Professor Rajat Gupta

Decentralisation offers one route to energy system decarbonisation, and local energy systems (LES) provide focal points for decentralisation. LES involve the integration of different generation, storage, and demand-side technologies across heat, power, and transport systems, within defined localities. Public support is necessary for LES deployment at pace and scale, but while past research has examined public attitudes towards individual technologies, few studies have investigated perceptions of a systemic shift towards LES. This paper presents findings from a nationally representative UK survey (n=3034) on LES. We compare two ways of exploring perceptions of decentralised energy: as a broad systemic shift, and as the cumulative deployment of multiple LES innovations. Results show high levels of public support for a systemic shift towards decentralisation, but more moderate levels of support for specific LES innovations. Regression analysis highlight the role of personal characteristics, climate concern, political beliefs, and engagement with technologies in influencing support for LES. Support is more predictable for decentralisation, whose meaning is clear in principle while containing ambiguities in practice. Support for LES innovations is less predictable and is explained by the diversity with which households interpret the multiple propositions afforded by LES innovations. For LES to benefit from majority public support for a systemic shift, policy and industry actors need to better understand the diverse set of perceptions and values that LES hold for the public and seek broader and deeper engagement with the public around specific LES innovations, as well as around systemic change more broadly.

In the face of climate change and associated energy system change, there is a growing literature and more general recognition of the ‘four Ds’ (decarbonization, decentralization, digitalization, and democratization). Yet there has been very little quantitative work that analyzes public perceptions of these changes. Utilizing data from a Canada-wide, nationally representative survey (n=941), this study conducted provincial and regional assessments to spatially explore the public’s views of moves toward innovative local energy system change through the development of what we call Local Smart Grids (LSGs). Through descriptive statistics and t-tests, we sought to answer three main questions: i) To what extent does the public support energy democracy via new local energy systems? ii) What does the public desire in terms of participation? and iii) What motivates the public to participate? We find overall support for energy democracy across Canada, yet varied support among provinces and regions. Canadians seem to want to participate in moves toward energy democracy, although we found a strong preference for more passive participatory actions. Additionally, support and a desire to participate is predominantly motivated by environmental factors, including combating climate change, with community and social motivations playing a secondary role, followed by financial motivations. These findings, some of the first of their kind in the realm of energy democracy in Canada, provide useful insights relevant to scholars, policymakers, and practitioners working on LSG implementation as well as others with an interest in socio-technical innovation and energy system change.

Understanding the factors that drive the use of residential electricity in India is essential for designing policies that can reduce its expected growth. This study empirically examines the magnitude and causes of variation in electricity use in a sample of Indian dwellings with and without air-conditioning (AC), using an interview-based survey approach applied in 41 dwellings located across two cities representing the composite climate of India. Statistical analysis was used to unpack the relationship between electricity use and socio-technical factors. Despite the small sample size and having the same climatological realm, there was a wide variation observed in electricity use by income groups and presence of ACs. The mean annual residential electricity consumption (REC) was observed to be highest in high-income group dwellings (5,618 kWh/year), followed by middle-income group dwellings (3,870 kWh/year) and lowest in low-income group dwellings (2,169 kWh/year). The mean REC of AC dwellings (4,208 kWh/year) was found to be nearly double that of non-AC dwellings (2,260 kWh/year) with significant seasonal variation. Multivariate regression analysis revealed that presence of ACs, household size (number of occupants), annual non-AC appliance hours, dwelling size (number of rooms) and income group accounted for 80% of the variability in REC across the study sample. Residential energy policy in India should consider these key factors that drive REC. To be effective, such policy programmes need to be customised for different income groups, adopting incentives as well as energy awareness campaigns to influence both purchasing and habitual behaviours.

Local Smart Grids (LSGs) are emerging during the climate crisis, as governments and industry recognize the need to better integrate intermittent renewable energy, storage, transportation, heating, and smart technologies. Such projects can represent profound changes to the status quo of energy and citizen lifestyles. They are also being associated with the ‘4 Ds’, whereby LSGs are decarbonizing, decentralizing, digitalizing, and potentially democratizing energy systems. Yet due to their recent arrival, there is very little social scientific research that has aimed to better understand the views, expectations, and support for this change. We attempt to fill this important gap in the literature through the analysis of two nationally representative surveys in the United Kingdom (UK) (n=3034) and Canada (n=941). This analysis highlights within and between-country trends, including how the variation in responses regarding the ‘four Ds’, demographic factors, and other variables may explain the differences we see in terms of support for energy system change in the UK and Canada. Our analysis also shows that there are common elements including the importance of the decentralization, and especially the democratization of energy in shaping support. We hope that this study will help governments, industry, community groups, and local residents themselves in both countries come together to advance the kind of LSGs that address climate change, and represent a supported, just energy transition. 

The UK government has announced its Ten-point plan to annually install 600,000 low carbon heat pumps by 2028. Yet there is a lack of evidence showing potential overheating risk in dwellings retrofitted with heat pumps. This paper examines the prevalence and magnitude of summertime overheating across 24 naturally-ventilated social housing dwellings retrofitted with ground source heat pumps (GSHPs). The dwellings are located in a socially deprived area in Oxford (UK). The empirical study included longitudinal monitoring of indoor temperatures in the living rooms and bedrooms during the non-heating seasons of 2021 and 2022 (May-September), which included a record-breaking heat wave in July 2022. Indoor temperature and CO₂ levels were monitored across a subset of six dwellings in bedrooms alongside monitoring of window opening state in three bedrooms to understand the effect of natural ventilation in removing excess heat. About 136 thermal comfort surveys were conducted to ascertain the subjective responses of residents. Overheating risk assessment was carried out using CIBSE static and adaptive methods, which revealed that summertime overheating was prevalent across half the dwellings in the non-heating season of 2022, as compared to 17% overheated dwellings in 2021. Bungalows with upgraded cavity wall insulation and top floor flats facing south and south west had propensity to overheat. The variation in indoor temperature and CO₂ levels across a small sample also indicated the relationship between overheating and residents’ behaviour. Given that majority of the dwellings were occupied by retired elderly people with low income who are vulnerable to heat and cannot afford active forms of cooling, it is vital to deploy passive design measures such as appropriate shading devices suitable for a heating dominated climate and enhanced ventilation as part of home energy retrofits. Implementing reversible heat pumps coupled with solar PVs can provide cooling during heat waves, while delivering low carbon heat in the winter.

