Validation of the use of Australian input-output data for building embodied energy simulation

Traditional!y, the simulation of buildings has focused 011 operational energy consumption in an attempt to determine the potential for energy savings. Whilst operational energy of Australian buildings accounts for around 20% of total energy consumption nationally, embodied energy represents 20 to 50 times the annual operational energy of 1110st Australian buildings. Lower values have been shown through a number of studies that have analysed the embodied energy of buildings and their products, however these have now shown to be incomplete in system boundary. Many of these studies have used traditional embodied energy analysis methods, such as process analysis and input-output analysis, Hybrid embodied energy analysis methods have been developed, but these need to be compared and validated. This paper reports on preliminary work on this topic. The findings so far suggest that current best-practice methods are sufficiently accurate for most typical applications, but this is heavily dependant upon data quality and availability.

High performance low-energy buildings

The era of legislation and creditable methods towards producing sustainable buildings is upon us. Yet, a major barrier to achieving environmental responsive design is in the lack of available information at the programming or pre-design phases of a project. The review and evaluation of climate as well as energy-efficient strategies could be difficult to consider at these preliminary stages. Until recently, introducing energy simulation tools at the design stage has been difficult and perhaps next to impossible at a pre-design or programming stage. However, analysis of this sort is essential to ‘green building rating’ or performance assessment schemes such as LEED (Leadership in Energy and Environmental Design) and BREEAM (Building Research Establishment Environment Assessment Method). This paper discusses the implementation of a particular tool, ENERGY-10, where ‘basecase’ building defaults are compared to a low-energy case which has applied multiple energy-efficient strategies automatically. An annual hour-by-hour simulation provides a daylighting calculation with a subsequent thermal evaluation. Calculation results provide energy consumption, peak load equipment sizing, a RANK feature of the energy-efficient strategies, reporting of CO2, SO2 and NOx reduction, optimum glazing type as well as excellent graphic output. Consideration is given as to the approach of how such information can be introduced into the building project brief enforcing a low-energy
performance target.

Optimising the life cycle energy performance of residential buildings

A holistic approach to low-energy building design is essential to ensure that any efficiency improvement strategies provide a net energy benefit over the life of the building. Previous work by the authors has established a model for informing low-energy building design based on a comparison of the life cycle energy demand associated with a broad range of building assemblies. This model ranks assemblies based on their combined initial and recurrent embodied energy and operational energy demand. The current study applies this model to an actual residential building in order to demonstrate the application of the model for optimising a building’s life cycle energy performance. The aim of this study was to demonstrate how the availability of comparable energy performance information at the building design stage can be used to better optimise a building’s energy performance. The life cycle energy demand of the case study building, located in the temperate climate of Melbourne, Australia, was quantified using a comprehensive embodied energy assessment technique and TRNSYS thermal energy simulation software. The building was then modelled with variations to its external assemblies in an attempt to optimise its life cycle energy performance. The alternative assemblies chosen were those shown through the author’s previous modelling to result in the lowest life cycle energy demand for each building element. The best performing assemblies for each of the main external building elements were then combined into a best-case scenario to quantify the potential life cycle energy savings possible compared to the original building. The study showed that significant life cycle energy savings are possible through the modelling of individual building elements for the case study building. While these findings relate to a very specific case, this study demonstrates the application of a model for optimising building life cycle energy performance that may be applied more broadly during early-stage building design to optimise life cycle energy performance.

Towards a BIM-based energy rating system

Governments in Australia are faced with policy implementation that mandates higher energy efficient housing (Foran, Lenzen & Dey 2005). To this effect, the National Construction Code (NCC) 2013 stipulates the minimum energy performance for residential buildings as 114MJ/m2 per annum or 6 stars on an energy rating scale. Compliance with this minimum is mandatory but there are several methods through which residential buildings can be rated to comply with the deemed to satisfy provisions outlined in the NCC. FirstRate5 is by far the most commonly used simulation software used in Victoria, Australia. Meanwhile, Building Information Modelling (BIM), using software such as ArchiCAD has gained a foothold in the industry. The energy simulation software within ArchiCAD, EcoDesigner, enables the reporting on the energy performance based on BIM elements that contain thermal information. This research is founded on a comparative study between FirstRate5 and EcoDesigner. Three building types were analysed and compared. The comparison finds significant differences between simulations, being, measured areas, thermal loads and potentially serious shortcomings within FirstRate5, that are discussed along with the future potential of a fully BIM-integrated model for energy rating certification in Victoria. © 2014, The Association for Computer-Aided Architectural Design Research in Asia (CAADRIA), Hong Kong.

