Using small reverse cycle air conditioners in relocatable classrooms - a case study

A 9-month study of four relocatable school buildings, each retro-fitted with small reverse cycle air conditioners (ACs), was conducted to investigate their effectiveness in heating and cooling the classrooms. A comparison with data from previous studies found the energy used by the ACs for heating these temporary classrooms was only 19–20% of the energy used by individual gas heaters installed in permanent classrooms. When equipment efficiencies were considered, the AC units supplied 20–27% less energy to heat the classrooms. The possible reasons for this reduction in supplied energy are explored in this paper. CO2 emissions for the AC units in heating mode, however, were calculated to be 16% greater than for individual gas heaters. The AC units were also used for cooling and on an average the total annual energy consumption for heating and cooling was found to be 11.6 kWh m−2. Responses to a small survey of staff and students about the use and operation of the conditioners are presented. Their responses were more favourable than the predictions of comfort levels in the classrooms using the Predicted Mean Vote–Predicted Percentage of Dissatisfaction (PMV–PPD) model, which indicated “uncomfortable” conditions on average summer days at 3:00 p.m. and average winter days at 10:00 a.m. Background noise levels in the classrooms with the air conditioners in use were above the recommended maximum design level of 45 dB(A); levels of up to 65 dB(A) were measured.

The influence of pacing during 6-minute supra-maximal cycle ergometer performance

The aim of this study was to evaluate the influence of pacing on performance, oxygen uptake (V̇O₂), oxygen deficit and blood lactate accumulation during a 6-minute cycle ergometer test. Six recreational cyclists completed three 6-minute cycling tests using fast-start, even-pacing and slow-fast pacing conditions. Cycle ergometer performance was measured as the mean power output produced for each cycling test. Energy system contribution during each cycling trial was estimated using a modified accumulated oxygen deficit (AOD) method. Blood lactate concentration was analysed from blood sampled using a catheter in a forearm vein prior to exercise, at 2 minutes, 4 minutes and 6 minutes during exercise, and at 2 minutes, 5 minutes and 10 minutes post-exercise. There was no significant difference between the pacing conditions for mean power output (P=0.09), peak V̇O₂ (P=0.92), total V̇O₂ (P=0.76), AOD (P=0.91), the time-course of V̇O₂ (P=0.22) or blood lactate accumulation (P=0.07). There was, however, a significant difference between the three pacing conditions in the oxygen deficit measured over time (P=0.02). These changes in the time-course of oxygen deficit during cycling trials did not, however, significantly affect the mean power output produced by each pacing condition.

Hybrid life-cycle inventory for road construction and use

Life-cycle assessment (LCA) is a technique that is used worldwide by clients and their design team to assess the impact of
their projects on the environment. The main advantage of LCA is in supporting decision making with quantitative data. LCA inventories
can be either fully developed or streamlined. Fully developed LCAs are time-consuming and costly to prepare. Streamlined LCAs can be
used as an effective decision-making tool when considering environmental performance during the design process, but with a loss of
inventory completeness. Acknowledging the advantages and disadvantages of both types of LCA, this paper proposes a hybrid LCA
method that uses input-output data to fill in those gaps routinely left in conventional LCA inventories.

Life-cycle energy analysis of building integrated photovoltaic systems (BiPVs) with heat recovery unit

Building integrated photovoltaic (BiPV) systems generate electricity, but also heat, which is typically wasted and also reduces the efficiency of generation. A heat recovery unit can be combined with a BiPV system to take advantage of this waste heat, thus providing cogeneration. Two different photovoltaic (PV) cell types were combined with a heat recovery unit and analysed in terms of their life-cycle energy consumption to determine the energy payback period. A net energy analysis of these PV systems has previously been performed, but recent improvements in the data used for this study allow for a more comprehensive assessment of the combined energy used throughout the entire life-cycle of these systems to be performed. Energy payback periods between 4 and 16.5 years were found, depending on the BiPV system. The energy embodied in PV systems is significant, emphasised here due to the innovative use of national average input–output (I–O) data to fill gaps in traditional life-cycle inventories, i.e. hybrid analysis. These findings provide an insight into the net energy savings that are possible with a well-designed and managed BiPV system.

User-generated content and the changing news cycle

Blogs represent a major development in media consumption and practice.  The Pew Center in the United States reported in mid-2005 that about eight million Americans had created blogs and 32 million read them.  That's equivalent to two-thirds the number of people who read a daily newspaper during a week, a challenging giguew in the context of dwindling circulations.  Blogs represent the start of the 'personal media' revolution, but are only the tip of a range of new media developments.  This paper describes the blog phenomenon and notes its arrival via a series of major new stories.  It suggests we are seeing the emergence of a new news cycle, as blogs and other internet-based media usurp broadcast's role in breaking news.  The paper describes a range of emerging digital journalism forms that make up the 'personal media' revolution.  These include blogs delivered via mobile phones (moblogs); video-based blogs (v-logs); newspapers' use of podcasting to deliver content; and wikis, or peer-generated online content. The media's reaction to this new form of content is described, and the other concludes by looking at the forces driving this new form of journalism.

