Indoor exposure to contaminants should be minimized to avoid adverse health and comfort effects. Experience shows that this qualitative statement is difficult to translate into measurable terms, such as performance indicators or metrics, which can be used as a basis for defining and assessing requirements in regulations and standards while holistically reflecting indoor air quality. The simplest and most commonly used approaches rely on ventilation airflow rates determined by experts or codes. These approaches have fundamental shortcomings in practice for systems that do not have steady contaminant sources or do not provide a constant airflow rate, such as natural, hybrid, or demand-controlled ventilation. More sophisticated approaches can be based on health damage, pollutant exposures, or perceived air quality but they generally entail a number of assumptions about the pollutants of concern and occupant scenarios. Such methods could lead to useful metrics. However, as of today, there is no clear set of metrics that can be used to assess the overall ventilation performance of a building with regard to its indoor air quality, or used in standards or regulations.

This workshop aimed to identify the pros and cons of performance-based approaches and metrics that can be considered to assess the IAQ performance of ventilation systems, as well as to draft guidelines for their use in standards and regulations.The workshop addressed IAQ performance for all building types and ages, with all types of ventilation system (natural, mechanical, hybrid systems). It did not cover the relevance of the associated metrics in terms of health, comfort or building damage, but looked at their relevance for comparing system performance or strategies in terms of IAQ. It focussed on performance-based approaches, such as those that focus on the performance to achieve rather than on the techniques or systems to be implemented.

The attendees at this workshop participated, either through presentation, or in active discussions during each session. Target attendees were experts, professionals, or scientists researching ventilation or IAQ issues related to existing or potentially new IAQ performance approaches, such as metrics. 

About one third of each session was dedicated to discussions with the audience based on presentations, sometimes with the help of an interactive voting system to instantaneously collect the opinion of the attendees. 

Keynote presentations focused on the specifications and needs for performance-based approaches and associated IAQ metrics for building ventilation, which consider pollutants and sources of concern. The regular session presentations reviewed IAQ indices, analyzed their pros and cons, and suggest edimprovements where necessary.

Topics addressed in presentations and discussions

• Factors that should influence IAQ assessment
• Is CO2 indoor pollutant?
• The potential for, and limits of, CO2 based indices, humidity or moisture, health damage, perceived air quality, air mixing behaviour, and pollutant distribution within a space
• The potential for, and limits of, combined indices
• Definition and use of rating methods for smart ventilation, DCVs, natural ventilation, etc. (equivalent ventilation principle)
• Barriers to performance-based standards (showing evidence of compliance, accounting for sources, sensors and controls, time-activity patterns)

Presentations & speakers

• Considerations on IAQ metrics from regulatory and compliance point of view – Use of IAQ metrics in practice, Peter Wouters, BBRI, Belgium
• Defining the metrics to assess the IAQ in low-energy residential buildings: results from IEA EBC Annex 68 Subtask 1, Marc Abadie, U. La Rochelle, France
• The promise and problems of performance-based ventilation, William P. Bahnfleth, Pennsylvania State University, USA
• What can (‘t) perceived air quality indices tell you about indoor air quality? Pawel Wargocki, DTU, Denmark
• Indoor carbon dioxide as metric of ventilation and IAQ: Yes or No or Maybe? Andrew Persily, NIST, USA
• IAQ assessment in high performing buildings, Kevin Teichman, Environmental Protection Agency, USA
• Rationale behind current ventilation airflow rates, Wouter Borsboom, TNO, the Netherlands
• Concentration versus m3 air per hour – the battle of assessors, Marcel G.L.C. Loomans, Eindhoven University of Technology, the Netherlands
• Status and perspectives for the development of IAQ metrics in the US, Iain Walker, LBNL, USA
• Performance-based control of an adaptive hybrid IAQ system. The user as key performance indicator, Bert Belmans, VU Brussel, Belgium
• Can contaminant air quality indices be used to analyse the risk of airborne cross infections in hospital environments? Manuel Ruiz de Adana Santiago, University of Cordoba, Spain
• Suitable ventilation in schools – mechanical or natural? Thomas Hartmann, ITG Dresden, Germany
• Radon measurement for the assessment of IAQ, Tiberiu Catalina, Technical University of Civil Engineering, Romania
• A review of pollutants and sources of concern and performance-based approaches to residential smart ventilation, Gaëlle Guyot, Cerema, France
• Indoor Air Quality and thermal comfort in Irish retrofitted energy efficient homes, Marie Coggins, National University of Ireland, Ireland
• Modelling trade-offs between building energy and health, Catherine Noakes, University of Leeds, UK
• Comparison of different performance-based approaches for the definition of ventilation requirements in dwellings, Samuel Caillou, BBRI, Belgium  
• The influence of different ventilation strategies and demand control on the indoor air quality in dwellings, Romy Van Gaever, BBRI, Belgium  
• Demand controlled ventilation in residential buildings, Caroline Markusson, SP, Sweden

Organisers

The workshop was organised by INIVE on behalf of the AIVC (Air Infiltration and Ventilation Centre). This event was organized with the technical and/or financial support of INIVE and the International Energy Agency’s Energy in Buildings and Communities Programme.

Recorded Presentations

The presentations listed below were recorded after the event. The links to the recordings & the slides are provided below

• Indoor carbon dioxide as metric of ventilation and IAQ: Yes or No or Maybe? Andrew Persily, NIST, USA | Slides, Recordings
• What can (‘t) perceived air quality indices tell you about indoor air quality? Pawel Wargocki, DTU, Denmark | Slides, Recordings
• Considerations on IAQ metrics from regulatory and compliance point of view – Use of IAQ metrics in practice, Peter Wouters, BBRI, Belgium | Slides, Recordings

For additional information please download the programme below.

All other material available, including presentations, abstracts and/or papers can be found here.