In order to obtain means for determining realistic convective heat transfer coefficients, a hierarchy of interacting and interdependent calculation methods have been developed by the authors. Both higher and lower level models have been used to develop and verify an 'intermediate level' computer code, which formed the basis for generating input convective heat transfer data for dynamic building models. The contribution considers the computation of convective heat exchange within three-dimensional, rectangular enclosures when buoyancy effects are significant.
One of the recent major developments to the ESP (Environmental System Performance) building/plant energy simulation package has been the integration of a technique capable of performing dynamic air flow analysis as part of the building thermal analysis, thereby permitting simultaneous dynamic modelling of energy and air flow within the building envelope. This paper briefly describes the model and its data requirements. It compares and discusses differences in zone energy requirements and temperature levels (obtained from ESP) when 1. applying traditional air changes rates and, 2.
A program is presented which runs on Apricot, Sirius and IBM-PC microcomputers and calculates the heating energy requirements of single zone, intermittently heated buildings with reasonable accuracy. Calculation of preheating energy is based on the average internal temperature concept of CIBS Energy Code 2. Solar gains and long-wave radiation losses are treated crudely on the basis of regression equations for radiation as a function of daily average external temperature for different periods of the day.
In this programme of work, methodologies for determining infiltration rates of large and complex buildings have been established. Theoretical considerations suggested that comprehensive information regarding interzonal air movements might be obtained from experimental techniques using multiple tracer gases. Field measurements to determine interzonal flows were carried out in office buildings using automated measurement systems developed for this purpose. Simpler techniques were found to be needed and were developed.
The introduction describes the principle of SVP (Solar Ventilation Pre-heating) and then reviews a number of current related topics. Heat recovery is considered. Work on other devices which produce solar heated air is reviewed. The main driving forces of natural ventilation are wind pressure and thermal buoyancy. One of the problems is that the magnitude of these forces is very variable. The basis of SVP demands a thorough knowledge of airflow through buildings.
The application of heat pumps to ventilation heat recovery in domestic houses is considered. It is shown that the most effective system is a combination of heat pump and heat recovery unit; a plate heat exchanger is the type commonly used. Such units are now commercially available, and can provide heat at a lower cost per kilowatt hour than the Economy 7 tariff. The performance of several units is presented, and seasonal running costs have been computed for a house equivalent to the Capenhurst low energy house design.
Work has been in progress for several years on the revision of Byggeforeskrifter (Norwegian Building Regulations), and the new chapter 54 sets quantitative requirements for the air tightness of sections of a building and the building as a whole. In this project, good and bad solutions are illustrated and an effort is made to show the importance of good workmanship. The commonest types of leakage were identified by examination of Leca pipes.The conclusion drawn from the investigations was that Leca pipes should be surface treated to prevent large air leakages.
A new Building Research Establishment audio-visual package, 'Remedies for condensation and mould in traditional housing' sets out the findings of field trials of some available remedies for condensation and mould, carried out in England and Scotland on estates which had a history of complaints of dampness. This research has led to a new understanding of the factors involved in the occurence of condensation and the ways in which they interact. Condensation is most likely to be a problem in the homes which use the least heating.
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