Glycogen availability does not affect the TCA cycle or TAN pools during prolonged, fatiguing exercise

The hypothesis that fatigue during prolonged exercise arises from insufficient intramuscular glycogen, which limits tricarboxylic acid cycle (TCA) activity due to reduced TCA cycle intermediates (TCAI), was tested in this experiment. Seven endurance-trained men cycled at approximately 70% of peak O(2) uptake (Vo(2 peak)) until exhaustion with low (LG) or high (HG) preexercise intramuscular glycogen content. Muscle glycogen content was lower (P < 0.05) at fatigue than at rest in both trials. However, the increase in the sum of four measured TCAI (>70% of the total TCAI pool) from rest to 15 min of exercise was not different between trials, and TCAI content was similar after 103 +/- 15 min of exercise (2.62 +/- 0.31 and 2.59 +/- 0.28 mmol/kg dry wt for LG and HG, respectively), which was the point of volitional fatigue during LG. Subjects cycled for an additional 52 +/- 9 min during HG, and although glycogen was markedly reduced (P < 0.05) during this period, no further change in the TCAI pool was observed, thus demonstrating a clear dissociation between exercise duration and the size of the TCAI pool. Neither the total adenine nucleotide pool (TAN = ATP + ADP + AMP) nor IMP was altered compared with rest in either trial, whereas creatine phosphate levels were not different when values measured at fatigue were compared with those measured after 15 min of exercise. These data demonstrate that altered glycogen availability neither compromises TCAI pool expansion nor affects the TAN pool or creatine phosphate or IMP content during prolonged exercise to fatigue. Therefore, our data do not support the concept that a decrease in muscle TCAI during prolonged exercise in humans compromises aerobic energy provision or is the cause of fatigue.

The effect of cure cycle heating rate on the fibre/matrix interface

Development of civil aerospace composites is key to future “greener” aircraft. Aircraft manufacturers must improve efficiency of their product and manufacturing processes to remain viable. The aerospace industry is undergoing a materials revolution in the design and manufacture of composite airframes. The Airbus A350 and Boeing 787 (both due to enter service in the latter part of this decade) will push utilisation levels of  composite materials beyond 50% of the total airframe by weight. This  change requires massive investment in materials technology, manufacturing capability and skills development. The Quickstep process provides the ability to rapidly cure aerospace standard composite materials whilst providing enhanced mechanical properties. Utilising fluid to transfer heat to the   composite component during the curing process allows far higher heat rates than with conventional cure techniques. The rapid heat-up rates reduce the viscosity of the resin system greatly to provide a longer processing window introducing greater flexibility and removing the need for high pressure during cure. Interlaminar fracture toughness (Mode I) and Interfacial Shear Strength of aerospace standard materials cured using Quickstep have been    compared to autoclave cured laminates. Results suggest an improvement in fibre-matrix adhesion.

Differential convergence of life-cycle inventories toward upstream production layers

We present an input-output analysis of the life-cycle labor, land, and greenhouse gas (GHG) requirements of alternative options for three case studies: investing money in a new vehicle versus in repairs of an existing vehicle (labor), passenger transport modes for a trip between Sydney and Melbourne (land use), and renewable electricity generation (GHG emissions). These case studies were chosen to demonstrate the possibility of rank crossovers in life-cycle inventory (LCI) results as system boundaries are expanded and upstream production inputs are taken into account. They demonstrate that differential convergence can cause crossovers in the ranking of inventories for alternative functional units occurring at second-and higher-order upstream production layers.

System boundary selection in life-cycle inventories using hybrid approaches

Life-cycle assessment (LCA) is a method for evaluating the environmental impacts of products holistically, including direct and supply chain impacts. The current LCA methodologies and the standards by the International Organization for Standardization (ISO) impose practical difficulties for drawing system boundaries; decisions on inclusion or exclusion of processes in an analysis (the cutoff criteria) are typically not made on a scientific basis. In particular, the requirement of deciding which processes could be excluded from the inventory can be rather difficult to meet because many excluded processes have often never been assessed by the practitioner, and therefore, their negligibility cannot be guaranteed. LCA studies utilizing economic input−output analysis have shown that, in practice, excluded processes can contribute as much to the product system under study as included processes; thus, the subjective determination of the system boundary may lead to invalid results. System boundaries in LCA are discussed herein with particular attention to outlining hybrid approaches as methods for resolving the boundary selection problem in LCA. An input−output model can be used to describe at least a part of a product system, and an ISO-compatible system boundary selection procedure can be designed by applying hybrid input−output-assisted approaches. There are several hybrid input−output analysis-based LCA methods that can be implemented in practice for broadening system boundary and also for ISO compliance.