air leakage

Examines providing some existing multifamily houses with mechanical ventilation with heat exchanger by installing new inlet air ducts to bring back the heat contents of the outlet air. 

Current moisture analysis methods for walls ignore air leakage effects or are not directly applicable to multilayered walls. Mathematical equations were developed for water vapour flow, vapour pressures, and moisture accumulation under steady state conditions with homogeneous one dimensional air flow through a multilayered wall.

Air tightness results for 40 New Zealand timber frame houses of varying age and construction detail are given. The steady pressure method was used at 6-9 indoor-outdoor pressure differences in the range 10-150 Pa. The data is presented in four ways: 1. air changes per hour at 50 Pa, 2. the coefficient and exponent of a generalized leakage function, 3. the leakage rate per unit shell area at 50 Pa, and 4. the equivalent leakage area at 50 Pa. Houses in the 0-5 and 6-20 year age groups were not significantly different in terms of air tightness.

As part of an investigation into the influence of a residential weatherization program on indoor air quality and energy efficiency, a multi-pollutant survey of the air inside 50 Wisconsin homes was conducted three times during the heating season

A tracer method was developed for the evaluation of workplace ventilation. Nitrous oxide or freon was used as the tracer. The concentration of the tracer gas was measured with an infra-red analyser. The versatility of the tracer technique for industrial hygiene applications was improved by the use of a microcomputer for data calculation, display and storage. Three applications are presented: 1. determination of the capture efficiency of a local exhaust hood, 2. the evaluation of the air leakage of a room, and 3. measurement of the local ventilation rates in a large industrial plant.

This paper discusses the situation in the Netherlands with respect to air tightness of dwellings and reflects discussions about this in the Dutch Standard Committee on Air Tightness of Buildings. Results of measurements and calculations are given and the considerations of different groups in thediscussion are included. Finally an attempt is made to produce a model for the prediction of air flow rates, infiltration losses and seasonal gas consumption on the basis of air leakage measurements.

Distinguishes two categories of leaks in buildings for cold storage. Thermal leaks through parts of the construction with poor thermal insulation and air leaks through openings in the walls allowing a more or less free flow of air. Outlines principles of infrared radiation and thermography. Discusses applications for both types of leaks. Under the conditions of high emissivity of the surface to be studied, and absence of local heating or cooling (sun,wind, rain), thermography is an effective method for the detection of thermalleaks and a powerful tool for localizing air leaks.

Retrofitting for air infiltration is undertaken for two principal reasons, to provide greater comfort and to save energy. Qualitative and quantitative measurement of air penetration is an essential prerequisite for planning anefficient retrofit for air infiltration. Describes methods of measurement with two examples of single family houses in sheltered and exposed locations.

In order to verify the calculation models of air infiltration using three wooden test houses which have the same type of construction but have different leakage distributions, airtightness of building components of these three houses were measured by means of the fan pressurization method, and then air infiltration was measured twenty-two times by C02 concentration decay technique.

ASHRAE is preparing a standard which addresses the maximum air leakage associated with good construction. This standard, 119P, links Standard 90, which addresses energy conservation in new residential construction, and Standard 62, which specifies the minimum acceptable ventilation to achieve adequate indoor air quality. Within Standard 119P there is currently a classification scheme that groups building tightness into categories depending on envelope leakage, floor area and building height.