Residential energy feedback is about providing personalized information on household energy use to consumers to encourage energy savings. This paper conducts a review of field based studies that have evaluated the impact of energy feedback on residential energy consumption. The review includes studies in real occupied homes that have deployed feedback intervention(s) and measured energy savings. Our study builds a taxonomy for energy feedback studies based on different characteristics of feedback such as frequency, type, presentation style, and methods of access. Energy savings from similar feedback types were found to differ depending on how the study was conducted. The reviewed studies deployed a range of feedback information including energy units, energy cost and tailored information conducted across diverse audiences (ethnicity, geographical positioning), varying experimental types (longitudinal, Randomized Control Trial) and, size and duration of the studies.

The duration of studies varied widely, ranging from one month to three years and revealed potential energy savings between 5% and 20%. While most studies achieved energy savings due to energy feedback, a few of them reported a  increase in energy consumption which could be due to rebound effect. Most of the studies provided current and historical electricity consumption. Others used Randomized Control Trial (RCT) design, comparing energy consumption and savings information with neighbours. Most of the studies were conducted in developed countries with cold climates,  with a shift towards providing real-time online feedback over the last two decades. There was lack of large-scale studies on residential energy feedback in  emerging economies where growth of air conditioning is happening. These studies might also consider the human behavior and cultural influences while evaluating impact of energy feedback. Our recommendation is that the academic and policy community address this gap since energy feedback is likely to stimulate positive energy behavior change amongst householders leading to energy savings.

In developing economies, residential energy consumption patterns have rapidly transformed with better energy access and service quality. Unlike other building types, residential buildings are more complex due to wide variations in their consumption patterns influenced by various factors. Researchers have characterised residential building stock based on distinct building archetypes. This paper presents a comprehensive review of relevant published research focusing on the classification of residential buildings based on their energy consumption. This review also focuses on residential archetype studies in the context of building science. The methodologies adopted by different researchers to characterise the energy use of residential building stock using an archetypal approach at different spatial scales (building to city scale and local to national scale) have been critically reviewed in this study. The paper will provide the researchers with a holistic understanding of the current directions and magnitude of ongoing research in this domain.

Residential demand response using low carbon technologies can potentially offer energy flexibility to the electricity network along with integration of renewable generation. This paper seeks to empirically evaluate the effectiveness of residential demand response trials on a low voltage feeder of a secondary substation in Barnsley (UK). The study used a sample of 14 well-insulated dwellings equipped with home batteries, heat pumps and solar photovoltaic systems coordinated using automated control.  Statistical analysis was undertaken using time-series monitoring data obtained at the individual dwelling level, dwelling sample and at the feeder level of the local low voltage network. Resident experience of the trials was assessed through qualitative data obtained from household telephone surveys. Over three weeks of trials, daily demand response interventions of two hours duration were applied to the sample of 14 dwellings. For evening peak times, the mean reduction in grid electricity import was found to be 1.3 kWh (67%) per dwelling for turn-down interventions which aimed to minimise import. For turn-up interventions between 1-3 pm, the mean increase in grid electricity import was found to be 5.8 kWh (645%) per dwelling. The effect of interventions was measured at the low voltage network level for two single-phase feeders, where penetration of trial homes was approximately one-third. A reduction in mean real power up to 21% was observed for turn-down interventions as well as an increase in real mean power up to 307% for turn-up interventions. In general, the trials had little effect on residents in terms of thermal comfort, hot water availability, noise disturbance or disruption to routines, and where such effects were noticed, they were broadly acceptable. The widespread implementation of residential demand response schemes will require increased roll-out of time-of-use tariffs, enhanced resident support and extensive monitoring of low voltage feeders in electricity substations.

Deploying smart local energy engagement tools (SLEETs) in local energy projects enables users to better observe and control energy, and potentially become active participants in local energy management. Using a cross-project approach, this paper examines the prevalence, effectiveness and inclusiveness of 84 SLEETs deployed in 72 local energy projects in the UK from 2008 to 2018. An original framework for characterisation of SLEETs was employed, which grouped them into seven types and characterised in terms of level of interaction and interface design. Our study shows information-driven tools were most popular in community energy groups, while digital energy platforms - or interaction tools with numeric interface - were found popular in smart local energy sysem (SLES) initiatives. In contrast, interaction tools with visual interface, and tools offering control were found to be less popular. Spatial analysis revealed SLEETs were mostly deployed in areas with grid constraints (technology), active community energy groups (people) and engaged local authorities (policy). Effective SLEETs were found to stimulate engagement amongst people (social engagement), and between people and technology (operation and control), while inclusive SLEETs enabled inclusion of vulnerable and low incomes households. The acceptance and implementation of SLES initiatives can be enhanced by having effective and inclusive SLEETs that align with local users’ requirements and are supported by local stakeholders to foster trust. In future there is a need to develop appropriate metrics (key performance indicator) or scoring methods to measure their prevalence, effectiveness, and inclusiveness in a consistent manner.

Low carbon technologies along with smart control have a role in residential demand side response (DSR) to shift the timing of household energy consumption away from peak times and align it with generation of renewable electricity. This paper empirically evaluates the impact of DSR trials on grid electricity import and resident experience regarding disruption to daily routines, thermal comfort and noise disturbance in 17 thermally efficient social housing dwellings (Barnsley, England). Four types of DSR trials were run through 22 interventions performed in March to April 2021. Each dwelling was equipped with a 5 kWh electro-chemical battery and air source heat pump, and all but one dwelling had solar photovoltaic (PV) panels (1.3-3.0 kWp). Interventions were applied against a flat (single) rate tariff as well as dynamic time-of-use tariffs. On average, secure turn-down interventions between 5-7 pm resulted in a reduction in grid electricity import of 1.2 kWh per household and a reduction in controllable load (heat pump plus battery energy) of 3.7 kWh per household. The batteries enabled 2.5 kWh per household of electricity to be exported to the grid for these interventions. On average, turn-up interventions between 1-3 pm resulted in an increase of 2.3 kWh per household in grid electricity import. Individual dwellings showed different levels of demand response depending on the levels and patterns of household electricity consumption.

