A review of moisture buffering capacity: from laboratory testing to full-scale measurement

It is important to control indoor humidity level in buildings as it influences occupant’s health and comfort. Hygroscopic building materials present great potential to passively regulate air humidity due to their ability to adsorb and desorb moisture. In recent years researchers have focused on this capacity, referred to as Moisture Buffering, as it has the potential to improve indoor thermal comfort and reduce HVAC usage and their consequent energy consumption. However, building designers generally do not consider this property an important factor, due to its unclear influence and difficulty in the quantification of its effects in real buildings. Therefore, it is complicated to develop an appropriate laboratory scale testing. The aim of this paper is toinvestigate the challenges related to moisture buffering measurement and to examine the approaches adopted by researchers. The significance of this study is to identify discrepancies between existing methods in the evaluation of the dynamic adsorption properties and presents areas for further development in testing

A review of moisture buffering capacity: from laboratory testing to full-scale measurement

It is important to control indoor humidity level in buildings as it influences occupant’s health and comfort. Hygroscopic building materials present great potential to passively regulate air humidity due to their ability to adsorb and desorb moisture. In recent years researchers have focused on this capacity, referred to as Moisture Buffering, as it has the potential to improve indoor thermal comfort and reduce HVAC usage and their consequent energy consumption. However, building designers generally do not consider this property an important factor, due to its unclear influence and difficulty in the quantification of its effects in real buildings. Therefore, it is complicated to develop an appropriate laboratory scale testing. The aim of this paper is toinvestigate the challenges related to moisture buffering measurement and to examine the approaches adopted by researchers. The significance of this study is to identify discrepancies between existing methods in the evaluation of the dynamic adsorption properties and presents areas for further development in testing

Development of earth occupation standards within the UK

Belgium Herbarium image of Meise Botanic Garden

Shifting perceptions: Establishing an Earth Building Organisation in the UK

The UK has a rich heritage of earthen buildings and recently a renewed interest in the use for contemporary construction. It is estimated that the UK has thousands of earth buildings including residential, educational, commercial and religious buildings built using a wide range of techniques. However earth building is relatively unknown within the construction industry and there is lack of awareness across all construction professions, funders and insurers; all key parties to further adoption of earthen building materials. This paper will review the establishment of the UK’s national earth building organisation, commenting retrospective on both the success and challenges faced. It was found that projects led by passionate individuals with support from within the organisation help overcome challenges associated with a new organisation with no natural geographic centre and widespread voluntary human resources. Beyond the initial need for developing the organisation a discussion regarding the need for charitable status and the resulting change of governance that has led to a successful project-led approach for the organisation. Similar national organisations in other countries will benefit from this review of the approach, which will help achieve our objective of the growth and awareness of earthen construction. <br/

Kinetics of CO2-fluid-rock reactions in a basalt aquifer, Soda Springs, Idaho

The dissolution of silicate minerals by CO2-rich fluids and the subsequent precipitation of CO2 as carbonate minerals represent a means of permanently storing anthropogenic CO2 waste products in a solid and secure form. Modelling the progression of these reactions is hindered by our poor understanding of the rates of mineral dissolution–precipitation reactions and mineral surface properties in natural systems. This study evaluates the chemical evolution of groundwater flowing through a basalt aquifer, which forms part of the leaking CO2-charged system of the Blackfoot Volcanic Field in south-eastern Idaho, USA. Reaction progress is modelled using changes in groundwater chemistry by inverse mass balance techniques. The CO2-promoted fluid–mineral reactions include the dissolution of primary plagioclase, orthoclase, pyroxene and gypsum which is balanced by the precipitation of secondary albite, calcite, zeolite, kaolinite and silica. Mineral mole transfers and groundwater flow rates estimated from hydraulic head data are used to determine the kinetics of plagioclase and orthoclase feldspar dissolution. Plagioclase surface area measurements were determined using the evolution of the U-series isotope ratios in the groundwater and are compared to published surface area measurements. Calculated rates of dissolution for plagioclase range from 2.4 × 10−12 to 4.6 × 10−16 mol/m2/s and orthoclase from 2.0 × 10−13 to 6.8 × 10−16 mol/m2/s respectively. These feldspar reaction rates, correlate with the degree of mineral–fluid disequilibrium and are similar to the dissolution rates for these mineral measured in other natural CO2-charged groundwater systems

