PEOPLEUlrich Filippi Oberegger

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Ulrich Filippi Oberegger

Senior Researcher
Institute for Renewable Energy

T +39 0471 055 637

ulrich.filippi@eurac.edu

https://orcid.org/0000-0002-7284-2472

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About

Main research activities:

Passive energy systems in buildings
Energy system transition scenarios with focus on buildings
Human-building interaction

Short CV:

Ulrich Filippi Oberegger is Senior Researcher in the Energy Efficient Buildings group of Eurac Research in Bolzano, Italy. He holds a PhD in Engineering Science. In the last 15 years he has been working in the group as scientific and technical coordinator or contributor in several EU, national, and regional research and industrial projects on energy in buildings.

Scientific Publications

Journal article2026

A simulation-based framework for parametric energy renovation strategies in European buildings

Fakhari M, Filippi Oberegger U, Turrin F, Lollini R

Ulrich Filippi Oberegger, Roberto Lollini, Francesco Turrin

This study presents a simulation-based framework for evaluating energy renovation strategies across European building typologies and climate zones. A factorial parametric approach was used to simulate over 800,000 combinations of envelope assemblies, HVAC systems, and shading controls for three archetypes (single-family, multi-family, office) across five European climate zones under both current and projected (2050, RCP 8.5) weather conditions. A Rhinoceros/Grasshopper workflow generated an extensive, public simulation results framework, enabling evidence-driven renovation scenario exploration. The framework enables detailed assessment of both staged and deep renovation pathways by simulating envelopes and system upgrades in both isolated and combined configurations. Baseline models were calibrated using European building stock datasets, ensuring realistic energy performance with deviations within ± 10 % for residential cases. Results showed that retrofit solutions reduce space-heating demand higher than cooling demand. All outputs are compiled in an open-access platform that allows users to filter scenarios by building characteristics or performance targets. By integrating large-scale parametric simulation, empirical calibration, and climate change projections, this study offers a screening-level evidence base for comparing retrofit strategies across climates and building typologies. The framework provides a reproducible basis for prioritizing such strategies to support early-stage decision process through a performance-based transparent comparison among technology choices.

DOI Source

DOI: 10.1016/j.enbuild.2026.116976

Conference proceedings article2025

Web-based tool to evaluate and compare energy efficient renovation options for buildings

Fakhari M, Filippi Oberegger U, Lollini R

Ulrich Filippi Oberegger, Roberto Lollini

This paper introduces the comprehensive web-based IWG5 tool to evaluate energy consumption, renovation costs, and environmental impacts for European residential and office building renovations. Developed to support the SET-Plan Implementation Working Group 5 on Energy Efficiency in Buildings, the tool establishes benchmarks across five European climate zones by integrating dynamic building performance simulations with environmental life cycle assessment and economic life cycle cost analysis. The database underlying the tool is built from extensive parametric simulations—covering over 800,000 cases— that explore various building typologies, retrofit options, and climate scenarios. Data on the current European building stock were collected and structured into representative reference models, with separate models developed for singlefamily houses, multi-family houses, and office buildings. Key building components such as envelope properties, HVAC systems, infiltration rates, and shading controls were systematically varied to assess their impact on energy performance and renovation viability. The tool also incorporates current and projected weather data to evaluate the effects of climate change on building performance. Validation through statistical data demonstrates that the database confirms both the accuracy of the parametric approach and the representativeness of the selected archetypes. The IWG5 Tool offers a holistic evaluation framework that can guide policymakers and professionals in developing cost-effective, environmentally responsible renovation strategies, contributing to the EU’s goals of reducing greenhouse gas emissions and achieving climate neutrality.

DOI Source

DOI: 10.1088/1755-1315/1554/1/012063

Inbook2024

Clustering of Building Stock

Prina MG, Filippi Oberegger U, Antonucci D, Ma Y, Shamsi MH, Sharifi M

Daniele Antonucci, Ulrich Filippi Oberegger, Matteo Prina

In Europe, buildings account for 40% of final energy demand. Building stock models assess the impacts of technologies on energy consumption, greenhouse gases, policies, city planning, renewable energy, renovation strategies, and health effects. Two approaches, top-down and bottom-up, generate these models using real data and simulations. In the big data era, information about buildings is increasingly available, allowing real analysis of building stocks (top-down approach). In the bottom-up approach, models are estimated through simulations of building archetypes and aggregated at stock level. Unsupervised machine learning like clustering is widely used to find and group similar buildings. Centroid- and density-based algorithms are most popular but subsequent evaluation of clusters is essential. In this chapter we demonstrate two applications of clustering on different building stocks. In the first, the aim is to generate heat saving cost curves for the residential sector. These curves allow policy makers to choose renovations that save most energy per Euro invested. In the second application, clustering is applied to a building stock in Flanders to generate synthetic data allowing to simulate energy efficiency scenarios for buildings. The archetypal modeling approach used classifies buildings based on characteristics and scales the energy consumption up to the entire housing stock.

