Hicham Johra- Ph.D.
- Researcher at SINTEF
Hicham Johra
- Ph.D.
- Researcher at SINTEF
Energy and buildings, building energy efficiency, building energy flexibility, indoor environment, material properties
About
105
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Introduction
Hicham Johra currently works at the Department of Built Environment, Aalborg University, Denmark. Hicham does research in Civil Engineering, Building Energy Flexibility, District Heating Network Modelling, Building Energy Efficiency and Building Material Characterization. Current projects are 'PRELUDE'', 'IBPSA Project 1', IEA EBC Annex 81, 82, 84 and 85.
Current institution
Additional affiliations
August 2024 - present
SINTEF Community
Position
- Research Scientist
Publications
Publications (105)
This report is supplementary material describing the experimental setup used for generating results gathered in the open-access dataset “Data of a Full-Scale Experimental Study on the Onset of Internal Natural Convection inside a Horizontal Insulation Layer“ (including both raw experimental data and summary results) stored on a dedicated zenodo.org...
The aim of this technical report is to give an overview of the performance of different heating and cooling caloric systems: magnetocaloric, elastocaloric, electrocaloric and barocaloric heat pumps. The performance of these innovative caloric heat pump systems is compared with that of conventional vapour-compression heat pumps. This overview is bui...
Short-term demand response leveraging the energy flexibility of the building stock is a key solution to decarbonise and ensure the reliability and sustainability of smart energy grids dominated by intermittent renewable energy sources. Most of the building demand response capacity depends on different forms of energy storage in the built environmen...
The operational building data presented in this paper has been collected from six office rooms located in an office building (research and educational purposes) located on the main campus of Aalborg University in Denmark. The dataset consists of measurements of occupancy, indoor environmental quality, room-level and system-level heating, ventilatio...
The aim of this lecture note is to present and exemplify the Kragten method to calculate the combined uncertainty (uncertainty budget) of a measurand from the standard uncertainty estimates of individual inputs of that measurand, and the mathematical formulation of that measurand. If these two elements are not available, the Kragten method cannot b...
This paper highlights innovative data treatment approaches for harnessing dynamic data in the building sector, focusing on commercial smart heat meters. Examples include closing the energy performance gap, two methods for disaggregating the total heat demand, and exploring fault detection in space heating systems across three apartments.
This paper introduces "pymodconn", a comprehensive python package developed for constructing modular sequence-to-sequence control-oriented deep neural networks. These deep neural networks (DNNs) are designed to predict the future dynamics of complex time-dependent systems for given known future data, e.g., control inputs, using past known system dy...
Hybrid ventilation is an energy-efficient solution to provide fresh air for most climates, given that it has a reliable control system. To operate such systems optimally, a high-fidelity control-oriented modesl is required. It should enable near-real time forecast of the indoor air temperature based on operational conditions such as window opening...
Indoor environmental quality (IEQ) measurement is a fundamental part of quantifying the performance of any space. Performing measurements and interpreting the results require expensive equipment and specialist knowledge for each parameter. Since holistic IEQ assessment requires investigation of multiple parameters across atmospheric, thermal, acous...
The accurate energy performance assessment of building elements remains an active research topic. Studies have indicated that the thermal mass of building envelopes could influence heat losses in dynamic conditions and lead to significant difference in performance compared to steady-state conditions. This article aims to identify the relevance of u...
The outdoor micro-climate caused by the presence of buildings can significantly differ from that around weather stations located outside of urban areas. However, the latter is often used to design buildings and size building systems. This could lead to significant mistakes and performance gaps. To date, there is a certain lack of experimental studi...
The EU aims to digitize the building stock across all member states to better understand energy use and achieve energy efficiency goals to address climate change. Smart heat meters are currently used for billing purposes in district heating (DH) grids. Their data is recorded as integer kWh values, which restricts usability for the modeling and anal...
Applying model-based predictive control in buildings requires a control-oriented model capable of learning how various control actions influence building dynamics, such as indoor air temperature and energy use. However, there is currently a shortage of empirical or synthetic datasets with the appropriate features, variability, quality and volume to...
