Pachano, J. E. (José Eduardo)
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- Multi-step building energy model calibration process based on measured data(Elsevier, 2021) Fernández-Bandera, C. (Carlos); Pachano, J. E. (José Eduardo)Building energy models are a key element in regulatory compliance calculations. These energy performance calculations often do not accurately reflect actual operating conditions. Therefore, evalua- tion of energy performance comparing actual energy use of a building with the outcome of dynamic sim- ulation models can be misleading, this difference is also known as the energy performance gap. The reduction of the gap is an important task aimed to provide confidence in the use of models for evaluation of energy efficiency. This paper is focused on reducing the technical issues (e.g. poorly adjusted thermal parameters in the envelope, inefficient boiler operator or lack of adjustment in parameters of heat pumps, baseboard radiators or air handling units) which are one of the main causes of the energy performance gap. The application of a multi-step, optimization-based, calibration methodology performed in a white-box simulation environment (EnergyPlus) using three months of ten minute time-step data to adjust HVAC parameter values with a genetic algorithm software (Jeplus) is validated on a real test site. Resulting in a BEM that fits the building’s hourly performance benchmark into international standards on three key levels: indoor temperature by Thermal Zone (TZ), heat production and electric consumption from heat pumps, which comprise all the components of a building energy model. A batch of 1500 h of heating operation, obtained from the building management system, has been used to calibrate the model. The results complied with the requirements of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Guideline 14–2002 at hourly interval, with NMBE 6–10%,Cv (RMSE) 630% and R2 P75% and with the International Performance Measurement and Verification Protocol (EVO) for Cv(RMSE) 620% and R2 P75% in the three aforementioned levels, which can be con- sidered a step forward in the area of calibrating white box models. In addition, to prove the strength and robustness of the results, the model has been checked in a long testing and independent period of 2.500 h of heating operations with the same level of compliance. The demonstrator is the library of a school located in Denmark. The HVAC system is composed of four air–water heat pumps that deliver heating to the whole compound with the backup support of a gas boiler. The library is heated with baseboard radiators system with the support of an air handling unit used for ventilation purposes.
- Enhancing self-consumption for decarbonization: An optimization strategy based on a calibrated building energy model(2023) Peppas, A. (Antonis); Fernández-Vigil, M. (María); Fernández-Bandera, C. (Carlos); Pachano, J. E. (José Eduardo)To face the challenge of climate change and achieve the decarbonization target set by the European Union, the current trend is to electrify building services, replacing the use of fossil fuels for renewable energy sources. The installation of grid-connected photovoltaic (PV) systems is becoming a popular strategy. However, the widespread application of PV solutions carries certain concerns about grid-network security and stability, since intermittent renewable energy excess pouring into the grid may exceed voltage limits. Therefore, an optimization of the consumption of a building's own PV production (self-consumption) to reduce the excess output is vital. The following paper performs a demand side optimization strategy of the building's thermostatic controllable loads (heating and cooling), which represent at least 50% of the total energy consumed by the building. The process is applied in a previously calibrated building energy model (BEM) that describes a fully operational building under a typical Mediterranean climate (Greece). The site contains a PV plant and a multi-split Variable Refrigerant Flow (VRF) system dedicated to maintain indoor comfort conditions. The technology used is simple, able to perform 15 minute time-step yearly optimizations while saving a large amount of computational time. It performs a bi-dimensional optimization of both: indoor thermal-zone set-points and ventilation air supply temperature. The optimization process performed is based on 2019 data gathered from European Project SABINA, resulting in a self-consumption improvement of 11.6% for summer scenario (reaching 69.16%) and 78.7% for winter (reaching 57.47%) in comparison to a non-optimized “business as usual” base model.
