humidity

Humidity-based DCV systems have been widely used in France for 35 years and are considered as a reference system, including for low-energy residential buildings. The on-going Performance 2 project delivers the new results of a thirteen-year monitoring in twenty-two social housing apartments. The involved consortium is composed of Cerema, Univ. Savoie Mont Blanc and two industrials partners: Aereco and Anjos. 

This study introduced a pre-assessment and control tool for indoor air quality (PACT-IAQ) which aimed at multiple pollutant concentrations simulations, pollutant loads estimations and decoration design scheme optimization. Multiple emission sources, sinks, ventilation, pollutant dissemination, and the combined effects of temperature and humidity on material emissions were considered in the tool. Two versions, namely the single zone and multi-zone models, were included in the tool.

Individual effects of temperature and humidity on formaldehyde emissions from manufactured fiberboards have been studied previously, but their combined effects and possible correlation with initial emittable concentration (C0) of building materials have not been reported yet. This paper investigated their combined effects on C0 theoretically from microcosmic perspective. Total formaldehyde content related to humidity and formaldehyde molecular phases affected by temperature in the porous material were considered.

Initial emittable concentration (C0), diffusion coefficient (Dm) and partition coefficient (K) are the three key emission parameters determining formaldehyde emissions from “dry” building materials. Previous studies of humidity effect on formaldehyde emissions were mainly focused on the analysis of steady-state emission rates or concentrations, whereas humidity effects on emission parameters were seldom discussed.

The IEA EBC Annex 68 project on “Indoor Air Quality Design and Control in Low Energy Residential Buildings” has been recently completed. The project considered indoor air pollution loads in dwellings, particularly how such pollutants are emitted in dependency of the hygrothermal conditions: temperature, moisture and air flows. Thus, a proper understanding of the mutual interactions between hygrothermal conditions and pollutants was needed to obtain optimal paradigms for demand-controlled ventilation.

Humidity-based DCV systems have been widely used in France for 35 years and are considered as a reference system, including for low-energy residential buildings. Indeed, most of the new residential buildings, which must be low-energy buildings to comply with the RT 2012 energy performance regulation, are equipped with such systems. Feedbacks from two long-term studies show the durability of the humidity sensitive components and show the robustness of this system to bad maintenance or use by occupants.

Japan is characterized by high humidity in summer and low humidity in winter. Therefore, summer is in a climatic condition where mold is easy to grow, and in fact, mold damage is occurring. Due to improvement of the thermal insulation and airtightness of houses, the temperature in the room is maintained high even in winter, and mold damage occurs. We will introduce the research we have conducted regarding humidity environment and health problems, and discuss future subjects. The outline is as follows. 

A smart ventilation system is generally equipped with a range of sensors. The data – or data derived from it - collected by these sensors can be used by both building owners, occupants and managers. A new generation of IoT  enabled residential ventilation systems allows collecting and analysing this data at scale to get a better view on typical IAQ conditions in dwellings. In this paper, the results from such an analysis on the first 900 installed devices of a new model with respect to moisture in relatively new Belgian dwellings is presented. 

People spend 70% -90% of their time indoors. Indoor air quality and human body’s health have a close relationship. With the advance of society, user comfort requirements for thermal environment are rising. Humidity is an important parameter for evaluating indoor air quality, which not only affects the thermal comfort of the human body but also seriously restricts the function of the building. In winter, the indoor humidity is dry. When using humidifier, the humidity around the humidifier is higher, but there is still a dry area in the room.

Since the turn of the century, alarming data produced by the Indoor Air Quality Observatory (OQAI) have led to changes in French legislation, including, most notably, the introduction of compulsory labelling for construction products (decree no. 2011-321 of 23 March 2011).