Draughtproofing the doors, windows and other sources of excessive air leakage of a dwelling can be an effective and relatively inexpensive means of improving comfort and reducing heat loss by natural ventilation. The doors and windows considered in this digest are existing components not originally designed for draughtproofing. Products for general use on these components have to fill a wide range of gap sizes, be durable and retain the ease of opening and closing.
The need to conserve energy in buildings of all types has led to improved standards of insulation, including those of flat roofs in domestic, public and industrial buildings. This Digest discusses the properties required of thermal insulation in flat and low-pitched roofs with continuous waterproof coverings. It reviews the wide range of products available and suggests criteria for selection.
Computational fluid dynamics may be used to predict the details of airflow in rooms served by displacement ventilation systems, provided a suitable turbulence model can be found. Since buoyant plumes are central to the displacement ventilation strategy, four turbulence models - three eddy-viscosity models (the 'standard' k-s model, a modified k-s model, and an RNG k-s model) and the Reynolds stress model - were applied to simulate airflow in a turbulent buoyant plume.
This paper deals with the description and determination of the purging flow rate, UP for ventilation systems or equivalent flow systems. The regional purging flow rate and its use are discussed and proposed. By using the mass conservation principle, UP is embodied in various accessible mathematical expressions in terms of the transfer probability. Some UP-related parameters are described. A Markov chain model is proposed for determining the transfer probability and exploring several useful ventilation indices.
The largest-ever exercise to validate dynamic thermal simulation programs (DSPs) of buildings has recently been completed. It involved 25 program/user combinations from Europe, the USA and Australia, and included both commercial and public domain programs. Predictions were produced for three single-zone test rooms in the UK. These had either a single-glazed or double-glazed south-facing window, or no window at all. In one 10-day period the rooms were intermittently heated and in another 10-day period they were unheated.
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