Retrofitting for ventilation, infiltration and comfort

Legislation is demanding that our existing building stock be improved to a minimum of 4.0 Star AGBRS (Aust. Green Building Rating Scheme) energy standards. In the 'Green Building Fund' scheme for office buildings and other government incentives, retrofitting our existing building stock makes plain good sense. However, many of the stakeholders (owners, facilities managers, occupants) do not know where to begin to invest, for making these savings. This paperdemonstrates through two case studies, in government related  office buildihgs,how real energy savings were approached and obtained. It illustrates a process whereby preliminary and pretesting results lead to solutions of building ventilation, infiltration and comfort improvement. Furthermore, it discusses how post building performance testing results verified improvement as well as provided inputs to energy simulation, indicating where further invested improvements could be made.
One case study illustrates how the weatherisation of a building prevented a 1.5 million dollar retrofitting spending, costing the client less than one-tenth of the initial retrofitting cost. Another example demonstrates how over-engineering and incorrect ventilation concepts can cost the client up to 70% of their energy bill. Both papers involve real evidence-based pre and post measurement results in existing occupied buildings.

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.

Simulation of a novel piezoelectric energy harvester

This paper focuses on a novel piezoelectric energy harvester for nanofiber PVDF to capture energy from vibration environment. A Resembling CMOS(R-CMOS) circuit consisting of two pMOS transistors and two nMOS transistors is presented, which can greatly increase the energy efficiency and reduce the power dissipation tremendously. Meanwhile, the novel harvester supplies smooth direct current. Simulation result of MULTISIM has shown that by using this novel piezoelectric energy harvester the input voltage (5v) can be rectified to be an output voltage (4.24v). The voltage conversion rate of the novel harvester is as high as 84.8% which is much larger than the rate of traditional rectifier circuit. Its potential application is in micro sensors, wireless transducers, and sensor networks.

Application of a discrete event simulation for robust system design of a melt facility

This paper presents a methodology to identify robust operating regions through the selection of controllable factory variables, using discrete event simulation. A casting plant melt facility was used as an industrial test bed to develop these techniques. A robust system design was determined by response surface analysis of key production parameters. Furthermore, robust operating policies that maximise throughput, while minimizing work-in-progress and thus energy consumption were identified.

Energy efficient envelope design for high-rise apartments

The energy required to create a comfortable living environment in  high-density cities in hot and humid climates usually demands a substantial electricity usage with an associated environmental burden. This paper describes an integrated passive design approach to reduce the cooling requirement for high-rise apartments through an improved building envelope design. The results show that a saving of 31.4% in annual required cooling energy and 36.8% in the peak cooling load for the BASECASE apartment can be achieved with this approach. However, all the passive strategies have marginal effect on latent cooling load, often less than 1%.

Experimental investigation and numerical simulation of heat transfer in quenching fluidised beds

Fluidisation characteristics at different surfaces of a work-piece of complex geometry are conducted in a fluidised bed at various conditions including fluidising number, bed temperature and fluidising medium. The quenching of the work-piece is performed experimentally. In particular, the major frequency and energy of the pressure fluctuations are measured as a function of either fluidising velocity or heat transfer position and the results are used to develop a mathematic model. A computational model is developed to simulate gas dynamics and heat transfer between the fluidised bed and the work-piece surface, as well as simulating the temperature within the work-piece. The predicted cooling curves are in good agreement with the experimental results. Based on the simulation results, the flow characteristics of the gas and the temperature of the dense gas-solid phase near the work-piece surface are analysed to understand the heat transfer mechanism in the fluidised bed.

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.

Modelling of fabric energy storage systems - a review

Fabric energy storage (FES) systems have gained in popularity in the recent years in response to the demand for energy efficient buildings. The dynamic heat transfer mechanisms of an FES require specialised techniques to predict its thermal performance. This requirement has been one of the barriers to the wider use of FES systems. Based on the research literature, this paper presents a critical review of the published mathematical models of FES systems. The paper discusses the usefulness of these models based on the following criteria: the inputs required; the accuracy of predictions; the ability to link with commercially available simulation software: and the degree of difficulty in using the models. The review found that the currently available mathematical models are either not able to predict the thermal behaviour of a building space with an FES system reliably or the models are too complicated and/or require too much specialised knowledge to make them useful.

Crushing simulation of foam-filled aluminium tubes

A numerical study is presented in this paper to investigate the energy absorption of foam-filled aluminium tubes during crushing. The post-buckling mode of the foam-tube structures has been successfully simulated. The predicted compressive load-displacement is in a good agreement with experimental results. The energy absorption ability of the composite structure due to plastic deformation in a crushing process is evaluated by comparison with the tube structure without foam. The results indicate that the energy absorption of a foam-filled tube structure is superior to the tube without foam. The influences of the friction and the geometric parameters of the structure on the energy absorption have also been investigated. Results from this study will assist automotive industry to design crashworthy components based on foam-filled tubes.

Advanced fabric energy storage systems in Australia

There is a growing interest in the use of advanced fabric energy storage (FES) systems in Australia. The influence of slab thickness and ventilation rate on the annual thermal load, and maximum heating and cooling demands for an office module using a ventilated hollow core concrete slab system has been investigated by simulation. Airflow through the panels was set at 1, 2 or 4 air changes per hour (ACH) for slab thicknesses of 205, 220 and 300 mm. These configurations were simulated using two different FES operational strategies for six capital cities in mainland Australia. The simulations show that FES systems can offer either energy and/or peak load savings in almost all locations investigated. Overall, compared to a conventional AC system, the tempering of incoming fresh air combined with night flushing of the FES system appears to be the most successful operational strategy.