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Prof. Laurent Georges
Energy and Process Engineering Department, Norwegian University of Science and Technology (NTNU), Kolbjørn Hejes vei 1b, Trondheim, Norway

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Research Keywords & Expertise

0 Building energy
0 Building Performance Simulation
0 Building energy flexibility and grid interaction
0 Indoor thermal environment
0 Heating and ventilation systems

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Building energy
Building Performance Simulation
Building energy flexibility and grid interaction
Heat pumps for buildings
Indoor thermal environment
Heating and ventilation systems
Building integration of energy systems
Computational fluid dynamics for airflows inside buildings

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Journal article
Published: 07 August 2021 in Energies
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This paper presents a statistical model for predicting the time-averaged total power consumption of an indoor swimming facility. The model can be a powerful tool for continuous supervision of the facility’s energy performance that can quickly disclose possible operational disruptions/irregularities and thus minimize annual energy use. Multiple linear regression analysis is used to analyze data collected in a swimming facility in Norway. The resolution of the original training dataset was in 1 min time steps and during the investigation was transposed both by time-averaging the data, and by treating part of the dataset exclusively. The statistically significant independent variables were found to be the outdoor dry-bulb temperature and the relative pool usage factor. The model accurately predicted the power consumption in the validation process, and also succeeded in disclosing all the critical operational disruptions in the validation dataset correctly. The model can therefore be applied as a dynamic energy benchmark for fault detection in swimming facilities. The final energy prediction model is relatively simple and can be deployed either in a spreadsheet or in the building automation reporting system, thus the method can contribute instantly to keep the operation of any swimming facility within the optimal individual energy performance range.

ACS Style

Ole Øiene Smedegård; Thomas Jonsson; Bjørn Aas; Jørn Stene; Laurent Georges; Salvatore Carlucci. The Implementation of Multiple Linear Regression for Swimming Pool Facilities: Case Study at Jøa, Norway. Energies 2021, 14, 4825 .

AMA Style

Ole Øiene Smedegård, Thomas Jonsson, Bjørn Aas, Jørn Stene, Laurent Georges, Salvatore Carlucci. The Implementation of Multiple Linear Regression for Swimming Pool Facilities: Case Study at Jøa, Norway. Energies. 2021; 14 (16):4825.

Chicago/Turabian Style

Ole Øiene Smedegård; Thomas Jonsson; Bjørn Aas; Jørn Stene; Laurent Georges; Salvatore Carlucci. 2021. "The Implementation of Multiple Linear Regression for Swimming Pool Facilities: Case Study at Jøa, Norway." Energies 14, no. 16: 4825.

Journal article
Published: 09 June 2021 in Applied Energy
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Previous studies have identified significant demand response (DR) potentials in using economic model predictive control (E-MPC) of space heating to exploit the inherent thermal mass in residential buildings for short-term energy storage. However, the economically viable realisation of E-MPC in residential buildings requires an effort to minimise the need for additional equipment and labour-intensive modelling processes. This paper reports on an experiment where a novel E-MPC setup was used for thermostatically control of a hydronic radiator in a highly-insulated residential building located on the NTNU Campus in Trondheim, Norway. The E-MPC utilized data from a heating meter, two temperature sensors and an existing weather forecast web service to train a linear black-box model. The results showed that the precision of model trained on excitation data that was generated using setpoints of either 21 or 24 °C was sufficient to obtain good control of the indoor air temperature while shifting consumption from high to low price periods. The findings of the experiment indicate that a minimal E-MPC setup is able to realize the significant DR potential that lies in utilizing the inherent thermal mass in residential buildings.

ACS Style

Michael Dahl Knudsen; Laurent Georges; Kristian Stenerud Skeie; Steffen Petersen. Experimental test of a black-box economic model predictive control for residential space heating. Applied Energy 2021, 298, 117227 .

AMA Style

Michael Dahl Knudsen, Laurent Georges, Kristian Stenerud Skeie, Steffen Petersen. Experimental test of a black-box economic model predictive control for residential space heating. Applied Energy. 2021; 298 ():117227.

Chicago/Turabian Style

Michael Dahl Knudsen; Laurent Georges; Kristian Stenerud Skeie; Steffen Petersen. 2021. "Experimental test of a black-box economic model predictive control for residential space heating." Applied Energy 298, no. : 117227.

Conference paper
Published: 29 March 2021 in E3S Web of Conferences
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In the one hand, energy planning tools compute the cost-optimal investment in the energy system minimizing life cycle costs (LCC). These tools often consider optimal control. The building (or cluster of buildings) is represented by a node where the time profiles of energy demands are given as inputs. The indoor temperate in buildings is typically not considered and may even be difficult to define for a cluster of buildings. Secondly, to perform optimization, the model of the energy system is often linear (e.g. using MILP). In the other hand, the building thermal mass has proven to be a cheap and large source of energy flexibility. Therefore, there is a need for a linear model of the building thermal dynamics when there is a limited knowledge of the indoor temperature. Consequently, the paper proposes a model that tracks the change of indoor temperature and space-heating power rather than their absolute values: the model focuses on the deviations from the reference energy profiles given as input. This framework gives a simple model that is less dependent on the boundary conditions (i.e. the weather, user behaviour and internal gains). In addition, a second-order model is proposed to characterize the transfer function. The model has only four parameters, which simplifies its identification. The model is validated using detailed building performance simulation, namely IDA ICE, on a Norwegian wooden detached house during demand response (DR).