The resident experience was evaluated by means of a series of telephone surveys. Householders were generally accepting of the trials in terms of changes in indoor temperature, hot water availability, noise disturbance and disruption to household routines. However, some general concerns were raised about the energy systems relating to indoor temperature, hot water temperature and energy costs. The general acceptability of automated DSR, conditional on thermal comfort limits and manual override, is promising for the wider application of residential DSR driven by price signals, although ongoing household engagement in DSR schemes will require a continued focus on the householder experience with training and support in using new technologies. A routine period of inspection should be employed to identify any issues with energy system issues ahead of DSR initiation.

Oversimplifying occupant behaviour using static and standard schedules has been iden‐ tified as a limitation of building energy simulation tools. This paper describes the use of hierarchical cluster analysis to establish the most typical indoor temperature profiles of Albanian dwellings based on monitored indoor temperatures in winter and summer, along with building and occupant surveys undertaken in 49 randomly selected dwellings in Tirana. Three statistically different pro‐ files were developed for each summer and winter, indicating that homes are used in different ways, as well as revealing possible comfortrequirements. Furthermore, statistical analysis was undertaken to determine the strength of the association between the clusters and contextual factors related to the building, household, and occupancy. A statistically significant association was found between the presence of children and the clusters in winter, suggesting that families with dependents use more energy. Building‐related factors including building type, building age, and wall insulation were found to be statistically significantly associated with clusters in summer. These profiles could provide more accurate outcomes of energy consumption of Albanian homes and energy savings from retrofits. They could also facilitate the development of low‐energy strategies and policies for specific households.

This study evaluated the actual environmental behaviours in an eco-development case study in the UK, which was designed to enable more sustainable lifestyles. Data analysis was based on the resident responses to a development-wide questionnaire survey (n = 89), household interviews (n = 12) and waste measurements. Reported energy- and water-saving behaviours were fairly common. The mean waste recycling rates (45% to 60%) were similar to local and national averages, and were below the target of 80%. The mean rates of purchasing organic food (37%), growing food (31%) and meat consumption (in 36% of all meals) indicated that the food behaviours were not more pro-environmental. Car-based modes of transportation were used for 71% of all the reported trips on average, which was higher than the national average, and the target of 55%. Despite these reported behaviours, most of the residents regarded their new lifestyles as more sustainable. This was related to the notion of energy efficiency and low-carbon technologies, rather than changes in behaviour. The findings of this study and similar studies indicated that enabling environmental behaviours in new developments is challenging. New policies need to be more holistic and support the delivery of not only well-performing buildings, but also developments that make sustainable urban living a reality.

Smart thermostats allow continuous learning, remote scheduling and control of indoor temperature. This paper empirically evaluates indoor environmental conditions, occupant experiences and prevalence of summertime overheating in three low energy dwellings with smart thermostats and compares the results with three similar dwellings with standard programmable thermostats. The study uses building performance evaluation methods combining time-series data on temperature, relative humidity, and window opening with survey data on occupant perception of thermal comfort and heating control over the period 2019 - 2020.

While there was little difference observed in the measured and perceived indoor temperatures between dwellings with and without smart thermostats, the six dwellings were different in the way they heated their homes and controlled their indoor environment. A wide indoor temperature range of 16oC-22oC was observed in dwellings with smart thermostats during the heating season. Majority of dwellings also experienced summertime overheating with temperatures in bedrooms going up to 34oC. Individual heating preferences dominated the use of smart or standard thermostats ranging from Cool Conserver, On-off Switcher to On-demand Sizzler. It is vital that energy models consider a range of heating preferences to avoid a gap between expectation and reality.

Summertime overheating in care settings has been identified as a key risk and research priority for the health and social care system. This paper examines the current and future risk of summertime overheating in two London-based care homes occupying modern and older buildings. Continuous monitoring of outdoor and indoor temperature in bedrooms, communal areas and offices in summer 2019 helped to establish the prevalence and intensity of overheating. Dynamic thermal simulation (EnergyPlusV8.9) of the two care settings assessed the potential for avoiding active cooling in future climate using passive solutions. In both care settings, indoor temperatures were observed to exceed 30°C during daytime hours, significantly higher than the recommended 26°C threshold of Public Health England. Although severity of overheating was lower in the older building, overheating was found to be prevalent and prolonged across both care settings with bedroom temperatures higher than lounges especially at night. Thermal simulation analysis showed that, with regards to temperature reduction and cooling load, nighttime ventilation was the single most effective passive solution for both buildings for the current climate, while a combination of night ventilation, external shading and high-albedo external walls was the most effective package solution. By the 2080s, air-conditioning was the most effective solution for reducing temperature, but also had the highest cooling load., highlighting the importance of balancing passive with active measures to improve thermal comfort and reduce cooling loads.

As governments worldwide address the climate crisis, energy systems are becoming both decarbonised and decentralised. In this study, we aim to increase understanding of the spatial dimensions of new forms of decentralised energy systems that integrate electricity, storage, transportation, and heating. Drawing on workshops and secondary data from three, early-stage case studies funded under a UK government programme, we examine how stakeholders responsible for development construct the ‘local’ in Smart Local Energy System (SLES) demonstrators. We employ three analytical concepts to address this aim: emplacement, place-framing, and place/boundary-making. In terms of emplacement, stakeholders use place-based narratives that draw on distinctive infrastructural, social, ecological, and political characteristics to argue that diverse locations (Oxford city, Oxfordshire, and the Orkney Islands) are ‘suitable’ places for decentralised energy. Stakeholders frame projects around non-local goals of creating technological and business models for replication across the UK and worldwide, even if some community-centred benefits are recognized. Lastly, our findings on place-making show pragmatism in flexing ‘local’ boundaries in order to align with project objectives. The three analytical concepts provide a useful framework to uncover ‘local’ complexities of early-stage decentralised energy projects, and emphasise intersections of space, place, and justice that deserve further scrutiny, notably in later stages of project implementation.​​​​​​​

This paper systematically examines the in-use energy and carbon performance of a large case study housing development in England, designed to be net true zero carbon. Remote monitoring during a one-year period was used to gather high-frequency data on dwelling heat use, grid electricity use, solar PV electricity generation and export and community heating system performance. Based on data from 74 dwellings, mean energy use of 76 kWh/m2/year and electricity use of 27.4 kWh/m2/year per dwelling placed the case study among the lowest energy housing developments in the UK. Nonetheless, heat usage and designed fabric efficiency fell short compared to other true zero carbon housing. The mean self-consumption rate of generated energy of 23% calls for the provision of home batteries. Heat usage variance was more prominent compared to findings in other studies. Based on the 2018/19 carbon factors, dwellings emitted 20.2 kgCO2e/m2/year on average, missing the zero carbon target. As found in other studies, this was attributed to the underperforming community heating system. This study comes timely in the context of the widespread calls for net zero carbon dwellings. The findings confirm the argument that the anticipated mainstreaming of zero carbon dwellings demands shifting towards an outcome-focused design approach.

