AIVC - Air Infiltration and Ventilation Centre

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air change rate

Methods of investigating natural ventilation Methodes d'etude de la ventilation naturelle = Ventilacion: metodos de estudio de la ventilation natural

Refers to previous article treating application of theory of graphical representation in building services of calculating natural ventilation rates in buildings. Illustrates technique using examples of several buildings. Concludes that at themoment this approach is too complex and costly for general application except in specialised cases. Considers simplified methods may be developed suitable for general use.

Residential energy conservation-the Twin Rivers project.

Gives general account of Twin Rivers project summarising main findings from 1972 to date. Includes section on air infiltration. Measurements of infiltration rates were taken using tracer gas method and regression equation found for the data.

The prediction of ventilation rates in houses and the implications for energy conservation

Developes mathematical model of air infiltration based on crack flow equations. Describes measurements made on test house. Shows that actual pressure distributions in walls deviate considerably from values in guidebooks. Finds background leakage area of house by pressurizing house with electric fan and measuring pressures. Suggests two distributions for leakage areas. Measures infiltration rate using helium tracer gas, recording temperature and pressure differences. Concludes that comparison between prediction and experimental results is encouraging.

Ventilation research in occupied houses

Gives results of measurements of air-change rates and heat loss in occupied and unoccupied houses on two sites, one exposed and the other sheltered. Observations of the wind pressures on the houses and of the window-opening habit of the occupants are discussed. These are used in conjunction with the results of a regional survey of the temperatures maintained and the window-opening habits in local authority houses to extend the application of the results of other housing.

Determination of the ventilation rate in a series of social houses

Describes the determination of infiltration rates for houses in Seneffe. Gives infiltration rates for individual rooms, found using O2 as tracer gas, and recording wind speed and direction. Determines global air renewal rate using N2O as tracer gas, by injecting gas through ventilators into all rooms and measuring concentration in each room. Calculates global concentration from individual measurements.

Ventilation measurement with a candle as a tracer gas source. Ventilationsmatning med laga som spargaskalla.

Practical measurement has shown that gasoil and candle flames provide constant tracer gas sources. Suggests their use for meaSuring ventilation. suggests application in temporary dwellings such as caravans, using candle as simulated "people" consuming oxygen and producing heat and carbon dioxide. Describes measurement methods using natural decay exponential equation. Graph illustrates sequence when air change rate fulfills requirements in swedish building code 1975 of 0.5 change/hour.

Residential air infiltration

When attempting to determine heating/cooling requirement of a home a difference in infiltration can drastically affect heating/cooling requirement imposed on air conditioning system. Describes "the super sucker" machine designed to depressurise homes so that infiltration can be measured under simulated windconditions and each area of leakage isolated. Illustrates machine photographically. Gives method of determining air change rates. Summarises test data for several homes which indicatethat infiltration could be effectively reduced by use of various caulking compounds.

Weatherstripping windows and doors. Calfeutrement de fenetres et des portes

Describes different types of weatherstrips and reports ageing and deformation test on strips and tests on air tightness and closing force. Concludes that tubular strips provided the highest degree of airtightness in both windows and doors, while angle strips were only slightly inferior in performance. Air leakage was considerably greater for strips of expanded and foam plastics and fibre strips. Tests on ageing properties indicated that special rubber mixtures such as silicone rubber and epdm were preferable to p.v.c.

Ventilation measurements in the Norris Cotton Federal Office Building in Manchester, NH

Reports measurements of ventilation rate in specially designed low energy office building. Air change rates were measured using sulphur hexafluoride as a tracer gas and air samples were analyzed for carbon dioxide. Gives tables of results. Discusses analysis of ventilation from CO2 data. Concludes that most of the spaces in the building were operating at or above recommended levels.

Ventilation measurements at model scale in a turbulent flow.

Treats measurements of ventilation rates in a model building and wind tunnel. 2 types of opening, circular holes and model windows were tested under 2 wind cOnditions. one wind condition was selected to give maximum flow through the model; with theother, ventilation was mainly due to turbulent pressure fluctuations. Illustrates different characteristics of theopenings. Draws comparisons between measurements and theoretical predictions. Discusses use of wind tunnels for ventilation studies. NOTES: A further comment on this paper was published in Building and Environment vol.15 no.141.

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