Lars-Erik Harderup

Previous experimental studies and field measurements on moisture buffering by indoor surface materials

An increased interest in moisture buffering in the indoor environment and the development of more refined hygrothermal calculation tools call for a better understanding of the phenomenon. There are many materials indoors with potential to act as moisture buffers, ranging from traditional finishing materials as gypsum plaster to textiles. The objective of this study is to show that the interest in moisture buffering is not a new issue. There have been significant laboratory studies made in the past. This study presents a review of such previous studies (1960-2000) on indoor surface materials from Germany and Sweden, not published in English before.

Moisture Safety in Cold Attics with Thick Thermal Insulation

AbstractDamage caused by moisture and mold in attics has increased in Sweden during recent decades. The main reasons are thicker thermal insulation between the living space and the attic and lack of a warm chimney. Very thick thermal insulation will result in attics that are more sensitive to convection from the living space. With only a thin layer of thermal insulation, the attic will be warmer as a result of convective heat transfer from the living space. With a warmer attic during the winter, a certain amount of vapor can enter into the attic from the occupied area without causing any damage. With very thick thermal insulation, however, vapor cannot be allowed to enter the attic. Without a chimney, the temperature in the attic will decrease (especially in winter), which will result in higher relative humidity and lower ventilation owing to a lack of buoyancy. A warm chimney will also increase the natural ventilation in the occupied area and hence decrease the amount of vapor entering into the attic by ...

Healthy Indoor Environments: The Need for a Holistic Approach

Indoor environments have a large impact on health and well-being, so it is important to understand what makes them healthy and sustainable. There is substantial knowledge on individual factors and their effects, though understanding how factors interact and what role occupants play in these interactions (both causative and receptive) is lacking. We aimed to: (i) explore interactions between factors and potential risks if these are not considered from holistic perspective; and (ii) identify components needed to advance research on indoor environments. The paper is based on collaboration between researchers from disciplines covering technical, behavioural, and medical perspectives. Outcomes were identified through literature reviews, discussions and workshops with invited experts and representatives from various stakeholder groups. Four themes emerged and were discussed with an emphasis on occupant health: (a) the bio-psycho-social aspects of health; (b) interaction between occupants, buildings and indoor environment; (c) climate change and its impact on indoor environment quality, thermal comfort and health; and (d) energy efficiency measures and indoor environment. To advance the relevant research, the indoor environment must be considered a dynamic and complex system with multiple interactions. This calls for a transdisciplinary and holistic approach and effective collaboration with various stakeholders.