To simulate time-dependent interior humidity, a moisture mass balance is applied to the control volume of the envelope of a residential structure. Moisture transport mechanisms incorporated include infiltration, cooling coil condensation, int
A small test house having a pitched roof/ventilated attic was installed in a high bay environmental chamber. The test house and its attic were extensively instrumented for measuring heat and moisture transfer. The test house was exposed to a ser
Studies moisture conditions in homes in 2 studies. In one study, 17 homes in 4 states were probed in mid-March 1977, and all moisture content levels were found to be within the acceptable range of equilibrium moisture contents. Inanother study, collects data for 16 homes in north-central Utah, Southern Alabama, Northern Ohio and central Maryland. Makes measurements in each home for approx 1 week in the summer and 1 week in the winter. All homes have well-ventilated attics.
States that in a tight house with a vapour barrier, an air management system is needed to provide fresh air and remove the build-up of moisture generated by the occupants. Briefly describes a typical air management system,incorporating an air-to-air heat exchanger, and discusses the need to provide an acceptable ventilation rate, which controls pollutant level but minimizes heat losses.
Shows that efficient moisture removal in a ventilated roof via ventilation openings is a function of roof length. Beyond a certain critical length all moisture diffusing in from below will be deposited in the roof. The critical roof length will be greater the more vapour tight the section beneath the roof space is. If a vapour barrier is necessary, as in an unventilated roof, it maybe that an unventilated roof is preferable in the first place.
Reports on seminar at University of Lund, Sweden and the factors affecting U-value: radiation, thermal capacity, moisture in materials, evaporation of precipitation moisture, convection, air movement, quality of work, cold bridges, ageing, air gaps.
Assesses the efficacy of an engineered mechanical ventilation system in controlling indoor humidity in one of the HUDAC Mark XI houses. Develops a mathematical model of the home, which is used to demonstrate the interaction between outdoor humidity, infiltration and ventilation rates, and indoor moisture generation and their influence on indoor humidity levels. Discusses the operating effectiveness of the rotary heat exchanger and the energy saved through its use.
Notes that altering interior moisture content of a building can influence both energy use and other performance characteristics. Gives an assessment of the moisture interaction as related to health and comfort of the occupants, fire safety, durability and maintainability and design and construction of light-frame housing. Reviews published recommendations.
This sixteen-page digest provides a guide to why condensation occurs in buildings and how to avoid it. Outlines causes of condensation problems in buildings.Gives 9 case studies. Discusses physical principles of moisture transfer. Describes vapour sources in buildings. Outlines ways of reducing thecondensation risk in buildings. Gives methods for predicting when condensation will occur.
States condensation caused by high humidity is a major problem in British homes. Describes a conventional heat pump dehumidifier for removing moisture from the air. Describes the advanced dehumidifier developed by the Electricity Council Research Centre which is designed to work in cold damp conditions typical of British winters. Gives details of the design and reports that tests of a prototype show that the design is more than twice as effective in terms of litres of water extracted per unit energy than conventional designs.
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