Exergy applied to lunar base design

This paper explores design considerations for energy efficiency in lunar habitats. It considers several previous lunar energy studies in regards to energy types and stages of energy requirements. If we are to obtain true sustainability in energy processes, we will need to design according to the principles “exergy”, considering both the first and the second laws of thermodynamics in a holistic and thorough evaluation of energy capture, transformation, and use. Such an evaluation will ascertain the source of energy, its processing and energy potential stages, as well as the task required. Traditional designs of facility thermal systems are frequently extremely wasteful: they dramatically increase both first costs and operating costs because they treat heating and cooling systems as separate entities, instead of an integrated energy system. Energy processes, the state of energy required to do a particular task, the embodied energy to complete or manufacture an object, and the wasted energy released are all important to conservation and obtaining an efficient and effective use (quality) of energy. If the regulation of energy processes is a concern in terrestrial habitation, it should be even more so for extra-terrestrial habitation where there is little margin for waste of any sort.

Life cycle cost analysis of silicon and organic building integrated photovoltaic systems (BiPV)

Despite the undisputed benefits associated with photovoltaic (PV) technology, the financial barrier acts as the major hurdle before it is seen as a commercial competitive form of renewable energy. Many studies have been performed outlining the life cycle energy benefits of PV technology. However, there has been limited number of studies dedicated to the life cycle cost impacts. The aim of this paper is to identify whether life cycle cost analysis is the best approach to determining the cost contributors or savings associated with this technology. This paper has been structured similarly to previous life cycle energy studies to consider the cost implications involved within each area of the products lifecycle. Amongst many new developments, traditional silicon based units have been challenged by the introduction of new organic systems; and recent studies highlight that these systems offer major cost reductions. Based on an analysis of current literature, this paper identifies that the recent growth and development of both organic and silicon based systems have had a considerable effect on the cost of PV cells. The competitive nature of the renewable energy market will also impact on a life cycle cost analysis; and any potential findings will valid for a limited timeframe.

Thermal simulation studies of a low energy university building in Australia

A key criterion by which any building will be judged when its environmental impact is assessed is its thermal performance. This paper describes the simulation of an office module in a three-storey university building in south eastern Australia. The module, located at the north-west corner of the top floor of the building, was chosen because it is likely to have the highest cooling load - a primary concern of energy conscious designers of commercial buildings for most parts of Australia.

In the paper, the initial key assumptions are stated, together with a description of a "reference" or base case, against which improvements in thermal performance were measured. The simulation process identified the major influences on thermal performance. This enabled changes in materials and construction, as well as basic design concepts to be evaluated. Features incorporated into the base case such as a metal roof and glazed walkway were found to have adverse influence on energy consumption, and were consequently rejected in preference for an improved design which included a hypocaust slab system on the roof of the office module. The final design was predicted to reduce the annual energy consumption for heating and cooling by 72% and 76% respectively.

La performance thermique est l'un des critegraveres cleacutes de l'eacutevaluation environnementale de tout bacirctiment. Cet article deacutecrit la simulation d'un module de bureau appartenant agrave un immeuble de trois eacutetages d'une universiteacute du sud-est de l'Australie. Ce module, situeacute agrave l'angle nord-ouest de l'eacutetage supeacuterieur du bacirctiment a eacuteteacute choisi car c'eacutetait lui qui, vraisemblablement, avait la charge de refroidissement la plus eacuteleveacutee, ce qui est une preacuteoccupation majeure des concepteurs conscients des problegravemes d'eacutenergie des bacirctiments commerciaux dans la plus grande partie du pays. Le processus de simulation a fait apparaicirctre trois influences principales sur la performance thermique par rapport agrave un cas de base. Cela a permis d'eacutevaluer les modifications apporteacutees aux mateacuteriaux et agrave la construction ainsi qu'aux avant-projets. Les caracteacuteristiques inteacutegreacutees dans le cas de base comme le toit meacutetallique et la passerelle vitreacutee avaient une influence neacutefaste sur la consommation d'eacutenergie et ont donc eacuteteacute rejeteacutees au beacuteneacutefice d'un concept ameacutelioreacute qui comprenait une dalle de type hypocauste sur le toit du module de bureau. Le concept final devrait reacuteduire la consommation annuelle d'eacutenergie pour le chauffage et le refroidissement de 72 % et 76 % respectivement, ce qui donne une ideacutee de la valeur ajouteacutee au processus de production agrave partir de proceacutedures avanceacutees de modeacutelisation et de simulation.

Recent studies on yarn tension and energy consumption in ring spinning

High energy consumption remains a key challenge for the widely used ring spinning system. Tackling this challenge requires a full understanding of the various factors that contribute to yarn tension and energy consumption during ring spinning. In this paper, we report our recent experimental and theoretical research on air drag, yarn tension and energy consumption in ring spinning. A specially constructed rig was used to simulate the ring spinning process; and yarn tension at the guide-eye was measured for different yarns under different conditions. The effect of yarn hairiness on the air drag acting on a rotating yarn package and on a ballooning yarn was examined. Models of the power requirements for overcoming the air drag, increasing the kinetic energy of the yarn package (bobbin and wound yarn) and overcoming the yarn wind-on tension were developed. The ratio of energy-consumption to yarn-production over a full yarn package was discussed. A program to simulate yarn winding in ring spinning was implemented, which can generate the balloon shape and predict yarn tension under a given spinning condition. The simulation results were verified with experimental results obtained from spinning cotton and wool yarns.

Reliability of building embodied energy modelling: an analysis of 30 Melbourne case studies

Building design decisions are commonly based on issues pertaining to construction cost, and consideration of energy performance is made only within the context of the initial project budget. Even where energy is elevated to more importance, operating energy is seen as the focus and embodied energy is nearly always ignored. For the first time, a large sample of buildings has been assembled and analysed in a single study to improve the understanding of the relationship between energy and cost performance over their full life cycle. Thirty recently completed buildings in Melbourne, Australia have been studied to explore the accuracy of initial embodied energy prediction based on capital cost at various levels of model detail. The embodied energy of projects, elemental groups, elements and selected items of work are correlated against capital cost and the strength of the relationship is computed. The relationship between initial embodied energy and capital cost generally declines as the predictive model assumes more detail, although elemental modelling may provide the best solution on balance.