References of "Randaxhe, François"
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See detailTowards nzeb goal for newly built office buildings in Europe using high temperature cooling.
Randaxhe, François ULg; Lemort, Vincent ULg; Lebrun, Jean ULg

Conference (2016, May 24)

In the design phase of a building, many HVAC systems options are available to satisfy the basic requirements related to its use. The design engineer is responsible for considering various systems and ... [more ▼]

In the design phase of a building, many HVAC systems options are available to satisfy the basic requirements related to its use. The design engineer is responsible for considering various systems and recommending a system that will meet the project goals and perform as desired. In addition, high efficiency requirements are imposed to the HVAC equipments through strong regional regulation such as the Energy Performance of Buildings Directive which requires minimum efficiency of HVAC equipments in the market. In reaction, major improvements have been made by manufacturers to improve the performance of their systems and meet all these criteria. With the nearly zero energy goal for all newly constructed buildings in Europe after 2020, it seems very likely that the design of the future building should rely on today’s technology to meet these targets. The integration of High Temperature Cooling in buildings can bring a fresh perspective in this context. The study presents the sensitivity analysis of a primary system to chilled water supply temperature for a water cooled chiller with a cooling tower and a free-chilling heat exchanger. It allows a proper assessment of the impact of the chilled water temperature on the primary system performance. [less ▲]

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See detailGlobal optimization of the production and the distribution system for typical European HVAC systems
Randaxhe, François ULg; Lemort, Vincent ULg; Lebrun, Jean ULg

in Energy Procedia (2015), 78

European countries have agreed on a new 2030 Framework with a 30% improvement in energy efficiency compared to projection and a 40% cut in greenhouse gas emissions compared to 1990 levels. With an ... [more ▼]

European countries have agreed on a new 2030 Framework with a 30% improvement in energy efficiency compared to projection and a 40% cut in greenhouse gas emissions compared to 1990 levels. With an estimated 11% of all the electrical energy used in Europe consumed by HVAC systems, the improvement of their efficiency is a key element to reach these targets. When looking at the energy flow in typical European HVAC systems, one can observe important degradation in efficiency associated to heating and cooling energy transportation systems together with a non-optimal use of the production plant. These inefficiencies are direct consequences of the system design with, quite often, a lack of consideration of the system part load or its off-design operation. This research attempts to identify the sensitivity of both cooling and heating HVAC systems to these conditions and to propose an approach to optimize the design and the operation of HVAC systems integrated in buildings considering trade-off between primary systems efficiency, distribution losses and auxiliaries consumption. [less ▲]

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See detailProceedings of the Ninth International Conference on System Simulation in Buildings - SSB 2014
Lemort, Vincent ULg; Randaxhe, François ULg

in System Simulation in Buildings (2015)

This 9th International Conference on System Simulation in Buildings has been the opportunity to gather researchers coming from 13 countries, sharing the last results of their research works. Some of the ... [more ▼]

This 9th International Conference on System Simulation in Buildings has been the opportunity to gather researchers coming from 13 countries, sharing the last results of their research works. Some of the presented works were conducted in the frame of projects from the International Energy Agency’s Energy in Buildings and Communities Programme (EBC). [less ▲]

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See detailSimulation of a passive house coupled with a reversible heat pump/organic Rankine cycle unit
Dumont, Olivier ULg; Carmo, Carolina; Randaxhe, François ULg et al

Conference (2014, December)

This paper presents a dynamic model of a passive house located in Denmark with a large solar absorber, a horizontal ground heat exchanger coupled with a HP/ORC unit. The HP/ORC reversible unit is a module ... [more ▼]

