Configurations of model predictive control to exploit energy flexibility in building thermal loads

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A model predictive control (MPC) framework is developed in the present study, with the final objective to improve the energy flexibility of building thermal loads through demand-side management. Three different configurations are tested and tuned, with the following objective functions: minimizing the delivered energy to the building, the electrical energy used by the HVAC system (heat pump) or the cost of this electricity use. To validate these MPC configurations, a Matlab-Trnsys co-simulator is also created, in order to run the MPC on a virtual plant composed of a detailed building model. The MPC strategy manages to run effectively on the chosen study case (a residential building with heat pump in Spain), and the differences between configurations are discussed.Peer ReviewedPostprint (author's final draft

Review of control strategies for improving the energy flexibility provided by heat pump systems in buildings

Peer ReviewedPostprint (author's final draft

Energy-efficient ventilation control strategies for surgery rooms

Surgery room specific energy use is among the highest in the built environment due to stringent indoor environmental quality and infection control requirements. This study uses a calibrated energy model to evaluate the environmental and economic performance of a variety of ventilation control strategies that reduce surgery room energy use while maintaining indoor environmental quality and infection control performance. The individual control strategies evaluated in this study are (1) temperature and relative humidity reset, (2) air recirculation, (3) airflow reset, and (4) particle concentration based airflow control. Combinations of these strategies are also evaluated. The best performing combinations of control strategies can reduce surgery room primary energy use, CO2 emissions, and energy costs by up to 86% relative to the standard practice. Temperature and relative humidity reset is the strategy that offers the largest benefits. Particle concentration based airflow control shows modest results partly due to the conservative infection control performance target. Future research should define infection control performance thresholds during operation.Peer ReviewedPostprint (author’s final draft

The uncertainty of the energy demand in existing mediterranean urban blocks

The objective of the paper is to describe a stochastic model that has been developed to obtain load profiles for household electricity. For the study, several profiles have been generated in order to simulate the electrical demand of a residential building block or neighbourhood and evaluate the uncertainty of its energy use. The paper is divided in three different parts: development of the model, validation and determination of the uncertainty demand. In the first parts the basis of the model and how it works is explained. The second one represents the validation of the model, the input data and its results. The last step is focused on a statistical analysis of the electricity demand of a block of dwellings to evaluate minimum number of dwellings needed to estimate the average demand representative of the Mediterranean dwelling with different levels of accuracyPostprint (author’s final draft

Stochastic model for electrical loads in Mediterranean residential building: validation and applications

A major issue in modelling the electrical load of residential building is reproducing the variability between dwellings due to the stochastic use of different electrical equipment. In that sense and with the objective to reproduce this variability, a stochastic model to obtain load profiles of household electricity is developed. The model is based on a probabilistic approach and is developed using data from the Mediterranean region of Spain. A detailed validation of the model has been done, analysing and comparing the results with Spanish and European data. The results of the validation show that the model is able to reproduce the most important features of the residential electrical consumption, especially the particularities of the Mediterranean countries. The final part of the paper is focused on the potential applications of the models, and some examples are proposed. The model is useful to simulate a cluster of buildings or individual households. The model allows obtaining synthetic profiles representing the most important characteristics of the mean dwelling, by means of a stochastic approach. The inputs of the proposed model are adapted to energy labelling information of the electric devices. An example case is presented considering a dwelling with high performance equipment.Peer ReviewedPostprint (author's final draft version

Evaluation of the energy performance strategies in competition tenders to achieve Nearly Zero Energy Buildings: two case studies in Barcelona and Merano

This paper shows the experiences of two typologies of tender competition to achieve Nearly Zero Energy Buildings (nZEB) target, realized in 2013 in two cities: Barcelona (Catalunya) Spain and Merano (Bolzano) Italy. This work was carried out in the framework of AIDA Project assisting Municipalities in the Integrated Energy Design (IED) process by IREC and EURAC, as partners of the European project consortium. In particular, this paper shows the approach used during the evaluation of proposals in submission phase, from the analysis of the design solutions presented to achieve the energy target and the energy performance (demand and generation on site), as well also the score assignation (energy efficiency item). Moreover, the total score is the sum of different points from different criteria achieved (urban integration, architectural and functional quality, aesthetic, etc.). This means, that presently, the nZEB target is an important aspect, but not necessary, to reach to win the competition. In conclusion, this paper highlights the importance of the definition of tender and specification documents related to the Energy efficiency, from the early stages of the architectural design, to achieve a nZEB and integrated the IED processPostprint (updated version

