Indoor Air Quality Campaign in an Occupied Low-Energy House with a High Level of Spatial and Temporal Discretization

International audienceBackground and gaps. The topic of indoor air quality (IAQ) in low-energy buildings has received increasing interest over the past few years. Often based on two measurement points and on passive measurements over one week, IAQ studies are struggling to allow the calculation of pollutants exposure. Objectives. We would like to improve the evaluation of the health impacts, through measurements able to estimate the exposure of the occupants. Methodology. This article presents detailed IAQ measurements taken in an energy-efficient occupied house in France. Two campaigns were conducted in winter and spring. Total volatile organic compounds (TVOC), formaldehyde, the particle numbers and PM2.5, carbon dioxide (CO2), relative humidity (RH), temperature (T), ventilation airflows, and weather conditions were dynamically measured in several points. Laboratory and low-cost devices were used, and an inter-comparison was carried out for them. A survey was conducted to record all the daily activities of the inhabitants. IAQ performance indicators based on the different pollutants were calculated. Results. PM2.5 cumulative exposure did not exceed the threshold available in the literature. Formaldehyde concentrations were high, in the kitchen, where the average concentrations exceeded the threshold. However, the formaldehyde cumulative exposure of the occupants did not exceed the threshold. TVOC concentrations were found to reach the threshold. With these measurements performed with high spatial and temporal discretization, we showed that such detailed data allow for a better-quality health impacts assessment and for a better understanding of the transport of pollutants between rooms

Effect of energy renovation on indoor air quality and thermal environment in winter of a primary school in a highly polluted French alpine valley

International audienc

Effect of energy renovation on indoor air quality of a French school building

International audienceIndoor air quality (IAQ) and thermal comfort issues in schoolsare of particular public concern because children represent avulnerable population group to air pollution. In fact, their respiratoryand immune systems are still developing and a long-term exposureto indoor air pollutants might have a significant impact on theirhealth and scholarly. This study focuses on the effect of the energyrenovation of two classrooms which consists of the implementationof a dual flow ventilation system with high efficiency filters (F7).The classrooms are located in an alpine valley (France) known forits high level of atmospheric pollution. To do this, carbon dioxide(CO2), temperature (T), relative humidity (RH) and PM2.5 weremonitored continuously over twice two-month periods before andafter the renovation in winter 2018 and 2020, respectively. Inaddition, the ventilation airflows were measured and a dailyquestionnaire that report the information on general condition in theclassroom were recorded day-to-day. The results of these campaignsindicate that before the renovation, the two rooms were confined,estimated by IAQ index such as ICONE index which are equal to 2.The CO2 concentration reached to 4790 ppmv due to a very low airexchange rate 0.05 h-1. During the high PM2.5 levels episodesobserved in outdoor air, the low air exchange rate limited thetransport of PM2.5 from the outside to the inside of the classrooms.As a result, the percentages of concentration exceedance comparedto WHO recommendations were 23% and 17%, in class 1 and class2 respectively, while it reached 68% in outdoor air.After the renovation, the ventilation airflow was higher thanbefore renovation and reached to 2.46 h-1. As consequence, a drasticreduction of the confinement was measured with ICONE index ofclass 2 reaching to 0. The CO2 concentrations are remained low witha maximum value of 1150 ppmv. Rather the high air renewalgenerates a significant inflow of outdoor particulate pollution whichthe indoor PM2.5 concentrations range were 20-80 µg.m-3 during theoutdoor air pollution episodes. However, the indoor concentrationswere all the time lower than those observed outside withindoor/outdoor concentration ratio about 0.5. It can be assumed thatthe filtration of the supply air allowed to limit the entrance of theparticles. However, this figure should be taken with caution becauseof the complex physic associated with particle behaviours (e.g.sedimentation, resuspension, etc). In addition, it is interesting to notethat a dysfunction of the ventilation system led to a situation closeto that before renovation, both with regard to the rate of ventilationairflow, as well as the concentrations of CO2 and PM2.5

Relevance of CO2-based IAQ indicators: Feedback from long-term monitoring of three nearly zero-energy houses

International audienceNowadays, many countries include requirements for building airtightness in their current national regulations or energy-efficiency programs, mainly for concern about reducing building energy consumption due to air leakage. Moreover, more and more countries impose a mandatory justification with an air leakage measurement at building commissioning. Therefore, the uncertainty of the measurements results has become a key concern in several countries over the past year. More specifically, the influence of wind speed has been identified as one of the major sources of error on the measurement result. The goal of this paper is to present the experimental facility we design and built to improve the uncertainty estimates and the measurement protocol based on model scale experiments in controlled laboratory conditions. We first present the similarity criteria we identified for our model scale experiment. Secondly, we present the experimental design. Finally, we characterize the wind speed inside the wind tunnel and we present the preliminary results regarding the reproduction of fan pressurization tests on the model for different leakage distributions