Moisture buffering in surface materials due to simultaneous varying relative humidity and temperatures:Experimental validation of new analytical formulas

Buildings are subjected to the indoor environment, especially in non-controlled climates. Temperature and humidity variations might effect or even damage materials sensitive to moisture. For this reason, it is important to understand the response of hygroscopic materials to variable indoor environmental conditions. Existing methods looked into the dynamic sorption capacity of materials, by analysing the impact of only humidity fluctuations, with temperature usually considered non-influential or non variable. However, temperature fluctuations may impact the moisture capacity of the materials, as materials properties might substantially vary with temperature. Moreover, in existing protocols, the humidity variations are considered to be varying under square wave fluctuations, which may not be applicable in environments, where the indoor is influenced by daily and seasonal climate variations, which presents more complex fluctuation. In this study, a simulation method that can predict the impact of environmental condition on materials under simultaneous temperature and humidity fluctuations was developed. Clay and gypsum plaster were analysed in the numerical model and results were then validated with experimental data. Materials were subjected to either sinusoidal and triangular temperature and RH variations and different cycle time intervals. The investigation of sinusoidal and triangular environmental variations pushed to a better understanding of materials response to different environments and to the improvement of the simplified model. The development of a simplified model can realistically predict the potential future impact of climate changes on buildings without the use of complex and memory demanding computational methods

A review of liquid metal anode solid oxide fuel cells

This review discusses recent advances in a solid oxide fuel cell (SOFC) variant that uses liquid metal electrodes (anodes) with the advantage of greater fuel tolerance and the ability to operate on solid fuel. Key features of the approach are discussed along with the technological and research challenges that need to be overcome for scale-up and commercialisation

Kinetics of CO2-fluid-rock reactions in a basalt aquifer, Soda Springs, Idaho

The dissolution of silicate minerals by CO2-rich fluids and the subsequent precipitation of CO2 as carbonate minerals represent a means of permanently storing anthropogenic CO2 waste products in a solid and secure form. Modelling the progression of these reactions is hindered by our poor understanding of the rates of mineral dissolution–precipitation reactions and mineral surface properties in natural systems. This study evaluates the chemical evolution of groundwater flowing through a basalt aquifer, which forms part of the leaking CO2-charged system of the Blackfoot Volcanic Field in south-eastern Idaho, USA. Reaction progress is modelled using changes in groundwater chemistry by inverse mass balance techniques. The CO2-promoted fluid–mineral reactions include the dissolution of primary plagioclase, orthoclase, pyroxene and gypsum which is balanced by the precipitation of secondary albite, calcite, zeolite, kaolinite and silica. Mineral mole transfers and groundwater flow rates estimated from hydraulic head data are used to determine the kinetics of plagioclase and orthoclase feldspar dissolution. Plagioclase surface area measurements were determined using the evolution of the U-series isotope ratios in the groundwater and are compared to published surface area measurements. Calculated rates of dissolution for plagioclase range from 2.4 × 10−12 to 4.6 × 10−16 mol/m2/s and orthoclase from 2.0 × 10−13 to 6.8 × 10−16 mol/m2/s respectively. These feldspar reaction rates, correlate with the degree of mineral–fluid disequilibrium and are similar to the dissolution rates for these mineral measured in other natural CO2-charged groundwater systems

Straw bale construction in northern China:Analysis of existing practices and recommendations for future development

Straw bale buildings in China have been mainly limited to rural farm houses and self-builders. An expansion of strawbale construction into main-stream medium-rise buildings has the potential to make a significant contribution to the reduction of both embodied and operational carbon in China as well as removing a major source of pollution. As a response, there has been the construction of straw bale buildings, however these buildings have several issues, resulting in the limited adoption of the technology. This paper makes recommendations for future straw bale design in northern China based on an inspection of existing buildings. The issues identified with existing construction details were subjected to computational simulation analysis which identified shortcomings in existing practice and proposes revisions to design detail in order to accommodate the environmental conditions in northern China. The paper provides a unique insight into current straw bale practice in northern China and proposes a practical and environmentally sound solution to the pollution crisis in this region