Experimental testing of variable speed heat pump control strategies for enhancing energy flexibility in buildings

Thermal mass of buildings and domestic hot water tanks represent interesting sources ofthermal energy storage readily available in the existing building stock. To exploit them to their full potential,advanced control strategies and a coupling to the power grid with heat pump systems represent the mostpromising combination. In this paper, model predictive control (MPC) strategies are developed and tested ina semi-virtual environment laboratory setup: a real heat pump is operated from within a controlled climatechamber and coupled with loads of a virtual building, i.e., a detailed dynamic building simulation tool.Different MPC strategies are tested in this laboratory setup, with the goals to minimize either the deliveredthermal energy to the building, the operational costs of the heat pump, or the CO2emissions related to theheat pump use. The results highlight the ability of the MPC controller to perform load-shifting by chargingthe thermal energy storages at favorable times, and the satisfactory performance of the control strategies isanalyzed in terms of different indicators, such as costs, comfort, carbon footprint, and energy flexibility. Thepractical challenges encountered during the implementation with a real heat pump are also discussed andprovide additional valuable insightsPeer ReviewedPostprint (published version

CO2 concentrations and thermal comfort analysis at onsite and online educational environments

In building areas with high occupancy, such as classrooms, transmission routes of SARS-CoV-2 are increased when indoor air quality is deficient. Under this scenario, universities have adopted ventilation measures to mitigate contagious environments. However, the lack of adequate equipment or designs in old educational buildings is a barrier to reach minimum requirements. This study aims to quantify the indoor air quality and thermal comfort at universities and compare it to conditions in students’ households. In this regard, several classrooms in buildings of the Polytechnic University of Catalonia were monitored for temperature, CO2 concentration and relative humidity. The people who used these classrooms were surveyed about their comfort perceptions. A sample of students was also monitored at their homes where they reported to studying during the exam period. By means of point-in-time surveys, students reported their daily comfort, for comparison with the monitored data. The results show that the recommendations for CO2 concentration, temperature, and relative humidity are not always met in any of the study spaces. These factors are more critical at universities due to the high occupancy. In addition, the surveys highlighted the perception that the environment is better at home than at university.Peer ReviewedPostprint (published version

Rehabilitación energética de edificios públicos en base a niveles coste-óptimos y NZEB

El artículo presenta el trabajo realizado en el marco del proyecto RePublic_ZEB, el cual tiene como objetivo promover la rehabilitación de edificios públicos hacia niveles de consumo casi nulo. Se describe cómo el análisis coste-óptimo puede establecerse como metodología para definir los requisitos mínimos que se deberían alcanzar para rehabilitar un edificio público con criterios de consumo casi nulo. En este contexto, en el artículo se presenta el análisis del parque de edificios públicos de Cataluña, así como los criterios para seleccionar las categorías de referencia: oficinas y hospitales. Para el edificio de referencia de la oficina, se implementa la metodología completa, que consta de dos etapas principales: (a) definición técnica y económica de medidas de eficiencia energética; (b) análisis coste-óptimo en base a los estándares europeos de la Norma EN-UNE. Del análisis de los resultados preliminares se proponen cuáles serían los requerimientos mínimos para rehabilitar la oficina con criterios de consumo casi nulo. Por último, se evalúa la incertidumbre asociada a los costes de inversión, viendo como ésta puede tener una repercusión sobre las medidas que cumplen los requerimientos de una rehabilitación hacia niveles de consumo casi nulo.Consejo General de la Arquitectura Técnica de Españ

Energy model for thermal energy storage system management integration in data centres

In the last years the total energy demand of data centres has experienced a dramatic increase which is expected to continue. This is why data centres industry and researchers are working on implementing energy efficiency measures and integrating renewable energy to overcome energy dependence and to reduce operational costs and CO2 emissions. The cooling system of these unique infrastructures can account for 40% of the total energy consumption. To reduce the energy consumption, free cooling strategies are used more and more, but so far there has been little research about the potential of thermal energy storage (TES) solutions to match energy demand and energy availability. Hence, this work presents a dynamic energy model able to study the implementation of different energy efficiency strategies and see its effects on the operational conditions, power consumption and ecological footprint. Operational data from a real 125 kW IT data centre located in Barcelona has been used to validate the energy model