Comparing Spatial Interpolation Techniques of Local Urban Temperature for Heat-related Health Risk Estimation in a Subtropical City

INTRODUCTION: The threat of elevated temperatures and more intense and prolonged heat waves coupled with urban heat islands presents a significant risk to human health. City planners and policymakers need tools that predict how overheating risk varies within a city under different climate change and mitigation scenarios. A key driver of determining overheating risk is exposure to local urban temperatures and the extent to which such exposure may be modified by built environments where the majority of people spend their time. Due to the dispersion of monitoring stations, techniques are needed to extrapolate from single point measurements and their modifying determinants. This research aims to compare nine GIS spatial interpolation techniques of estimating street-level temperature in a subtropical city. METHODS: Taipei city, Taiwan, is located in a subtropical zone with one of the highest population densities in the world. Taipei experienced warmer winters and hotter summers in recent 10 years with average temperature from 16.4 to 30.1 °C, and expected to rise from 0.8(RCP2.6) to 3.2(RCP8.5)°C in 2081-2100. In this study, data from the Taiwan Central Weather Bureau weather stations and the Taiwan Environmental Protection Administration air monitoring sites were used. Nine interpolation techniques were applied. These were validated by using records from two sources to cross-validate by comparing Standardised mean error and Standardised Root-Mean-Square error. RESULTS: Kriging techniques have better prediction performance than four non-geostatistical interpolation techniques. The performance of OCK techniques indicated the built environment, such as the nearby village park area or home density, can be important modifiers of external temperature in cities. DISCUSSION: Local urban climates are complex systems; selecting a robust interpolation technique that accounts for underlying drivers is essential for policymakers. This research provides the basis to further estimate overheating risk by estimating local outdoor street-level temperature and the modifying effects of the built environment

Uncertainty-based optimal energy retrofit methodology for building heat electrification with enhanced energy flexibility and climate adaptability

To reach net zero emissions by 2050, the UK government relies heavily on heat degasification in buildings by using heat pump technology. However, existing buildings may have terminal radiators that require a higher operating temperature than what heat pumps typically provide. Increasing the size of radiators and thermally insulating building envelopes could be a potential solution, but the feasibility of these practices is uncertain due to space constraints and high retrofit costs. This study investigates the feasibility and potential benefits of incorporating air-source heat pumps into existing gas boiler heating systems to meet heating demands. The proposed probabilistic optimal air-source heat pump design method enhances energy flexibility and climate adaptability, taking into account a wide range of uncertainty sources and multiple flexibility services (e.g., energy and ancillary services). Heating systems of three educational buildings at the University of Cambridge are used as a testbed to assess and validate the effectiveness of the proposed method, under future climate scenarios and projected decreases in heating demand due to climate change. Results indicate that the best retrofit alternative of the hybrid heating system reduces carbon emissions by 88%, total costs by 54% over its lifespan, and has an average payback period of around 3 years. Air-source heat pumps can meet the majority of the heating demand (around 80%) with gas boilers used for “top-up” heating during high demand. Furthermore, air-source heat pumps' design capacity can fulfil future cooling demand even if retrofit optimization is initially focused on meeting heating needs

Impact assessment of climate change on thermal comfort in a naturally ventilated school

Objective: The objective underlying the present study was to assess the impact of climate change on the thermal performance of a naturally ventilated school building in an urban site in central London. Methods: First, the general regulatory framework was described and the current trends in the field of sustainable school design in the UK were investigated. Emergent themes in relation to sustainability issues were identified by the examination of recently built paradigms. The second part of the study adopted a case study approach. The current and theoretical environmental performance under a climate change scenario of the Haverstock Secondary School in Camden Town was studied. The methods used included monitoring of Dry Bulb Temperature ( C) and Relative Humidity (%), occupant questionnaire survey and thermal simulation by making use of computer modelling software. Results: The outcome of the field study suggested that the building suffers from overheating during summer. However, this could be attributed to wrong control system settings of the Monodraught windcatcher system. The simulation study demonstrated that the Building Bulletin 101 criteria against overheating can be met by a combination of rapid ventilation provided by manually controlled openings and temperature-dependent system controls of the windcatcher system

A case study on the impact of fixed input parameter values in the modelling of indoor overheating

Global efforts to reduce greenhouse gas emissions from buildings while also improving their environmental resilience have intensified. These efforts are often supported by building stock models which can inform policymakers on the impact of policies on energy consumption, greenhouse gas emissions and the indoor environment. The input values of such models are commonly informed by reference tables, which can result in inaccurate specification and incomplete representation of the distribution of possible values. In this modelling case study of a semi-detached dwelling archetype, the influence of using a reference U-value (2.1 W/(m2K)) for solid walls in England on heat-related mortality rate is compared to a probabilistic specification based on empirical evidence (median = 1.7W/(m2K)). Using the theoretical reference U-value generally resulted in a lower indoor overheating risk compared to the use of the empirically derived U-values pre-retrofit, but a larger increase in heat-related mortality rate following internal wall insulation (1.20%) than the use of the empirical median (0.94%, 95 % Confidence Interval = 0.87–0.99 %). This highlights the potentially significant implications of using fixed reference values. Future work will employ this probabilistic framework on multiple influential parameters

London's urban heat island: Impact on current and future energy consumption in office buildings