This paper brings together objective and subjective data on indoor temperature and thermal comfort to examine the magnitude and perception of summertime overheating in two London-based care homes occupying modern and older buildings. Continuous monitoring of indoor and outdoor temperature, relative humidity and CO2 levels was conducted in summer 2019 along with thermal comfort surveys and semi-structured interviews with older residents and staff of the care settings. Indoor temperatures were found to be high (>30 °C) with bedroom temperatures often higher at night than daytime across both care settings. Limited opening due to window restrictors constrained night-time ventilation. Overheating was prevalent with four out of the five monitored bedrooms failing all four overheating metrics investigated. While 35-42% of staff responses perceived indoor temperatures to be uncomfortably hot, only 13-19% of resident responses were found to do so, indicating that elderly residents tend to be relatively insensitive to heat, leaving them open to overheating without realising it. Residents and staff in the modern care setting were less satisfied with their thermal conditions. As hybrid buildings, care settings need to keep both residents and staff comfortable and healthy during hot weather through night-time ventilation, management of heating and supportive institutional practices.

We explore methodological issues core to the cost-benefit evaluation of building adaptations designed to protect against heat risks to residents of care homes in England in the context of the uncertainties relating to the loss of life expectancy in heat death. We used building physics modelling to quantify the impact of external window shading on indoor temperatures. We calculated associated heat mortality and loss of life expectancy under three sets of assumptions of life-shortening based on: (Method 1) an England & Wales (E&W) life-table, (Method 2) E&W life-table scaled to match observed average survival of care home residents and (Method 3) assuming that those dying of heat have a life expectancy of six months. External window shading was estimated to reduce mean indoor temperatures by 0.9 °C in a ‘warm’ summer and 0.6 °C in an ‘average’ summer. In a care home of 50 residents, the heat deaths and years of life lost (YLL) averted by such shading were estimated by the three life-expectancy assumptions (Methods 1, 2, 3) to be: 0.07, 0.47 and 0.28 heat deaths and 0.29, 0.76 and 0.14 YLL for the warm year and 0.05, 0.31 and 0.19 heat deaths and 0.20, 0.51 and 0.10 YLL for the average year. Over a 20-year time horizon and assuming an annual discount rate of 3.5%, the monetized benefit of reduced YLL would be around £90,000, £230,000 and £44,000 with the three life-expectancy assumptions. Although this range represents appreciable uncertainty, it appears that modest cost adaptations to heat risk may be justified in conventional cost-benefit terms even under conservative assumptions about life expectancy.

This paper presents the methodology and results of in situ testing of building fabric thermal performance to calibrate as-built energy models of three low-energy dwellings in the UK, so as to examine the gap between as-designed and as-built energy performance. The in situ tests included repeat testing of air permeability (AP) integrated with thermal imaging survey and heat flux measurements of the building fabric elements, along with concurrent monitoring of indoor temperature during the pre-occupancy stage. Despite being designed to high thermal standards, wall and roof U-values were measured to be higher than expected. Thermal imaging surveys revealed air leakage pathways around door/window openings, penetrations and junctions between walls and ceilings, indicating poor detailing and workmanship. AP was found to have increased after the initial test due to post-completion alteration to the building fabric. Though the results did not meet design expectation, they were within the UK Building Regulations. Calibration of energy models with temperature monitoring provided a less extreme energy performance gap than simply replacing the designed values with test results. Insights from this study have reinforced the need for building regulations to require integrated testing of building fabric as part of housing delivery to ensure performance targets are realised.

The transition of the Net Zero Energy (NZE)  concept from building to settlement scale has been theoretically approached in a number of studies. This paper examines the benefits and barriers associated with the implementation of the NZE concept at a settlement scale, by adopting a comprehensive approach for the design, construction, and monitoring of NZE settlements that was developed in the EU Horizon 2020 ZERO-PLUS project and implemented in four case studies. First, the ZERO-PLUS approach is presented, followed by an analysis of associated benefits and encountered barriers. Next, the roles of different stakeholders involved in the process are identified through stakeholder analysis. Finally, new dynamics that emerge and are critical to the successful implementation of NZE settlements are discussed. The ZERO-PLUS approach leads to achieving NZE settlements with an initial cost that is on average 16% lower than the cost of a typical NZEB, while achieving a net regulated energy consumption of less than 20 kWh/m2/year and renewable energy production of more than 50 kWh/m2/year. The implementation of NZE settlements revealed two main issues: 1) the external barriers that were raised by the planning policies and regulations; and 2) the challenge of managing and integrating the needs and requirements of project stakeholders. To overcome these barriers while reaping the benefits of the approach, the management of such projects needs to focus from the outset on the establishment of a project management structure that will ensure the coordination and integration of various stakeholders. The use of a standardized collaboration protocol from the preliminary design stage is recommended to facilitate future projects. Simultaneously, regulations need to be updated towards facilitating NZE settlement implementation.

Measurement and verification (M&V) has become necessary for ensuring intended design performance. Currently, M&V procedures and calculation methods exist for the assessment of Energy Conservation Measures (ECM) for existing buildings, with a focus on reliable baseline model creation and savings estimation, as well as for reducing the computation time, uncertainties, and M&V costs. There is limited application of rigorous M&V procedures in the design, delivery and operation of low/zero energy dwellings and settlements. In the present paper, M&V for four pilot net-zero energy settlements has been designed and implemented. The M&V has been planned, incorporating guidance from existing protocols, linked to the project development phases, and populated with lessons learned through implementation. The resulting framework demonstrates that M&V is not strictly linked to the operational phase of a project but is rather an integral part of the project management and development. Under this scope, M&V is an integrated, iterative process that is accompanied by quality control in every step. Quality control is a significant component of the M&V, and the proposed quality control procedures can support the preparation and implementation of automated M&V. The proposed framework can be useful to project managers for integrating M&V into the project management and development process and explicitly aligning it with the rest of the design and construction procedures.