This paper examines building energy flexibility at an aggregated level and addresses the main barriers and research gaps for the development of this resource across three design and development phases: market and policy, early planning and design, and operation. We review methodologies and tools and discuss barriers, challenges, and opportunities,...
Dynamic simulation of a double-skin façade (DSF) with computational fluid dynamics (CFD) can be challenging due to the lack of validated models and benchmarking datasets. Furthermore, there is a lack of consensus in the scientific community on what constitutes a successfully validated DSF model. The present review study identifies simulation trends...
The outdoor micro-climate caused by the presence of buildings can significantly differ from that around weather stations located outside of urban areas. However, the latter is often used to design buildings and size building systems. This could lead to significant mistakes and performance gaps. To date, there is a certain lack of experimental studi...
Comparing, validating and assessing the accuracy of dynamic models is crucial for multiple applications in the field of energy, buildings and indoor environmental engineering. To that matter, various comparison metrics and key performance indicators have been developed or borrowed from other fields of science, and a few popular guidelines have reco...
Accepted for publication in the proceedings of the IBPSA Building Simulation Conference 2023, Shanghai, China.
Technical Reports are published for timely dissemination of research results and scientific work carried out at the Department of the Built Environment at Aalborg University. This medium allows publication of more detailed explanations and results than typically allowed in scientific journals.
Energy flexibility, through short-term demand-side management (DSM) and energy storage technologies, is now seen as a major key to balancing the fluctuating supply in different energy grids with the energy demand of buildings. This is especially important when considering the intermittent nature of ever-growing renewable energy production, as well...
Hybrid ventilation is an energy-efficient solution to provide fresh air for most climates, given that it has a reliable control system. To operate such systems optimally, a high-fidelity control-oriented modesl is required. It should enable near-real time forecast of the indoor air temperature based on operational conditions such as window opening...
This article presents a new methodology to disaggregate the energy demand for space heating (SH) and domestic hot water (DHW) production from single hourly smart heat meters installed in Denmark. The new approach is idealized to be easily applied to several building typologies without the necessity of in-depth knowledge regarding the dwellings and...
Extensive research demonstrates the importance of user practices in understanding variations in residential heating demand. Whereas previous studies have investigated variations in aggregated data, e.g., yearly heating consumption, the recent deployment of smart heat meters enables the analysis of households’ energy use with a higher temporal resol...
One of the initiatives to reach the European decarbonization goal is the roll-out of smart heating meters in the building stock. However, these meters often record the total energy usage with only hourly resolution, without distinguishing between space heating (SH) and domestic hot water (DHW) production. To tackle this limitation, this paper prese...
The District Energy Simulation Test (DESTEST) is a series of common exercises about modelling building stocks and district heating networks aiming at testing, benchmarking and verifying different urban-scale energy system simulation tools. For each common exercise, participants are modelling a case with well-defined characteristics, grid topology a...
Energy flexibility, through short-term demand-side management (DSM) and energy storage technologies, is now seen as a major key to balancing the fluctuating supply in different energy grids with the energy demand of buildings. This is especially important when considering the intermittent nature of ever-growing renewable energy production, as well...
The District Energy Simulation Test (DESTEST) is a series of common exercises about modelling building stocks and district heating networks aiming at testing, benchmarking and verifying different urban-scale energy system simulation tools. For each common exercise, participants are modelling a case with well-defined characteristics, grid topology a...
Thermal conductivity is an important property of oxide glasses, but its structural origins remain largely unknown. Here, we provide detailed modal information on thermal conductivity in a calcium aluminosilicate glass by relying on recent advances in lattice dynamics methods. We probe various structural features using molecular dynamics simulations...
![Fig. 3. Demand-side management illustrated (modified from Ref. [29])....](profile/Katinka-Johansen-2/publication/360184722/figure/fig1/AS:1187066754928644@1660030177701/Demand-side-management-illustrated-modified-from-Ref-29-Notes-Peak-shaving_Q320.jpg)
This research explores the demand-side management strategy of using the built environment for short-term thermal energy storage, here conceptualised as a niche innovation within the socio-technical Danish district heating landscapes. In particular, the research explores perceptions of this niche innovation among district heating sector professional...
