ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation traditionally was not a major concern because it was felt that between operable windows and envelope leakage, people were getting enough air. In the quarter of a century since the first oil shock, houses have become much more energy efficient. At the same time, the kinds of materials and functions in houses were changing in character in response to people's needs.
Air exchange rates of ten residential buildings were measured according to ASTM-E741-83 using SF6 as a decaying tracer. Air exchange rates were also predicted based on the characteristics of the HVAC system, openings (such as windows), leakage areas, pertaining average wind speed, average indoor/outdoor temperature difference and wind and stack coefficients. It was found that measured air exchange rates were higher by 34% than those predicted if the literature coefficients were used.
In order to estimate air change rates (ACH) on Natural Ventilation (NV) processes a number of factors should be known as general and openings dimensions, pressure distribution over the facades, internal heat sources (or sinks) and head losses. The atmospheric boundary layer (ABL) characteristics change with the terrain roughness and affect the pressure distribution. Construction features determine infiltration rates, flow regimes through openings and its head losses so affecting the internal airflow.
Field measurements were made during the heating season to compare IAQ between an air– conditioned building (Building A) and a naturally ventilated building (Building B) situated in the centre of Pyongyang and similar in architectural design, number of occ
We present a series of analogue laboratory experiments of the transient exchange flow between a room filled with warm air and a cold exterior following the opening of a doorway. Our experiments suggest that the time-scale for mixing the fluid in the room below the top of the doorway is independent of the door height. We then describe the steady-state two-layer stratification that is established when, in addition to the exchange flow, a localised heat source provides heat at the base of the room.
Video camera calibrations and field tests for air change rates in a test house were performed to develop a new method of measuring air change rates using a video imaging technique. From the camera calibrations, it was found that good correlation was achieved between image signals and luminous reflectance of achromatic color chips by appropriately adjusting the pedestal level of the video camera so that the image signals were made equal to zero for the black level of the picture.
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