Air leakage and duct wall conduction in forced air distribution systems often waste 20% to 40% of the energy used to condition residences in hot, humid climates. The simulation of these forced air distribution system leakages, their attendant uncontrolled airflows within the building system, and their consequential energy uses may be achieved by treating building spaces as pressure vessels (nodes) that are interconnected with the forced air distribution system, the outdoors, and each other through the basic laws of pressure and airflow.
Modem, massive building envelope technologies (masonry and concrete systems) are gaining acceptance by builders today. All U.S. thermal building standards, including ASHRAE 90.1and90.2 and the Model Energy Code, are linked to the steady-state clear wall R-value. They also have separate requirements for high mass walls. Very often, only steady-state R-value is used as a measure of the steady-state thermal performance of the wall. This value does not reflect the dynamic thermal performance of massive building envelope systems.
Airflow in buildings is one of the major factors that governs the interaction of the building structure with the mechanical system, climate, and occupants. If the airflow at any point within a building or building assembly can be determined or predicted, the temperature and moisture (hygrothermal or psychometric) conditions can also be determined or predicted. If the hygrothermal conditions of the building or building assembly are known, the performance of materials can also be determined or predicted.
Loose-fill pumice, fly ash, and sawdust have been used to construct insulated walls for retrofit or new construction of small residential buildings. Pumice in sandbags was demonstrated as exterior insulation for an existing adobe house in New Mexico. Such houses are rarely insulated because of the cost and difficulty of providing exterior insulation. Prototype stand-alone walls were also constructed using fly ash and sawdust blown into continuous polypropylene tubing, folded as it is filled to form the shape of the wall. Other materials could also be used.
Condensation on windows creates obscured view, can cause building damage, and may lead to mold growth and poor indoor air quality. The Canadian Standards Association (CSA) has developed new procedures to evaluate window condensation potential, using a combination of computer simulation and testing. This paper summarizes results of a study into various aspects of computer simulation related to the evaluation of condensation potential. These findings were used to assist in the development of the CSA procedures.
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