Do deep low carbon domestic retrofits actually work?

​This paper uses a socio-technical building performance evaluation (BPE) approach to assess the pre- and post- actual performance of two discrete deep low energy retrofits in the UK – a Victorian solid-wall house and modern 1990s cavity-wall house. A ‘low-energy first, then low-carbon’ approach was adopted in both cases, to achieve an 80% reduction in annual CO2 emissions. Pre-retrofit, both houses had lower measured annual gas consumption as compared to predictions made by energy models, although the electricity consumption in the modern house was higher than modelled, due to occupancy pattern and occupant behaviour. Post-retrofit, it was found that the Victorian house achieved nearly 75% CO2 reduction, while the modern house achieved only 57% CO2 reduction over the baseline emissions. Key reasons were higher than expected air permeability rates, installation issues with micro-renewable systems, lack of proper commissioning, usability of controls, occupant preferences and behaviour. Despite the gap between expected and actual carbon emissions, occupant comfort and satisfaction was significantly improved across both retrofits. This evidence-based understanding of the process and outcomes of deep low carbon retrofits is vital not only for learning and innovation, but also for scaling-up deep retrofit programmes for meeting national and international carbon targets

Building performance simulation of advanced energy technologies to achieve net zero energy dwellings in UK

This paper systematically presents the methodology and initial findings from modelling and simulation of advanced energy conservation, generation and management technologies applied to two case study dwellings to achieve a net zero energy (NZE) target. The specific objectives are to meet the Energy Performance in Buildings Directive as follows: reduction of net regulated energy to or below 0 kWh/m2 per year and generation of at least 50 kWh/m2 per year, on average, in the NZE settlement. The findings reveal that to meet the specific targets set out for the project aligned with the EU Directive: - A majority of technological intervention must come from community renewables, - buildings built to current UK Building Regulations, will need to reduce regulated loads by about half, and - the NZE targets in particular are not particularly stringent regarding energy efficiency but are highly expectant with regard to renewable energy

Empirical evaluation of the energy and environmental performance of a sustainably-designed but under-utilised institutional building in the UK

This paper presents a systematic, socio-technical and empirical evaluation of the actual energy and environmental performance of a sustainably-designed institutional building (Southeast England), intended to be a teaching tool and ‘living laboratory’ of sustainability. Despite the building being designed to high sustainability standards (Energy Performance Certificate rating of A, low reliance on fossil fuels, natural ventilation and rainwater harvesting) and also being under-utilised during the in-use stage (lower hours of occupation and number of occupants), its actual energy-related carbon dioxide-equivalent emissions are four times more than predicted. This is due to poor energy management of the building, underperformance of the biomass boiler and wasteful energy practices in terms of excessive winter overheating in the atrium, inappropriate lighting controls, and electrical equipment being left on standby. Due to lack of training and understanding of the energy manager, the building management system was not used adequately and issues with installation, commissioning and maintenance of the biomass boiler led to its disuse; however the photovoltaic system generated electricity as expected. Findings from the study show how a mixed-methods approach of building performance evaluation (BPE) should be embedded as part of the build process, to ensure that performance outcomes are met in reality

Do deep low carbon retrofits actually work?

This paper presents the findings from building performance evaluation studies of two deep retrofits in UK – Victorian house and Modern 1990s house. Both case studies were designed to achieve 17 kgCO2/m2/year (equivalent to 80 % reduction) and adopted a fabric-first approach. Post-retrofit, it was found that the Victorian house achieved a 75 % CO2 reduction, while the modern house achieved 57 % CO2 reduction over the baseline. Key reasons for these are higher than expected air-permeability rates of the building fabric post-retrofit, lack of occupant understanding in operating low carbon technologies and unusual electricity using behaviors of occupants particularly in the modern house

Comparative building performance evaluation of a ‘sustainable’ community centre and a public library building

This paper uses a forensic building performance evaluation approach to undertake a comparative evaluation of the in-use energy and environmental performance data (collected over two years) of two civic buildings located in Southeast England – a small community centre (<1000m2) and a medium-sized public library building (~4500m2), which are designed to high sustainability standards (EPC A rating) and low heating demand met by on-site low/zero carbon technologies. Although both buildings achieved measured air-permeability rates of ~5m3/hr.m2, they encountered similar issues related to poor documentation of ‘as-built’ drawings, poor handover and guidance, problems with integrating and maintaining new technologies (heat pumps, biomass boilers and solar thermal), lack of calibration of sub-meters, and issues with automatic window controls. However the actual carbon emissions of the community centre are double the predicted, while they are almost five times in the case of library building. This is because the community centre management team overcame some of the issues through their continuous engagement and interest in the building’s performance, whereas the management team of the Library building failed to engage with energy management, resulting in disuse of the biomass boiler and solar thermal system

