Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances a designer wishes to use intermittent ventilation, rather than constant ventilation, but there are no easy equivalencies available. This report develops a model of efficacy that allows one to calculate how much intermittent ventilation one needs to get the same indoor air quality as a the continuous value specified.
This AIVC Technical Note has been produced in the frame of the EU RESHYVENT project, conducted from January 2002 to December 2004. An outline of this project is given in the introduction of this report. The report initially was aimed at the project participants; however, many information may also be of general interest to manufacturers and designers of hybrid residential ventilation systems. Therefore it has been made available to a wider audience by publication as an AIVC TN.
The basic strategy for providing indoor air quality in residences is to dilute indoor sources with outdoor air. This strategy assumes that the outdoor air does not have pollutants at harmful levels or that the outdoor air is, at least, less polluted than the indoor air. When this is not the case, different strategies need to be employed to ensure adequate air quality in the indoor environment. These strategies include ventilation systems, filtration and other measures.
Submitted by Maria.Kapsalaki on Tue, 09/17/2013 - 08:57
Ventilation is required to provide to remove or dilute pollutants and incidentally meets metabolic oxygen requirements for occupants. In addition ventilation may also be required to provide oxygen for combustion devices and as a means of summer cooling.
Ductwork is used for transport of air used for ventilation or air conditioning in buildings. The supply air is typically conditioned (filtered, warmed or cooled, sometimes humidified or dehumidified). It is important that the air is distributed properly in the building. Thus the duct system must be well balanced regarding airflow rates, or have provisions controlling the air distribution. The ducts should have a low leak rate. A primary function is also thermal insulation to protect the heat content of the air.
This review attempts to summarise available airtightness, minimum ventilation rate and indoor air quality requirements, standards, codes of practice and regulations. It also attempts to determine the nature and type of thermal insulation requirements and the rationale behind the data outlined in this report. Attempts have also been made to normalise the data, where appropriate to enable comparisons to be undertaken.
Infiltration has long served the residential ventilation needs in North America. In Northern Europe it has been augmented by purpose-provided natural ventilation systems - so-called passive ventilation systems - to better control moisture problems in dwellings smaller than their North American counterparts and in a generally wetter climate.
In recent years a substantial number of monitoring exercises have been made to determine the way in which occupants react to and/or are affected by the indoor environment. These cover a diverse range of aspects including:
indoor air quality;
moisture and condensation;
the build up of pollutants;
the impact of airtightness and reduced ventilation rates;
the actions of occupants in controlling their environment.
The first chapter aims to provide the reader with an overview of the basics of acoustics, which are required as part of the ventilation systems design process. With this knowledge the designer can, with the remaining chapters, apply these principles to providing quiet and effective ventilation in buildings. A detailed analysis of background, components, problems and methods for achieving quiet ventilation systems in buildings.
In recent years, the 'usability' of ventilation and air infiltration models (both public domain and commercially available) has increased greatly. Possible areas of application for 15 such models are identified in this report. (These are mainly 'network' models.) In addition, it discusses the input data that must be provided in order to use them. The capabilities of the models are described and full contact details on how to obtain them are provided.