- Two-stage multi-step energy model calibration of the cooling systems of a large-space commercial building(Elsevier, 2023) Saiz, J. (J.); Fernández-Vigil, M. (María); Fernández-Bandera, C. (Carlos); Pachano, J. E. (José Eduardo)Buildings play a major role in energy expenditure, representing 40% of Europe’s total energy consumption. It is estimated that heating, ventilation, and air conditioning systems consume between 50–60% of the total energy spent inside the building, thus corresponding to 20% of global worldwide energy consumption. Hence, there is a need to improve the accuracy of building thermal simulation and energy models that are essential in regulatory compliance calculations. In the present study, the authors empirically validate an optimizationbased calibration methodology based on its application to a fully operational commercial building located in Pamplona, Navarre. The methodology used a white-box two-stage model in EnergyPlus, which combines a load profile object and a district cooling component to distribute the cooling load inside the building’s thermal zones. The study optimized the parameters and performance curves of different cooling system components using a second-generation non-sorting genetic algorithm in jEPlus software and 985 h of ten-minute time-step data. Finally, a multi-level benchmark is executed, which evaluates the electric energy consumption of the building’s heat pumps and the interior temperature of the different thermal zones for summer 2020 conditions. The assessment of the thermal and energy performance of the simulation model was conducted according to the requirements of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Guideline 14-2002, and the Chartered Institution of Building Services Engineers, Operation Performance Technical Memoranda 63.
- Photovoltaic plant optimization to leverage electric self consumption by harnessing building thermal mass(2020) Salom, J. (Jaume); Peppas, A. (Antonis); Ramos-Ruiz, G. (Germán); Fernández-Bandera, C. (Carlos); Pachano, J. E. (José Eduardo)The self-consumption without surplus to the grid is one of the aspects of the new Spanish law for prosumers. Increasing the share of renewable energy sources into the grid inherently leads to several constraints. The mismatch between the energy demand and the renewable energy production, which is intermittent in nature, is one of those challenges. Storage offers the possibility to decouple demand and supply, and therefore, it adds flexibility to the electric system. This research evaluates expanding electricity self-consumption without surplus to the grid by harnessing thermal mass storage in the residential sector. The methodology is investigated by using a variable refrigerant flow air conditioner system. Because there is no option to export the excess capacity to the grid, this research proposes an approach to profiting from this surplus energy by activating structural thermal mass, which is quantified from the information acquired using a building energy model. For this purpose, an EnergyPlus model of a flat in Pamplona (Spain) was used. The optimization analysis was based on a set-point modulation control strategy. Results show that under adequate climatological circumstances, the proposed methodology can reduce the total electric energy from the grid between by 60¿80%.
- Calibración de equipos climáticos en modelos energéticos detallados (Caja blanca)(Universidad de Navarra, 2024-02-13) Pachano, J. E. (José Eduardo); Echeverría-Trueba, J. B. (Juan B.); Fernández-Bandera, C. (Carlos)El crecimiento de la población a nivel mundial y la persistente dependencia energética de los combustibles fósiles intensifican los impactos del cambio climático, los cuales están mayormente asociados a las emisiones de dióxido de carbono. Investigaciones demuestran que el consumo de energía en los edificios representa el 40 % del consumo global de energía primaria y contribuye al 36 % de las emisiones de carbono. A raíz de la tendencia actual, influenciada por diversos factores sociales, económicos y políticos, se estima que el consumo de energía y las emisiones podrían duplicarse o incluso triplicarse para el año 2050. Por lo tanto, la mejora de los edificios existentes puede generar un ahorro energético de entre el 50 % y el 90 % a nivel mundial. Es evidente que la reducción del consumo energético en los edificios resulta vital para optimizar la asignación de recursos en diferentes áreas críticas de desarrollo, tales como la salud, la educación y la reactivación económica, entre otras. Diversos países alrededor del mundo han optado por abordar este desafío, incorporando políticas energéticas en los códigos de construcción y estableciendo programas de certificación que establecen límites de consumo energético. Estas iniciativas tienen como objetivo encontrar soluciones que mejoren la eficiencia energética, reduzcan los costos de mantenimiento y disminuyan las emisiones de CO2. La realización de un estudio energético de los edificios se posiciona como una de las herramientas más efectivas para desarrollar una estrategia de ahorro energético, ya que permite evaluar el estado actual del edificio y proponer