By observing animal housing in severely cold conditions it was realised that an airtight building with mechanical ventilation did not provide the optimum solution, but better results were obtained from porous buildings. Reports aninvestigation made on a large model building simulating the humidity and temperature conditions in animal housing during winter. The model had a porous ceiling of flax straw.
A fair comparison of ventilation systems is almost an impossible achievement. Even an economic comparison causes difficulties; the different systems render different room air qualities which cannot be counted in money.
Calculations show that natural ventilation exploiting wind and specific gravity differences may reduce the need for ventilation heat. This is not done as usual by ventilation through open doors and windows but through fine porous air-permeable outside walls. The optimum thickness of the heat insulation layer is defined, giving maximum saving of total heating and ventilation energy.
Briefly reviews factors to be taken into account in considering natural ventilation in commercial and industrial buildings. These factors include the location of the building, surrounding buildings, activity within the building and results required of the installation. Notes some of the problems andpossible advantages of combining natural and fan powered systems.
Assesses the role of natural ventilation in modern hospitals. Considers optimum standards of air change rates for winter and summer conditions and reviews factors within the hospital context that are likely to affect the achievement of natural ventilation. Notes an air change rate of 1.5/hr. is usually assumed for heat loss calculation. Finds cross ventilation is unlikely to be achieved and designs should be based on single sided ventilation. Reports tracer gas measurements of natural ventilation in Southland Hospital, Shoreham by Sea.
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.
Presents code of practice which supersedes CP3:chapter 1(c):1950. Deals with ventilation of buildings for human occupation. Outlines main reasons for provision of ventilation and gives recommended quantitative air flowrates. Shows that these form the basis for air supply recommendations for different types of buildings, and rooms characterised by usage. Gives basis for choice between natural and mechanical ventilation. Provides guidance on design of natural ventilation systems. chapter headings are: General, General principles of ventilation, natural ventilation, appendices.
Presents a simple model for the calculation of wind induced ventilation. The model requires as input, pressure coefficient data, wind direction, and the open areas for each element of the building. Gives an example of the model applied to a model livestock building. Gives flow chart and listing of computer program. Note model does not include temperature effects.
Discusses the mechanisms of natural ventilation. Gives equations for stack effect and ventilation due to wind. Discusses use of natural ventilation in livestock buildings. Shows how minimum and maximum ventilation rates for winter housed cattle can be calculated using physiological data and a model for calculating the critical temperatures. Gives sample calculation of the ventilation rate necessary for beef cattle housed in a 9m. wide building.
Describes an automatic measurement system for air infiltration and discusses factors influencing the measurements in single rooms or in a group of connected rooms. The system works on the decay rate method and is controlled by a purpose-designed controller. The test data are evaluated off-line by computer. Discusses in detail the instrumentation and test procedure Gives results of measurements made in a detached house and correlations of the test data with wind and temperature difference data. Gives a comparison with pressurization data.