Heat pumps (HPs) are an excellent solution to supply heating and cooling for indoor space conditioning and domestic hot water (DHW) production. Conventional HPs are typically electrically driven and operate with a vapour-compression thermodynamic cycle of refrigerant fluid to transfer heat from a cold source to a warmer sink. This mature technology...
Fibre materials are widely used as insulation materials in both clothing and the building industry. The transport of heat and air through fibre insulation materials are accountable for both the energy need for indoor space conditioning and the indoor environment quality inside buildings. A better understanding of the thermodynamics of those materia...
The aim of this technical report is to give an overview of the performance of different heating and cooling caloric systems: magnetocaloric, elastocaloric, electrocaloric and barocaloric heat pumps. The performance of these innovative caloric heat pump systems is compared with that of conventional vapour-compression heat pumps. This overview is bui...
The aim of this lecture note is to give an overview of the Coefficient of Performance (COP) of conventional vapour-compression heat pumps for building applications (space cooling, space heating and domestic hot water production). The COP data has been collected from various experimental and numerical studies reported in peer-reviewed scientific jou...
The aim of this technical report is to present and give an overview of a dataset collecting the main thermo-physical properties of various common construction and building materials used in the built environment and composing elements of buildings and infrastructures. In addition, suggestions and recommendations are made for the thermo-physical pro...
In this work, we study the structure–topology–property relations of a series of melt‐quenched lithium germanate glasses. These glasses exhibit the so‐called germanate anomaly, that is, the germanium atoms feature a distribution of four‐coordinated and higher coordinated germanium species, manifesting itself as anomalies in several material properti...
Glare is a common local visual discomfort that is difficult to identify with conventional light sensors. This article presents an artificial intelligence algorithm that detects subjective local glare discomfort from the image analysis of the video footage of an office occupant’s face. The occupant’s face is directly used as a visual comfort sensor....
Hands-on experiments in laboratories are fundamental educational tools for technical sciences. However, laboratories are expensive and not always accessible to students: lockdown and in-person meeting restrictions due to the ongoing Covid-19 pandemic, distant location of teachers and students, facilities used for higher-priority purposes. Moreover,...
Accurate convective heat transfer coefficient (CHTC) is crucial to assess the night ventilation performance accurately. Previous experimental studies proposed CHTC correlations tailored for night cooling with diffuse ceiling ventilation (DCV) and mixing ventilation (MV). A holistic approach integrating the building energy simulation and optimizatio...
Glare is a common local visual discomfort that is difficult to identify with conventional light sensors. This article presents an artificial intelligence algorithm that detects subjective local glare discomfort from the image analysis of the video footage of an office occupant's face. The occupant's face is directly used as a visual comfort sensor....
In Europe, one of the most sustainable solutions to supply heat to buildings is district heating. It has good acceptance in the Northern countries, a low-carbon footprint, and can easily integrate intermittent renewable energy sources when coupled to the electrical grid. Even though district heating is seen as a vital element for a sustainable futu...
This article discusses different statistical methods to compare the predictions (in the form of time series) of urban-scale building energy models. It focuses on inter-model comparison without empirical measurements as a reference case. It is thus suggested to build a reference time series as a point-to-point mean average of all the models to be co...
Hands-on experiments in laboratories are fundamental educational tools for technical sciences. However, laboratories are expensive and not always accessible to students: lockdown and in-person meeting restrictions due to the ongoing Covid-19 pandemic, distant location of teachers and students, facilities used for higher-priority purposes. Moreover,...
In this work, we study the thermal conductivity of densified soda lime borosilicate glasses with varying B2O3/SiO2 ratio. Densification is induced by hot compression up to 2 GPa at the glass transition temperature. We find that the structural and mechanical properties of the glasses exhibit a similar response to hot compression as other oxide glass...
The convective heat transfer coefficient (CHTC) is a crucial parameter for night ventilation performance estimation. This paper investigates the heat transfer of night ventilation with diffuse ceiling ventilation (DCV) concept in an office room. A series of dynamic full-scale experiments were conducted with different thermal mass distribution schem...
The convective heat transfer coefficient (CHTC) is a crucial parameter for night ventilation performance estimation. This paper investigates the heat transfer of night ventilation with diffuse ceiling ventilation (DCV) concept in an office room. A series of dynamic full-scale experiments were conducted with different thermal mass distribution schem...