ACS Style

Laurent Georges; Elin Storlien; Magnus Askeland; Karen Byskov Lindberg. Development of a data-driven model to characterize the heat storage of the building thermal mass in energy planning tools. E3S Web of Conferences 2021, 246, 10001 .

AMA Style

Laurent Georges, Elin Storlien, Magnus Askeland, Karen Byskov Lindberg. Development of a data-driven model to characterize the heat storage of the building thermal mass in energy planning tools. E3S Web of Conferences. 2021; 246 ():10001.

Chicago/Turabian Style

Laurent Georges; Elin Storlien; Magnus Askeland; Karen Byskov Lindberg. 2021. "Development of a data-driven model to characterize the heat storage of the building thermal mass in energy planning tools." E3S Web of Conferences 246, no. : 10001.

Conference paper
Published: 29 March 2021 in E3S Web of Conferences
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The objective of this work is to investigate the indoor environment in bedrooms ventilated by window opening during night-time. How window opening behaviour affects indoor air quality (IAQ), and how window opening behaviour and IAQ is influenced by external factors, are important questions. The context is renovation of detached wooden houses in Norway. To motivate building owners to renovate their ventilation system, it is important to know the typical indoor environment in bedrooms of existing buildings with natural ventilation. Ten bedrooms in six case houses were investigated by measuring temperature, relative humidity, CO2, particulate matter, formaldehyde and TVOC. The window opening angle was also logged with an accelerometer. The measurements were conducted over 2 to 3 weeks, during March and April. The dwellings were renovated single-family and terraced houses from 1950 – 80, in Trondheim. All the bedrooms had natural ventilation, and the occupants stated they used to open bedroom windows at night. Participants answered a questionnaire about motivations and habits regarding window opening. The most common reason given for not opening was low outdoor temperatures. The window opening behaviour was both predictable and continuous. Windows were open every night in most of the bedrooms, and most of the windows were opened to the same position every night. High CO2 levels during night were found in two bedrooms. In the other bedrooms, the CO2 concentration was satisfying during night-time, although higher concentrations were found in some bedrooms during daytime. Finally, indoor temperature measurements confirmed that many occupants prefer a low bedroom temperature.

ACS Style

Vegard Heide; Silje Skyttern; Laurent Georges. Indoor air quality in natural-ventilated bedrooms in renovated Norwegian houses. E3S Web of Conferences 2021, 246, 01001 .

AMA Style

Vegard Heide, Silje Skyttern, Laurent Georges. Indoor air quality in natural-ventilated bedrooms in renovated Norwegian houses. E3S Web of Conferences. 2021; 246 ():01001.

Chicago/Turabian Style

Vegard Heide; Silje Skyttern; Laurent Georges. 2021. "Indoor air quality in natural-ventilated bedrooms in renovated Norwegian houses." E3S Web of Conferences 246, no. : 01001.

Journal article
Published: 01 February 2021 in Energy and Buildings
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Grey-box models are data-driven models where the structure is defined by the physics while the parameters are calibrated using data. Low-order grey-box models of the building envelope are typically used for two main applications. Firstly, they are used as a control model in Model Predictive Control (MPC) where the thermal mass of the building is activated as storage (for instance in demand response). Secondly, they are used to characterize the thermal properties of the building envelope using on-site measurements. The influence of the data pre-treatment on the performance of grey-box models is hardly discussed in the literature. However, in real applications, information about data pre-processing by sensors or data acquisition systems is expected to be limited. Therefore, the influence of the sampling time, low-pass filters and anti-causal shift (also called data labeling) are analyzed for grey-box models in deterministic and stochastic innovation form. The influence on the optimizer performance is also investigated. The datasets are generated from virtual experiments using multi-zone building performance simulations of a residential building (in lightweight wooden construction) heated using different types of excitation signals. Results show that the parameters of deterministic grey-box models are significantly influenced by the training data while the data pre-treatment has a limited impact on the model and optimizer performance. Depending on the training data, the value taken by some parameters is not physically plausible. On the contrary, stochastic models are significantly influenced by the data pre-treatment, especially the sampling time, and less by the training data. The parameters can become non-physical for large sampling times. However, the anti-causal shift proves to be efficient to keep the parameters almost constant with increasing sampling times. Even though the parameter values of the deterministic model are less physically plausible, the simulation performance of deterministic models is higher than using the equivalent stochastic models. These results suggest that deterministic models seem better suited for MPC while stochastic models are better suited for the characterization of thermal properties (if suitable data pre-treatment is applied).

ACS Style

Xingji Yu; Laurent Georges; Lars Imsland. Data pre-processing and optimization techniques for stochastic and deterministic low-order grey-box models of residential buildings. Energy and Buildings 2021, 236, 110775 .

AMA Style

Xingji Yu, Laurent Georges, Lars Imsland. Data pre-processing and optimization techniques for stochastic and deterministic low-order grey-box models of residential buildings. Energy and Buildings. 2021; 236 ():110775.

