In buildings with mechanical ventilation there are spaces with substantial pressure differences, which bring exfiltration, infiltration and transferred air between the rooms. For such buildings we have converted a multiple cell theory to a quadratic programming problem, and developed a computer programme, MCSPID for airflow identification. Today MCSPID is inpractical use to simultaneously determine flow rates for airsupply, exhaust air, transferred air, infiltration and exfiltration with a single tracer gas.
As the thermal performance of buildings continues to improve, air exchange will eventually become the dominant mechanism for building heat loss. Although, therefore, an essential parameter of the energy equation, ventilation is nevertheless vital forthe dilution and removal of pollution generated within buildings. An inadequate supply of fresh air or poor air distribution will result in high levels of indoor contaminants, discomfort and a poor living environment, it could also result in more serious health related problems.
AC pressurisation is a method for measuring the airtightness of buildings. This technique, which is also called the infrasonic method, employs a reciprocating piston or bellows to impose a sinusoidal small change in volume inside the building
The Air Infiltration and Ventilation Centre is currently finalising the detailed work program for its Numerical Database. This is being developed in response to the need to establish a core of numerical data, suitable for model validation, themodelling of real buildings, assessment of standards, the effects of new building methods and the use of differing ventilation systems.
As part of its new operating programme, the Air Infiltration and Ventilation Centre is establishing a numerical database to be used both in support of design studies and for the verification of numerical models. In addition to being available as a computer database, it is intended to present selected source data and simple algorithms in loose leaf form as a new volume in the AIVC's series of Application Guides.
This article briefly describes a new piece of apparatus, recently developed at UMIST, which can be used for the determination of ventilation rates in, and air movement rates between, four interconnected cells.
These problems can be overcome by compensating for the pressure drop over the flow meter in such a way that the pressure on the duct side of the grille remains the same before and after the positioning of the flow meter. This is a very well known technique. However in the field of air conditioning, devices using this principle are rare. The compensation of the pressure drop is performed by a fan and regulator which blows just enoughair through the flow meter to meet the pressure compensation before the grille.
Ten years ago the automated constant concentration tracer gas (CCTG) method was conceived at the Technological Institute, Tastrup, Denmark. This technique is now used by researchers toexamine a wide variety of air infiltration and ventilation related problems. At this juncture it would seem appropriate to summarise the development of the CCTG system and examine its use in present day research.
After the oil crisis in the seventies the main aims of ventilation research changed. Many energy saving measures had been taken by the authorities, among them the reduction of infiltration heat losses. The Ministry of Building and Urban Development ordered the production and installation of better quality airtight windows, and the draughtproofing of existing window assemblies.
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