is presented by Merzkirch, Maas [16]. The system overall revealed strong interdependancies among all measured pollutants leading to a highly improved air features and a good comfort [15][16][17].…”