The purpose of night ventilation (NV) is to improve building energy and thermal comfort performance. The key to accurately predicting NV performance is selecting the appropriate convective heat transfer coefficient (CHTC) at different surfaces of the built environment. The current CHTC correlations used in building energy simulation tools are limit...
Applying phase change material (PCM) for latent heat storage in sustainable building systems has gained increasing attention. However, the nonlinear thermal properties of the material and the hysteresis between the two-phase change processes make the modelling of PCM challenging. Moreover, the influences of the PCM phase transition and hysteresis o...
At present, the building industry accounts for 30 – 50% of raw material consumption in Europe. The exhaustion of natural resources and increased demand for housing with the rising world population underlines a growing need for sustainable building materials. Bio-based materials show significant potential in being renewable materials with low or neg...
The ever-increasing global demand for concrete engenders concerning sustainability issues. In addition to the large CO2 emissions induced by the production of cement, the fabrication of concrete requires important mining and excavation for the extraction of specific minerals, sand, and aggregates, which can endanger local ecosystems. Seacrete (also...
The ever-increasing global demand for concrete engenders concerning sustainability issues. In addition to the large CO2 emissions induced by the production of cement, the fabrication of concrete requires important mining and excavation for the extraction of specific minerals, sand, and aggregates, which can endanger local ecosystems. Seacrete (also...
District heating has been found to be a key component of future and reliable smart energy grids comprising 100% of renewable energy sources for countries with dominant heating season. However, these systems face challenges that require a deeper understanding of the coupling between the distribution networks and the connected buildings, to enable de...
This paper presents GEENIE, a video game simulating the thermodynamics of a building. The game is used to introduce a university course about control of Heating, Ventilation and Air Conditioning systems. The purpose of the game is to rapidly engage the students with the importance of having automated control systems in buildings to ensure a high qu...
For a very long time activities related to efficient domestic hot water (DHW) production and distribution have been neglected and left behind due to an insignificant share in total energy use for buildings. It is in recent years that DHW has emerged as one of the key energy factors in the total energy use in buildings and its share is continuously...
Understanding the variation of thermal conduction in disordered oxides is important for applications related to energy saving and electronics but currently lacks fundamental insight into the phonon propagation mechanisms. In this Letter, we report a strong correlation between thermal conductivity and the speed of sound within two families of modifi...
The thermal conductivity (κ) of glasses is known to always be lower than that of their corresponding crystals due to the stronger phonon-phonon scattering in the former. However, it is unknown whether this relation holds for metal-organic frameworks. Here, we report our discovery of an inverse relation in κ between glass and crystal for two zeoliti...
District heating has been found to be a key component of future and reliable smart energy grids comprising 100% of renewable energy sources for countries with dominant heating season. However, these systems face challenges that require a deeper understanding of the coupling between the distribution networks and the connected buildings, to enable de...
Energy flexibility represents a key building feature for the future energy systems, where the deployment of renewable energies will increase and the possibility to adapt the energy loads according to the requirements of the grid will be needed. Nevertheless, despite the given attention, a uniform understanding and a commonly accepted definition is...
S.Ø. Jensen (ed.), J. Parker (ed.), P. Engelmann (ed.), A. Marszal-Pomianowska (ed.), H. Johra, T. Weiss, T. Péan, A.S. Derakhtenjani, J. Candanedo, A. Athienitis, E. Mlecnik, I. De Jaeger, D. Saelens, H. Kazmi, I. Vigna, M. Lovati, R. Pernetti, R. Lollini, Y.J. Yu, K. Klein, L. Frison, P. Engelmann, Y. Zhou, S. Cao, J. Le Dréau, L. Aelenei, S. O'C...
S.Ø. Jensen (ed.), A. Marszal-Pomianowska (ed.), J. Parker (ed.), H. Johra, A. Knotzer, J. Salom, T. Péan, E. Mlecnik, H. Kazmi, R. Pernet, K. Klein, L. Frison, P. Engelmann, L. Aelenei, R.A. Lopes, D. Aelenei, R.G. Junker, H. Madsen, A.Q. Santos, B.N. Jørgensen, Z. Ma (2019). Principles of Energy Flexible Buildings. International Energy Agency - E...