Chicago/Turabian Style

Xingji Yu; Laurent Georges; Lars Imsland. 2021. "Data pre-processing and optimization techniques for stochastic and deterministic low-order grey-box models of residential buildings." Energy and Buildings 236, no. : 110775.

Conference paper
Published: 30 June 2020 in E3S Web of Conferences
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Wood stoves are widely used in Nordic countries. They offer a good opportunity to use biomass for space-heating and to reduce the peak power of all-electric buildings. However, wood stoves are highly concentrated heat sources with limited control compared to other typical heat emission systems, which makes the assessment of their impact challenging. This study introduces a simulation-based parametric study of a detached house equipped with a wood stove located in Oslo, Norway. The respective impact of different building parameters and stove nominal powers on the building performance is illustrated. The analysis shows that the annual total space-heating needs (i.e. the sum of the base load, modelled as ideal heaters representing the electrical radiators, the stove and the heating of the ventilation supply air) increased significantly due to the higher average indoor temperature. The resulting heat emission efficiency of the stove ranged between 66% and 90%. However, the stoves covered between 28% and 62% of the total space-heating needs. When using the stove, the maximum hourly-averaged power for the electrical radiators decreased between 5 W/m2 and 31 W/m2 during the peak hours of the electricity grid. The building thermal mass, insulation level, as well as the combination of internal door position with the bedroom temperature setpoint, had a significant impact on the calculated values. Finally, the study revealed that the occupant behaviour modelling should be improved to better capture the wood stove impact on the energy performance using building simulations.

ACS Style

Martin Thalfeldt; Anders Skare; Laurent Georges; Øyvind Skreiberg. Parametric Energy Simulations of a Nordic Detached House Heated by a Wood Stove. E3S Web of Conferences 2020, 172, 25007 .

AMA Style

Martin Thalfeldt, Anders Skare, Laurent Georges, Øyvind Skreiberg. Parametric Energy Simulations of a Nordic Detached House Heated by a Wood Stove. E3S Web of Conferences. 2020; 172 ():25007.

Chicago/Turabian Style

Martin Thalfeldt; Anders Skare; Laurent Georges; Øyvind Skreiberg. 2020. "Parametric Energy Simulations of a Nordic Detached House Heated by a Wood Stove." E3S Web of Conferences 172, no. : 25007.

Conference paper
Published: 20 March 2020 in Soil and Recycling Management in the Anthropocene Era
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Electric water heater (EWH) is widely used to provide reliable and long-lasting domestic hot water to occupants in residential buildings. EWH has been widely recognized as an important source of building energy flexibility, which could benefit both the building occupants and the power system operators through various demand response (DR) programs. DR programs applied to EWHs are investigated in this paper. Optimal control strategies are developed to operate a portfolio of EWHs in order to reduce energy costs. A control-based model of EWH is developed using the data from field experiments and a statistical grey-box modelling approach (here using the CSTM-R package). The results show that the aggregated EWHs can optimize their heating schedule in order to reduce the overall cost without compromising the comfort of occupants.

ACS Style

Xingji Yu; Shi You; Hanmin Cai; Laurent Georges; Peder Bacher. Data-Driven Modelling and Optimal Control of Domestic Electric Water Heaters for Demand Response. Soil and Recycling Management in the Anthropocene Era 2020, 77 -86.

AMA Style

Xingji Yu, Shi You, Hanmin Cai, Laurent Georges, Peder Bacher. Data-Driven Modelling and Optimal Control of Domestic Electric Water Heaters for Demand Response. Soil and Recycling Management in the Anthropocene Era. 2020; ():77-86.

Chicago/Turabian Style

Xingji Yu; Shi You; Hanmin Cai; Laurent Georges; Peder Bacher. 2020. "Data-Driven Modelling and Optimal Control of Domestic Electric Water Heaters for Demand Response." Soil and Recycling Management in the Anthropocene Era , no. : 77-86.

Review
Published: 31 October 2019 in IOP Conference Series: Earth and Environmental Science
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This paper provides a review of heat and ventilation measures that can be applied to ambitious energy renovation of detached houses in Nordic countries. In this review, requirements for solutions are defined. Key technologies are described and analysed in the context of renovation. The review focuses on strategies that are simple, cost-effective and robust, and can be transposed to the Norwegian context. The review revealed that a wider range of concepts and strategies than commonly used in Norway seem to be relevant. No solution or system appears to be an obvious and universal choice. A number of very different system solutions, with their pros and cons, are relevant, depending on the individual house and situation. Some combined heat and ventilation systems include hydronic space heating. This is however not common in Norwegian houses, and installing this is a major cost and intervention. Wood stoves, on the other hand, are regular, and can be used for peak heating. These factors seem to be crucial for the choice of system. Improved airtightness after renovation makes systematic ventilation measures necessary. Assumptions for occupant preferences and behaviour also seem to be important for choice of system. There are also differences in the commonly used HVAC concepts and strategies for renovation between the Nordic countries. These differences do not seem to be explained by climate only, and differences in building code may be part of the reason. A number of demonstration projects on ambitious energy upgrading are completed, but few of them have been systematically monitored and evaluated.

ACS Style

V Heide; L Georges; A G Lien; H M Mathisen. Review of HVAC strategies for energy renovation of detached houses towards nZEB in cold climates. IOP Conference Series: Earth and Environmental Science 2019, 352, 012048 .

