Ventilation has a considerable influence on both the indoor air quality and energy consumption of buildings. Three parameters can be identified which are of key importance in the assessment of ventilation behaviour: air change rate, interzonal air flows, air leakage characteristics. This paper describes measurement techniques which enable these parameters to be evaluated. The listof techniques presented is not exhaustive and the descriptions given are not particularly detailed.
For more than four years air infiltration measurements have been made on two nearly identical side-by-side test houses in Gaithersburg, Maryland, USA. This testing of the complete seasonal weather influence on air infiltration has, in the past two years, included constant concentration tracer gas measurements (CCTG). These multizone air infiltration measurements have added further detail on the response of air infiltration into the house to weather changes and the variation of air infiltration between different house locations.
The construction and performance of a dynamic wall house are described. It is suggested that such houses function much like the traditional houses with leaky walls and active chimneys. Only here ventilation is controlled while a significant part of the energy required to heat the ventilation be lost. A model is proposed to explain how much walls function at relatively low ventilation rates. The approach promises to improve indoor air quality and thermal envelope performance at reduced construction and energy costs.
A simplified model of air infiltration has been developed at Lawrence Berkeley Laboratory, in order to expand the use of air flow calculation techniques outside the field of research. The validity of the programme must be checked. Benefit has been gained from work dedicated to the same problem in the field of building thermal analysis. Following this idea, a detailed validation methodology is proposed. Progression in the complexity of the modelled structures, use of high accuracy data are sine qua non to this task.
A simplified pocket calculator model has been developed which can simulate the air flow distribution in multizone structures. The model is based on lumped parameters and includes several assumptions to simplify the description of air flow due to wind and stack effect and their superimposition. This paper gives a brief overview of the model and describes several applications. Results obtained from a mainframe based research tool. The examples show that the simplified method can be used to predict air mass flows within reasonable accuracy for different types of buildings.
Sections include: measuring procedure air tightness of facades; evaluation of measuring air tightness in practice; infrared thermography; thermographical research in air tightness, ability to detect air tightness deficiencies with thermography; ability to quantify air leakage; architectural analysis of airtightness deficiencies; recommendations.
Air change rates are measured by an IR-gas-analyser coupled with a microcomputer which is programmed to control measurements as well as data acquisition and evaluation. The implemented programs provide an instant access to results. The experimental equipment is installed in compact form on mobile units. Measurements have been taken in a university laboratory by using the decay- and constant-emission-method to examine air change rates under various conditions. Typical results are presented and show where each of the two methods is more appropriate.
A computerised portable unit for measuring the ventilation efficiency by the tracer gas technique is described. The hardware of the unit is designed from readily available equipment. The software of the unit is menu-driven to be operated by computer non-experts. The software include several analytical models of ventilation processes and in the present study, age analysis and the air exchange efficiency are discussed.
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