relative humidity

Design of ventilation systems in Belgium is currently based on the Belgian Standard NBN D 50-001:1991. This regulation is more than 25 years old, and is not anymore suited to new technologies developed in the frame of increasing energy performance of buildings and its associated ventilation systems. This standard defines four classic ventilation systems, going from A (natural ventilation) to D (double-flux ventilation eventually with heat recovery). One of its main shortcomings is that it does not consider demand controlled ventilation (DCV) systems.

Bio-based insulation materials represent an alternative to petro-based materials which may contribute to enhance buildings energy efficiency. Nevertheless, these material must respond to indoor air quality requirements and prove their resistance to moulds. In this study, VOCs emissions of a wood fibre board were characterised at 50% and 85% of relative humidity (RH) as well as its potential to mould growth. Relative humidity variation impacted significantly some VOCs emissions and colonies from Aspergillus niger developed onto the material.

We have developed a new evaluation method of “thermal radiative power” (TRP) for investigating the impact of building surface material albedo on urban environment. The simulation system ENVI-met is used. This system is a 3D computer model which analyzes micro-scale thermal interactions within urban environments. It simulates urban-scale environmental conditions such as roofs, exterior wall, and ground surface temperatures. Focuses of this research are on the climate change in urban and community scale in cold climates.

The climate of South Korea is that of high temperatures and high humidity in the summer season and low temperatures and low humidity in the winter. Humidifiers and dehumidifiers are used to create a cool indoor environment, and the demand for building materials with moisture adsorption/desorption functions is increasing. To investigate the performance of moisture adsorption/desorption new mineral fiber boards, a chamber test and mock-up test were performed and compared to mineral fiber boards.

Mechanical ventilation may be necessary to provide adequate ventilation in new houses due to the relatively low rates of infiltration achieved in new construction. However, in hot and humid climates, increased ventilation may raise indoor humidity to an undesirable level. A study was undertaken by the Florida Solar Energy Center (FSEC) to evaluate the humidity effects of different mechanical ventilation strategies for such climates. The study was conducted in a new 141-m2 manufactured house sited at the FSEC campus.

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 avoidance of mould growth in dwellings is of worldwide concern. In England and Wales, therelevant Building Regulations guidance document recommends ventilation provisions to control bothmoisture and other pollutants in buildings. The performance criterion for moisture states that thereshould be no visible mould on external walls in a properly heated dwelling with typical moistureproduction.

The investigation was conducted to investigate the relationship between thermal conditions andindoor air quality during summer in a new unit-type nursing home. Almost all occupants in the nursinghome spend the daytime in the nursing homes common space area. We set out to examine how theindoor environment changes and what influence the thermal environment has on odor, and thereforetook readings in the common space for room temperature, relative humidity, CO2 concentration andodor levels.

The fungal index is a biological climate-parameter, which represents the environmental capacity toallow fungal growth. The author developed software that determines the computed fungal index,which was estimated using the Excel software "INDEX" from the measured temperature and relativehumidity. The computed fungal index and the measured fungal index, determined using a fungaldetector encapsulating fungal spores, were determined in 10 rooms in six dwelling houses.

The severe impact on health associated with biocontaminants, such as dust mites, has become increasingly apparent in recent years. Consequently, a considerable effort has taken place to develop biocontaminant growth models and to assess the efficacy of possible psychrometric control measures, involving the modification of room conditions. However this approach is not always successful due to the low correlation between room conditions and those within the microenvironments inhabited by biocontaminants.