Electret media or "charged" media are electrostatically charged materials that attract, like magnets do, microscopic charged or uncharged particulates. Those media are not the same in structure, stability, distribution of charge and size of their internal electric fields. Charge and structure together determine an electret media performance. In this paper the results of different filter media put to the tests are presented.

An optimal placement of outside air intakes is important for a good IAQ protection. A proper intake placement can also reduce the need for filtration, and reduce re-entrainment of chemical emissions.

In this paper the author relates his experiment : while interviewing unhappy building occupants he realized that it was necessary to step back from the specific complaints and begin with the basics of proper ventilation, moisture control, temperature control before embarking on costly scientific investigations to solve the problem.

This paper presents the advantages and drawbacks of natural ventilation. . The author points out that a natural ventilation would be satisfying, mainly for buildings in mild climates, in taking account the type and quantity of sources in the occupied spaces.

SUBURET stands for Sustainable Building Retrofit. The basic idea behind the sustainability concept is that normal renovation work fails to meet future needs and, far from exploiting the available potential, prevents any real modernization of the building stock. The name SUBURET designates both the workshop itself and all the R&D initiatives proposed.
The SUBURET programme aims to promote advanced retrofit concepts and technologies specifically focused on housing and office buildings and based on the following principles:

A simple model of a rotating duct cleaning brush was presented using large deformation elastic theory. The results obtained by the model were compared with the results obtained by a laboratory test. Especially, the effect of air drag on the brush behaviour was considered.

Rotating brushes are commonly used in cleaning air ducts. A very simple model simulating the behaviour of a typical brush bristle is presented. The model consists, in effect, of a combination of a polynomial trial solution, the point collocation method, Simpson's integration rule and a Mathcad code. The main interest from the cleaning point of view is in determining the contact force and the contact angle between the bristle tup and the duct surface. The effect of the degree n of the polynomial trial solution - n=4, n=6, n=8 - is studied.

The bristle of a rotating cleaning brush for air ducts was modelled using large deformaion elastic theory. The point collocation method with a trial solution consisting of undertermined parameters was employed to discretize the resulting non-linear problem. The main interest was in determining the value of the bristle tip contact normal force N, the bristle tip contact angle B and the torque T needed to rotate a brush. The results obtained using the simple model were compared with the results obtained from a laboratory test.

This thesis is based on studies undertaken during the period 1998-2003 at the HVAC laboratory of Helsinki University of Technology.The thesis focuses on dust accumulation in, and removal from, recently installed supply air ducts and on the bristle behaviour of rotating duct cleaning brushes. The results of dust accumulation, measured using three different methods, were compared and the amount of dust in newly installed air ducts was evaluated. The vacuum tests was found to be an efficient method of collecting dust samples on the duct surface.

The purpose of the present study was to evaluate the possibility to reproduce heat and air flowcharacteristics in a machine room where high heat generating systems and devices are installed. For this purpose, in an experiment room was air-conditioned by double floor air supply on the assumption that the machine room, data were selected such as air flow rate of the systems and various boundary conditions were elected. Further, double floor supply air flow rate distribution, and heat and air flow distribution in the room were measured.