This article is available open access and shared under a Creative Commons license: (http://creativecommons.org/licenses/by/3.0/). Copyright @ 2011 Elsevier B.V.This paper presents the results of a computational study on the energy consumption and related CO2 emissions for heating and cooling of an office building within the Urban Heat Island of London, currently and in the future. The study developed twenty weather files in an East-West axis through London; the weather files were constructed according to future climate change scenario for 2050 suitable for the UK which have been modified to represent specific locations within the London UHI based on measurements and predictions from a program developed for this purpose (LSSAT). The study simulated an office with typical construction, heat gains and operational patterns with an advanced thermal simulation program (IESVE). The predictions confirm that heating load decreases, cooling load and overheating hours increase as the office location moves from rural to urban sites and from present to future years. It is shown that internal heat gains are an important factor affecting energy performance and that night cooling using natural ventilation will have a beneficial effect at rural and city locations. As overheating will increase in the future, more buildings will use cooling; it is shown that this might lead to a five-fold increase of CO2 emission for city centre offices in London in 2050. The paper presents detailed results of the typical office placed on the East-West axis of the city, arguing the necessity to consider using weather files based on climate projections and urbanheat island for the design of currentbuildings to safeguard their efficiency in the future.EPSR

Risk identification of residential energy demand: the case studies of Australia, Chile, the United Kingdom and the United States

A wide range of residential sector energy models have been developed in recent years to determine energy demand and CO2 emissions and to evaluate energy saving policies. However, modelling outputs are subject to significant variations due to multiple sources of uncertainty, primarily stemming from input parameters and assumptions. This study aims to assess the transferability of the Transferable Energy Model (TREM) and quantify the prediction uncertainty of residential sector energy demand until 2030 in four case study countries (Australia, Chile, United Kingdom and the United States). TREM is able to determine the future annual energy demand in the residential sector according to the area of energy use (space heating, hot water provision, cooking, electrical appliances, lighting), whilst quantifying uncertainties in the results. Significant variations (between −12% and +63%) in residential energy demand in the year 2030 with respect to 2010 were found among the case study countries, suggesting that single total energy demand estimates are associated with considerable uncertainties. This paper also presents a comprehensive database of the range of possible variations in residential energy demand related to a wide range of energy saving measures in each case study country

Seeing is believing, or is it? An assessment of the influence of interior finish characteristics on thermal comfort perception at a University campus in a temperate climate

Being a ‘condition of mind’, thermal comfort can be considered to be both a physiological and psychological response. Research shows that other than the physiological factors which are well established in prevailing thermal comfort standards, behavioural and psychological factors equally affect how humans adapt to the thermal conditions of their environment. Human response to thermal conditions is often based on predispositions associated with their perception and expectations of the physical environment. This paper examined the impact of interior finish characteristics on thermal comfort perception in learning spaces by analysing thermal comfort perceptions of students across 48 lecture theatres surveyed during the winter and spring season between 2012 and 2015 in University College London. A taxonomy of interior finish characteristics was first developed to guide the classification of the lecture theatres into different groups for statistical analysis. Results from hypothesis testing found small yet statistically significant differences in thermal comfort as a function of the colour hues (ȴ с 0.1) as well as the perceived naturalness (ȴ с 0.0ϲ) of interior finish characteristics. The findings of this study may have potential implications for the interior design of low carbon and healthy buildings that aim to minimize energy used for space heating whilst maintaining high indoor thermal comfort

Retrofit solutions for solid wall dwellings in England: the impact of uncertainty upon the energy performance gap

This study seeks to evaluate the impact of uncertainty in the pre-retrofit thermal performance of solid walls of English dwellings on post-retrofit energy use. Five dwelling archetypes, broadly representative of English solid wall properties, were modelled pre- and post-retrofit, under different wall insulation scenarios, using dynamic thermal simulation. Findings indicate that whilst solid wall insulation could result in a significant reduction of space heating demand, uncertainties in the pre-retrofit solid wall U-value could lead to a gap between the anticipated and actual energy performance. Specifically, results show that if the current U-value assumption of 2.1 W/m2K is indeed an overestimation of the in-situ U-value of solid walls, then the anticipated carbon savings could be significantly reduced by up to 65%. Practical application: The performance gap observed in this study revealed that the actual carbon savings arising from the retrofit of solid wall properties could be significantly lower than predicted. This will not only affect UK Government carbon reduction targets but it can also result in a lack of confidence amongst stakeholders who may consequently doubt the effectiveness of energy retrofit measures, thus reducing their uptake. Uncertainties regarding solid wall U-values may necessitate the re-examination of the carbon targets set for the retrofit of solid wall dwellings and the exploration of alternative ways to further reduce their carbon emissions, e.g. by specifying higher insulation thicknesses

A review of approaches and applications in building stock energy and indoor environment modelling

Current energy and climate policies are formulated and implemented to mitigate and adapt to climate change. To inform relevant building policies, two bottom-up building stock modelling approach: 1) archetype-based and 2) Building-by-building have been developed. This paper presents the main characteristics and applications of these two approaches and evaluates and compares their ability to support policy making. Because of lower data requirements and computational cost, archetype-based modelling approaches are still the mainstream approach to stock-level energy modelling, life cycle assessment, and indoor environmental quality assessment. Building-by-building approaches can better capture the heterogeneous characteristics of each building and are emerging due to the development of data acquisition and computational techniques. The model uncertainties exist in both models which may affect the reliability of outputs, while stochastic archetype models and timeless digital twin model have the potential to address the issue. System dynamics modelling approach can describe and address the dynamics and complexity of often-conflicting policies and achieve co-benefit of multiple policy objectives. This paper aims to provide comprehensive knowledge on building stock modelling for modellers and policymakers, so they could use a building stock model with an appropriate user interface without having to fully understand the underlying algorithms or complexities