There has been increasing recognition that climate change may lead to risk of summertime overheating in UK dwellings with potentially adverse consequences for human comfort and health. This paper investigates the magnitude of summertime overheating over one month in 2017, in four new flats built to identical thermal standards, with similar occupancy patterns and located in the same block in a development in Southeast England. Both static and adaptive methods were used to assess the overheating risk, while the variation in indoor temperatures across the flats was examined through key building characteristics including floor level, glazing orientation, exposed surface area to floor area ratio (SA/FA), glazing area to floor area ratio, and ventilation. Data collection included continuous monitoring of indoor and outdoor temperature, relative humidity, CO2 levels and opening/closing of windows. Summertime overheating was found to be prevalent in all four flats but was most pronounced in two top floor flats with high SA/FA ratio and east/west facing glazing. Due to limited window opening and locational limitations of one flat, some conclusions were derived from three flats. Though the study sample is small, it is clear that overheating in new housing is a current issue and designing for avoidance of summertime overheating should become mainstream.

A long-standing challenge for area-based mass retrofits has been the ability to rapidly and accurately target appropriate dwellings for energy improvements. This paper demonstrates the application of a data-driven localised Geographical Information System (GIS)-based domestic energy mapping approach to create house-by-house baseline energy models and predict the potential for whole house energy retrofits in a case study of 431 dwellings in Oxford (UK). Top-down spatial datasets on energy, housing, socioeconomics and fuel poverty are combined with bottom-up energy modelling underpinned by actual dwelling details gathered through questionnaire surveys by the local community group. Multiple routes of identifying suitable dwellings were tested such as grouping dwellings with high energy use, those with high levels of fuel poverty and by common dwelling characteristics. About 300 dwellings were found to be suitable for a whole house retrofit package, equating to 89-94% mean energy reduction over baseline. While the most common dwelling typology, 1930s semi-detached had high retrofit need, it fell in area with low annual household income. The second most common dwelling typology, 1930s terrace, was dominant in areas with median level of household income. Funding programmes will need to be customised for different household segments to increase the take-up of energy retrofits.

This paper uses a case study-based approach to comparatively evaluate the relationship between measured and perceived indoor environmental conditions in two office buildings, one naturally ventilated and one mechanically ventilated, located in south England. Environmental parameters (indoor and outdoor temperature and relative humidity, and indoor CO2 concentration) were continuously monitored at 5-minute intervals over a 19-month period (March 2017 to September 2018). During this time, occupant satisfaction surveys (both transverse and longitudinal) recorded occupant perceptions of their working environment, including thermal comfort, resulting in approximately 5700 survey responses from the two case studies combined.

In the NV office, CO2 levels were high (often >2000ppm) and indoor temperature was both high (>27°C) and variable (up to 8°C change in a working day). In contrast, the MV office environment was found to operate within much narrower temperature, RH and CO2 bands. This was particularly evident in the little seasonal variation observed in the CO2 levels in the MV office (rarely above 1200 ppm); whereas in the NV office, CO2 concentrations exceeded 2000 ppm on 12% of working days during the heating seasons and less than 1% in the non-heating season. Despite these differences in measured indoor environmental conditions, occupants’ overall satisfaction with their environment was similar in both buildings. Occupants of the NV building were found to be more tolerant of higher indoor temperatures while neutral thermal sensation corresponded to a higher indoor temperature, indicating the role of adaptation. This has important implications for energy use in managing the indoor environment.

This paper presents the systematic review on thermal comfort studies in Indian residential buildings, helpful in identifying the present research scenario, data gaps and policy interventions. Majority of the studies are performed in composite climate (ten), followed by warm-humid (seven) and a very few from cold (two) and hot-dry (two) climates. None of the thermal comfort study is found from temperate climate. Besides, the seven studies have considered multiple climates for assessment of thermal comfort in residential buildings. This shows that thermal comfort studies in Indian residential buildings are scarce, scattered and unorganized. Further, due to differences in socio-cultural set-up and local adaptations, the prodigious variations in occupant’s comfort requirements are reported. This review argues the dynamic modifications in individual behaviours due to change in cost of building energy services and comfort requirements. Only four studies have partially considered the occupant behaviour regarding control of indoor thermal environment. The results obtained from these studies indicate that there is strong need of localised thermal comfort model that will not only help in improving comfort requirements but also the building energy performance. Moreover, this review paves way for research development in India where high residential building stock is yet to be built.

Most studies on the link between indoor environments and productivity have been conducted in controlled, static conditions often unrepresentative of the real world. This paper uses a case-study-based, real-world approach to empirically investigate the link between indoor environment and workplace productivity in a mechanically-ventilated office environment in southern England. Evidence gathered during the baseline period was used to implement two interventions limiting peak temperature and CO2 concentrations. Environmental parameters (temperature, relative humidity, CO2) were monitored continuously. Transverse and longitudinal surveys recorded occupant perceptions of their working environment and self-reported productivity, while performance tasks provided proxy measures of worker performance in terms of cognitive ability, speed and accuracy. 

Workplace productivity was perceived to decrease when occupants perceived thermal discomfort and stuffy air. Correlations with perceived changes in productivity were stronger for perceived rather than measured environmental conditions and for perceived air quality rather than either measured RH or CO₂ concentration. This implies that occupants’ subjective feelings can impact their perceived productivity more than objective environmental conditions. Furthermore median task scores were 15% lower when conducted at CO₂ levels above 800ppm compared to below 800ppm. Insights from the study can help to optimise indoor office environments and improve workplace productivity.

Building performance evaluation (BPE) is becoming an important tool for the improvement of building design and operations globally. However, with low energy buildings becoming more complex and clients increasing their interest in the evaluation of the impact of design and technologies on indoor environments, occupant health and productivity, gaps are often found between design expectations and actual performance. Often the causes are not just a result of one factor but due to complex interactions between building fabric, mechanical services and the behaviours of occupants which occur throughout the design, construction and use of a building. Although a few BPE techniques such as the Building Use studies (BUS) questionnaire survey are beginning to be used internationally to evaluate user perception and satisfaction, largely BPE forms a fragmented whole with tools and methods that are not widely applicable. 

