Browsing by Author "Lumbreras, Mikel"
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Item Data driven model for heat load prediction in buildings connected to District Heating by using smart heat meters(2022-01-15) Lumbreras, Mikel; Garay-Martinez, Roberto; Arregi, Beñat; Martin-Escudero, Koldobika; Diarce, Gonzalo; Raud, Margus; Hagu, Indrek; Tecnalia Research & Innovation; EDIFICACIÓN DE ENERGÍA POSITIVAAn accurate characterization and prediction of heat loads in buildings connected to a District Heating (DH) network is crucial for the effective operation of these systems. The high variability of the heat production process of DH networks with low supply temperatures and derived from the incorporation of different heat sources increases the need for heat demand prediction models. This paper presents a novel data-driven model for the characterization and prediction of heating demand in buildings connected to a DH network. This model is built on the so-called Q-algorithm and fed with real data from 42 smart energy meters located in 42 buildings connected to the DH in Tartu (Estonia). These meters deliver heat consumption data with a 1-h frequency. Heat load profiles are analysed, and a model based on supervised clustering methods in combination with multiple variable regression is proposed. The model makes use of four climatic variables, including outdoor ambient temperature, global solar radiation and wind speed and direction, combined with time factors and data from smart meters. The model is designed for deployment over large sets of the building stock, and thus aims to forecast heat load regardless of the construction characteristics or final use of the building. The low computational cost required by this algorithm enables its integration into machines with no special requirements due to the equations governing the model. The data-driven model is evaluated both statistically and from an engineering or energetic point of view. R2 values from 0.70 to 0.99 are obtained for daily data resolution and R2 values up to 0.95 for hourly data resolution. Hourly results are very promising for more than 90% of the buildings under study.Item Data driven process for the energy assessment of building envelope retrofits(2020-06-30) Garay-Martinez, Roberto; Arregi, Beñat; Lumbreras, Mikel; Zurro, Belén; Gonzalez, Jose Manuel; Hernandez, Jose Luis; Tecnalia Research & Innovation; EDIFICACIÓN DE ENERGÍA POSITIVAIn the last decades, a growing industry has been created in relation to building envelope retrofits. Linked to the lack of financial capacity of many building owners, innovative instruments such as energy performance contracts have been promoted by public bodies. This kind of instruments require of detailed energy assessment processes in order to define the expected heat load reduction and the associated economic flows between building owners and Energy Services Companies. When dealing with building envelopes, existing methods for building envelope heat loss characterization require of substantial efforts in terms of equipment and time, which makes them difficult to apply in real practice. In this paper, a novel method is proposed based on whole-building heat load assessment by means of heat meters, and analytical calculations of building envelope transmission heat load coefficients. This method, which requires minimal or no additional equipment, can be used over historical data from District Heating systems. It assigns a specific load fraction to building envelope heat transfer and allows to assess the expected reduction due to the building envelope retrofit. Numerical and experimental data is presented based on an educational building in the city of Burgos, Spain.Item District Heating De-Carbonisation in Belgrade. Multi-Year transition plan(2020-11-20) Marijuan, Antonio Garrido; Garay, Roberto; Lumbreras, Mikel; Vladic, Ljubisa; Savić, Radmilo; Savic, Radmilo; EDIFICACIÓN DE ENERGÍA POSITIVA; Tecnalia Research & InnovationA large share of the city of Belgrade is heated by a District Heating network. Established in 1965, the network delivers 3.6 TWh to more than 20 million square meters of households industries and businesses, by means of a 1460km-long network. The system has been continuously upgraded and adapted to new technologies and already operates at relatively low temperature, with modernized substations. However, the delivered heat is still produced mainly by means of carbon intensive technologies. Conscious of the need to de-carbonise the city, a multi-year transition plan was established, where large investments have been secured, comprising greater interconnection levels, installation of large solar thermal plants and waste incineration plants, and the conversion of a power plant into CHP, among others. In this paper, the criteria for the selection of the technologies, the identification of enabling investments, interaction with stakeholders, securing of financing, and status of the plan are presented. After the execution of the de-carbonisation roadmap, it is expected that the DH system will reduce its carbon intensity by 50%.Item Energy & economic assessment of façade-integrated solar thermal systems combined with ultra-low temperature district-heating(2020-10) Lumbreras, Mikel; Garay, Roberto; Tecnalia Research & InnovationThis paper conducts an energy and economic assessment of District Heating (DH) integrated Solar Thermal (ST) systems. An implementation with building-integrated ST collectors coupled to a Low Temperature District Heating (LTDH) system is studied, with special focus on unglazed collectors. ST heat is exploited in the building through direct use, while excess heat is delivered to the network. A novel control strategy for heat flows in the system is proposed. A meta-analysis of several DH configurations, interconnection schemes and installed ST capacity is performed in three different climates: Sevilla (Spain), Bordeaux (France) & Copenhagen (Denmark). Heat loads corresponding to buildings with various insulation levels and domestic hot water loads are assessed in hourly simulations. The proposed interconnection concept provides a variety of connection modes to the DH network, allowing up to a 50% increase in the provision of solar heat compared to an isolated ST system. Positive Return of Investment (ROI) for such a setup is achieved in 22% of the studied cases. The DH network is found to be a suitable heat sink in up to 25% of the buildings with ST systems installed.Item Energy meters in District-Heating Substations for Heat Consumption Characterization and