DOI Source

DOI: 10.1007/978-3-031-47909-0_5

Book2021

European Building Stock Analysis: a country by country descriptive and comparative analysis of the energy performance of buildings

Gevorgian A, Pezzutto S, Zambotti S, Croce S, Filippi Oberegger U, Lollini R, Kranzl L, Müller A

Simon Pezzutto, Ulrich Filippi Oberegger, Roberto Lollini

Project: EU H2020 BuiltHub - Dynamic EU building stock knowledge hub

ISBN: 978-88-98857-68-5

The EU aimed to decrease greenhouse gas (GHG) emissions by 20% by 2020 compared to 1990 levels. In parallel, renewable energy sources (RES) production was expected to increase by 20%, along with a 20% overall efficiency upgrade (1). By 2030, an integrated policy framework will compel EU Member States (MSs) to direct a coordinated approach and provide investors with applicable regulatory guidelines. By that year, the EU intends to decrease domestic emissions of GHG by 40% relative to 1990 levels. National policies are designed to permanently improve energy efficiency (EE) and increase the energy produced with RES to 27% (2). In order to achieve the 2050 targets, the EU must pursue further efforts. The EU MSs have declared a goal of decreasing GHG emissions in Europe by 80–95% relative to 1990 levels by 2050 (3). Primary energy demand in the EU amounted to about 1800 Mtoe/y in 2010, principally attributed to different heating and cooling (H&C) applications (almost 900 Mtoe/y, accounting also for industrial heat). The entire building sector accounts for around 720 Mtoe/y (40% of the entire EU primary energy demand). The most significant shares of energy demand within the European building stock are assigned, in decreasing order, to space heating (SH), domestic hot water (DHW), and space cooling (SC) with around 3200, 890, and 107 TWh/y, respectively (4). Recently, the EU and all of its MSs conducted a thorough investigation to classify their building stocks based on building typologies and existing floor area, without specifying energy demand values for SH, SC, and DHW according to the various construction periods. The results presented in this book correlated with the contribution towards energy efficiency and sustainable green design features into new/existing buildings. Buildings have become a top priority in recent years for building owners, designers, contractors, engineers, and facility managers. This book intends to address a deliberate and, for the first time, established data analysis of the whole European building stock—revealing a current trend of building final energy consumption and efficiency. The results concern different sectors and types of buildings. The whole picture of the European building stock analysis has established that building energy efficiency is not just the result of applying one or more isolated technologies but rather a complex process of establishing new energy-efficient materials, equipment, and operational strategies

Source

Journal article2021

Sensitivity analysis as support for reliable life cycle cost evaluation applied to eleven nearly zero-energy buildings in Europe

Pernetti R, Garzia F, Filippi Oberegger U

Ulrich Filippi Oberegger, Federico Garzia

Project: EU H2020 CRAVEzero - Cost Reduction and market Acceleration for Viable nearly zero-Energy buildings

Life cycle cost analysis represents a strategic tool for supporting the decision-making process while designing a new building or a renovation towards a nearly zero-energy target. Nevertheless, one of the main obstacles undermining the wide application of life cycle cost analysis deals with the effort in collecting the whole set of inputs and boundary conditions and the associated reliability of the results. To address the issue, this work compares the application of different sensitivity analysis methodologies on eleven nearly zero-energy buildings with different uses and in several European contexts, highlighting the strengths and weaknesses. Moreover, it introduces and assesses an approach for applying sensitivity analysis in life cycle cost evaluations to find an effective balance between the effort for calculation, data collection and the reliability of life cycle cost. A main result is the demonstration of a sensitivity analysis procedure to identify and evaluate parameters and boundary conditions with the largest impact on the life cycle cost of the analysed buildings, namely, the interest rate, construction and equipment maintenance costs, structural element costs, and electricity prices. These parameters lead to variations in LCC of up to 37%, with an average of 26% around the median. By focusing a more detailed analysis on these parameters, we could assess the potential life cycle cost range due to input uncertainties with a high degree of confidence while keeping efforts for practitioners reasonable.

