From energy crisis to sustainable indoor climate : 40 years of AIVC : selected papers from the 40th AIVC Conference, 15–16 October 2019

In the past 40 years, since the first oil crisis in the seventies, energy and climate goals have been shaping many countries´ policy and legislative agendas. The building sector plays a crucial role in achieving these goals, considering the energy use attributed to buildings and its huge potential for improved energy performance. Whereas in the past most of the focus was on reducing the energy consumption, it is now clear that better performing buildings must ensure an acceptable Indoor Environmental Quality (IEQ), by providing higher Indoor Air Quality (IAQ) and comfort levels for their occupants. Building ventilation entails both challenges and opportunities to achieve this goal. Since 1980, the annual conference of the Air Infiltration and Ventilation Centre AIVC has been the meeting point for presenting and discussing major research results and developments regarding infiltration and ventilation in buildings. In 2019 the AIVC completed its 40th year of existence and the conference organizers thought that it would be good to pay attention to the evolution during these 40 years. This is the context which defined the core theme of the joint 40th AIVC, 8th TightVent and 6th Venticool Conference, organized in Ghent, Belgium: “From energy crisis to sustainable indoor climate – 40 years of AIVC". Over 120 contributions were presented at the conference after a call for abstracts on aspects of smart ventilation in relation to indoor air quality and health, building and ductwork airtightness, and ventilative and resilient cooling. There were two separate calls for abstracts and papers depending on whether the authors were interested in the peer review of their papers or not. This special issue of the International Journal of Ventilation presents a selection of the peer reviewed conference papers addressing issues raised by the conference topics. The analysis of infiltration related energy use is the subject of a Spanish study (Poza-Casado et al.). The study aims to assess the energy impact of uncontrolled airflows through the envelope in residential buildings in Spain. For this purpose, airtightness results of more than 400 blower door tests have been analyzed, showing great potential for energy saving in the country through better air tightness. However, in projects where airtightness requirements are imposed, testing procedures to measure air infiltration should allow to obtain reliable test results in an affordable way. Three other papers are dealing with these issues. A new test device for building air tightness is introduced and validated by a Dutch research team (Lanooy at al.), using the buildings ventilation system for pressurization, to allow for a cheaper and faster test procedure. Prignon et al. contribute to the quantification of uncertainty in pressure and air flow rate measurements in fan pressurization tests, by analyzing the uncertainty in zero-flow pressure approximations due to short-term fluctuation of wind speed and direction during testing. Further, a paper by Paralovo et al. proposes a new approach for passive tracer gas testing to overcome limitations of existing methods. The study pursues as tracer a suitable gas that can be co-captured using commercial passive samplers employed in common IAQ studies, and investigates a suitable source design for the new tracer. With the increased building airtightness in energy-efficient buildings, the design, installation and operation of ventilation systems are important in order to guarantee healthy and comfortable indoor environments and improve energy performance. A number of papers present and analyze improved ventilation concepts to contribute to these goals. Single room mechanical ventilation units with heat recovery are the subject of a Belgian study (Parthoens et al.), since these systems have advantages especially in the frame of refurbishments. The paper tackles three aspects to improve the design of these units: the noise attenuation, the enthalpy recovery and the flow control strategies for multiple units. Berquist et al. investigate the performance of a demand controlled mechanical ventilation system with heat recovery in the Canadian arctic, where solutions for prevention of frost build-up and draught were tested in a demonstration house. A supply-only mechanical ventilation concept is studied by a French research team (Leconte et al.). A centralized supply system is complemented with active air vents in the different rooms of an experimental house, while various demand control ventilation strategies are tested based on the setting of each active air vent. Scheuring and Weller apply building energy simulation to assess the performance of four single sided window opening strategies based on CO2-concentrations for an office room in a Mediterranean, subtropical and moderate climate zone. Predicted comfort and energy use are evaluated in comparison with results for an intake/exhaust mechanical ventilation system. Further, Toumpoulidis et al. discuss the monitored performance of a solar air heater collector, partly operated as a solar chimney, in an outdoor test cell in Greece, and its potential to cover the cooling load of a building. In order to assess the role of building ventilation on indoor air quality and indoor environmental quality correctly, it is necessary to develop improved design tools and metrics. This is the subject of four remaining papers. De Jonge and Laverge show the importance of taking dynamic VOC source-models into account when designing demand controlled ventilation systems and controls. They present results of thermal, airflow and contaminant simulation models to analyze the influence of temperature and humidity on indoor VOC concentrations in a test house. Lastovets et al. calibrate a dynamic nodal model to simulate the thermal environment in rooms with displacement ventilation (DV) and investigate the effect of thermal mass on the temperature stratification in a lecture room with DV. Braun and Zeiler report on measured CO2-concentrations inside a baby bed in comparison to background CO2-levels measured in the sleeping quarter. The results show that it is not sufficient to only assess CO2 concentrations in the bed room as the conditions significantly deviate from those in a crib. Finally, Mahdavi et al. explore the possibility to cover aspects of user control and satisfaction in building performance evaluation procedures. Their paper presents a protocol to evaluate the controllability of the indoor environment by building users, referred to as ‘ecological valency’, in a systematic and reproducible manner by documenting five main categories of control devices. We would like to thank the authors for their efforts to contribute to this special issue, the members of the scientific committee of the 40th AIVC conference for their valuable comments in reviewing the papers, and the editor-in-chief of the Journal, Ben Hughes, for the opportunity and support to organize this special issue.

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