PR1989

Vol1: Twenty four papers from the tenth AIVC Conference, titles as follows: “Keynote Speech”; “Annex 14 - Condensation and Energy”; “Annex 18 - Demand Controlled Ventilating Systems”; “Trends in Airflow Design and Management,contributions by IEA Annex 20”; “Air Infiltration Measurement Techniques”; “The Performance of the Passive Perflurocarbon Method”;”Experimental Study of Air Flow Patterns in a Three Bedroomed House”;”Multizone Flow Analysis and Zone Selection Using a New Pulsed Tracer Gas Technique”; “Mathematical Modelling of Infiltrat

Building codes that address radon control in residential buildings are a relatively new development in the larger trend toward increased efforts to understand and control indoor air quality. A residential radon construction standard has been developed in the Pacific Northwest region of the United States. The Northwest Residential Radon Standard (NRRS) seeks to provide a measured public policy response that is commensurate with current knowledge of both the health risk and the state of building science.

In Sweden, the energy crisis in the early seventies resulted in attempts to lower the air change rate in buildings to reduce energy consumption. For many building categories, this lead to a deterioration of the indoor climate or problems with moisture and mould growth, Today, many residents demand higher ventilation rates, often the motivation is concerns about health and comfort. In this paper is presented results of measured air change rates in Swedish dwellings during the period 1974-88.

Pressurization, or depressurization, of buildings is a tool to assess the airtightness of building envelopes. A common working pressure is 50 Pa, and the airtightness is expressed in terms of the number of air changes per hour at 50 Pa. To compare buildings of different size a more efficient measure is to define a nondimensional leakage area. We suggest a method to define and calculate the relative leakage area from pressurization data. The method corrects for calibration errors and the effects of aeromotive and buoyancy forces.

In central units of air heating systems the supply air flow must meet the actual heating demand. Most of central units for air heating systems have only one fan , which is designed for the maximum air flow at the maximum heating capacity . Fan motors are designed for variable - voltage-drive to enable a reduction of air flow to the necessary value at different heating demands. However, the electrical efficiency is decreasing strongly. The supply air fan is working mostly under part - load conditions . Therefore the control strategy used now is very ineffective .

This paper gives an overview of air infiltration and ventilation developments and trends in Norway. The paper is divided into an infiltration part and aventilation part. Some key figures for Norway: Inhabitants: 4.4 mill., Low-rise housing: 1.3 mill; blocks of flats: 0.3 mill; degree days (base:20 deg.C): 3500-7600 deg.C D.

This paper describes tracer gas methods and equipment developed to measure infiltration and inter-zone air flow rates in New Zealand houses. Air flows in houses have been studied in detail, in order to understand the role of ventilation in controlling indoor moisture, and the role of air flows through the construction cavities in transferring mloisture to parts of the structure most sensitive to moisture. The main technical content of this paper, however, concerns an automated tracer gas detection and delivery system based around a gas chromatograph and an electron capture detector.

The COMIS workshop (Conjunction of Multizone Infiltration Specialists), using a multi-national team, is planning to develop a reliable, smooth running multizone infiltration model on a modular base. This model not only takes crack flow into account but also covers flow through large openings, single-sided ventilation, cross ventilation and HVAC-systems. The model contains a large number of modules which are peripheral to a steering program. COMIS can also be used as a basis for future expansion in order to increase the ability to simulate buildings.

A tracer gas technique for determining volumes and air flow rates in multi-cell systems with a single tracer gas is considered. Tracer gas is injected in all cells simultaneously according to a cetain pattern and the resulting tracer gas concentrations are recorded. We show how the volumes and flow rates can be identified from the measurements using the quadratic programming method. A characteristic of this method is that the unknown model parameters, i.e. the volumes and flows, can be determined subjected to given constraints.