Cooling the UK housing stock post-2050s

This paper investigates the risk of projected post-2050s overheating in existing, retrofitted and new-build dwellings in the United Kingdom. As shown in the previous research, passive measures may not be sufficient in mitigating overheating risk. Therefore, mechanical cooling technologies that may be deployed to ‘adapt’ to a warming climate are tested for energy and CO2 implications. For retrofits, heating demand is projected to remain dominant, whereas in post-2016 new-build, greater cooling system efficiency will be important. Thermal mass is shown to reduce future cooling load. The heat recovery element of mechanical ventilation with heat recovery may be rendered unnecessary in super-efficient homes. Ceiling fans coupled with natural ventilation may be sufficient in providing thermal comfort in the north of England. Ultimately, not planning for future overheating and cooling systems could create a new performance gap in design, construction and occupant behaviour. Practical application : Overheating, already experienced in dwellings throughout the United Kingdom and projected to increase in occurrence, should be considered in all new design and retrofit. Dwellings designed to meet thermal comfort performance targets may be at risk of non-compliance as a result of a warming climate. Furthermore, dwellings designed to meet energy performance targets may be at risk of non-compliance as a result of potential need for cooling systems. The findings have implications for policy-making in relation to decarbonisation of the electricity grid, implementation of the Green Deal and upgrading building regulations to future-proof new and existing housing against a warming climate

Intent and outcomes from the Retrofit for the Future programme: key lessons

The Retrofit for the Future programme, sponsored by UK government's Technology Strategy Board (TSB) from 2009 to 2013, demonstrated innovative approaches to deep retrofitting of social housing, using a whole-house approach for achieving an 80% CO2 reduction target. The intent and outcomes of this programme (in which all authors participated) are critically examined through a cross-project meta-study of the primary data, substantiated by insights from secondary sources. Given that only three (out of 45) projects met the expected CO2 target in reality, despite generous funding and professional expertise, it suggests that decarbonizing existing housing will not be particularly easy. Important lessons are found in this initiative's formulation, target setting, monitoring and evaluation procedures, and feedback mechanisms. These lessons can inform the formulation, delivery and effectiveness of future national energy retrofit programmes. Furthermore, to support the ‘scaling up’ of effective retrofit programmes and reduce the gap between intent and outcome, it is recommended that attention be moved from what level of CO2 reductions are to be achieved to how (delivery models) these radical reductions can be achieved and by whom (supply chain). Such alternative delivery models to the ‘whole house’ approach include retrofit over time, city-scale retrofit and community-based energy retrofits

Spintronics: Fundamentals and applications

Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.Comment: invited review, 36 figures, 900+ references; minor stylistic changes from the published versio

Active Galactic Nuclei at the Crossroads of Astrophysics

Over the last five decades, AGN studies have produced a number of spectacular examples of synergies and multifaceted approaches in astrophysics. The field of AGN research now spans the entire spectral range and covers more than twelve orders of magnitude in the spatial and temporal domains. The next generation of astrophysical facilities will open up new possibilities for AGN studies, especially in the areas of high-resolution and high-fidelity imaging and spectroscopy of nuclear regions in the X-ray, optical, and radio bands. These studies will address in detail a number of critical issues in AGN research such as processes in the immediate vicinity of supermassive black holes, physical conditions of broad-line and narrow-line regions, formation and evolution of accretion disks and relativistic outflows, and the connection between nuclear activity and galaxy evolution.Comment: 16 pages, 5 figures; review contribution; "Exploring the Cosmic Frontier: Astrophysical Instruments for the 21st Century", ESO Astrophysical Symposia Serie

An integrated ultrasound curriculum (iUSC) for medical students: 4-year experience

A review of the development and implementation of a 4-year medical student integrated ultrasound curriculum is presented. Multiple teaching and assessment modalities are discussed as well as results from testing and student surveys. Lessons learned while establishing the curriculum are summarized. It is concluded that ultrasound is a well received, valuable teaching tool across all 4 years of medical school, and students learn ultrasound well, and they feel their ultrasound experience enhances their medical education