English

Gives a general description of air-to-air heat exchangers. Discusses criteria for measuring the performance of heat exchangers. Briefly discusses factors affecting actual performance. Describes the heat exchanger facility atLawrence Berkeley Laboratory. Reports tests on four commercially available heat exchangers and one home-made exchanger. Gives results of tests of effectiveness and airstream static pressure drop. Concludes that heat exchangers with performance characteristics superior to those tested can be manufactured for a reasonable cost.

Describes some of the problems encountered when the full-scale wind pressure measuring system was set up in an experimental building at the University of Hong Kong. Discusses effects such as excessive damping caused by the air trapped in the pressure- balancing tubings, and the interference between transducers. Describes modifications of the measuring system to overcome these problems.

The Lawrence Berkeley Laboratory measured the indoor air quality at Fairmoor Elementary School in Columbus, Ohio. A mobile laboratory was used to monitor air outdoors and at three indoor sites (two classrooms and a large multipurpose room); tests were made at three different ventilation rates. The parameters measured were outside air flow rates, odor perception, microbial burden, particulate mass, total aldehydes, carbon dioxide, carbon monoxide, sulfur dioxide, ozone, and nitrogen oxides.

Reviews the ventilation requirements for residential buildings and the recently discovered contaminants of indoor air which will have an influence on the required ventilation rates. Describes methods of measuring air leakage and the rate of air infiltration. Cites work aimed at finding the correlation between air leakage and air infiltration. Outlines the role of heat recovery devices and recommends areas of further research. An appendix reports on a Canadian Mortgage and Housing Association seminar "Controlled ventilation with exhaust air heat recovery for Canadian housing".

Discusses sources of radon in buildings and the prediction of levels of radon and daughters. Derives differential equations governing the decay and venting of radon and its daughters. A computer program based on these equations has been written to predict radon and daughter concentrations, total potential alpha energy concentration and equilibrium factor. The program can account for time dependence of ventilation and emanation rates and is readily used by building designers.

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 study of the energy consumption and ventilation requirements of typical existing public schools in New York. Electricity and fuel-oil consumption data from May 1970 to April 1973 from 19 schools were analysed.

Notes one of the principal ways in which members of the public receive natural irradiation is by breathing the decay products of radon 222. Reviews data on radiation exposure and the incidence of cancer for uranium miners. Discusses uncertainties and inadequacies in the data. Gives estimates for the incidence of lung cancer in the general public, caused by radon exposure.