Prediction Using Machine-Learning Techniques(2020-11-20) Lumbreras, Mikel; Garay, Roberto; Marijuan, Antonio Garrido; Tecnalia Research & Innovation; EDIFICACIÓN DE ENERGÍA POSITIVAThe use of smart energy meters enables the monitoring of large quantity of data related to heat consumption patterns in buildings connected to DH networks. This information can be used to understand the interaction between building and the final users´ without accurate information about building characteristics and occupational rates. In this paper an intuitive and clarifier data-driven model is presented, which couples heat demand and weather variables. This model enables the disaggregation of Space-Heating & Domestic Hot water demand, characterization of the total heat demand and the forecasting for the next hours. Simulations for 53 building have been carried out, with satisfactory results for most of them, reaching R2 values above 0.9 in some of them.Item RELaTED Project: New Developments on Ultra-Low Temperature District Heating Networks(Multidisciplinary Digital Publishing Institute (MDPI), 2020-12-25) Marijuan, Antonio Garrido; Garay, Roberto; Lumbreras, Mikel; Sánchez, Víctor; Macias, Olga; Rozas, Juan Perez Sainz DeDistrict heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning district heating-connected reversible heat pump systems that allow to reach adequate thermal levels for domestic hot water as well as the use of the network for district cooling with high performance. These developments will be demonstrated in four locations: Estonia, Serbia, Denmark, and Spain.Item RELaTED, An Approach to a decentralized Ultra Low Temperature District Heating(2019) Garay, Roberto; Lumbreras, Mikel; Sánchez Zabala, Víctor; Tecnalia Research & InnovationTrends for heating energy in European Cities are the decarbonization of energy sources and the reduction of heat loads. District heating (DH) networks are key systems to reach the targets due to the cost competitiveness and high performance levels they show. However, DH networks require a conversion to adapt for the need of the future. It is necessary to reduce the operation temperature so that it is possible to increase the performance of renewable systems and operation criteria needs to be adopted for the introduction of weather-dependent, distributed heat sources such as solar systems. In this paper is presented the RELaTED, a novel DH networks scheme with decentralized Ultra-Low Temperature performance. This way, it is possible the adaptation of new and existing networks to several operational schemes. Transitory phases for the conversion of actual DH and how this affects the whole system are discussed along the paper.Item Simulation of unglazed solar thermal systems integrated into façade & combined with ultra-low temperature district heating(International Building Performance Simulation Association, 2019) Lumbreras, Mikel; Garay, Roberto; Corrado, Vincenzo; Fabrizio, Enrico; Gasparella, Andrea; Patuzzi, Francesco; Tecnalia Research & InnovationThis paper presents a theoretical simulation of thermal and economical assessment of façade integrated Solar Thermal (ST) in combination with Ultra Low Temperature (ULT) District-Heating (DH). This paper is in line with existing R&D activities for the integration of unglazed systems in building envelopes, where facades provide an almost unexplored area for increasing solaractivated building envelopes. The combination of building-integrated solar systems with DH networks avoids the use of local storage and allows a novel combination of heat directionality, both from building to the heat grid and vice versa. A control algorithm for heat supply is presented, so that the performance of the overall system is the optimal. Energetic results from solar simulations and economic assessment derived from the balance of building energy demand and solar production are presented. Over a fullyear period the proposed unglazed system produces as much as 50% additional heat when compared with an isolated ST system and profitable economic metrics are reached over a simulation time of 20 years. Finally, it is concluded the heat sink nature of a DH network, for as many as 25-35% of the buildings connected to the DH includes ST system.Item Technical & Economical assessment of the interconnection between façade integrated solar thermal system and low temperature district-heating(2019) Lumbreras, Mikel; Garay, RobertoThis paper explores the techno-economic viability of coupling unglazed solar thermal façade system with a low temperature district heating network. this concept allows a more efficient control strategy for heat is allowed, where direct solar heat and heat from district heating are alternated in order to maximize the efficiency of the whole system. ST heat is directly used in the building when there is underproduction and when ST overproduces, this system allows to take profit from the network for the delivery of the excess heat. The use of unglazed collectors for low-intrusive architectural interaction in façades is discussed. Each system separately have proven efficiency, however, the most novel part of the study is finding a method which permits de combination of both technologies, proposing technical solutions and economic studies. Unglazed system reach thermal efficiency up to more than 30% in reference of the total radiation in the south façade, which are similar to other high efficiency solar systems. As for the economic results, it has been made an economic assessment at mid-time sight and positive economic meters have been achieved. Moreover, economic results from simulations prove the viability for unglazed solar district heating when integrated massively in facades.Item Unglazed Solar Thermal Systems for Building Integration, coupled with District Heating Systems. Conceptual Definition, Cost and Performance Assessment(IOS Press, 2018) Lumbreras, Mikel; Garay, Roberto; Martin, KoldobikaIn this paper, the energy performance of a Solar Thermal (ST) façade system is studied for its connection to a District Heating System. This concept allows for the direct use of ST heat in the building, while taking profit from the network for delivery/selling of excess heat and purchase of heat during periods of underproduction. The use of Unglazed Collectors for low-intrusive architectural interaction in façades is discussed. Studies are carried out on the heat production of the system and its capacity to cope with local demands. Economic studies are carried out in order to balance the investment and operational costs/profits of the system.