Matthew Gregg

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.

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.

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.

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.

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 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.

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.

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.

– 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.

As the impacts of climate change become more prominent within the next 50 years and beyond, the risk of overheating in homes is a concern. This is specifically relevant in the UK's suburbs where 84% of the population reside. To assess this future impact and the effectiveness of adaptive retrofitting, probabilistic climate change data for the 2030s and 2050s are used to assess the overheating risk in six suburban house archetypes in three cities in the UK: Bristol, Oxford and Stockport. The risks of overheating in typical constructions are assessed and the possibility of preventing overheating through the use of adaptation packages is evaluated through dynamic thermal simulation. Homes in Oxford show the greatest risk of overheating. The most effective (passive) package for tackling future overheating tends to combine fabric improvements and internal heat gain reduction. To assist planners and policy-makers in assessing and preventing overheating risk at a stock level, this adaptation package is further evaluated in selected neighbourhoods across the three case study cities, using the geographical information system (GIS)-based DECoRuM-Adapt (Domestic Energy, Carbon Counting and Carbon Reduction Model) model. The implications for public policy are that the existing housing stock must be future-proofed for a warming climate, particularly retrofit programmes (e.g. the Green Deal) and any upgrading of building regulations.

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.