Field studies to investigate winter indoor thermal conditions of mechanically ventilated houses with different R-value building envelopes

摘要

Since 1978 R-values of the building envelope of local houses have been continuously increased. Whole home mechanical ventilation systems are becoming more and more popular for New Zealand house owners. Positive pressure roof cavity ventilation systems are the most common type of ventilation systems used in thousands of local houses. To investigate winter indoor thermal conditions of mechanically ventilated Auckland houses with different R-value of insulation and glazing in their envelopes, two local houses built in 2000 and 2012 with positive pressure roof cavity ventilation systems are selected for field studies of winter indoor microclimatic conditions. The study not only identifies improvement of winter indoor thermal conditions of two local houses with increased R-value in their envelopes, associated with the updated New Zealand building standards or codes since 2000, but also the major problems of local housing thermal design according to the current building standards or codes in a climate with a mild and wet winter. Also, investigated are the impacts of a positive input ventilation system on winter indoor thermal comfort conditions of a house. The study compares and evaluates winter indoor thermal conditions of a house with or without a positive pressure ventilation system.