AMA Style

V Heide, L Georges, A G Lien, H M Mathisen. Review of HVAC strategies for energy renovation of detached houses towards nZEB in cold climates. IOP Conference Series: Earth and Environmental Science. 2019; 352 (1):012048.

Chicago/Turabian Style

V Heide; L Georges; A G Lien; H M Mathisen. 2019. "Review of HVAC strategies for energy renovation of detached houses towards nZEB in cold climates." IOP Conference Series: Earth and Environmental Science 352, no. 1: 012048.

Conference paper
Published: 31 October 2019 in IOP Conference Series: Earth and Environmental Science
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To reduce the space-heating needs, balanced mechanical ventilation equipped with a heat recovery is frequently implemented in highly-insulated residential buildings. This standard ventilation strategy tends to homogenize temperature inside the building, in other words, to reduce temperature zoning. In some countries, such as Norway, many users would like colder bedrooms. It has been proved that a significant part of the occupants in Norwegian passive houses opens bedroom windows during several hours every night during winter. Dynamic simulations have shown that it strongly increases the space-heating needs and that control only is unable to create temperature zoning in an energy-efficient way. The building concept should be changed. In the present contribution, the physical processes during temperature zoning are further explained. Detailed dynamic simulations of a detached single-family house are performed using the simulation software IDA ICE for different insulation levels, construction modes (which also influence the thermal insulation in partition walls) and control strategies. Alternative mechanical ventilation strategies are compared. They manage to reduce the influence of mechanical ventilation on the increased space-heating needs due to window opening but they cannot improve the large contribution of heat conduction through partition walls between heated areas and unheated bedrooms. Among the investigated ventilation strategies, decentralized ventilation has intrinsically the best performance.

ACS Style

L. Georges; E. Selvnes; V. Heide; H.M. Mathisen. Energy efficiency of strategies to enable temperature zoning during winter in highly-insulated residential buildings equipped with balanced mechanical ventilation. IOP Conference Series: Earth and Environmental Science 2019, 352, 012057 .

AMA Style

L. Georges, E. Selvnes, V. Heide, H.M. Mathisen. Energy efficiency of strategies to enable temperature zoning during winter in highly-insulated residential buildings equipped with balanced mechanical ventilation. IOP Conference Series: Earth and Environmental Science. 2019; 352 (1):012057.

Chicago/Turabian Style

L. Georges; E. Selvnes; V. Heide; H.M. Mathisen. 2019. "Energy efficiency of strategies to enable temperature zoning during winter in highly-insulated residential buildings equipped with balanced mechanical ventilation." IOP Conference Series: Earth and Environmental Science 352, no. 1: 012057.

Journal article
Published: 16 September 2019 in Applied Energy
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Building performance simulation (BPS) is a powerful tool for engineers working in building design and heating, ventilation and air-conditioning. Many case studies using BPS investigate the potential of demand response (DR) measures with heat pumps. However, the models are often simplified for the components of the heat pump system (i.e. heat pump, electric auxiliary heater and storage tank) and for their interactions. These simplifications may lead to significant differences in terms of DR performance so that more comprehensive models for a heat pump system may be necessary. The contribution of this work is twofold. Firstly, this work investigates the influence of the modeling complexity of the heat pump control on different key performance indicators for the energy efficiency, the DR potential and the heat pump operation. To this end, the performance of six different heat pump controls is compared. Secondly, it describes the implementation of a comprehensive control for a heat pump system in BPS tools. This control is not often documented in the BPS literature and is error-prone. Generic pseudo-codes are provided, whereas IDA ICE is taken as an example in the case study. A predictive rule-based control is implemented to study price-based DR of residential heating. It is shown that a realistic operation of the heat pump system can be achieved using the proposed modeling approach. The results prove that the modeling complexity of the system control has a significant impact on the performance indicators, meaning that this aspect should not be overlooked. For some performance indicators, e.g. the annual energy use for heating and average water tank temperature, it is shown that a proportional (P-) and proportional-integral (PI-) control can lead to similar results. If the heat pump operation is investigated in detail and a short-time resolution is required, the difference between P- and PI-controls and their tuning is important. As long as the heat pump operation and electrical power at short timescales are not of importance, the choice of controller (P or PI) is not crucial. However, the use of P-control significantly simplifies the modeling work compared to PI-control. If DR is performed for domestic hot water, it is also demonstrated that the prioritization of domestic hot water heating can indirectly influence the operation of auxiliary heaters for space-heating, significantly increasing the use of electricity. However, the electricity use is only slightly increased if DR control is only used for space heating.

ACS Style

John Clauß; Laurent Georges. Model complexity of heat pump systems to investigate the building energy flexibility and guidelines for model implementation. Applied Energy 2019, 255, 113847 .

AMA Style

John Clauß, Laurent Georges. Model complexity of heat pump systems to investigate the building energy flexibility and guidelines for model implementation. Applied Energy. 2019; 255 ():113847.

Chicago/Turabian Style

John Clauß; Laurent Georges. 2019. "Model complexity of heat pump systems to investigate the building energy flexibility and guidelines for model implementation." Applied Energy 255, no. : 113847.