This paper develops and demonstrates a novel BPE framework to bring consistency and flexibility in evaluating actual building performance. The paper critically reviews and evaluates existing BPE methods and techniques (derived from BPE studies undertaken in UK and elsewhere) and situates them in different building life stages. Using a hierarchical approach, a ‘BPE framework’ is devised for new and existing buildings as well as refurbishments. The framework is designed to have four graduated levels starting at the ‘basic’ level and developing incrementally to ‘core’, ‘comprehensive’ and ‘advanced’ levels. The working of the BPE framework is demonstrated by applying it to four discreet BPE studies to enable cross-comparison of different BPE approaches based on their stage of application, depth and duration of BPE investigations. Such a graduated and flexible framework helps to bring consistency in evaluating building performance in an otherwise fragmented field, to help minimise the performance gap between design intent and actual outcomes and improve building performance.

This paper presents the results of a meta-analysis of hourly indoor summertime temperature datasets gathered during the summer of 2013 (May to September), from 63 dwellings, located across the UK. The sample consisted of unmodified dwellings (existing); dwellings with varying levels of fabric improvements (retrofitted) and dwellings constructed to higher levels of the Code for Sustainable Homes (new). Indoor and outdoor temperature data from bedrooms and living rooms from these homes were collected at five-minute intervals using temperature sensors. These data were processed and analysed for summertime overheating, using both static criteria (CIBSE Guide A) and the criteria associated with the EN15251 adaptive thermal comfort model (CIBSE TM52). The results show that despite a relatively cool summer, sufficiently high temperatures were found in a high proportion of dwellings, which were overheated according to the static criteria, although the prevalence of overheating was found to be much lower when assessed by the adaptive method. Considerably higher temperatures were found in bedrooms, much higher than living rooms. Interestingly, dwellings with higher levels of insulation experienced overheating twice as frequently as uninsulated dwellings. It is necessary to consider the overheating risk during the design and retrofit of homes, to avoid air-conditioning in future.

This paper empirically evaluates the extent of energy resilience achieved in a socially-deprived community in Oxford, through deployment of solar photovoltaic (PV) systems and smart batteries (internet enabled and controllable) across a cluster of 82 dwellings (households). The methodological approach comprised dwelling and household surveys, along with high frequency monitoring of household electricity consumption, solar PV generation, battery charge and discharge data. In the monitored households, average daily electricity consumption was found to be positively related with dwelling size, number of occupants and number of appliances used. Although 117MWh of PV electricity was generated within a year across 74 dwellings, peak generation did not match peak consumption, demonstrating the need for battery storage. Home batteries were found to increase self-consumption of PV electricity and offset grid demand through discharge of stored PV electricity marginally at an average of 6%, depending on the size of the PV system, surplus PV electricity available and size of the battery. Aggregating solar generation and storage at a community level showed that peak grid electricity demand between 17:00 and 19:00 was reduced by 8% through the use of smart batteries across 74 dwellings. In future, a local energy sharing scheme could be developed, wherein not all dwellings would need to have solar PV systems, but rather have internet enabled batteries that could be monitored and controlled virtually.

The green building movement in India is lacking an important link: ensuring that design intent of such buildings is

actually realized. This paper undertakes an exploratory investigation to develop and test a customized building

performance evaluation (BPE) approach (I-BPE framework) for the Indian context. As academia is considered to be

an initial primary outlet of BPE, a survey of experts is conducted to investigate the drivers and barriers for

implementing BPE-based methods in educational curricula. The I-BPE approach is tested in a case study building to

gain insights for refining the underlying methods and processes for conducting further BPE studies in a context of

India. The expert survey reveals the lack of trained people for teaching BPE as a key challenge to its adoption,

implying that trained people are needed as much as frameworks. To enable widespread adoption of I-BPE in India,

what will be necessary is a new cadre of building performance evaluators who can be trained (or upskilled) through

formal or continuing education. This will need to be driven both by policy (energy code) and market transformation

('green' rating systems). A series of delivery routes are suggested to enable rapid and deeper learning.

This paper uses a case study-based approach to empirically investigate the relationship between indoor environment and workplace productivity in two contrasting office environments: one naturally-ventilated (NV), the other mechanically-ventilated (MV). Environmental parameters were continuously monitored over 19 months. Transverse and longitudinal surveys recorded occupants’ perception of their working environment and self-reported productivity, while performance tasks (numerical and proofreading) measured cognitive capability as proxy for measured productivity. Indoor temperatures and CO2 concentrations were found to be higher and more variable in the naturally-ventilated office. However, the correlation between occupant perception of their indoor environment and perceived productivity was stronger in the MV office. Occupants of the NV office were found to be more tolerant of their environment than their counterparts in the MV office. Task performance was affected by indoor environmental conditions such as indoor temperature and CO2 concentration. Interestingly in the NV office, the median scores were up to 12% higher for tests conducted at CO₂ concentrations

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 (

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.

Modelling results demonstrate the magnitude of projected summertime overheating in care and extra-care schemes, yet there appears to be little awareness amongst designers about the risk of overheating and implementation of long-term adaptation approaches such as external shading, provision of cross-ventilation. Although age, location, and orientation are found to have notable effect on the magnitude of overheating, they are difficult aspects to change in existing buildings, yet they provide insights into adaptive responses with regard to retrofit, management and use of care settings. Designers also need to focus on long term planning of care settings rather than near future, to anticipate the effects of climate change on care settings.

achieve a reduction of operational energy usage to 0-20 kWh/m2 per year through a transition from single NZE buildings to NZE settlements, in which the energy loads and resources are optimally managed. In addition, investment costs will be at least 16% lower than current nZEB costs. In this paper, the methodology that was developed in order to optimize the energy, environmental and cost plans of the four case studies through the best integration and combination of the selected innovative energy technologies with excellent architectural and

engineering design is described. In addition the evaluation of the four NZE settlements in terms of energy, environmental and cost performance is presented. 

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.

