AIVC - Air Infiltration and Ventilation Centre

Search form

EBC

You are here

Home

mathematical modelling

The multi-chamber theory reconsidered from the viewpoint of air quality studies.

A general multi-chamber model is presented and explored from the viewpoint of air quality studies. The model involves the following key concepts: purging flow rate and age distribution of both air and contaminants. From the physical and mathematical properties of the model, are deduced estimates of themagnitude of, and the relations between, the key concepts. The practical use of the model is illustrated.

A new analytical approach to the long term behaviour of moisture concentrations in building cavities - 2. Condensing cavity.

A previous paper analysed a mathematical model of a non-condensing cavity. This paper extends the analysis of the first paper to analyse the seasonal moisture behaviour of a condensing building cavity. Climate statistics are used to calculate the duration of the winter wet-up period, and a rate of condensation formula is integrated to give total winter condensation. Although engineering design calculations cannot yet be attempted, some illustrative examples are given based on field data. The results give preliminary verification of the model analysed in both papers.

A new analytical approach to the long term behaviour of moisture concentrations in building cavities - 1. Non-condensing cavity.

This paper, the first of two, presents a conceptual model of moisture concentrations in a building cavity. The model is comprehensive and general considering air infiltration, vapour diffusion and material hygroscopicity under non-steady state conditions. The resulting linearised coupled differential equations are analytically solved to study the case of long term cavity moisture behaviour. Dimensionless parameters and algebraic formulae are presented describing all important moisture performance parameters for a non-condensing cavity.

A computer algorithm for predicting infiltration and interroom airflows

This report discusses the extension of an infiltration predicting technique to the prediction of interroom air movements. The airflow through openings is computed from the ASHRAE crack method together with a mass balance in each room. Simulta

Modeling and measurement of pollutants inside houses in Pittsburgh, Pennsylvania

Mathematical models for predicting indoor pollutant levels are being developed and compared with measured concentration in three residential dwellings - a relatively new townhouse constructed according to rigid energy-conservation guidelines,

Verification of calculation models of air infiltration using three types of test houses.

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.

The influence of climate and ventilation system on airtightness requirements.

Air infiltration typically accounts for a third of the energy loss in a heated building. The driving forces for natural air infiltration are wind and temperature differences. For a given combination of weather conditions the amount of air infiltration is determined by the character of the building envelope, mainly its airtightness. A useful technique in characterizing this housing quality is to measure air leakage. An air leakage standard for new construction has been in effect in Sweden since 1975.

Predicting thermal comfort of people in naturally ventilated buildings

Describes a new procedure for predicting the thermal comfort of people in naturally ventilated buildings. The procedure starts by obtaining, for each important wind direction, velocity ratios between points of interest inside the proposed bu

Experimental determination of empirical flow coefficients for air infiltration through pitched roofs

The heating and cooling loads due to air infiltration may be estimated by a mathematical model that requires knowledge of the leakage characteristics of each component of the envelope. To extend the modelisation to the pitched roofs common in Portugal, characteristics of roofs were determined by a differential pressure method.

Computer analysis of building ventilation and heating problems

This paper presents a mathematical model, implemented in a general computer code, that can provide detailed information on the velocity and temperature fields prevailing in three-dimensional buildings of any geometrical complexity, for a given v

Pages