In this paper, fatigue life estimation for delamination growth of laminated fibre reinforced polymer (FRP) composite structures in mode I and mode II based on fracture mechanics is presented. The proposed method was applied to delamination of glass/epoxy laminated composite. Both the threshold energy release rate ( ) and the delamination propagation based on Paris' law were studied. The double cantilever beam (DCB) specimen for mode I and 3 points End-Notched Flexure (3ENF) specimen for mode II were used for monotonic fracture tests and the resistance and as a function of delamination length were determined. For DCB tests, the fatigue onset life test was conducted and the threshold energy release rate, , was found for the subcritical region. Constant amplitude, displacement controlled cyclic fatigue test for both modes was conducted and the delamination crack growth rate ( ) as a function of maximum cyclic energy release rate and for DCB and 3ENF specimens were determined, respectively. From curve fitting to the experimental data, the Paris' law material constants C and m for mode I and mode II were obtained. Finally, the SEM fractography studies of delaminated surfaces of 3ENF static and fatigued specimens have been done and the different features observed on these surfaces were discussed.

Social housing retrofit is often seen as a way to contribute to carbon reductions as it typically encompasses large-scale interventions managed by one landlord. This work investigates the carbon savings potential of a deep retrofit in a local authority owned 107-flat tower block, taking into account the tenants' pre-retrofit heating strategies. Prior to the retrofit, temperature and relative humidity monitoring was undertaken in 18 flats for 35 days. The measurements were then used to develop occupant heating profiles in the 18 homes. Dynamic thermal simulation of the flats pre-and post-retrofit using the identified user heating profiles highlights that for these fuel poverty constrained flats the estimated carbon savings of retrofit will be typically half those predicted using standard rules for temperatures in living spaces. KeywordsPrebound effect, rebound effect, MVHR, occupant behaviour, retrofit, fuel poverty Practical applicationThe findings presented in this paper demonstrate the impact of fuel poverty on the expected benefits from social housing retrofit schemes, providing information relevant to multiple stakeholders: 1. Building industry: The study highlights the need to use empirical data in building energy modelling, as typical conditions could be far from representative in social homes 2. Policy makers and social landlords: Targets for CO 2 reduction may not be achieved through retrofitting, but the social impact could be much greater and more critical than assumed. The findings under this work help to direct incentives for retrofit schemed towards the social and health benefits achieved.

This paper explores a range of barriers to the implementation of retrofit programmes to domestic properties, through reporting on the process of delivering a social housing retrofit project by a registered social landlord (RSL) in Sunderland, in the North East of England. The paper first describes the policy context for RSLs in terms of the housing condition requirements and targets to reduce carbon dioxide emissions set by national government, and the subsequent shift by RSLs to retrofitting their properties to higher energy performance standards. During the project, a number of barriers were identified by the project team (which includes the authors), relating to decision-making processes, communication between partners, procurement and supply chains training and internal expertise, energy consumption monitoring and the type of low and zero carbon dioxide technologies to install. The article explores these, both as experienced and reported by the RSL, and identified by the wider project team, and considers what lessons could be learned regarding delivery of similar projects in the social housing sector.

In dwellings connected to district or communal heating schemes occupants are commonly charged based on actual heat consumption, providing a direct link between heat consumption and weekly heating cost. This article investigates how the use of fixed-rate, shared-cost charging without dwelling-level metering affects the heating and controls use in communal network social housing. Living room and radiator temperatures in 50 flats were monitored over a winter heating season and occupants surveyed at monitoring install and removal. The primary stated and observed heating strategy was to leave the heating always on and control through the radiator thermostatic radiator valves. Of people who used timer control, total heating hours reduced with increased frequency of manual intervention. Mean indoor temperatures up to 27.7°C were observed, implying many residents are adapted to higher indoor temperatures. Thus, the current model encourages wasteful behaviour and education on use of controls is key to transitioning residents to charging for actual heat use. Practical application: This article intends to inform the landlords of communal network social housing schemes on the impacts that shared-cost recovery methods of charging for heat has on heating and controls use. This charging method can impact the behaviour of the network occupants resulting in higher heat consumption, overall higher heating costs and subsequently higher carbon emissions from the site if occupants are not adequately trained in how to operate their heating effectively. Where similar charging methods are implemented, the article hopes to inform operators of the potential vulnerabilities of the network occupants to changes in the method of charging for heat.