DOI Source

DOI: 10.1016/j.scs.2021.103139

Journal article2021

Towards integrating occupant behaviour modelling in simulation-aided building design: Reasons, challenges and solutions

Mahecha Zambrano J, Filippi Oberegger U, Salvalai G

Ulrich Filippi Oberegger

Project: EU ITA-CH BIPV meets history - Competitive value chain for viable BIPV in building renovation

Occupant behaviour is an important source of uncertainty in building energy performance simulations. This has led to the development and integration of different modelling approaches that represent the complex, stochastic nature of human-building interaction. Yet, several barriers prevent their wide use in simulation-aided building design. The procedures and practical solutions for integrating occupant behaviour models are segmented through the literature. Accordingly, this paper examines the state-of-the-art in the application of occupant behaviour models. Based on the PRISMA methodology, the literature is critically analysed to: i) identify and map the barriers between theory and application; ii) propose a simulation framework establishing the steps for integrating occupant behaviour models into building performance simulations; iii) synthetise practical solutions and highlight remaining challenges towards a simulation framework adequately integrating occupant behaviour. The paper stresses the added value within the decision-making process at different building design stages. Furthermore, key elements for identifying the appropriated modelling approach for each occupant behaviour aspect are presented considering factors such as type of behaviour, building type, and spatial and temporal scale. Ultimately, this critical review establishes guidelines for the integration of occupant behaviour into building design practice and defines a research pathway for bridging the gap between the OB research field and the simulation-aided building design practice.

DOI Source

DOI: 10.1016/j.enbuild.2021.111498

Journal article2021

Unlocking thermal comfort in transitional spaces a field study in three Italian shopping centres

Avantaggiato M, Belleri A, Filippi Oberegger U, Pasut W

Annamaria Belleri, Ulrich Filippi Oberegger

Shopping centres are commonly laid out as small individual stores connected by transitional spaces. Setpoint temperatures used to control transitional spaces are normally the same as in traditional indoor environments despite substantial differences in use, time of permanence and users' needs. Currently, there are no comfort guidelines for transitional spaces and the literature lacks relevant studies on the topic. There is an untapped potential for energy savings and improved indoor environmental quality. The main objective of this work is to evaluate the suitability of Fanger's comfort model and adaptive comfort model for transitional spaces. We assessed users' thermal perception and potential impacting factors in three Italian shopping centres. 724 customers were interviewed on their thermal comfort, thermal sensation, thermal preference, and clothing level while experiencing the transitional space. In addition, the thermal environment at the interview locations (dry-bulb temperature, globe temperature, relative humidity, and air speed at different levels) and the outdoor temperature were monitored. The study demonstrated that Fanger's model and the adaptive comfort model are not suitable for transitional spaces. Customers were inclined to adapt to a much wider range of indoor environmental conditions. An operative temperature of up to 27.5 °C was still deemed comfortable by more than 80% of the customers. These results unlock a large potential for energy savings and pave the way for passive solutions such as natural ventilation.

DOI Source

DOI: 10.1016/j.buildenv.2020.107428

Journal article2020

Bottom-up building stock retrofit based on levelized cost of saved energy

Filippi Oberegger U, Pernetti R, Lollini R

Ulrich Filippi Oberegger, Roberto Lollini

Project: EU FESR BuildDOP - Evaluation tool to ensure best building performance from design to operation

Policy makers need scientific support to set ambitious yet realistic environmental targets for the transition to energy efficient buildings and to develop cost-effective policies to meet these targets, but comprehensive, manageable procedures to this aim are still lacking. Our proposed method ranges from baseline creation to transition scenarios depending on annual retrofit budget and specifies the buildings to renovate according to location, size, and age, and the energy efficiency measures to apply based on cost and energy saving. We show how to extrapolate a baseline from few available data, determine retrofit costs, and create calibrated models to estimate energy savings. Retrofits are ranked by levelized cost of saved energy, which ensures that for any budget allocated to retrofit maximum energy savings are obtained at minimum cost to society. The results are summarized in an energy efficiency cost curve enabling policy makers to estimate potential costs and energy savings. We demonstrate the method on a housing stock in northern Italy and show that facade insulation of old buildings in colder climates can compete with gas heating. About 60% baseline energy consumption can be saved doubling current investments, while a maximum saving of 75% requires over three times the current investments.

