Forecasting summer-time overheating in UK homes using time series models

Heatwaves are projected to become more frequent, intense and long-lasting in the UK and the prevalence of overheating in dwellings is set to increase. As a result, occupants will experience increased levels of thermal discomfort, heat stress and heat-related morbidity and mortality. Since the use of mechanical air conditioning in dwellings is unsustainable, and not widely affordable, it is of utmost importance to understand when heat related health risks are anticipated in free-running dwellings. This is crucial for vulnerable occupants, such as the elderly, for whom the accurate detection of future heat risks could prepare them (or their carers) for timely mitigation, for example, through additional window ventilation or the use of shading. Many countries deploy Heat-Health Warning Systems (HHWS) to alert their populations, however, these generally apply to a wide area and are based exclusively on regional weather forecasts. Consequently, HHWSs are unable to identify where, when, or to what extent individual buildings (and their occupants) will be affected. Previous studies have investigated the use of time series forecasting models, with the majority considering the use of Model Predictive Control. There is, however, no rigorous scientific evidence to support the belief that such models can provide accurate predictions in free-running dwellings during heatwaves and over multi-day forecasting horizons. This thesis therefore examines the use of black-box forecasting models to provide reliable predictions of the impending indoor temperatures in UK homes. Having established the viability of this approach, the application of such models in the context of an indoor Heat-Health Warning System (iHHWS) has been explored. This research led to five main findings: (i) linear AutoRegressive forecasting models with eXogenous inputs (ARX), i.e. weather forecasts, can provide satisfactory accuracies during heatwaves for time horizons up to 72 h ahead; (ii) more complex semi-parametric Generalized Additive Models (GAMs) were not capable of significantly improving the forecasting accuracy at forecasting horizons over 6 h (iii) logistic GAMs can predict the window opening state with adequate discrimination, however, integration of the window state into forecasting models did not improve their accuracy; (iv) forecasting models could be usefully incorporated within an iHHWS, however, the warning lead-time should be constrained to less than 24 h in order to guarantee high confidence in such a system; (v) a weighted metric such as the Cumulative Heat Index (CHI) could further reduce the risks of false or missed warnings, increasing the dependability of the iHHWS.</div

Indoor air Quality and Its Effects on Health in Urban Houses of Indonesia: A case study of Surabaya

There is a possibility that the sick building syndrome has already spread widely among the newly constructed apartments in major cities of Indonesia. This study investigates the current conditions of indoor air quality, focusing especially on formaldehyde and TVOC, and their effects on health among occupants in the urban houses located in the city of Surabaya. A total of 471 respondents were interviewed and 82 rooms were measured from September 2017 to January 2018. The results indicated that around 50% of the respondents in the apartments showed some degrees of chemical sensitivity risk. More than 60% of the measured formaldehyde levels in the apartments exceeded the WHO standard, 0.08 ppm. The respondents living in rooms with higher mean formaldehyde values tended to have higher multiple chemical sensitivity risk scores. KEYWORDS: Indoor air quality, Sick building syndrome, QEESI, Formaldehyde, Developing countrie

Thermal Comfort in Sun Spaces: To what extend can energy collectors and seasonal energy storages provide thermal comfort in sun space?

Preparation for fossil fuel substitution in the building sector persists as an essential subject in architectural engineering. Since the building sector still remains as one of the three major global end energy consumer – climate change is closely related to construction and design. We have developed the archetype sun space to what it is today : a simple but effective predominant naturally ventilated sun trap and as well as living space enlargement. With the invention of industrial glass orangery’s more and more changed from frost protecting envelopes to living spaces from which we meantime expect thermal comfort in high quality. But what level of thermal comfort provide sun spaces? And to what extend may sun spaces manage autarkic operation profiting from passive solar gains and, beyond that, surplus energy generation for energy neutral conditioning of aligned spaces? We deliver detailed information for this detected gap of knowledge. We know about limited thermal comfort in sun spaces winter times. This reasons the inspection of manifold collector technologies, which enable to be embedded in facades and specifically in sun space envelopes. Nonetheless, effective façade integrated collectors are ineffective in seasons with poor irradiation. Hence, the mismatch of offer and demand we have experienced with renewable energies ignites thinking about appropriate seasonal energy storages, which enlarges the research scope of this work. This PhD thesis project investigates on both, a yearly empirical test set up analysis and a virtual simulation of different oriented and located sun spaces abroad Germany. Both empirical and theoretical evaluation result in a holistic research focusing on a preferred occupation time in terms of cumulative frequencies of operational temperature and decided local discomfort, of potential autarkic sun space operation and prospective surplus exergy for alternative heating of aligned buildings. The results are mapped geographically for Germany. Fossil fuel substitution, as far as this thesis elaborated, is closely related to quality of thermal comfort, sun space orientation and energetic standard of the aligned building. Unexpectedly, spaces, which define envelopes incorporating collectors in combination with storage technologies both profit and suffer to some extend in respect to thermal comfort. Essentially, we can conclude, that the more area-wise efficient and the more integral the collector technology is incorporated into façade design, the more distinct significance of thermal comfort quality and fossil fuel substitution is. Eventually, this dissertation determines the potential of a new generation of sun spaces in the context of energy transition

