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Wessberg, Magnus (2019) Indoor climate analysis and model based control of massive construction historic buildings. Doctoral thesis, Czech Technical University in Prague.


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Indoor climate in historic buildings pose both practical and scientific challenges. There are two fundamental challenges that must be addressed. The first challenge is establishing a proper indoor climate with respect to both human comfort and, above all, conservation of the building itself and itsinterior including artworks and furniture. The second challenge is achieving the desired indoor climate in a non-invasive, sustainable, and energy efficient way. With a focus on preservation, relative humidity is the most important parameter. Not only the level but also the change rate of relative humidity is of importance. Although the methods and technical equipment for humidity control in historic buildings have been widely investigated, a number of problems need further investigation, including efficiency and safety. This thesis explores the link between technical implementation and target ranges for indoor climate, including control strategies and algorithms that take into account cost effectiveness, energy efficiency, and sustainability. The first addressed method is intermittent heating of massive historic buildings. To control the change rate of relative humidity at a heat-up event, a simplified model is presented for heat and moisture transfer during the heat-up period. In addition, a method is presented and validated to derive the hygrothermal parameters and the time constant of the building from measurements measured at a step response test. Finally, the study considers a feedforward control algorithm that uses the model to predict and control the change rate of relative humidity during the heat-up procedure. The method has been validated on measurements and models of three churches on the island of Gotland, Sweden. Unheated historic buildings often face problem with high humidity levels that can lead to increased risk of mould growth. One of the energy efficient methods that can decrease the mould growth risk is adaptive ventilation. Adaptive ventilation was designed to be a low energy and low impact option, but needs validation and further development. The main questions are if the measure is sufficient to limitthe risk for mould growth, how it influences the stability in relative humidity, and if it is an energy efficient measure. These aspects are widely addressed in the thesis. A great deal of attention is paid to installation aspects of the case study objects and subsequent thorough data analysis. The performed research shows that adaptive ventilation essentially lowers the number of hours of risk for mould growth on a yearly basis, but there is still an increased risk for some short periods when adaptive ventilation is not a sufficient measure. The performed study also indicates that the adaptive ventilation measure is likely to increase risk of mechanical damage to objects due to increased variability of relative humidity fluctuations. Finally, in a three year study of Skokloster Castle, three climate control measures are compared: dehumidification, conservation heating, and adaptive ventilation. This comparison includes efficiency to prevent risk for mould growth, indoor climate stability, and energy efficiency. The study shows that dehumidifying had the best result regarding all three criteria for rooms located in the upper floors, which typically lack internal moisture sources. However, rather than a method to eliminate the risky levels of relative humidity, the air-tightness of the interiors was revealed as the prime mitigation measure for the given interior class.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: Indoor climate, relative humidity, humidity control, intermittent heating, mould, adaptive ventilation, dehumidification, energy efficiency
Subjects: English > Climate Control
English > Damage functions
English > Climate Control > Dehumidification
English > Climate Control > Heating
English > Climate Control > Ventilation
English > Damage functions > Biological damage
English > Damage functions > Mechanical damage
Spara och bevara - Publications
Depositing User: Susanna Carlsten
Date Deposited: 29 Nov 2019 09:40
Last Modified: 29 Nov 2019 09:40

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