humidity

Explores how water gets into a structure, why it doesn't leave, and how these architectural flaws become HVAC problems. States that mechanical engineers need to understand the roots of the problems in order to defend their work if IAQ becomes a problem once the building is occupied. The article reviews air control and pressurization, ventilation and humidity control and provides some resources to help expand the reader's knowledge of design and construction errors that lead to HVAC problems.

Thermal bridges are the typical locations for moisture and mould problems in buildings. Low surface temperatures in combination with a high humidity level in buildings can lead to severe problems and complaints by the occupants. Thermal bridges lead also to a significant increase of the energy losses in well insulated buildings. At present, thermal bridge problems still frequently occur in new buildings but especially in rehabilitation projects. In several countries so-called thermal bridge atlases already exist.

We describe the potential of using hygroscopic materials that release moisture and latent heat in order to reduce the temperature of building envelopes and, there upon, conduction cooling loads. It is analysed 3 different weathers and a classic Brazilian wall with different values of paint permeance on both external and internal surfaces. The results are presented in terms of temperature, moisture content profiles and heat fluxes, showing how to save energy from the natural movement of moisture.

The paper traces the paradigm changes for house design in warm-humid climates, from the preference for traditional elevated, lightweight, ventilated buildings, through the advocacy for heavy construction, to the present conclusion that both can be equally good. The extension of selection criteria is suggested, to include psychological factors, which seem to favour the lightweight, cross-ventilated buildings. The success of these depends on the cooling effect of air movement, hence an attempt is made to quantify this effect.

Moulds are a health concern. High levels of moulds in a building environment are to be avoided. Some species or high concentrations of mould are a serious health risk, and must be dealt with if we want to maintain healthy indoor environments. Gives New York City remediation guidelines, and lists methods to control mould growth: 1) Repair indoor and outdoor water leaks, 2) Clean and disinfect smooth surfaces, 3) Clean and dry other materials or remove them, 4) Discard porous contaminated materials, 5) Control moisture sources (e.g.

For more than 100 years, temperature control has been the principal concern of our industry. That focus and our collective efforts have achieved immense improvements in the human condition – improvements so fundamental that they are usually overlooked and unappreciated, even by ourselves. We seldom reflect on what the world was like before the refrigeration of food and medicine, or before the availability of low-cost, reliable heat in the winter and cooling in the summer. However, in spite of- or because of- those achievements, the expectations of the public have moved higher.