Reports insights from research project "Optimalisatie koelhuisbouw" (Optimisation of cold store buildings) by the Delft Technical University for the Foundation for Cooling Technique Development. Pleads for standardisation of the maximum admissible heat gain by air leakage and yearly averaged pressure differences between the cold room and its surroundings. Gives some numerical examples. Uses theory of specific equivalent leak opening.
Radon, an inert radioactive gas, and its products of decomposition, will attack the lungs when present in high enough concentrations. Notes high concentrations of radon in mines and other underground spaces and even in well water. Radioactivity of building materials is a problem in Sweden. States concentration of radon in air is highly dependent on ventilation. Radioactivity in a dwelling is highest in the morning and drops in the daytime when doors and windows are open. Normally an air change rate of 0.5 per hour keeps radon content of indoor air at an acceptable level.
Describes use of an acoustic method developed by Keast to detect air leaks. A loud source of sound is placed inside the building and a microphone, stethoscope, rubber hose or sound meter is used to detect places where anincrease in sound indicates air leakage. Finds method is effective in detecting simple leaks but will not spot complex paths through walls.
Reports tests on 4 different windows of air leakage and sound transmission loss. Expresses each of these two quantities by a single parameter and finds reasonable correlation between the parameters. Concludes, within the limitations of the method, that the air leakage class of a window can be deduced from field measurements of sound transmission loss, when the acoustical performance in perfect sealing conditions is known.
Describes the operating characteristics of a small aspirated concentration sensor based on a hot-film anemometer. Constant aspiration velocity past the sensor produces a linear output over a wide range of tracer gas concentrations, and a useful bandwidth of 0-500 Hz. A simple experimental technique for dynamic calibration is presented, with frequency response inferred from a model of the effects of molecular diffusion and hot-film response.
The requirement for better methods of predicting infiltration and natural ventilation rates has been reinforced by the incentive to reduce energy consumption in buildings. Natural ventilation is basically dependent on the effects of wind and temperature difference and on the resistance to airflow through the building. Discusses in detail these factors and highlights areas requiring further study. Briefly illustrates energy savings available by controlling natural ventilation.
Outlines factors influencing natural ventilation rates. Discusses techniques for measuring natural ventilation. Gives results of pressure measurements, made by the Building Research Establishment, of the leakage of houses and of tracer gas measurement of room ventilation rates. Discusses variation in air leakage rates with time. Gives results of measurements of the distribution of air leakage between components of the building shell.
Discusses acceptable levels of CO2 contamination in occupied rooms. Describes measurements in a classroom over 3 days using an infra-red analyser with natural ventilation via the windows. Illustrates curves for CO2 concentrations in 8 graphs for closed windows. Notes that limiting value of 0.1% by volume CO2 (1000ppm) is reached in from 5 to 15 minutes. Repeated sudden ventilation by opening windows is not practicable. Evaluates air change rate. Concludes energy saving for ventilation in heavily populated rooms is only attainable by mechanical ventilation with heat recovery.
Reviews ventilation criteria for occupied buildings. Considers minimum ventilation for the control of carbon dioxide, odours, cigarette smoke, moisture and radon. Discusses future work to improve ventilation routes.
Steeply sloping ventilated roofs are preferred for single and two-family houses in West Germany. Notes lack of any scientifically substantiated notions concerning physical laws governing air exchange between ventilated zones and outside air. Describes air flow and heat transfer investigations in a 48 deg. sloping roof. Gives details of roof constructions. Illustrates roof space and distribution of thermocouples and arrangement for injecting tracer gas. Describes experimental procedure. Provides some measurement results. Compares theoretical bases with experimental results.
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