stack effect

Correlates hourly infiltration in 3 adjacent unoccupied test houses to determine the relative contribution of wind and stack effects. The database, obtained using tracer gas techniques over 2000 hourly readings in each house, is sorted to a single 45 degree sector. Different weather sealing techniques give mean infiltration rates of 0.19, 0.45, and 0.59 ach for the 3 houses. Addition of independent wind and temperature induced pressures correlate only part of the weather induced data variability leaving a residual RMS scatter of about 0.004 ach.

Makes an experimental investigation of the distribution of pressure differences across the walls of a 20-storey student residence building at the University of Ottawa. Measures the wind velocity at the test building as well as the temperature distributions both inside and outside the building.

Reports the results of an experimental assessment of the effect of a chimney on the air leakage characteristic of an unoccupied two-storey detached house heated by either gas or electric furnace. Measurements were taken of air tightness values and air infiltration rates with the chimney capped anduncapped.

Uses a similitude approach to develop predictive graphs for the ventilation rate due to the stack or chimney effect. Uses a half scale model of an open side wall structure with a continuous and restricted open ridge, and finds that:< 1. Ventilation rate is approximately proportional to ridge outlet width< 2. Outlet Reynolds number response ie ventilation rate to changes in Grashof number is a function of the ratio between building height and ridge width.

Two series of pressurisation and ventilation measurements have been made in a low-energy house. One of the objectives of the work was to assess the extent to which the ventilation pattern of the house could be improved by modifying its leakage distribution. The first series of measurements was interpreted to understand the ventilation pattern and to make recommendations for the modifications. The second series was used to find out the effects of the modifications.

Describes method for calculating the adventitious ventilation of a building using information from a pressurization test. The method requires a knowledge of the surface pressures on a building, calculated from wind speed and direction, the inside-outside temperature difference, and the distribution and characteristics of openings in the building shell. Applies formulae to threebuildings and finds a great dependence of infiltration on wind direction. Discusses the effect of wind and stack effect, separately and combined.

Describes a computer technique for analysing air movement resulting from stack effect in a tall building. Describes the method which determines the air flows for all possible paths through exterior walls and within the building. The building is divided into multi-storey zones based on the design of the building and the HVAC system. Gives an example of the method applied to a building under two different climatic conditions. Considers the problem of thedifficulty in opening doors due to excess pressure across the door.

Presents a model for predicting air infiltration that eliminates many site- specific parameters normally required. The only information necessary is the geometry and leakage of the structure obtained from fan pressurization measurements. Theleakage quantities, expressed in terms of effective areas, are total leakage area and the leakage areas of the floor and ceiling. Weather parameters are mean wind speed, terrain class, and average temperature difference. The model separates the infiltration problem into two distinct parts: stack and wind regimes.

The authors show how the shape and surroundings of buildings and their situation in relation to prevailing winds affect the pressure distribution in a building. Variations in positive and negative pressure zones in relation to wind speed and direction in discussed and the so-called "stack effect". Model tests carried out in wind tunnels on both high and low buildings are reported.

Discusses ways of modifying distribution of stack effect through building by design and construction. Suggests many of the problems caused by stack effect could be alleviated byincreasing air tightness of building enclosure and interior separations. Discusses influence of mechanical ventilation systems on stack effect. Shows that pressurization does not eliminate stack effect but alters distribution of pressure differences.