This paper presents a dynamic model of a passive house located in Denmark with a large solar absorber, a horizontal ground heat exchanger coupled with a HP/ORC unit. The HP/ORC reversible unit is a module able to work as an Organic Rankine Cycle (ORC) or as a heat pump (HP). There are 3 possible modes that need to be chosen optimally depending on the weather conditions, the heat demand and the temperature level of the storage. The ORC mode is activated, as long as the heat demand of the house is covered by the storage to produce electricity based upon the heat generated by the solar roof. The direct (free) heating is used when the storage cannot cover the heat demand of the house. Finally, when direct heating is not sufficient to cover the heat demand because of poor weather conditions, the HP mode is activated. Dynamic simulations of the whole system are presented for different typical days of the year in the Modelica language. A peak of 3.28 kW of power is reached in ORC mode with a heat input of 59.5 kW from the solar roof (23.9 kWh are produced during a typical summer day). In a representative winter day, 17.28 kWh are consumed by the heat pump with a daily average COP of 4.1. Conclusions regarding control strategies and enhancement of the global system are drawn. A control strategy with a low storage temperature set-point (50˚C) allows reducing electrical consumption from 11% up to 24% when compared to higher set-point (60˚C). The system performance to produce power could also be optimized if an extra tank is included to store heat uniquely to produce electricity with the ORC during the peak electricity consumption. Finally, this technology is a promising way to achieve Net Zero Energy Building at low price compared to competitive products (heat pump combined with PV for example). The system presents a higher global COP because the heat produced on the roof can heat the storage directly. [less ▲]

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See detailSimulation-assisted evaluation of potential energy savings: Application to an administrative building in France
Randaxhe, François ULg; Bertagnolio, Stéphane ULg; Lemort, Vincent ULg

in Randaxhe, François; Bertagnolio, Stéphane; Lemort, Vincent (Eds.) International Conference for Enhanced Building Operations ICEBO 2012 at Manchester, October 23-26, 2012 (2012, October)

The case study presented here falls within a project of feasibility studies to improve the energy efficiency, the carbon footprint and the environmental impacts of several administrative buildings in ... [more ▼]

The case study presented here falls within a project of feasibility studies to improve the energy efficiency, the carbon footprint and the environmental impacts of several administrative buildings in France. The first part of the paper briefly presents the data obtained during a classical audit and inspection procedure: the description of the building in term of design, the HVAC system characteristics, the occupancy and operating profiles and the control strategy applied. The second part of the paper gives the first results obtained using an evidence-based calibrated building energy simulation model to analyze the actual building global consumption but also analyze the local consumptions (heat pumps, air handling units, terminal units, lightings, pumps,...). The last part of the paper then demonstrates the possibilities given by the building energy simulation model to evaluate potential energy saving scenarios through different examples. The advantages and drawbacks of the applied methods and tools are also discussed. [less ▲]

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See detailEnergy and comfort performance analysis of monitored thermally activated building systems combined with geothermal heat pumps
Gantiez, Clément ULg; Lemort, Vincent ULg; Hoogmartens, Jan et al

in International High Performance Buildings Conference at Purdue, July 16-19, 2012 (2012, July)

The combination of geothermal heat pumps (GEO HPs) and thermally activated building systems (TABS), that allow both low temperature heating and high temperature cooling, could yield primary energy savings ... [more ▼]

The combination of geothermal heat pumps (GEO HPs) and thermally activated building systems (TABS), that allow both low temperature heating and high temperature cooling, could yield primary energy savings of around 20- 71% in comparison with conventional heating/cooling systems. However, the potential energy savings are rarely reached in practice due to bad integration of the different subsystems and inefficient control. The present paper presents the analysis of two monitoring campaigns by stressing the influence of relevant parameters such as the performance of components (heat pump, ground heat exchangers, TABS, etc.), building characteristics and the implemented control strategies. The buildings have been monitored and analyzed in the frame of the WKSP-project realized by Institute of Building Services and Energy Design (IGS) at Technical University of Braunschweig. The results show good performance of ground coupled heat pump with seasonal COP up to around 5. Moreover, the use of ground heat exchangers to perform free chilling allows seasonal EER up to 20. Furthermore, the control strategies implemented in the different buildings are quite different. It is also shown that this system can lead to a running cost reduction up to 50% compared to conventional systems and that CO2 emissions can be reduced by 40%. [less ▲]

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