Object co-location and memory reuse for Java programs

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What kind of expertise is needed for low energy construction

The construction industry is responsible for 40% of European Union (EU) end-use emissions but addressing this is problematic, as evident from the performance gap between design intention and on-site energy performance. There is a lack of the expertise needed for low energy construction (LEC) in the UK as the complex work processes involved require ‘energy literacy’ of all construction occupations, high qualification levels, broad occupational profiles, integrated teamworking, and good communication . This research identifies the obstacles to meeting these requirements, the nature of the expertise needed to break down occupational divisions and bridge those interfaces where the main heat losses occur, and the transition pathway implied. Obstacles include a decline in the level, breadth and quality of construction vocational education and training (VET), the lack of a learning infrastructure on sites, and a fragmented employment structure. To overcome these and develop enhanced understanding of LEC requires a transformation of the existing structure of VET provision and construction employment and a new curriculum based on a broader concept of agency and backed by rigorous enforcement of standards. This can be achieved through a radical transition pathway rather than market-based solutions to a low carbon future for the construction sector

Who are the 'middle actors' in sustainable construction and what do they need to know?

This paper explores what knowledge and skills are needed, and how those skills and knowledge might be gained, in order to deliver more sustainable outcomes from construction, using the concept of ‘middle actors’. ‘Middle actors’ are the individuals who occupy the space between ‘top-down’ policy and instruction, and ‘bottom-up’ norms. In construction, ‘middle actors’ with influence on building performance include clerks of works, project managers, tradespeople and technical advisers. There is a relentless drive for more sustainable buildings that use less energy, generate less waste during construction and use, and provide healthy environments for people to live and work in. This direction of travel can no longer be considered ‘new’ and yet it remains far from the mainstream. To create buildings which are sustainable, we need to consider not only technology and design changes, but how to alter the wider system of construction. We use middle actors as the lens through which to examine these non-technical changes, and the skills and knowledge required to achieve them. A review of the concept of middle actors as it has been applied to construction and an overview of skills and knowledge needs for sustainable construction is followed by identifying middle actors in new build and retrofit, commercial and domestic projects currently under way with one developer in Leeds, UK. The skills and knowledge needed by ‘middle actors’ to deliver more sustainable outcomes from their projects are described, based on empirical data gathered from project teams, and further structured by considering when in the project cycle they are needed, and what routes to gaining the required skills and knowledge might be most effective. This analysis reinforces that there is no single route to achieving more sustainable buildings and instead the activities, responsibilities and networks of individuals need to be carefully considered in developing training programmes for construction teams

Post-construction thermal testing: Some recent measurements

In the UK, it has become apparent in recent years that there is often a discrepancy between the steady-state predicted and the measured in situ thermal performance of the building fabric, with the measured in situ performance being greater than that predicted. This discrepancy or gap in the thermal performance of the building fabric is commonly referred to as the building fabric 'performance gap'. This paper presents the results and key messages obtained from undertaking a whole-building heat loss test (a coheating test) on seven new-build dwellings as part of the Technology Strategy Board's Building Performance Evaluation Programme. While the total number of dwellings involved in the work reported here is small, the results illustrate that a wide range of discrepancies in thermal performance was measured for the tested dwellings. Despite this, the results also indicate that it is possible to construct dwellings where the building fabric performs thermally more or less as predicted, thus effectively bridging the traditional building fabric performance gap that exists in mainstream housing in the UK

The monitored performance of four social houses certified to the Code for Sustainable Homes Level 5

This paper presents the energy and water use of 4 social houses certified to the Code for Sustainable Homes Level 5 in Gainsborough, UK. The houses were monitored over 2 years, from July 2012 to September 2014. As the houses have the same construction and energy efficiency characteristics, the study offered a unique opportunity to investigate the effects of occupant behaviour on the dwellings performance. Electricity, gas and water consumptions were measured through data logging and meter readings. Surveys and interviews were conducted throughout to gain insights into tenants understanding and interactions with low energy features in their homes. Significant differences were observed in the amount of energy and water used. The annual space heating consumptions differentiated by a factor of 2.2 per square metre of floor area. Hot water heating demands varied by a factor of 3.5 per square metre of floor area or by 2.5 per person per year. Mains water consumptions varied by a factor of 2.2 litres per person per day in 2013

A UK practitioner view of domestic energy performance measurement

There is a growing body of evidence concerning the energy efficiency performance of domestic buildings in the UK, driven by policy-based agenda, such as the need for zero carbon dioxide homes by 2016 for new build homes, and Green Deal and energy company obligation for sustainable refurbishment. While there have been a number of studies funded and results presented in this area, little work has been done to understand the drivers, practices and issues of data collection and analysis. There are a number of major building performance evaluation (BPE) studies in the UK, yet behind many of these research projects are practical issues of data loss, experimental error, data analysis variances and resident issues that are common when studies move from the actual to the living lab. In this paper the issues of domestic energy are addressed by leading BPE practitioners in the UK. They identify issues of client demands, technical failure, costs and implementation. The work provides insights of both academic and industry-based practitioners and considers not only the practicalities of building performance studies, but also implications for these types of studies in the future

Exploiting Java objects behavior for memory management and optimizations

We study the behavior of Java objects in order to explore potential garbage collection optimization opportunities in Java programs. Our study has led to one probable strategy for using heap buffers effectively through obtaining liveness and type information of objects. To allow examination of the Java memory, we implement a heap profiling tool by instrumenting an existing Java virtual machine. The tool records useful object events during program execution, and groups the objects according to their types. We apply the tool to different benchmarks and analyze the results. We also try to characterize the objects' behaviors and suggest that memory occupied by certain objects can be reused by other objects, leading to improved performance of the program. We implement a simple prototype to demonstrate the feasibility of the object reuse approach. © Springer-Verlag 2004.link_to_subscribed_fulltex