Conference paper
Published: 13 August 2019 in E3S Web of Conferences
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Wood stoves are widely used in dwellings for space heating, however transient heat output and relatively large heat emission might cause problems with over-heating in new well-insulated buildings. This paper introduces a simplified power sizing method for the building integration of wood stoves which was compared to dynamic building performance simulations. The analysis showed that on average the simplified method predicted the temperature increase in the living room similarly to dynamic simulations. However, in some cases the difference was up to 60%, which is significant when carried forward to selecting the optimal stove heat capacity. Precise use of the simplified power sizing method requires accurate knowledge of the building structures and effective thermal capacity of the room with the wood stove. Typically, this kind of knowledge is unavailable when selecting a wood stove and the method needs to be developed further. These investigations confirmed that more knowledge of the occupant behaviour and preference on thermal comfort is needed.

ACS Style

Martin Thalfeldt; Anders Skare; Laurent Georges; Øyvind Skreiberg. A Simplified Power Sizing Method for the Correct Building Integration of Wood Stoves. E3S Web of Conferences 2019, 111, 1 .

AMA Style

Martin Thalfeldt, Anders Skare, Laurent Georges, Øyvind Skreiberg. A Simplified Power Sizing Method for the Correct Building Integration of Wood Stoves. E3S Web of Conferences. 2019; 111 ():1.

Chicago/Turabian Style

Martin Thalfeldt; Anders Skare; Laurent Georges; Øyvind Skreiberg. 2019. "A Simplified Power Sizing Method for the Correct Building Integration of Wood Stoves." E3S Web of Conferences 111, no. : 1.

Conference paper
Published: 13 August 2019 in E3S Web of Conferences
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Energy flexibility of buildings can be used to reduce energy use and costs, peak power, CO2eq- emissions or to increase self-consumption of on-site electricity generation. Thermal mass activation proved to have a large potential for energy flexible operation. The indoor temperature is then allowed to fluctuate between a minimum and maximum value. Many studies investigating thermal mass activation consider electric radiators. Nevertheless, these studies most often assume that radiators modulate their emitted power, while, in reality, they are typically operated using thermostat (on-off) control. Firstly, this article aims at comparing the energy flexibility potential of thermostat and P-controls for Norwegian detached houses using detailed dynamic simulations (here IDA ICE). It is evaluated whether the thermostat converges to a P-control for a large number of identical buildings. As the buildings are getting better insulated, the impact of internal heat gains (IHG) becomes increasingly important. Therefore, the influence of different IHG profiles has been evaluated in the context of energy flexibility. Secondly, most studies about energy flexibility consider a single indoor temperature. This is questionable in residential buildings where people may want different temperature zones. This is critical in Norway where many occupants want cold bedrooms (~16°C) during winter time and open bedroom windows for this purpose. This article answers to these questions for two different building insulation levels and two construction modes (heavy and lightweight).

ACS Style

Thea Johnsen; Katrine Taksdal; John Clauß; Xingji Yu; Laurent Georges. Influence of thermal zoning and electric radiator control on the energy flexibility potential of Norwegian detached houses. E3S Web of Conferences 2019, 111, 1 .

AMA Style

Thea Johnsen, Katrine Taksdal, John Clauß, Xingji Yu, Laurent Georges. Influence of thermal zoning and electric radiator control on the energy flexibility potential of Norwegian detached houses. E3S Web of Conferences. 2019; 111 ():1.

Chicago/Turabian Style

Thea Johnsen; Katrine Taksdal; John Clauß; Xingji Yu; Laurent Georges. 2019. "Influence of thermal zoning and electric radiator control on the energy flexibility potential of Norwegian detached houses." E3S Web of Conferences 111, no. : 1.

Journal article
Published: 08 April 2019 in Energies
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This work introduces a generic methodology to determine the hourly average CO2eq. intensity of the electricity mix of a bidding zone. The proposed method is based on the logic of input–output models and avails the balance between electricity generation and demand. The methodology also takes into account electricity trading between bidding zones and time-varying CO2eq. intensities of the electricity traded. The paper shows that it is essential to take into account electricity imports and their varying CO2eq. intensities for the evaluation of the CO2eq. intensity in Scandinavian bidding zones. Generally, the average CO2eq. intensity of the Norwegian electricity mix increases during times of electricity imports since the average CO2eq. intensity is normally low because electricity is mainly generated from hydropower. Among other applications, the CO2eq. intensity can be used as a penalty signal in predictive controls of building energy systems since ENTSO-E provides 72 h forecasts of electricity generation. Therefore, as a second contribution, the demand response potential for heating a single-family residential building based on the hourly average CO2eq. intensity of six Scandinavian bidding zones is investigated. Predictive rule-based controls are implemented into a building performance simulation tool (here IDA ICE) to study the influence that the daily fluctuations of the CO2eq. intensity signal have on the potential overall emission savings. The results show that control strategies based on the CO2eq. intensity can achieve emission reductions, if daily fluctuations of the CO2eq. intensity are large enough to compensate for the increased electricity use due to load shifting. Furthermore, the results reveal that price-based control strategies usually lead to increased overall emissions for the Scandinavian bidding zones as the operation is shifted to nighttime, when cheap carbon-intensive electricity is imported from the continental European power grid.

