English

The purpose of ventilation system is to provide and remove the airflow from room in accordance with its design. Unfortunately, in practice, this basic task is very often not fulfilled, which is frequently caused by negative handling by the users of the building. The most common reason for improper operation of the mechanical ventilation system is its insufficient output in particular sections of the system.

To measure a flow in a closed duct, one of the available methods is to explore the velocity field. The duct is divided in elementary sections in which the velocity is measured. Using these elementary results, a mean velocity is calculated. Knowing the exact section of the duct, the mean flow rate can then be deduced. With this method, the quality of the flow measurement is there very dependent on the number of individual velocity measurements and on the scheme of distribution of these measurements in the duct section. 

The preliminary Standard prEN16211 deals with methods, including method uncertainties for measuring air flow rates on site. It has its background in the Nordic countries, where these guidelines have been used for decades. PrEN16211 include an alternative method for flow measurement in a duct compared to EN 12599. An average flow can be obtained from just a few measurement points when a straight duct is used and some simple flow conditions are met.  

The PerFluorocarbon Tracer (PFT) method is a low-cost approach commonly used for measuring air exchange in buildings using tracer gases.  It is a specific application of the more general  Continuous-Injection, Long-Term Sampling (CILTS)  method. The technique  is widely used but there has been little work on understanding the uncertainties (both precision and bias) associated with its use, particularly given that it is typically deployed by untrained or lightly trained people to minimize experimental costs.

The present paper addresses experiences with infiltration and ventilation in the Active House concept, based on the Active House Specification and realized Active Houses. The Active House Specification is based on a holistic view on buildings including Comfort, Energy and Environment. It uses functional requirements to indoor air quality and thermal comfort, and does not have component requirements to airtightness or specific ventilation solutions. Experiences from realised Active House projects show that better airtightness than nationally required has been achieved.

This paper describes the method, in which human observers assess indoor air quality. This method is at present necessary to determine actual levels of air quality indoors in non-industrial buildings to fulfil comfort requirements specified by the standards. The paper attempts to identify the potential drawbacks of the method, its limitations and the factors influencing these measurements. Examples are given illustrating, how the measurement uncertainty influences the estimated level of indoor air quality.