Buildings will play a significant role in providing a safe and efficient operation of the future energy system. The aim of this work is to investigate how typical cost-effective renovation packages contribute to energy consumption reduction as well as influence the energy flexibility in a Danish single-family from 1970s, and if simple rule-based co...
Buildings are a key active element of the future Smart Grids with large shares of renewable energy, as they can provide flexible energy usage to help balancing power production intermittence. There is currently no consensus yet on how to quantify building energy flexibility. The various KPIs found in literature can be classified into 4 main categor...
![Primary energy consumption [kWh/m 2 year].](publication/336929143/figure/tbl2/AS:820226157457414@1572568563813/Primary-energy-consumption-kWh-m-2-year_Q320.jpg)
As energy standards focus on reducing energy use in new buildings, attention is drawn to the gap between the expected and actual building operation and energy performance. This performance gap can be associated with the building construction, its systems, its unbalanced operation, the assumptions on occupancy profiles during the design phase, or th...
The future low-carbon emission societies rely on energy systems bearing an increasing share of renewable energy sources (RES). Consequently, demand-side management and energy flexibility become a key solution to compensate for the intermittent nature of RES. District heating systems hold a large potential for energy flexibility if households are ac...
Intermittent energy resources challenge the ways in which the existing energy system operates. Studies suggest that residential buildings can provide a flexibility service for district heating (DH) systems. This technique involves load shifting by heating buildings to higher temperatures at times when energy is more readily available, thus diminish...
Buildings will play a significant role in providing a safe and efficient operation of the future energy system. The aim of this work is to investigate how typical cost-effective renovation packages contribute to energy consumption reduction as well as influence the energy flexibility in a Danish single-family from 1970s, and if simple rule-based co...
Intermittent energy resources challenge the ways in which the existing energy system operates. Studies suggest that residential buildings can provide a flexibility service for district heating (DH) systems. This technique involves load shifting by heating buildings to higher temperatures at times when energy is more readily available, thus diminish...
The aim of this lecture note is to detail the methodology of the Laser Flash Analysis for the measurement of thermal diffusivity of small test samples. Such measurements can be conducted with the Laser Flash Apparatus LFA 447 (Netzsch Gerätebau GmbH) at the Building Material Characterization Laboratory of Aalborg University - Department of Civil En...
Despite the importance of thermal conductivity for a range of modern glass applications, its compositional dependence and structural origins in modified oxide glasses remain poorly understood. In particular, the thermal conductivity of oxide glasses with network formers other than silica remain almost unexplored and no thorough connection with stru...
The main goal of the ENOVHEAT project is to develop, build and test a prototype of an innovative heat pump based on active magnetic regenerator technology. This device can be coupled to a ground source heat exchanger and an under-floor heating system to provide for the space heating needs of a low-energy house in Denmark. However, the use of a simp...
This article presents a PCM solar air heat exchanger integrated into ventilated window developed to maximize the use of the solar energy to pre-heat the ventilated air. The system is designed to improve the indoor air quality and thermal comfort by continuous pre-heated air supply at a reduced energy use through the capturing and storing of solar e...
The goal of the project CleanTechBlock 2 is to develop and test a durable and sustainable construction wall element which complies with the building regulations of 2020, and has a certain aesthetics attractiveness. The CleanTechBlock (CTB) prefabricated elements consist of cellular glass insulation blocks mounted in between two layers of brick maso...
Diffuse ceiling ventilation system is an air distribution system in which part of the suspended ceiling made of perforated panels is used as an air diffuser for the supply of fresh air. This method has been proven to have a higher cooling capacity compared to conventional air distribution systems. The cooling capacity of the system, however, depend...
The objective of this study is to investigate and assess the energy flexibility performance of typical Danish office buildings constructed at different periods. Four building study cases have been compared with different heating demands, structural thermal masses, envelope insulation levels and infiltration rates. All cases are equipped with the sa...
![Fig. 3. Floor plans and thermal zones [11].](profile/Hicham-Johra/publication/335142515/figure/fig1/AS:791425079844864@1565701851060/Floor-plans-and-thermal-zones-11_Q320.jpg)
The significant expansion of intermittent renewable energy sources can compromise the stability of energy grids due to the mismatch between instantaneous energy use and production. Buildings have a large potential for energy storage and demand-side management, which can offer energy flexibility to a Smart Grid system. Smart control of heating, vent...
