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Moisture in indoor air: findings of 40 years

This extended summary is a part of a more extensive summary (technote to be published) that compiles a number of AIVC publications that deal with ventilation and health in relation to moisture in air, and the development over time.

Big humidity data from smart ventilation systems

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. 

Detailed numerical modelling of moist air flow through a complex airtightness defect

Mastering building airtightness is essential to meet the requirements of current and future building codes, not only for saving energy but also for ensuring moisture safety. Perfect airtightness is difficult to achieve: failures are often observed, due to bad design or poor workmanship. Some published investigations proved that leaking air mostly flows through porous material and thin air channels, due to material imperfections and construction tolerances.

Carbon Dioxide Concentrations and Humidity Levels Measured in Belgian Standard and Low Energy Dwellings with Common Ventilation Strategies

One of the most commonly used strategies to reduce the heating demand in low energy buildings is reducing the leakage level of the building envelope. Dedicated ventilation systems are then installed to compensate for the reduced air change rate in an energy efficient way. Most occupants, however, operate their ventilation system at very low flow rates. Together with the emission of bio-effluents, linked to the presence of the occupants, moisture production related to household activities is one of the most important sources of indoor air pollution in dwellings.

The powerdomus environment for simulating HVAC systems

In this paper, the new capabilities of PowerDomus to simulate central HVAC systems combined to its whole-building hygrothermal model is presented. First, models for the primary (chiller, cooling tower, primary pumps and condensation pumps) and secondary (cooling and dehumidifying coil, humidifier, fan and mixing box) systems are presented. Those mathematical models have been integrated into the whole-building PowerDomus program.

Moisture and Condensation in Residential Buildings in a Relatively Dry Region

It is not unusual to face moisture problems in buildings in cold climates and wet regions. It is, however, unusual to have the same problem in a relatively dry region such as Jordon, which has moderate weather conditions and mild winters. Nevertheless, a significant proportion of houses and residential apartments in Jordan are affected. The monitoring of inside air conditions, wall surface temperatures, ventilation and living style has shown that a high relative humidity (RH >75%) occurs at walls resulting in possible condensation.

Effects of Coupled Heat and Moisture Transfers through Walls upon Indoor Environment Predictions

The non-uniform behaviour of the air inside a room, which is important in comfort analysis, can be evaluated by zonal models. While not as fine-grained as CFD simulation, they do give useful information about temperature and moisture distributions that is not available from lumped-parameter models. Therefore, we have developed a tool, called SimSPARK, to automatically build dynamic zonal simulations of a building zone.

Dependence of radon concentration on pressure difference in a crawl-space

Radon concentration in a crawl space remained at the same level during autumn ( 756 Bq m-3 ) and inwinter ( 767 Bq m-3 ) because both air exchange rate and negative pressure (measured across thefoundation wall) increased after a installation of a new ventilation system in the crawl space. Inaddition, relative humidity and water content remained constant in the crawl space air during the sameperiod of time. Radon entry rate was explained by the pressure difference across the crawl space wallwith percentages of 51 % (winter) and 76 % (autumn).

THE USE OF A THERMAL DUAL - PROBE FOR THE MOISTURE MEASUREMENT OF BUILDING FABRICS: THE TESTING OF THE TECHNIQUE VIA COMPARISONS WITH MEASUREMENTS FROM AN X-RAY SYSTEM

The measurement of moisture in building fabrics has been of interest for many years due to thepotentially devastating consequences of moisture problems within buildings. A range of potentialtechniques are available with which to measure the moisture content of building fabrics in-situ and thispaper focuses on one particular technique, the thermal dual-probe. Note that this method is distinctfrom the single probe technique. Essentially, a short pulse of electrical energy is applied to a wirewithin the heating needle.

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