ACS Style

John Clauß; Sebastian Stinner; Christian Solli; Karen Byskov Lindberg; Henrik Madsen; Laurent Georges. Evaluation Method for the Hourly Average CO2eq. Intensity of the Electricity Mix and Its Application to the Demand Response of Residential Heating. Energies 2019, 12, 1345 .

AMA Style

John Clauß, Sebastian Stinner, Christian Solli, Karen Byskov Lindberg, Henrik Madsen, Laurent Georges. Evaluation Method for the Hourly Average CO2eq. Intensity of the Electricity Mix and Its Application to the Demand Response of Residential Heating. Energies. 2019; 12 (7):1345.

Chicago/Turabian Style

John Clauß; Sebastian Stinner; Christian Solli; Karen Byskov Lindberg; Henrik Madsen; Laurent Georges. 2019. "Evaluation Method for the Hourly Average CO2eq. Intensity of the Electricity Mix and Its Application to the Demand Response of Residential Heating." Energies 12, no. 7: 1345.

Journal article
Published: 11 January 2019 in Applied Energy
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The building energy flexibility potential of a Norwegian single-family detached house is investigated using predictive rule-based control (PRBC) and building performance simulation (using IDA ICE). Norwegian timber buildings are lightweight and four different insulation levels are considered. Both on-off and modulating air-source heat pumps are analyzed and compared to direct electric heating which is the most common heating system for Norwegian residential buildings. A detailed model for both the heat pump system and the building is implemented, a level of detail not found in previous research on building energy flexibility. The three PRBC investigated have the following objectives: reduce energy costs for heating, reduce annual CO2eq. emissions and reduce energy use for heating during peak hours. This last objective is probably the most strategic in the Norwegian context where cheap electricity is mainly produced by hydropower. The results show that the price-based control does not generate cost savings because lower electricity prices are outweighed by the increase in electricity use for heating. The implemented price-based control would create cost savings in electricity markets with higher daily fluctuations in electricity prices, such as Denmark. For the same reasons, the carbon-based control cannot reduce the yearly CO2eq. emissions due to limited daily fluctuations in the average CO2eq. intensity of the Norwegian electricity mix. On the contrary, the PRBC that reduces the energy use for heating during peak hours turns out to be very efficient, especially for direct electric heating. For air-source heat pumps, the control of the heat pump system is complex and reduces the performance of the three PRBC. Therefore, results suggest that a heat pump system should be modeled with enough detail for a proper assessment of the building energy flexibility. First, by varying temperature set-points there is a clear interaction between the prioritization of domestic hot water and the control of auxiliary heaters which increases energy use significantly. Second, the hysteresis of the heat pump control and the minimum cycle duration prevent the heat pump from stopping immediately after the PRBC requires it. Finally, the paper shows that the influence of thermal zoning, investigated here by cold bedrooms with closed doors, has a limited impact on the building energy flexibility potential and the risk of opening bedroom windows.

ACS Style

John Clauß; Sebastian Stinner; Igor Sartori; Laurent Georges. Predictive rule-based control to activate the energy flexibility of Norwegian residential buildings: Case of an air-source heat pump and direct electric heating. Applied Energy 2019, 237, 500 -518.

AMA Style

John Clauß, Sebastian Stinner, Igor Sartori, Laurent Georges. Predictive rule-based control to activate the energy flexibility of Norwegian residential buildings: Case of an air-source heat pump and direct electric heating. Applied Energy. 2019; 237 ():500-518.

Chicago/Turabian Style

John Clauß; Sebastian Stinner; Igor Sartori; Laurent Georges. 2019. "Predictive rule-based control to activate the energy flexibility of Norwegian residential buildings: Case of an air-source heat pump and direct electric heating." Applied Energy 237, no. : 500-518.

Conference paper
Published: 12 December 2018 in Springer Proceedings in Energy
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This study aims to assess the effects of using wood stoves on indoor air quality (IAQ) regarding fine PM, ultrafine PM, CO2 and relative humidity in Norwegian residential houses. Measurements were performed in an old natural ventilated house and a new mechanical ventilated house. Three locations for PM measurements were selected: close to the stove opening, in the middle of the room and at the supply air inlet, with original installed stoves typical for the buildings’ time of construction. Each measurement lasted 3 h, which includes monitoring of the background concentration, the light up process, the burning and the refill processes. The results show peaks of fine and ultrafine PM emissions during the light up and refill phases, connected to opening of the wood stove door. The ultrafine PM peaks were higher and occurred more frequently than the fine PM ones, indicating that not only the opening of the wood stove door caused these PM peaks. Significant differences were found between the two houses regarding the relative distribution between fine PM and ultrafine PM. Peak concentrations of ultrafine PM took longer time to fall back towards background levels compared to the fine PM concentrations. No clear correlations were found between the load of the stove and PM emissions, and further research is required to assess why. Yet the situation was not alarming as the 24 h mean PM2.5 concentration in both houses was below the WHO guideline. CO2 emissions in both houses were on average always at a healthy level.

ACS Style

Mathieu Hamon; Guangyu Cao; Øyvind Skreiberg; Laurent Georges; Morten Seljeskog; Roger Khalil; Alexis Sevault; Hans Martin Mathisen. Assessment of the Effects of Using Wood Stoves on Indoor Air Quality in Two Types of Norwegian Houses. Springer Proceedings in Energy 2018, 887 -897.

