Hygrothermal performance of attics
Samuelson, I.
1998
J. Thermal Env. & Bldg. Sci, Vol 22, pp 132-146
attic, moisture
Samuelson, I., (1998), "Hygrothermal performance of attics", J. Thermal Env. & Bldg. Sci, Vol 22, pp 132-146.
| Abstract: |
| This paper describes the results of measurements of temperature and relative humidity in six different attics (roof spaces) under controlled conditions. All six attics have the same dimensions and have been constructed adjacent to each other in a single line, but with different insulating materials and ventialted in different ways. Using this fund of measured data, a number of researchers have attempted to apply their mathematical models and, starting from the basis of measured ambient climatic conditions, have calculated expected values of temperature, relative humidity, and in one case, the moisture ratio in the attics. The results of these calculations showed difficulties in matching the performance of the models to real conditions. Notes that there is some degree of moisture buffering in hygroscopic insulation materials (cellulose materials) compared with non hygroscopic insulation (mineral wool). However, the difference is not particularly large; there are considerable differences in moisture and temperature variations in roofs with high and low ventilation rates. The higher the amount of ventilation using outdoor air, the greater the variations; The climate in the attic becomes drier the less it is ventilated. States that moisture can be introduced during the building stage or in normal use. Building moisture must be allowed to dry out before it can cause damage. During the subsequent use stage, convection of moist air up into the attic must be prevented. This is done by ensuring that the structure is airtight in combination with an internal negative pressure.
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