nitrous oxide

The local ventilation efficiency of a mechanical ventilation system may in general terms be defined as "providing air in those parts of a room where it is required". In this paper different definitions of the local ventilation efficiency and methods for measuring it are discussed. Presents results from measurements of ventilation efficiency. A test room was mechanically ventilated and nitrous oxide used as a tracer gas. A number of sensors were placed in the room with the aim of determining the variations in the air change rates within the room.

Reports findings of investigations carried out by West German Federal Ministry of Health in July 1978 into the internal climate in the one third of the rooms in a representative West Berlin school which are located in the building core. These rooms have mechanical ventilation and artificial lighting. Gives results of measurements of room temperatures, air change rates, (measured using N2O as a tracer gas), concentration of carbon dioxide and acoustic performance of the rooms.

Proposes a method of linking pressurization measurements in buildings with infiltration rates. The method is based on a simple theoretical model. Gives details of whole house pressurization tests and tracer gas measurements of ventilation rate (using N2O) in fifteen houses. Gives details of the theoretical model and compares field measurements with model predictions. Finds good agreement and concludes model may be used to estimate air change rates using leakage data. Finds surface pressure coefficients for typical house shapes and notes a dearth of data of this type.

The ventilation rate and energy consumption of one of the ECRC test houses was monitored continuously during one heating season, with one bedroom window open by various amounts. Results show that a very small window opening is sufficient to satisfy ventilation requirements most of the time. 

Reviews tracer gas methods for measuring ventilation rate and discusses the diffusion of gases. Describes four tracer gas methods; rate of decay, equilibrium concentration, transfer index and constant concentration. Discusses the analysis of results. Describes an experimental room and series of measurements of air change rate using two methods a) rate of decay, where a balloon filled with gas was burst as a point source and b) equilibrium concentration where tracer gas was released continuously at a constant rate.

Reports measurements of natural ventilation and leakage rates in two test rooms in a university building. Describes rooms and instrumentation. Gives results of pressurization tests with windows closed but not sealed, sealed, and weatherstripped. Gives results of measurements of ventilation rate using N2O as a tracer gas. Discusses the analysis of results and experimental errors. Compares measured rates with ventilation rates calculated using crackand ASHRAE methods.

Reports the results of three programmes of measurements of ventilation carried out in one-family houses, which in most cases were of the 'council house' type. The first programme measured ventilation rates using tracer gasin two houses room by room. Wind speed and direction were recorded but no general relation between ventilation and wind was found. The second measured ventilation rate in individual rooms in a house under six different wind conditions. The third measured ventilation rates in three identical homes.

Describes technique for measuring the volume of air leaving a house through the loft. Two tracer gases are used; nitrous oxide is released in the house and carbon dioxide in the loft. The mean concentration of N2O in the loft gives the volume of house air infiltrating the loft: and the mean concentration of CO2 gives the ventilation rate of the loft itself.< Gives two examples of the use of this technique and gives loft ventilation rate as a function of wind speed for one house.

Presents results of measurements of ventilation rate and window air leakage made in blocks of flats in Sweden. Describes measurement of ventilation rate using nitrous oxide as a tracer gas and pressurization tests on windows. Gives graphical results of tests. Finds that the majority of windows do not satisfy 1975swedish building code. Reports measurements of air leakage of windows before and after renewal of draught excluders. Concludes that old windows can be made relatively draught-free and that this is not expensive or time consuming.

Describes method of measuring air flow in mines using nitrous oxide as a tracer gas. Examines two methods of measuring airflow, releasing a continuous stream of a gas and releasing a known quantity of gas. Describes laboratory study andunderground tests of method. Concludes that technique is reliable and accurate.