n October 13 and 14, the Working Group for Wind Engineering and Fluid Mechanics, together with colleagues from the Department of Technical Meteorology at the University of Hamburg and the Institute for Combustion and Power Plant Technology at the University of Stuttgart, invited participants to a specialist workshop at Ruhr University.
The event focused on “Improving Immission Conditions in Residential Areas by Adjusting Exhaust Discharge Conditions – Alternative Measures to Chimney Height Increases.”

Representatives from the chimney sweeps’ trade, industrial associations, government authorities and ministries, consulting offices, as well as manufacturers of heating systems and filter technologies, came together to discuss the current findings presented by the project group.
Since January 1, 2022, new regulations for the discharge of exhaust gases according to §19 of the 1st Federal Immission Control Ordinance (1. BImSchV) apply to newly installed solid-fuel combustion systems. These regulations are based on VDI Guideline 3781 Part 4. Existing systems are exempt from these new requirements.
The research project, led by Dr.-Ing. Cornelia Kalender, aims to more precisely understand and document the relationships between plant technology, emission behavior, discharge conditions, and the resulting immission situation in surrounding residential areas.
To this end, model experiments are being conducted to quantitatively investigate how exhaust discharge conditions affect immission levels around solid-fuel heating systems in residential neighborhoods. These experiments follow an integrated methodology, combining physical modeling in a qualified boundary-layer wind tunnel with extensive numerical simulations using computational fluid dynamics (CFD).
In addition, technical measures intended to reduce emissions—and thus also immissions—are being identified and evaluated, particularly with regard to existing systems. The project seeks to determine which alternative technical measures can achieve an immission situation in neighboring areas equivalent to that of increasing chimney height according to the recognized state of the art (VDI 3781 Part 4).
Beyond informing an invited group of experts, the workshop also served as a platform to discuss relevant practical experiences that will be considered in the ongoing course of the project.