Infrastructure is a means to an end: it is built, maintained and expanded in order to enable the functioning of society. Present infrastructure operation is characterised by:  governance based on unmanaged growing demand, which is both inefficient and ultimately unsustainable; lack of integration of the end-users, in terms of the variety of their wants, needs and behaviours; separate and parallel delivery of different infrastructure streams prohibiting joint solutions. To achieve long-term sustainability, infrastructure needs to be designed and operated to provide essential service delivery at radically decreased levels of resource use. This new approach will need to: (1) incorporate the end-user, in terms of their wants and behaviours; (2) focus on the service provided; (3) use information and communication technologies more effectively; (4) integrate the operation of different infrastructure systems; (5) be governed in a manner that recognises the complexity and interconnectedness of infrastructure systems; and (6) rethink current infrastructure valuation. Possible configurations incorporating these aspects with the explicit goal of contributing to long term sustainability could be Multi Utility Service Companies or “MUSCos”. This article presents new insights and ideas generated by considering the challenge of the transition towards a MUSCo infrastructure. 

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.

This research study investigates the effects of the large-scale installation of domestic heat pumps on the UK electricity supply over the short to medium term. A BREDEM-based dwelling energy model, incorporating a model of heat pump performance, is enhanced for the effects of varying monthly temperatures. Data from the English Housing Survey (2007) is analysed using this model to estimate electricity consumption to 2020 and 2050, and simulate scenarios for replacing existing heating systems by ground or air source heat pumps. The type of heat pump (ground or air source) is determined by dwelling plot dimensions data from the EHS. Modelling results for 2020 showed that a policy of replacing the heating systems with the highest emissions could reduce or at least minimise the increase in electricity consumption and carbon emissions. Results for 2050 showed that replacement of some 80% of current gas-
fired systems would enable the UK to meet its target of 80% carbon emissions reduction in this sector when accompanied by simultaneous decarbonisation of the electricity supply. These results provide some support for the UK government’s policy of subsidizing heat pump installations through the Renewable Heat Incentive payments whilst indicating that meeting emission targets requires far greater adoption of these systems than current ambitions.

Community-led approaches have emerged in the UK as an alternative route for realizing reductions in domestic energy demand through changes in homeowners' understanding and behaviours when coupled with physical retrofitting. A socio-technical approach is used to develop and apply a monitoring and evaluation framework. This framework comprises assessment of longitudinal energy use, in-situ monitoring and qualitative social science surveys in order to evaluate the impacts (on changing individual and household energy behaviours) and effectiveness (on achieving real savings in energy use and carbon emissions) of energy retrofits of 27 owner-occupied homes across six low carbon communities (LCCs). Results indicate that the energy retrofits have been reasonably effective in terms of reducing energy use in dwellings (75% of homes experienced reductions in gas and/or electricity use). The research also reveals wider impacts of retrofits on indoor environmental conditions and behaviours of the occupants. Such impacts, intended or otherwise, may not be always positive; however, the LCCs appear particularly successful in facilitating the households, through increased motivations, capability, awareness and knowledge relating to energy use and behaviours. Insights from the study can help to inform future strategy implementation for reducing energy demand from existing housing to meet national CO2 targets.

Purpose – This paper aims to, using a systematic mixed-methods based monitoring and evaluation approach, investigate the unintended consequences of physical and technical home improvements on energy use, indoor environmental conditions and occupant behaviour in community-led retrofits. The study is part of a UK Research Council funded research project on evaluating the impacts and effectiveness of low carbon communities on energy behaviours.

Design/methodology/approach – A graduated measurement, monitoring and evaluation framework has been developed and applied to gather quantitative and qualitative data on energy use and behaviours has been developed and applied to 88 households across the UK. A mixed-methods approach is used, including occupant interviews, questionnaires, activity diaries and continuous physical monitoring of energy use, environmental conditions and low-carbon technologies.

Findings – The study has uncovered a number of unintended consequences associated with home energy improvements, both beneficial and detrimental, including improved comfort levels in retrofitted dwellings and reduction in energy use but also an increased likelihood of overheating following fabric

improvements, potential under-performance of low-carbon systems due to lack of understanding and inadequate installation and commissioning, along with adaptive energy behaviours leading to increased energy use and a widening gap between predicted and actual savings.

Research limitations/implications – Although 63 case study households are involved, it is difficult to provide statistical analysis from the emerging findings.

Practical implications – This paper demonstrates the unintended consequences of home energy improvements. It aims to bring awareness of these issues to various sectors and stakeholders involved in delivering community retrofit programmes or the National Green Deal programme.

Originality/value – The paper fulfils an identified need to study the impacts of home energy improvements within existing homes through a robust, comprehensive M&E approach.

This paper outlines the development and application of a domestic heat pump model for space heating and cooling energy. The model is intended to bridge the gap between the single Coefficient of Performance parameter currently used in the UK procedures for the assessment of the energy efficiency of dwellings and the dynamic simulation models frequently developed for the academic estimation of heat pump energy use. It is responsive to variations in source and sink temperatures whilst being simple enough to be embedded in a spreadsheet model. The model was developed by: building a regression model, using heat pump performance test results, relating heat pump coefficient of performance to the differential between source and sink temperatures - "lift"; deriving estimating rules for monthly supply temperature estimates for commonly-used heat pump sources and for demand temperatures for normal wet central heating sinks to give a monthly estimate for the source / sink differential; embedding the regression model in the UK standard model for domestic energy estimation, with additional routines to estimate energy consumption for additional heat and for space cooling. The model developed was validated by comparison with the existing BREDEM model. Compared with the standard BREDEM estimates, the resulting model showed correct response to changes in ambient temperatures, allowing correct estimating of consumption for additional heat under conditions of climate change. It showed variation of heat pump coefficient of performance across the year, allowing better estimation of winter peak load.

– To critically compare three future weather year (FWY) downscaling approaches, based on the 2009 UK Climate Projections, used for climate change impact and adaptation analysis in building simulation software.

Design/methodology/approach

– The validity of these FWYs is assessed through dynamic building simulation modelling to project future overheating risk in typical English homes in 2050s and 2080s.

Findings

– The modelling results show that the variation in overheating projections is far too significant to consider the tested FWY data sets equally suitable for the task.