AMA Style

Mathieu Hamon, Guangyu Cao, Øyvind Skreiberg, Laurent Georges, Morten Seljeskog, Roger Khalil, Alexis Sevault, Hans Martin Mathisen. Assessment of the Effects of Using Wood Stoves on Indoor Air Quality in Two Types of Norwegian Houses. Springer Proceedings in Energy. 2018; ():887-897.

Chicago/Turabian Style

Mathieu Hamon; Guangyu Cao; Øyvind Skreiberg; Laurent Georges; Morten Seljeskog; Roger Khalil; Alexis Sevault; Hans Martin Mathisen. 2018. "Assessment of the Effects of Using Wood Stoves on Indoor Air Quality in Two Types of Norwegian Houses." Springer Proceedings in Energy , no. : 887-897.

Conference paper
Published: 12 December 2018 in Springer Proceedings in Energy
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Using wood stoves is a common space-heating strategy in the Nordic countries. Currently, the lowest available nominal power of wood stoves is significantly oversized compared to the design space-heating load of highly-insulated houses. This oversizing might deteriorate the indoor thermal environment by causing overheating and a large vertical temperature stratification. Modelling the indoor thermal environment of rooms heated with a wood stove with acceptable computational time and accuracy, however, is a complex task. The purpose of this study is to analyze the accuracy of a new IDA-ICE zonal model currently under development and to calibrate it against measurements. For this, several experiments were conducted in a test cell, which was heated by an electric stove mimicking a wood stove with a nominal power of 4 kW. Room air temperatures in various positions were measured, while the stove that was placed in the middle of the room was run in cycles with different durations and surface temperature profiles, leading to a thermal stratification of 0.5–2.2 K/m. The zonal model could reproduce the temperatures at the bottom and top layers of the room with good accuracy. However, the model still needs further development and validation to reach good agreement with measurements in the middle layers of the zone. Nevertheless, already at this stage, the model could be used to roughly assess thermal stratification in rooms heated by wood stoves.

ACS Style

Martin Thalfeldt; Laurent Georges; Øyvind Skreiberg. Validation of a Zonal Model to Capture the Detailed Indoor Thermal Environment of a Room Heated by a Stove. Springer Proceedings in Energy 2018, 653 -663.

AMA Style

Martin Thalfeldt, Laurent Georges, Øyvind Skreiberg. Validation of a Zonal Model to Capture the Detailed Indoor Thermal Environment of a Room Heated by a Stove. Springer Proceedings in Energy. 2018; ():653-663.

Chicago/Turabian Style

Martin Thalfeldt; Laurent Georges; Øyvind Skreiberg. 2018. "Validation of a Zonal Model to Capture the Detailed Indoor Thermal Environment of a Room Heated by a Stove." Springer Proceedings in Energy , no. : 653-663.

Conference paper
Published: 12 December 2018 in Springer Proceedings in Energy
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Dynamical model identification is an essential element in the implementation of a model predictive controller. In this work, a control-oriented first order model was identified in a dedicated experiment on a super-insulated single-family house. First, parameters resulting from CTSM and the MATLAB System Identification toolbox were compared. Then, a comparison of model predictions and measurements showed that this simple model captures well the main dynamics of the building-averaged indoor temperature, after one week of training on rich data with sample time below 15 min. It was also observed that this prediction performance was not affected by the configuration of internal doors.

ACS Style

Pierre J. C. Vogler-Finck; John Clauß; Laurent Georges; Igor Sartori; Rafael Wisniewski. Inverse Model Identification of the Thermal Dynamics of a Norwegian Zero Emission House. Springer Proceedings in Energy 2018, 533 -543.

AMA Style

Pierre J. C. Vogler-Finck, John Clauß, Laurent Georges, Igor Sartori, Rafael Wisniewski. Inverse Model Identification of the Thermal Dynamics of a Norwegian Zero Emission House. Springer Proceedings in Energy. 2018; ():533-543.

Chicago/Turabian Style

Pierre J. C. Vogler-Finck; John Clauß; Laurent Georges; Igor Sartori; Rafael Wisniewski. 2018. "Inverse Model Identification of the Thermal Dynamics of a Norwegian Zero Emission House." Springer Proceedings in Energy , no. : 533-543.

Conference paper
Published: 12 December 2018 in Springer Proceedings in Energy
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A detailed multi-zone building model of an existing zero emission residential building (ZEB) has been created using the software IDA Indoor Climate and Energy (IDA ICE). The model will later be used for investigating control strategies for the heating system to activate the building energy flexibility. The main purpose of this paper is to show how reliable the model reproduces the short-term thermal dynamics and the temperature zoning of the building. This is of particular interest for the control of heating, ventilation and air conditioning (HVAC) systems in order to provide meaningful insights of active demand response (ADR) measures. The model has been validated using data sets from seven experiments. Two dimensionless indicators, the normalized mean bias error (NMBE) and the coefficient of variation of the root mean square error (CVRMSE) were applied in order to evaluate the trend of the average indoor temperatures. The first approach considered standard operating conditions, where the measured indoor air temperature was used as input for the control of the electrical radiator and the total electricity use of the radiator as an output. Excitation sequences have been used in the second approach, where the electric power of the radiator has been imposed and the operative temperature taken as the output. The model shows good agreement between the temperature profiles from the measurements and the simulations based on the NMBE and CVRMSE remaining below 5% for most cases.

