The use of lightwells and courtyards for natural ventilation in high-rise buildings is exaimed using both wind tunnel and field measurements of the pressures and neutral pressure zone caused by wind and temperature differences. Though air flow patterns are complex for complex building designs, air exchange rates in lightwells and courtyards were generally seen great enough to assure clean air for natural ventilation via air infiltration. However the cost of land in urban settings will probably make mechanical ventilation systems the economic choice.
This paper reports the results of measurements of inside surface temperatures on a basic double window arrangement consisting of two sheets of glass surrounded by insulated construction. Principal variables were air space width, height, and overall temperature difference. Carefully controlled natural convection conditions were provided on the warm side, with forced convection on the cold side. Results were also obtained for the average surface to surface thermal conductance of each configuration.
This paper discusses the flow of air around ideal (cubic) structures on plane surfaces subjected to a turbulent boundary layer wind. These winds are shown to follow a power-law variation with height, while winds significantly effected by thermal stratification follow a log-linear distribution. Discussion of stagnation zones, flow separation, and pressure changes is included, with possible effects upon air quality and infiltration. Also discussed are variations in building design and addition of neighboring buildings, both which produce very complex winds, yet to be quantized.
An analysis of ventilation necessary to maintain air quality in an above-ground fallout shelter was done, making use of theoretical models, and generalizing the results to fit measurements on actual shelter data. Results show that, at most, boundary surface heat loss serves as a safety factor for ventilation systems, and thus ventilation systems should be designed to remove the entire thermal load generated within the shelter. This, when considered in addition to weather and load expectations, establishes an upper limit on ventilation equipment size.
This report contains a brief description of an air infiltration measuring device jointly developed by the National Bureau of Standards and Princeton University's Center for Environmental Studies. The device maintains a constant concentration of a tracer gas (SF6) in each room of a structure by injection, and relates the infiltration rate for each room to the rate of gas injected. Specifics of construction and use are included.
This report describes research undertaken to investigate the various factors affecting the air infiltration through windows. These factors examined include: 1) The effect of edge and face clearance or window fit 2) The effect of groove clearance on weatherstripping 3) The effect of weatherstripping 4) The effect of locking windows 5) A comparison of infiltration and exfiltration through windows 6) The effect of sash shrinkage, and 7) Theeffect of one-piece storm windows.
The purpose of this research project is for the Thermal Engineering Section of NBS to conduct air leakage measurements on selected large buildings tovalidate calculation formula developed by Shaw and Tamura, (see Shaw, C.Y., and Tamura, G.T., 'The Calculation of Air Infiltration Rate Caused by Wind and Stack Action for Tall Buildings', ASHRAE Trans., Vol. 83 part 2).
A comprehensive computer program for the prediction of air flow and smoke migration in the building was applied to the 11 story administration building of the National Bureau of Standards. Natural air leakage rates under various climatic conditions for several ventilation system operations were obtained. The computed results were compared with measured air leakage rate by using the sulphur hexafluoride tracer gas technique. Smoke migration was simulated for the selected pressurization conditions.
This report describes a technique which models the infiltration process for an entire enclosure more accurately than standard methods. Both air flow and convective/conductive heat transfer are accounted for to (a) improve building heat load calculations, (b) determine the important characteristics of existing (and new) buildings for infiltration heat loads, and (c) account more accurately for wind effects.
The effect of ventilation on airborne contamination was studied in a new operating suite containing operating rooms with conventional ventilation (17-20 ach) and operating rooms with zonal ventilation, where the air change in the central part of the room was about 80 ach. The efficacy of the ventilation was first examined with gas tracer experiments and foundsatisfactory. Experiments using potassium iodide particles showed the transfer between adjacent rooms in the suite to be less than .001% with closed doors and from 1% to .025% when the doors were opened once a minute.
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