The main objective of the ENOVHEAT project is to develop, build and test the prototype of an innovative and efficient heat pump system based on the active magnetic regenerator technology and to demonstrate that it can be used for building space heating applications. The numerical investigation presented in this article tested different configuratio...
This article presents the results of a numerical study investigating the influence of the main building parameters on the indoor space heating energy flexibility of a Danish house. The focus is placed here on the envelope insulation level, the structural thermal mass, the additional thermal mass of indoor content (indoor items/furniture, PCM integr...
The concept and methodology of a magnetocaloric heating network is proposed. A small thermal network consisting of several magnetocaloric heat pumps (MCHP) is considered from the point of their scaling and connection properties. We found a linear scaling law following the heating power variation with AMR mass, which can be included in an MCHP looku...
The main objective of the ENOVHEAT project is to develop, build and test the prototype of an innovative and efficient heat pump system based on the active magnetic regenerator technology and to demonstrate that it can be used for building space heating applications. With a maximum COP of 3.93 and a nominal useful heating power output of 2600 W, the...
![Figure 1-4: Logo of the ENOVHEAT project [28].](profile/Hicham-Johra/publication/326128441/figure/fig4/AS:884250056351745@1587833050245/Logo-of-the-ENOVHEAT-project-28_Q320.jpg){kind=logo}
https://vbn.aau.dk/files/549462029/PHD_Hicham_Johra_E_pdf.pdf
To prevent future energy crisis and tackle the problems of climate change, modern society must promote a radical evolution in our energy systems. The building sector, and in particular its heating needs, have clearly been identified as one of the main targets for the reduction of the gl...
The EnovHeat project aims at developing an innovative heat pump system based on the magnetocaloric effect and active magnetic regenerator technology to provide for the heating needs of a single family house in Denmark. Unlike vapor-compression devices, magnetocaloric heat pumps use the reversible magnetocaloric effect of a solid refrigerant to buil...
Many numerical models for building energy simulation assume empty rooms and do not account for the indoor content of occupied buildings. Furnishing elements and indoor items have complicated shapes and are made of various materials. Therefore, most of the people prefer to ignore them. However, this simplification can be problematic for accurate cal...
Questions
Questions (2)
Aalborg University is organizing the 13th Nordic Symposium on Building Physics (NSB 2023). It will be held in Aalborg, Denmark, on the 12-14thof June 2023. The NSB 2023 theme is “Building physics as a key player for the sustainable built environment”. This conference is held in English. It is not limited to cold climates and has participants from all over the world.
For more information: https://www.nsb2023.org
📢 IEA EBC Annex#81 calls for datasets of B2G services:
The Annex#81 subtask C3 team is coordinating a survey to collect open datasets for building-to-grid services (B2G) and would like to kindly ask you to contribute by providing a description and link to your data using this Google Form (https://docs.google.com/forms/d/e/1FAIpQLSdqV6MxY0DiJUar9kdkXypXq7EhuhxLP9OzHaN7WjZ9xlFaOg/viewform).
🔖 This survey aims to collect data (time series and metadata) from buildings performing demand-response, demand-side management or energy flexibility. The dataset may be from existing, simulated, or semi-simulated hardware-in-the-loop buildings.
The collected datasets will be used for:
➡️ Gathering use cases and assessing typical DR strategies, buildings types, energy systems and data requirements,
➡️ Testing energy flexibility KPIs for the review activity of C3 on existing KPIs for B2G services,
➡️ And, possibly, comparing the existing solutions against “grid challenges” from the proposed C3 web-based showcase platform.
⌛️This survey should take approximately 20-30 minutes to complete.
Thank you in advance for your valuable contributions!
Don't hesitate to share that post.
Feel free to reach us (Hicham Johra: hj@build.aau.dk; Flávia de Andrade Pereira: flavia.deandradepereira@ucdconnect.ie) if you have any questions.
#Annex81 #survey #dataset #B2G #KPIs #DR #DSM #datadriven #smartbuildings #flexibility #metadata #datarequirements
