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Reflectance and temperature of bare field soil were measured to determine the relationship between soil water content and spectral reflectance and temperature. Reflectance in the six reflective Thematic Mapper (TM) wavebands plus a 1.15 to 1.30 μm waveband (referred to as MMR5) was measured using a ground-based radiometer across a soil water gradient provided by a line source sprinkler system. Temperature was measured using a hand-held infrared thermometer. The results of this study show that TM band 7 reflectance (2.05-2.30 μm) provided improved estimates of surface soil water content (0-0.5 cm depth) over estimates using reflectance information from all seven TM bands. Good correlations were found between band ratio spectral indices of TM5/TM7, MMR5/TM7, and MMR5/TM5 and surface soil water content. A soil temperature normalization utilizing daily values of maximum vapor pressure deficit was found to provide improved estimates of soil water content to depths greater than 0.5 cm over estimates using other temperature normalizations.

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There is little doubt that moisture is a very important factor in relation to material durability. The need for tools to assist in the better understanding and systematic evaluation of moisture movement with the view of incorporating the results within the overall framework of the defect investigation, quality control, and long-term monitoring of moisture, have led to the development of various moisture monitoring and predicting techniques. With the purpose of helping to harmonise the interests in this field, this thesis addresses three major issues in the area of wood moisture. Various studies carried out have been shown that there are substantial discrepancies between specific timber species and published charts for equilibrium moisture content. One of the main objectives of this research was to focus on establishing the equilibrium moisture content for a range of relative humidity and temperature on an individual basis, for twenty commercially important species used in the United Kingdom. The rationale for carrying out the project, the results from the initial trial and the mainstream experiment, the hardware and methodology developed are provided. To meet the requirements of long term accurate and reliable moisture monitoring and to provide comprehensive moisture information, a new type of moisture sensor and related measurement system were developed. The methodology of system design and test procedures are described, emphasising the anti-polarisation method, noise rejection and contact resistance reduction techniques employed. Other aspects of the electrical performance of timber were also investigated. Results from a case study showed that the sensor developed can operate in the critical range of relative humidity with sensitive and accuracy. In the final part of the project, two moisture transport models were developed. Mathematical prediction models in both one dimension and three dimensions are presented for simulating the adsorption and desorption processes in wood. Comparisons are made against long-term experimental data for the one dimensional model. The finite differential method was employed to solve the mathematical expressions developed, resulting in accurate prediction of concentration-driven moisture flows. Investigations were also carried out into the moisture diffusion coefficient and moisture behaviour in the three principal wood directions by using the sensor developed which provided isothermal real-time continuous data.

This thesis is an investigation into the moisture performance of straw bales used in the construction of buildings. The principle of taking bales of straw off the field and stacking them up on themselves to form the walls of a simple building is a practise that started over a hundred years ago. The modern form of this building method is more sophisticated, and is spreading world wide from its origins in the arid regions of America. Despite advances in modern methods of construction there has been concern and doubt over the suitability of straw bale for use as a building material in a temperate maritime climate. The main concern being that the higher levels of environmental moisture will have the potential to damage the straw over time. In order to assess the moisture performance of the straw bales in the walls of a building in this damp climate, a simple and effective means of measuring the moisture in-situ has been developed as part of this research. The overarching methodology for this research is to develop a more accurate version of a probe that uses a block of wood to measure moisture. An environmental chamber in the laboratory has been used to establish the hygrothermal relationship between the timber to be used in the probe, and samples of the straw used in construction. This is the first time that a continuous set of sorption and desorption isotherms have been created for samples of straw and timber simultaneously, a process that took six months to complete. This data was used in the design of a new wood block probe, and examples of the new probes were installed in the walls of a straw bale house with a known moisture history. The resulting readings from the new probe were compared to those from a professional agricultural straw moisture probe. These results could be checked against the readings of the relative humidity and temperature in the wall. Forty-eight pairs of the new wood block probe were calibrated in the laboratory. Fourteen diverse examples of straw bale construction were selected as case study buildings. Having been surveyed for this research, a number were then selected to have the new probes installed, and evidence of their moisture performance was recorded. Sufficient data was acquired through this process to confirm the suitability of straw bales for use in the construction of buildings, in a temperate maritime climate.