Research and practical implications

– It is recommended that future research should consider harmonisation of the downscaling approaches so as to generate a unified data set of FWYs to be used for a given location and climate projection. If FWY are to be used in practice, live projects will need viable and reliable FWY on which to base their adaptation decisions. The difference between the data sets tested could potentially lead to different adaptation priorities specifically with regard to time series and adaptation phasing through the life of a building.

Originality/value

– The paper investigates the different results derived from FWY application to building simulation. The outcome and implications are important considerations for research and practice involved in FWY data use in building simulation intended for climate change adaptation modelling.

Purpose – This paper presents new research on the potential pathways for integrated adaptation that could make England's suburbs more resilient to future climate conditions. It focuses on the role of central government, local agencies and householders in making adaptations to the built and natural environment.



Design/methodology – This paper uses evidence from three facilitated workshops run with built environment and policy professionals associated with climate change adaptation in three cities in England: Oxford, Bristol and Stockport. The workshop contributions are presented in relation to the potential role that central government, local agencies and residents could play in adapting suburbs.



Findings – Central government, local agencies and householders form an interconnected network of agents responsible for adaptive action in suburbs. Professional and institutional stakeholders expect central government to take a lead and ensure planning policies and building regulations support effective adaptation. However, those local authorities and agencies that are expected to offer leadership locally do not have the resources to make adaptation happen on the ground. Overall, the stakeholders in this research believe that effective adaptation in suburbs may only happen once householders and government have experienced worsening climatic conditions. This could be a very costly stance in the long term.



Originality/value – This paper provides empirical evidence on how stakeholders engaged in suburban adaptation are making changes now, and on how they envisage change in the future. It reveals clearly the challenges involved in integrating mitigation and adaptation actions and highlight the complexities around implementation on the ground.

The majority of the English population lives in suburbs and this is where the impacts of climate change will significantly affect people's domestic lives: heat stress, respiratory problems, flooding, drought, deterioration of green spaces and damage from storms. A recognized need exists to adapt suburbs (homes, gardens and public space) physically to mitigate against further climate change and to adapt to inevitable weather patterns. A number of potential adaptation options, addressing different risks, are identified and tested using a range of methods, including modelling, and workshops with residents and professional and institutional stakeholders. The ‘best’ solutions are those that reduce the climate risk within the context of local adaptive capacity. Solutions are effective, acceptable and feasible given the type of suburb; its location; microclimate; housing type; the climate risk it faces; the socio-economic composition of its residents and their attitudes; resources; and governance conditions. It is essential to consider both the totality of the suburban environment and the combined effects of mitigation and adaptation measures. However, the biggest challenge is implementation which entails a better understanding of the problem by a range of stakeholders, a more supportive policy context, more resources, and clearer responsibilities.

This paper uses probabilistic climate change data from the UK Climate Change Projections 2009 to define extreme climate change in order to model the effect of future temperature change, particularly summer overheating on the energy consumption of, and comfort in, existing English homes (located in Oxford). Climate change risk is then analysed as a factor of climate hazard, exposure and vulnerability. With the risk of overheating theoretically identified, the risk of overheating and the future change impact on space heating energy use is then virtually detailed for four English home types modelled using future weather years in a dynamic simulation modelling software (IES). A range of passive adaptation measures are then critically reviewed with regard to their effectiveness in minimising the negative impacts of climate change and to identify the most effective measures in reducing or eliminating the negative impacts of climate change on comfort and energy consumption. In addition the adaptation options are grouped and tested as packages in order to identify the optimal solution for adaptive retrofitting of English homes. For all homes modelled, user-controlled shading proved to be the most effective adaptation. Increasing the surface albedo of the building fabric and exposure of thermal mass were also revealed to be effective although proving to be complicated and requiring detailed consideration of the optimal locations. Ultimately among the passive options tested, the research found that none could completely eliminate the risk of overheating in the homes, particularly by the 2080s.

Mitigation of climate change, and adaptation to the inevitable changes in the climate, are equally important in suburban neighbourhoods, where 84 per cent of the British population choose to live. However, the policy on climate change adaptation of the existing built environment is only beginning to emerge in the UK. In this chapter, a robust methodological framework for quantifying climate change risks on a suburban neighbourhood level is described. Climate change hazards and impacts are first detailed using the UK Climate Projections 2009 (UKCP09) data set. Climate change scenarios are then downscaled spatially and temporally, and cross-referenced with local environmental features of each city that may exacerbate or ameliorate the climate change impacts. Finally, a matrix of adaptation strategies on a neighbourhood, individual dwelling and occupant level are developed for specific suburban neighbourhoods in three UK cities (Bristol, Oxford and Stockport), in response to the impacts derived from possible future climate hazards.

How can occupant feedback methods inform the management and design of low-carbon and whole-house refurbishment of dwellings? This is particularly relevant for large-scale, whole-house refurbishment programmes tasked with achieving deep cuts in carbon dioxide (CO2) emissions. Evidence from pre-refurbishment occupancy can influence which interventions are chosen and increase their efficacy. A critical review is undertaken of a portfolio of short- and long-term occupant feedback techniques for evaluating occupants' perception of comfort, satisfaction, behaviour, and expectations. A number of these occupant feedback techniques are then tested empirically at the pre-refurbishment stage for two discrete case-study house types as part of ongoing research. The evidence reveals wide gaps between modelled and actual energy consumption; poor indoor CO2 and daylight levels, low operating internal temperatures, as well as problematic noise transmission. Such findings influence the selection of suitable user-centred low-carbon refurbishment interventions and ensure that there is a robust learning process for building owners, occupants, designers, and building managers. To optimize time, cost, and occupant involvement, it is important that feedback from occupants on building performance focuses on 'need-to-know' rather than 'nice-to-have' factors.

This paper describes the methodological approach for development, application and analysis of findings from an interactive user-friendly Sustainability Appraisal Toolkit (SAT) developed to facilitate the assessment of the energy and carbon impact and financial viability of achieving higher levels of the Code for Sustainable Homes. SAT runs on MS-Excel and is used to evaluate the technical feasibility of achieving Code levels 4, 5 and 6 for a representative sample of newly built dwellings in UK for different scales of development. A range of strategies are evaluated on both demand and supply sides of energy to meet different code levels. The research emphasizes the importance of maximizing energy efficiency improvements to the fabric and form of a dwelling, before adding low/zero carbon systems, and promotes a"low-energy first and then low-carbon" approach.