Thermal comfort in sun spaces:

Preparation for fossil fuel substitution in the building sector persists as an essential subject in architectural engineering. Since the building sector still remains as one of the three major global end energy consumer – climate change is closely related to construction and design. We have developed the archetype sun space to what it is today : a simple but effective predominant naturally ventilated sun trap and as well as living space enlargement. With the invention of industrial glass orangery’s more and more changed from frost protecting envelopes to living spaces from which we meantime expect thermal comfort in high quality. But what level of thermal comfort provide sun spaces? And to what extend may sun spaces manage autarkic operation profiting from passive solar gains and, beyond that, surplus energy generation for energy neutral conditioning of aligned spaces? We deliver detailed information for this detected gap of knowledge. We know about limited thermal comfort in sun spaces winter times. This reasons the inspection of manifold collector technologies, which enable to be embedded in facades and specifically in sun space envelopes. Nonetheless, effective façade integrated collectors are ineffective in seasons with poor irradiation. Hence, the mismatch of offer and demand we have experienced with renewable energies ignites thinking about appropriate seasonal energy storages, which enlarges the research scope of this work. This PhD thesis project investigates on both, a yearly empirical test set up analysis and a virtual simulation of different oriented and located sun spaces abroad Germany. Both empirical and theoretical evaluation result in a holistic research focusing on a preferred occupation time in terms of cumulative frequencies of operational temperature and decided local discomfort, of potential autarkic sun space operation and prospective surplus exergy for alternative heating of aligned buildings. The results are mapped geographically for Germany. Fossil fuel substitution, as far as this thesis elaborated, is closely related to quality of thermal comfort, sun space orientation and energetic standard of the aligned building. Unexpectedly, spaces, which define envelopes incorporating collectors in combination with storage technologies both profit and suffer to some extend in respect to thermal comfort. Essentially, we can conclude, that the more area-wise efficient and the more integral the collector technology is incorporated into façade design, the more distinct significance of thermal comfort quality and fossil fuel substitution is. Eventually, this dissertation determines the potential of a new generation of sun spaces in the context of energy transition

