relative humidity

How accurately can reduced-order dynamic building energy simulation models (with Dymola simulation software) simulate the indoor climate (i.e., indoor air temperature, relative humidity and CO2-concentration) in common inhabited residential buildings? In order to address this question, high resolution measurement data of a zero-energy case study dwelling were gathered through a measurement campaign. A dynamic multi-zone modelling approach has been applied to have room-level indoor climate results.

The current research investigates the relative humidity conditions in Swedish dwellings (678 apartments and single-family houses), comparing measurements from the 2007/2008 BETSI-survey (heating season), with the recommendations of the EN 16798:2019. Analysis shows that 61.4% of the apartments and 29.8% of the single-family houses belong to Cats. 3 and 4, which correspond to moderate and low level of expectation, respectively (mainly due to low 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.