States that although controlled mechanical ventilation is becoming more widespread, the installations and their application are capable of improvement. Illustrates diagrammatically and explains methods of improving the components, their installation and operation. Considers ways of improving the air tightness of the buildings. Concludes by describing methods of simulating the performance of controlled mechanical systems, which facilitates the evaluation of measures aimed at improving their operation.
Presents four short articles treating aspects of building ventilation: 1) Achieving a balance - the work of the AIC, 2) House full of horrors - indoor air pollution and progress in eradicating hazards, 3) Letting off steam - test houses with ventilation system for condensation control, and 4) High and dry - condensation in the roof, eaves to eaves ridge ventilation.
Describes validation of a simple technique for infiltration measurement in large, multicelled, naturally ventilated buildings by reference to a computer model study and by field measurements in two naturally ventilated office buildings. The salient features of the technique are: 1) a single tracer gasis used, 2) measurements need only be carried out in part of the building, 3) an initially uniform distribution of tracer is not needed, and 4) artificial mixing of the tracer with the internal air is not essential.
An exposure chamber for testing passive dosimeters suitable for measuring indoor air pollutant concentrations has been designed. A simplified version of the chamber was constructed and formaldehyde passive sampling devices were exposed within this chamber. Both CSC prototype and AQRG dosimeters were tested, and an attempt was made at calibrating the devices by verifying their theoretical sampling rates. The sampling rate for CSC devices was found to behigher than expected.
Tests were performed in 3 homes for 1) carbon monoxide, 2) nitrogen dioxide, 3) nitric oxide, 4) total hydrocarbons and 5) formaldehyde. Total particulate matter, by a numerical counting method, was also measured in Homes 1 and 2.
A study was conducted to determine the air leakage rates in Skymark 1, a high rise condominium in Toronto, particularly air leakage rates of the exterior walls of "Florida Rooms" which were constructed by the enclosure of original open balconies.
A test method for determination of air flow resistance of exterior membranes and sheathings is described. The test specimen is placed between two chambers with different air pressures and the volumetric air flow rate through it at a steady state is determined. The relevant experimental quantities can presently be measured with precision better than 0.5% and with an accuracy of 2 to 3%, using commercial instruments. However, the instrumental precision does not mean much, due to the uncertainty introduced by material variability normally occurring in commercial products.
The multiple tracer gas technique of I'Anson et al. has been improved, in order to increase the rate at which samples can be taken. Using parallel gas chromatographic separation columns and an electron capture detector, it is now possible to take an air/tracer gas sample every thirty seconds in the case of a two-zone ventilation and air movement test. Rapid sampling enables a new,simplified analysis of the air movement between two connected zones to be employed. This analysis derives ventilation rates and intercell airflows simultaneously.
A large proportion of heated rooms depend primarily on natural convection for the distribution of heat within the occupied zone. A method of predicting air temperature variations with height is presented. Using the heat and mass flow rates of the driving convection plume, along with the corresponding parameters of downward flowing air streams at cool surfaces, an estimation of the maximum (upper) temperature and the minimum (lower) temperature can be made. Incoming air entry points can also be taken into account.
Explains the principles involved in condensation and the conditions producing condensation, both atmospheric and other sources of moisture. The behaviour of absorbent materials and surfaces is described. Interstitial condensation is explained. Designing to avoid condensation, taking account of the characteristics of the building fabric and the environment, is necessary. A worked example of estimating condensation risk is given.
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