Space Design for Thermal Comfort and Energy Efficiency in Summer

Passive cooling for thermal comfort in summer is a big issue in low-energy building design. An important reason is global warming because global warming increases the number of cooling degree days. In addition, the energy demand of buildings has increased rapidly due to both the improvement of living standards and the globalisation of modern architecture. And finally, cooling a building is especially a challenge in countries where few resources are available. Passive cooling techniques, where solar and heating control systems are applied, largely depend on the design of the urban morphology and the building shape. The first research question is therefore: What is the relationship between spatial configuration, thermal environment and thermal summer comfort of occupants and how to apply spatial configuration as the passive cooling strategy in architectural design? Space is the empty part of a building, but its volume is important for the activities of occupants. Architects define the general spatial structure of a building mainly in the early design stages. There they define the spatial properties of a building, i.e. how the spaces are connected and what are the boundary conditions between the spaces. The final research question of this research therefore is: What is the relationship between spatial configuration, thermal environment and thermal summer comfort and how to apply spatial configuration as passive cooling strategy in architectural design in the early stages? In order to answer this research question, this dissertation is divided into two main parts. Part I is the theoretical research phase. The goal is to clarify the relationship between spatial configuration of buildings, the thermal environment and thermal comfort of occupants in summer. In this part, a literature review of the fundamental theoretical background knowledge of thermal comfort and passive cooling technology is summarised. As the author got his inspiration from Chinese vernacular architecture, the second step was conducting surveys and performing analyses of the spatial design, thermal environment and thermal summer comfort in Chinese vernacular buildings. Contemporary residential buildings were also investigated. A challenge was to find examples of contemporary buildings with appropriate spatial designs and thermal comfort as well as contemporary buildings with less successful spatial designs and thermal comfort. The third step was to find correlations&nbsp;between the occupants’ spatial and thermal perception through questionnaires. Questionnaires were held among Chinese as well as Dutch architecture students. The main research outcome of part I is the definition of “building microclimate”. Building microclimate is defined as “a type of microclimate which involves indoor spaces and spaces surrounding the indoor spaces in a particular building”. It is not just the microclimate around the building; it also includes the indoor climate. A suitable building microclimate is important for the occupants’ thermal comfort in summer. Another research outcome of part I is the revelation of the relationship between spatial perception and adaptive thermal comfort. Combining the relationship between spatial perception and adaptive thermal comfort with the new definition of building microclimate leads to the conclusion that the spatial configuration of a building plays an important role in creating a particular building microclimate. Part II is a practical research phase. The goal is to explore the possibility of using a spatial design method as a passive cooling strategy for thermal summer comfort and to demonstrate how to apply this method in the early design stages. As a first step, the potential of using a space analysis method for passive cooling and thermal comfort was investigated. A convex spatial analysis method was developed from the traditional space syntax method to analyse the natural ventilation potential. Both the logical relationship between the spaces and the boundary conditions between the spaces can influence the accessibility of a particular spatial configuration, and thus influence the potential for natural ventilation. The convex space analysis method is chosen for the preliminary analysis to show the logical relationships between spaces. It cannot completely predict natural ventilation, but it is a graphical method that is easy to use. Architects conceive design solutions generally through graphic methods, making the convex space analysis a good design tool. The extended visibility graph analysis (VGA) method is the best choice for the natural ventilation potential analysis for a spatial configuration. The isovist measure can be used for the natural ventilation potential of a single space. Two case studies were performed to demonstrate the proposed method for architectural design in the early design stages. The main finding of part II is the potential of using spatial indicators to predict the airflow performance of buildings. New applications of the developed space syntax methods are proposed to help architects in designing a contemporary building that is thermally more comfortable and that has a lower energy demand for cooling. This research is performed at the cross disciplines of architectural spatial design, passive cooling and thermal comfort. This research proposes several ideas for the first time. The term “building microclimate’ is one. The application of a spatial design parameter for thermal comfort is another. This research can contribute to the sustainable development of buildings, Chinese ones in particular. It can help design residential buildings for occupants with low and medium incomes by decreasing the necessity of air conditioning and improving the living environment for thermal comfort as well. This research is also valuable for passive or zero-energy design of houses in the Netherlands and the Mediterranean area. This research will enrich the green building science by introducing enhanced space syntax methods for adaptive thermal comfort and for passive cooling by means of spatial design. This thesis is mainly composed of a collection of the author’s published papers

Space Design for Thermal Comfort and Energy Efficiency in Summer:

