stack effect

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).

Buildings in cold climates must provide an indoor environment that is markedly different from that outdoors. The materials and components of the exterior envelope are subjected to large variations in conditions and greater demands are placed on the indoor environmental control system. Air pressure differences across building elements are augmented by buoyancy forces that influence air movement and indoor air quality. The potential for moisture condensation on and within the envelope is increased as is the danger of freezing in liquid systems.

A study has been made, both experimentally and analytically, of the characteristics of thermal performance of high-rise buildings using an idealized model building with a number of openings at various locations and temperature distributions. The building was assumed to have no internal partitions. The effect of the factors affecting the location of the neutral pressure level was of particular interest.

Discusses strategy for dealing with indoor air pollution in office and similar buildings, including verification of the mechanical ventilation system, measurement of building pressure, problems due to stack effect, presence of moisture. Suggests that the causes and cures of indoor pollution are diverse and surprisingly simple. Mechanical ventilation systems should be less complex, have dynamic stability and correct uncontrolled excessive moisture.

The typical infiltration load for a residential building has been found to range from one-third to one-half of the total space conditioning load. However, most infiltration measurements have been made on single-family houses. 

Ventilation and air exchange in buildings and industrial plants can be induced by external winds and by buoyancy forces. The dependence of the air exchange and heat transfer on a large number of factors, including the detailed configuration of the building and surroundings makes an analytical or numerical analysis of practical design problems impractical, particularly when both the buoyancy and the wind-induced pressures are of the same order of magnitude.

Air change rates were measured in one two-storey detached house with five basic types of passive ventilation systems: an intake vent in the basement wall, an outdoor air supply ducted to the existing forced air heating system, an exhaust stack extending from the basement to the roof, and two combinations of the supply systems and the exhaust stack. An expression was developed for estimating house air change rate from house airtightness, neutral pressure level and indoor-outdoor air temperature difference.

Studies the direct coupling of ventilation heat and solar gains to increase the performance of passive solar systems. Examples of particularly suitable buildings are described. The thermal model FRED, based on a thermal resistance network representing a three-zone building, is modified to include a simple airflow model driven by wind speed and temperature difference. The simulated building is ascribed symmetric permeabilities, then asymmetric permeabilities.

Makes a field study of energy consumption in 3 electrically heated high rise apartment buildings in Chicago, to see if stack effect causes significant variations in the heating requirements of apartments according to their location in tall buildings. The buildings have 30, 42, and 45 floors, and theheating consumption for December through March is computed and plotted against floor number. Results show that normal stack effect is suppressed in a tall apartment building when supply and exhaust fans are running.

Discusses the possible effects of wind, stack effect, vents and fans on air leakage, and the influence of air leakage openings and the location on the pattern of air flow through buildings. Considers the possible extent and location of condensation in relation to these patterns, as well as methods of controlling moisture entry and removal of accumulated moisture.