indoor air quality

In order to evaluate the impacts of volatile organic compounds (VOCs) emissions from building materials on the indoor pollution load and indoor air quality beyond the standard chamber test conditions and test period, mechanistic emission source models have been developed in the past. However, very limited data are available for the required model parameters including the initial concentration (Cm0), in-material diffusion coefficient (Dm), partition coefficient (Kma), and convective mass transfer coefficient (km).

This paper presents the initial reflections in the frame of Subtask 1 – Setting the Metrics of the IEA EBC Annex 68 – Indoor Air Quality Design and Control in Low Energy Residential Buildings. The first step of IEA Annex 68 aims at summarizing the current knowledge on target pollutants for residential buildings and at evaluating indoor air quality (IAQ), i.e. how to define indices that provide useful information allowing to achieve low risks for health in indoor spaces, and how to enable the comparison of solutions for achieving high IAQ taking into account energy efficiency.

In future building regulations 2020, building performance is going to be extended to global performance, including indoor air quality (IAQ). In the energy performance (EP) field, successive regulations pushed for a "performance-based" approach, based on an energy consumption requirement at the design stage. Nevertheless, ventilation regulations throughout the world are still mostly based on prescriptive approaches, setting airflows requirements. A performance-based approach for ventilation would insure that ventilation is designed to avoid risks for occupant’s health. 

In the field of energy performance, successive regulations pushed a "performance-based" approach, based at least on an energy consumption requirement at the design stage for heating and/or cooling systems (Spekkink 2005). Nevertheless, in the field of building ventilation, regulations throughout the world are mainly still based on “prescriptive” approaches, using airflows or air change rates requirements.  

HVAC systems in newly built or extensively renovated dwellings were all developed with the aim for energy saving with equal or better comfort. However, these systems (floor heating and DCV systems) have certain characteristics which increase the emissions of Volatile Organic Compounds (VOCs) and give VOCs the chance to accumulate to higher concentrations. This interaction is investigated based on dynamic simulations using a temperature and humidity dependent VOC emission model. 

The present paper aims at illustrating the practical use of the Annex68 IAQ Dashboard. To this end, numerical simulations have been performed to provide useable data about the Indoor Air Quality (IAQ) of a low-energy detached house. The dashboard has been used to compare three possible solutions of ventilation systems commonly found in French residential buildings i.e. natural ventilation using vertical ducts for extraction, self-regulated exhaust and balanced mechanical ventilation.

The modelling of air flows to investigate indoor air quality and energy issues has been a topic at the AIVC for all of its 40 years. Models have been developed that range in complexity from single-zone algebraic expressions that can be calculated by hand to complex multi-zone approaches that integrate contaminant transport and other functions.

The purpose of this summary is to review Air Infiltration and Ventilation Centre activities, as reflected in its publications, related to indoor carbon dioxide over the 40 years that have transpired since its creation. These activities, like most applications of indoor CO2 to the fields of ventilation and indoor air quality, have focused on the following: control of outdoor ventilation rates, i.e., demand control ventilation; use as a tracer gas to measure outdoor air change rates; providing an indicator or metric of IAQ; and, directly impacting human health, comfort and performance.

Indoor pollutants and particles pose a threat to human health as people spend 90% of their time in indoor spaces. A proper ventilation system should be able to remove indoor air pollutants, reduce particle depositions, at the lowest energy consumption by that system. In this work, particle concentrations and depositions are presented for two ventilation configurations (1) Displacement Ventilation (DV) and (2) the conventional ceiling supply and return.

To date, the vast majority of indoor air quality studies have relied on repeated visits to dwellings to obtain data derived from short-term monitoring exercises, a time-consuming process that places considerable constraints on personnel, equipment and costs. These studies have focussed on the use of research-grade instrumentation; however, recent developments in the field of consumer-grade indoor air quality sensor technology offers new opportunities.