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The Retrofit for the Future programme, sponsored by UK Government's Technology Strategy Board from 2009-13, demonstrated innovative approaches to deep retrofitting of social housing, using a whole-house approach for achieving an 80% CO 2 reduction target. This paper critically examines the intent and outcomes of this programme (in which all authors participated) 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 CO 2 target in reality, despite generous funding and professional expertise, it suggests that decarbonizing existing housing will not be particularly easy. Important lessons are learnt from the formulation, target-setting, monitoring and evaluation procedures and feedback mechanisms of this initiative, which can inform the delivery and effectiveness of future national energy retrofit programmes. Furthermore, to support '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 CO 2 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.

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 CO 2 emissions. Preretrofit, 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% CO 2 reduction, while the modern house achieved only 57% CO 2 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.

This paper uses a socio-technical building performance evaluation approach to forensically and systematically evaluate the actual performance of two case study dwellings located in a flagship eco-housing development in the UK, during the post-construction/initial occupation stage. The 12-month study captures the ‘as-built’ performance of the building envelope (principally heat loss) and installed equipment along with remote monitoring of energy use and environmental conditions, review of the handover processes and initial experiences of the occupants in relation to the home environment. It is found that actual annual energy use and CO2 emissions of the case study dwellings exceed design predictions by factors of 1.8 and 2.5, respectively. The main reasons for this gap are complex interdependencies that occur across the performance of building fabric and energy systems, usability of controls and occupant expectations and behaviour. Underperformance of mechanical ventilation and heat recovery systems and air source heat pumps results from inadequate commissioning and maintenance procedures and poor occupant control due to complex control interfaces. Furthermore, unclear user guidance and inadequate training during handover lead to poor occupant understanding of the mechanical ventilation and heat recovery systems and heat pumps, resulting in their misuse. The findings have proved that building performance evaluation processes are vital for examining operational outcomes and discovering performance-related issues that would otherwise go unreported and lead to bigger problems in future. Practical application: The methodological approach for evaluating housing performance adopted in this study provides design and construction teams with a practical approach to diagnose workmanship issues with building fabric and any installation or commissioning issues with energy systems and services. Maintenance regime of heating and ventilation system should be clarified at the installation and commissioning stage. Maintenance contracts should be set up for unfamiliar low carbon systems such as heat pumps, MVHR. Occupants need to be trained through graduated and extended handover that involves occupants trying out systems and controls in the presence of trained housing officers, supplemented by visual home user guides (developed by the architects) offering clear guidance on the daily and seasonal operation of systems and controls. Learning from such real-world case studies, from design to early occupation, is helpful in understanding the exact causes of the performance gap and how it can be addressed.

Research in UK and elsewhere has highlighted that older people are particularly vulnerable to negative health effects of overheating. This paper examines the magnitude, causes, preparedness and remedies for addressing the risk of summertime overheating in four case study residential care and extra-care settings across the UK, spanning different building types, construction and age. The methodological approach adopted is interdisciplinary, drawing from building science and social science methods, including temperature monitoring, building surveys, and interviews with design and management teams. The findings suggest that overheating is a current and prevalent risk in the case study schemes, yet there is currently little awareness or preparedness to implement suitable and long-term adaptation strategies (eg. external shading). There was a perception from designers to managers, that cold represents a bigger threat to older occupants' health than excessive heat. A lack of effective heat management was found across the case studies that included unwanted heat gains from the heating system, confusion in terms of responsibilities to manage indoor temperatures, and conflicts between window opening and occupant safety. Given that care settings should provide protection against risks from cold and hot weather, design, management and care practices need to become better focused towards this goal.