Passive cooling for thermal comfort in summer is a big issue in low-energy building design. An important reason is global warming because global warming increases the number of cooling degree days. In addition, the energy demand of buildings has increased rapidly due to both the improvement of living standards and the globalisation of modern architecture. And finally, cooling a building is especially a challenge in countries where few resources are available. Passive cooling techniques, where solar and heating control systems are applied, largely depend on the design of the urban morphology and the building shape. The first research question is therefore: What is the relationship between spatial configuration, thermal environment and thermal summer comfort of occupants and how to apply spatial configuration as the passive cooling strategy in architectural design? Space is the empty part of a building, but its volume is important for the activities of occupants. Architects define the general spatial structure of a building mainly in the early design stages. There they define the spatial properties of a building, i.e. how the spaces are connected and what are the boundary conditions between the spaces. The final research question of this research therefore is: What is the relationship between spatial configuration, thermal environment and thermal summer comfort and how to apply spatial configuration as passive cooling strategy in architectural design in the early stages? In order to answer this research question, this dissertation is divided into two main parts. Part I is the theoretical research phase. The goal is to clarify the relationship between spatial configuration of buildings, the thermal environment and thermal comfort of occupants in summer. In this part, a literature review of the fundamental theoretical background knowledge of thermal comfort and passive cooling technology is summarised. As the author got his inspiration from Chinese vernacular architecture, the second step was conducting surveys and performing analyses of the spatial design, thermal environment and thermal summer comfort in Chinese vernacular buildings. Contemporary residential buildings were also investigated. A challenge was to find examples of contemporary buildings with appropriate spatial designs and thermal comfort as well as contemporary buildings with less successful spatial designs and thermal comfort. The third step was to find correlations&nbsp;between the occupants’ spatial and thermal perception through questionnaires. Questionnaires were held among Chinese as well as Dutch architecture students. The main research outcome of part I is the definition of “building microclimate”. Building microclimate is defined as “a type of microclimate which involves indoor spaces and spaces surrounding the indoor spaces in a particular building”. It is not just the microclimate around the building; it also includes the indoor climate. A suitable building microclimate is important for the occupants’ thermal comfort in summer. Another research outcome of part I is the revelation of the relationship between spatial perception and adaptive thermal comfort. Combining the relationship between spatial perception and adaptive thermal comfort with the new definition of building microclimate leads to the conclusion that the spatial configuration of a building plays an important role in creating a particular building microclimate. Part II is a practical research phase. The goal is to explore the possibility of using a spatial design method as a passive cooling strategy for thermal summer comfort and to demonstrate how to apply this method in the early design stages. As a first step, the potential of using a space analysis method for passive cooling and thermal comfort was investigated. A convex spatial analysis method was developed from the traditional space syntax method to analyse the natural ventilation potential. Both the logical relationship between the spaces and the boundary conditions between the spaces can influence the accessibility of a particular spatial configuration, and thus influence the potential for natural ventilation. The convex space analysis method is chosen for the preliminary analysis to show the logical relationships between spaces. It cannot completely predict natural ventilation, but it is a graphical method that is easy to use. Architects conceive design solutions generally through graphic methods, making the convex space analysis a good design tool. The extended visibility graph analysis (VGA) method is the best choice for the natural ventilation potential analysis for a spatial configuration. The isovist measure can be used for the natural ventilation potential of a single space. Two case studies were performed to demonstrate the proposed method for architectural design in the early design stages. The main finding of part II is the potential of using spatial indicators to predict the airflow performance of buildings. New applications of the developed space syntax methods are proposed to help architects in designing a contemporary building that is thermally more comfortable and that has a lower energy demand for cooling. This research is performed at the cross disciplines of architectural spatial design, passive cooling and thermal comfort. This research proposes several ideas for the first time. The term “building microclimate’ is one. The application of a spatial design parameter for thermal comfort is another. This research can contribute to the sustainable development of buildings, Chinese ones in particular. It can help design residential buildings for occupants with low and medium incomes by decreasing the necessity of air conditioning and improving the living environment for thermal comfort as well. This research is also valuable for passive or zero-energy design of houses in the Netherlands and the Mediterranean area. This research will enrich the green building science by introducing enhanced space syntax methods for adaptive thermal comfort and for passive cooling by means of spatial design. This thesis is mainly composed of a collection of the author’s published papers

