Long term measurements of attic wood moisture content have shown that at least fifty kilograms of water may be stored in roof sheathing members over the course of the winter, to be released in the spring. Overlaid on this seasonal cycle there is a daily variation driven by temperature changes in the attic. A dynamic model is required to predict the resulting attic air humidity ratio. Hourly moisture flows in a typical attic - from ventilation and from the wood - are examined, and a simple first-principles dynamic mathematical model to relate them is developed.
Occupants can significantly influence both the heating energy requirements and the indoor air quality of a building by opening and closing doors and windows. If the effects of these actions are to be accurately estimated, both the quantity and character of these exchange flows must be determined. In this paper, data on gravity-driven exchange rates through open doors obtained from field experiments at the Alberta Home Heating Research Facility are compared with laboratory model simulations and theoretical predictions.
Development of infiltration and interroom airflow calculation methods, driven by a concern for indoor air quality have led to a computer simulation of interroom contaminant movement. The model, which assumes fully mixed room air, shows that open doorways provide rapid mixing between rooms in buildings using forced air heating. It also confirms that it is most energy efficient to remove the contaminant nearest its source. Detailed modeling of the variations in contaminant concentration within a room is not presently feasible for long term energy analysis simulations.
One of the recent major developments to the ESP (Environmental System Performance) building/plant energy simulation package has been the integration of a technique capable of performing dynamic air flow analysis as part of the building thermal analysis, thereby permitting simultaneous dynamic modelling of energy and air flow within the building envelope. This paper briefly describes the model and its data requirements. It compares and discusses differences in zone energy requirements and temperature levels (obtained from ESP) when 1. applying traditional air changes rates and, 2.
Measurements on the rate of air exchange in residential buildings have been carried out by the Swedish Institute for Building Research since 1970. The results of an analysis of these measurements are presented in this paper for about 500 buildings not having mechanical ventilation. The studied buildings include one- and two-storey, detached, single- family houses, row houses, and multifamily residential buildings built between 1900 and 1982 and of various design. In some cases, the buildings have been retrofitted by improving the insulation of the attic or the exterior walls.
The Lawrence Berkeley Laboratory (LBL) infiltration model was developed in 1980; since that time many simultaneous measurements of infiltration and weather have been made, allowing comparison of predictions with measured infiltration. This report presents the LBL model as it currently exists andsummarizes infiltration measurements and corresponding predictions. Thesemeasurements include both long-term and short-term data taken in houses with climates ranging from the mild San Francisco Bay area the the more extreme Midwest.
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