ACS Style

John Clauß; Pierre Vogler-Finck; Laurent Georges. Calibration of a High-Resolution Dynamic Model for Detailed Investigation of the Energy Flexibility of a Zero Emission Residential Building. Springer Proceedings in Energy 2018, 725 -736.

AMA Style

John Clauß, Pierre Vogler-Finck, Laurent Georges. Calibration of a High-Resolution Dynamic Model for Detailed Investigation of the Energy Flexibility of a Zero Emission Residential Building. Springer Proceedings in Energy. 2018; ():725-736.

Chicago/Turabian Style

John Clauß; Pierre Vogler-Finck; Laurent Georges. 2018. "Calibration of a High-Resolution Dynamic Model for Detailed Investigation of the Energy Flexibility of a Zero Emission Residential Building." Springer Proceedings in Energy , no. : 725-736.

Journal article
Published: 10 December 2018 in Building and Environment
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In building performance simulation (BPS), zonal models are intermediate models between standard models assuming perfectly-mixed room air and Computational Fluid Dynamics (CFD): they aim to predict the air temperature and velocity fields as well as the pollutant distribution inside a room using a computational time significantly lower than using CFD. The article aims at validating a transient zonal model that is currently implemented in the commercial BPS tool, IDA ICE. In theory, this one-dimensional model can address a large variety of airflows and requires almost no a priori knowledge of the flow to be computed. The model is validated against measurements in a laboratory heated by either electric radiators or an electric stove designed to mimic surface temperatures of real stoves. Unlike radiators, the case of stoves has never been addressed in the literature and is challenging due to the strong thermal coupling between the room air and walls. Heat emitters have been placed either in the middle of the room or along walls. The zonal model remarkably well predicts the time evolution of the air temperature stratification in the room for all test cases. For a heat emitter in a central position, the wall surface temperatures are predicted correctly. Nevertheless, for a heat emitter along walls, these walls cannot be considered isothermal anymore, an assumption found in most BPS tools. The paper suggests that an automatized method to divide walls in the vicinity of heat emitters is necessary for a reliable prediction of the wall surface temperatures.

ACS Style

L. Georges; M. Thalfeldt; Ø. Skreiberg; W. Fornari. Validation of a transient zonal model to predict the detailed indoor thermal environment: Case of electric radiators and wood stoves. Building and Environment 2018, 149, 169 -181.

AMA Style

L. Georges, M. Thalfeldt, Ø. Skreiberg, W. Fornari. Validation of a transient zonal model to predict the detailed indoor thermal environment: Case of electric radiators and wood stoves. Building and Environment. 2018; 149 ():169-181.

Chicago/Turabian Style

L. Georges; M. Thalfeldt; Ø. Skreiberg; W. Fornari. 2018. "Validation of a transient zonal model to predict the detailed indoor thermal environment: Case of electric radiators and wood stoves." Building and Environment 149, no. : 169-181.

Journal article
Published: 01 June 2018 in Energy and Buildings
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In this study, the objective is to redesign a previous concept for a single-family Zero greenhouse gas Emission Building (ZEB). The concept is redesigned based on comparing greenhouse gas (GHG) emission loads and compensation from different design solutions applied in Norwegian single-family ZEB pilot buildings and selected sensitivity studies. The objective is to see if a previously developed ZEB model (2011) can be redesigned to achieve a life cycle energy and material emission balance (ZEB-OM), which previously was not achieved. Five different design parameters are evaluated: area efficiency, embodied emissions in the envelope, insulation thickness, heating systems and different roof forms with respect to the photovoltaic area. Embodied emissions reductions were possible in the ground foundation, from around 1 kg CO2/m2 to 0.6 kg CO2/m2 per year. Both models are able to compensate for all operational emissions. The new model is in addition able to compensate for 60% of embodied emissions, whereas the previous model only could compensate for 5%. The new model does not reach the life cycle energy and material balance. The paper presents and discusses different approaches for achieving the ZEB-OM balance. Further concept model optimization is needed.

ACS Style

Torhildur Fjola Kristjansdottir; Aoife Houlihan-Wiberg; Inger Andresen; Laurent Georges; Niko Heeren; Clara Stina Good; Helge Brattebø. Is a net life cycle balance for energy and materials achievable for a zero emission single-family building in Norway? Energy and Buildings 2018, 168, 457 -469.

AMA Style

Torhildur Fjola Kristjansdottir, Aoife Houlihan-Wiberg, Inger Andresen, Laurent Georges, Niko Heeren, Clara Stina Good, Helge Brattebø. Is a net life cycle balance for energy and materials achievable for a zero emission single-family building in Norway? Energy and Buildings. 2018; 168 ():457-469.

Chicago/Turabian Style

Torhildur Fjola Kristjansdottir; Aoife Houlihan-Wiberg; Inger Andresen; Laurent Georges; Niko Heeren; Clara Stina Good; Helge Brattebø. 2018. "Is a net life cycle balance for energy and materials achievable for a zero emission single-family building in Norway?" Energy and Buildings 168, no. : 457-469.