la implementación de medidas de conservación de energía, optimización de los sistemas de climatización y adopción de nuevas tecnologías. Por esta razón, resulta imperativo abordar adecuadamente el complejo problema de establecer el rendimiento energético real de un edificio. La obtención de un modelo de simulación energética de edificios que reduzca la brecha entre la simulación y la realidad constituye uno de los desafíos actuales. Un gemelo digital, capaz de representar de manera confiable la física del edificio en condiciones normales de operación, permite evaluar múltiples soluciones en un entorno no intrusivo y de bajo coste, como es el caso de la simulación. Si los estudios de conservación de energía pudieran respaldarse en un modelo energético calibrado, cuyo comportamiento energético se asemeje al del edificio real, la calidad de los resultados en ahorro energético y el rendimiento de dichas medidas de conservación mejorarían significativamente. Entre las numerosas ventajas de estos modelos, se encuentran la capacidad de identificar áreas críticas dentro del edificio que requieren mayor estudio, el diseño de estrategias de conservación de energía, el establecimiento de una línea base para contratos energéticos, la optimización del sistema de climatización, la puesta en marcha de equipos de climatización y la detección de fallos. La presente tesis de investigación se basa en el trabajo previo de Bandera, Ramos et al, quienes se enfocaron en calibrar la envolvente del edificio. Al conocer la cantidad de energía que se pierde a través de la envolvente, podemos determinar la demanda energética del edificio (Anexo 49). Una vez que la envolvente se encuentra calibrada, considerando las solicitudes y cargas (ocupación, equipos, iluminación, etc.), se obtiene una demanda energética que debe ser atendida exclusivamente por los sistemas de climatización del edificio. El objetivo de este trabajo es calibrar los parámetros de los diferentes componentes de los equipos del sistema de climatización, generando un modelo energético del edificio que correlacione las condiciones internas de temperatura con la demanda térmica y el consumo energético de los equipos de producción térmica (rendimiento de la instalación). Solo al realizar esta doble evaluación, manteniendo las condiciones de temperatura interior de los espacios y obteniendo un consumo energético similar al real, podremos hablar de un modelo térmico y energético completo del edificio (modelo calibrado).
- Seasonal adaptation of VRF HVAC model calibration process to a mediterranean climate(Elsevier, 2022) Peppas, A. (Antonis); Fernández-Bandera, C. (Carlos); Pachano, J. E. (José Eduardo)Today, Building Energy Models (BEM) have become essential in regulatory compliance calculations, the correct assessment of it’s Air Conditioning (AC) systems is critical for the reduction of the performance gap between BEMs and reality and increase the accuracy of evaluating buildings energy performance and it’s systems efficiency. Given that multi-split Variable Refrigerant Flow (VRF) systems have grown in the market in recent years becoming a particular trending solution to achieve building indoor comfort; the present paper focus on technical issues when modelling such VRF systems inside EnergyPlus, a white- box simulation environment, especially regarding the effects weather conditions have on the behaviour of VRF systems and it’s correlation with the AC system performance curves. The study performs an empir- ical validation of an optimization-based calibration methodology assessing multiple levels: average inte- rior temperature of the different building spaces and electric energy consumption from VRF outdoor unit. It is performed using fifteen minute time-step seasonal data obtained from a fully operational building located in a typical Mediterranean climate (Greece), adjusting the parameter and curve values of the VRF system using a genetic NGSA-II algorithm (Jeplus software) for both summer and winter conditions. The generated BEM captures the building’s hourly performance for summer conditions using 1717 hours to fit into international standards. Complying with the requirements of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Guidelines 14-2002 for hourly energy consump- tion, reaching an NMBE 6–10% ,Cv(RMSE) 630% and R2 P75% while keeping indoor temperatures on every room with a RMSE 61 C. The resulting BEM proved stable during the 2077 hours of it’s summer evaluation period, fitting into the new unseen weather and building operation conditions of 2020 which can be considered a step forward in the area of calibrating white box models. While for winter conditions the study demonstrates the value of the calibration methodology while presenting the importance of weather influence on VRF systems. Using a total of 802 hours the applied technology greatly improves the results from the baseline model, reaching a partially calibrated BEM model for winter. Which rein- forces the fact that regardless of how good a baseline model is, building operating conditions and weather may will always generate a design/performance gap and therefore the calibration of a BEM is unavoidable.