Measurement of pollutant emissions in two similar very low energy houses with cast concrete and timber frame

This article is devoted to Indoor Air Quality (IAQ) in two low energy houses, with different frames (cast concrete (I-BB) and timber frame (I-OB)) built in platform INCAS of INES (National Institute of Solar Energy -in french: Institut National de l’Energie Solaire). In order to quantify pollutant emissions due to building materials and products, an experimental protocol consisted in stopping ventilation systems -”balanced ventilation”- of each house (a little before and during the measurement campaign), closing doors and windows, and not allowing occupant. Measurements started quickly after the end of construction: 70 days for I-BB and 224 days for I-OB. To measure IAQ, an experimental protocol was developed using continuous recorders (TSI Q-TRAK 7565 for CO2, multi-gas PID monitor Graywolf with TG502 VOC Probe for TVOC, NO2, O3; KIMO KH200 KISTOCK for ta and RH) and passive samplers (radial diffusive samplers Radiello® for specific VOCs -hydrocarbons and glycol ethers- and aldehydes). The duration of each measurement campaign was 7 days (from 02/04/2010 to 09/04/2010 for I-BB and from 23/05/2011 to 30/05/2011 for I-OB). Logging intervals for continuous recorders were 10 minutes. So that to estimate emissions due to building materials and eventual associated health effects, we focused on Volatile Organic Compounds (VOC: including specific VOCs and aldehydes) both with passive samplers Radiello® and continuous recorder Graywolf. Results reveal that in these low energy houses, building materials and products emit a great quantity of VOC with an indoor concentration 7 times higher than outdoor levels (both for I-OB and I-BB). Each frame has a main pollutant: Toluene for I-BB with a concentration almost twice higher than WHO guideline value (260μg/m3, 7days), and hexanal for I-OB : averaged value around 570 μg/m3 against ≈140 μg/m3 for I-BB. This study confirms clearly the importance of ventilation systems in these new low energy buildings and in general rules. If well dimensioned they should improve energy efficiency in order to increase IAQ, comfort and human well being.