Heat pump controls to exploit the energy flexibility of building thermal loads

Smart controls for heat pumps are required to harness the full energy flexibility potential of building thermal loads. A literature review revealed that most strategies used for this purpose can be classified in two categories: simpler rule-based control (RBC), and model predictive control (MPC), a more complex strategy based on optimization and requiring a prior model of the systems. Both RBC and MPC can use external penalty signals to prompt their actions. The price of electricity is most often used for this purpose, leading to strategies of cost reduction. As an alternative penalty signal, a novel marginal CO2 emissions signals was also conceived. In this thesis, both an RBC and an MPC controllers were developed as supervisory controls for an air-to-water heat pump supplying the heating and cooling needs of a residential building type from the Mediterranean area of Spain. The RBC strategy modulates the temperature set-points, while the MPC strategy minimizes the overall summed penalties (costs or emissions) due to the heat pump use, while balancing with comfort constraints and a proper operation of the systems. The MPC controller in particular required the development of a simplified model of the building envelope and of the heat pump performance, both adjusted differently for heating or cooling. The MPC included several novelties, such as the mixed-integer formulation, the heat pump simplified model based on experimental data and the consideration of its computational delay. The developed controllers were then tested, firstly in an experimental “hardware-in-the-loop” setup, with a real heat pump installed in the laboratory facilities, and connected to thermal benches that emulated the loads from a building model. Implementing the control strategies on a real heat pump enabled to highlight some practical challenges such as model mismatch in the MPC, communication issues, interfacing and control conflicts with the heat pump local controller. Secondly, a simulation-only framework was developed to test other configurations of the controllers, with TRNSYS as the main dynamic building simulation tool, coupled with MATLAB for the MPC controller. In that case, the real heat pump was replaced by a detailed model which was specially developed for this purpose. It is based on static tests performed in the laboratory, and therefore reproduces the dynamic behavior of the heat pump with high fidelity. The results from experimental and simulation studies revealed the ability of both types of controllers to shift the building loads towards periods of cheaper or less CO2-emitting electricity, these two objectives being in fact contradictory. In the cases where the reference control presented a large margin for improvements, the RBC and MPC controllers performed equally and provided important savings: around 15% emissions savings in heating mode, and 30% cost savings in cooling mode. In the cases where the reference control already performed close to optimally, the RBC controller failed to provide improvements, while the MPC benefitted from its stronger optimization and prediction features, reaching 5% cost savings in heating mode and 10% emissions savings in cooling mode. The research carried out in this thesis covered many aspects of energy flexibility in buildings: creation of input penalty signals, graphical representation of flexibility, development of controllers, performance in realistic experimental setup, fitting of appropriate models and compared performance in heating and cooling. The development efforts and barriers hindering the deployment of MPC controllers at large scale for building climate control have additionally been discussed. The performance of the developed controllers was evidenced in the thesis, proving their potential for load-shifting incentivized by different penalty signals: they could become a strong asset to unlock demand-side flexibility and in fine, help integrating a larger share of RES in the grid.Para aprovechar todo el potencial de flexibilidad energética de las cargas térmicas en los edificios equipados con bombas de calor se requiere de sistemas de control inteligente. Una revisión bibliográfica ha revelado que la mayoría de las estrategias de gestión utilizadas para esta finalidad pueden ser clasificadas en dos categorías: control en base a reglas (RBC en inglés) o predictivo (MPC en inglés), basado en optimización y en el uso de modelos. Tanto RBC como MPC pueden utilizar señales externas de penalización para fundamentar sus decisiones. El precio de la electricidad es utilizado a este fin de forma habitual en estrategias de reducción de coste. Una nueva señal de emisiones marginales de CO2 fue también creada como alternativa. Se han desarrollado un controlador RBC y un MPC para sistemas de bombas de calor aire-agua que cubren las demandas de climatización y agua caliente en el ámbito residencial. El RBC modula las consignas de temperatura, y el MPC minimiza las penalizaciones totales del sistema, al mismo tiempo que se consideran restricciones operativas y de confort. En particular, el MPC ha requerido el desarrollo de nuevos modelos simplificados, para predecir la demanda del edificio y el rendimiento de la bomba de calor, tanto en modo calefacción como en modo refrigeración. Otras novedades añadidas en la configuración del MPC son la formulación entera mixta, y la consideración del retraso debido al tiempo de cómputo. Los controladores fueron testeados, primeramente, en un entorno experimental -hardware-in-the-loop-, con una bomba de calor real instalada en el laboratorio y conectada a unos bancos térmicos que emulan las cargas térmicas del edificio. El entorno experimental ha permitido poner de manifiesto algunos retos prácticos tales como la discrepancia en el modelo del MPC y conflictos de conexión con el controlador local de la bomba de calor. En segundo lugar, un entorno de simulación ha sido creado para testear diversas configuraciones, usando TRNSYS acoplado con MATLAB. Para ello, se ha desarrollado un modelo detallado de la bomba de calor, basado en ensayos realizados en laboratorio, que reproduce el comportamiento dinámico de la bomba de calor con alta fidelidad. Tanto los resultados experimentales como los simulados han revelado la capacidad de los dos tipos de control de desplazar las cargas del edificio hacia periodos donde la electricidad era más barata o había menos emisiones de CO2, estos dos objetivos presentando de hecho impactos contradictorios. En los casos donde el control de referencia presentaba un amplio margen de mejora, los controladores RBC y MPC han demostrado la capacidad de actuar eficientemente y proveer ahorros importantes: alrededor de un 15% de emisiones en modo calefacción, y de un 30% de coste en modo frío. En aquellos casos en el que el control de referencia actuaba de forma cercana a la óptima, los controladores RBC no han sido capaces de aportar mejoras significativas, mientras que el MPC ha demostrado la capacidad de conseguir ahorros de un 5% de coste en modo calefacción y de un 10% de emisiones en modo frío. La investigación realizada en esta tesis ha abarcado amplios aspectos de la flexibilidad energética en los edificios: la generación de señales de penalización, la representación gráfica del potencial de flexibilidad, el ajuste de modelos simplificados, el desarrollo de controladores, el ensayo en entorno experimental y de simulación, con la consecuente evaluación de su rendimiento comparado en periodos de invierno y de verano, así como una discusión de las barreras que dificultan la implementación de controladores MPC y RBC a gran escala. Finalmente, la tesis ha evidenciado el rendimiento de los controladores desarrollados si se formulan de forma adecuada, demostrando su potencial para el desplazamiento del consumo eléctrico en la edificación residencial con sistemas de bomba de calor respondiendo a diferentes señales de penalización. En conclusión, los sistemas propuestos pueden ser elementos muy valiosos para favorecer la necesaria flexibilidad de la demanda térmica en la edificación y posibilitar la integración de sistemas de generación renovables en la re

Full Proceedings, 2018

Full conference proceedings for the 2018 International Building Physics Association Conference hosted at Syracuse University