DOI

DOI: 10.1016/j.enbuild.2020.109757

Journal article2018

Multi-objective optimization algorithm coupled to EnergyPLAN software: The EPLANopt model

Prina MG, Cozzini M, Garegnani G, Manzolini G, Moser D, Filippi Oberegger U, Pernetti R, Vaccaro R,

Ulrich Filippi Oberegger, Matteo Prina, Wolfram Sparber, Marco Cozzini

Project: Regional Energy Modelling

The planning of energy systems with high penetration of renewables is becoming more and more important due to environmental and security issues. On the other hand, high shares of renewables require proper grid integration strategies. In order to overcome these obstacles, the diversification of renewable energy technologies, programmable or not, coupled with different types of storage, daily and seasonal, is recommended. The optimization of the different energy sources is a multi-objective optimization problem because it concerns economical, technical and environmental aspects. The aim of this study is to present the model EPLANopt, developed by Eurac Research, which couples the deterministic simulation model EnergyPLAN developed by Aalborg University with a Multi-Objective Evolutionary Algorithm built on the Python library DEAP. The test case is the energy system of South Tyrol, for which results obtained through this methodology are presented. Particular attention is devoted to the analysis of energy efficiency in buildings. A curve representing the marginal costs of the different energy efficiency strategies versus the annual energy saving is applied to the model through an external Python script. This curve describes the energy efficiency costs for different types of buildings depending on construction period and location.

DOI

DOI: 10.1016/j.energy.2018.02.050

Journal article2017

Building performance evaluation through a novel feature selection algorithm for automated arx model identification procedures

Antonucci D, Filippi Oberegger U, Pasut W, Gasparella A

Daniele Antonucci, Ulrich Filippi Oberegger

ARX models are an effective instrument to evaluate continuous building performance from insufficient monitoring data. However, selecting the right model features is NP-hard. The problem of finding a minimal subset of informative inputs has been studied extensively in various fields but automatic, fast, and reliable procedures for finding optimal models for building performance evaluation are still missing. We propose a novel feature selection algorithm named Greedy Correlation Screening (GCS), which identifies a possible solution at a time by greedily maximizing the correlation between inputs and output and minimizing cross-correlations between inputs. These two objectives are competing, thus leading to best tradeoffs. Among these, the best model is automatically selected by applying filters and quality criteria such as the adjusted coefficient of correlation and non-correlation of residuals.

The performance of the proposed heuristic method is compared to two of the best algorithms used in the field, such as GRASP for feature selection and NSGA-II (Non-dominated Sorting Genetic Algorithm). The application on a real case study demonstrates that the proposed method solves the problem of feature selection in building performance estimation efficiently and reliably. Moreover, the model creation is automatic, making it ideal for integration into a Building Management System (BMS) in order to detect faults and perform short-term predictive control.

DOI Source

DOI: 10.1016/j.enbuild.2017.06.009

Journal article2017

Energy retrofit and conservation of a historic building using multi-objective optimization

Roberti F, Filippi Oberegger U, Lucchi E, Troi A

Alexandra Troi, Ulrich Filippi Oberegger

When deciding on the best historic building retrofit, energy savings and thermal comfort can be quantitatively evaluated using an energy model, whereas conservation compatibility is intrinsically qualitative and reflects the perspective of the local heritage authority. We present a methodology that permits finding and comparing optimal retrofits for historic buildings in a multi-perspective and quantitative way. We use an analytic hierarchy process to quantify conservation compatibility by distilling a conservation score from the opinions of 10 experts in the field. This score, along with energy needs for heating and cooling and thermal comfort, are the three targets of a multi-objective optimization aimed at identifying optimal retrofits for a medieval building in the north of Italy, destined to become a museum. Retrofit measures considered were different kinds of external and internal envelope insulation, improvement of airtightness, replacement of windows, and ventilative cooling. The result is a portfolio of optimal retrofits that cover the whole range of conservation compatibility. We show that in the analyzed case heritage preservation is compatible with a four-fold reduction in energy needs at a high thermal comfort level. Even higher energy savings are only achievable at the cost of heritage degradation.

DOI Source

DOI: 10.1016/j.enbuild.2016.12.028

Book2021

European Building Stock Analysis: a country by country descriptive and comparative analysis of the energy performance of buildings

Gevorgian A, Pezzutto S, Zambotti S, Croce S, Filippi Oberegger U, Lollini R, Kranzl L, Müller A

Simon Pezzutto, Ulrich Filippi Oberegger, Roberto Lollini

Project: EU H2020 BuiltHub - Dynamic EU building stock knowledge hub

ISBN: 978-88-98857-68-5

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Ulrich Filippi Oberegger

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Scientific Publications

A simulation-based framework for parametric energy renovation strategies in European buildings

Web-based tool to evaluate and compare energy efficient renovation options for buildings

Clustering of Building Stock

European Building Stock Analysis: a country by country descriptive and comparative analysis of the energy performance of buildings

Sensitivity analysis as support for reliable life cycle cost evaluation applied to eleven nearly zero-energy buildings in Europe

Towards integrating occupant behaviour modelling in simulation-aided building design: Reasons, challenges and solutions

Unlocking thermal comfort in transitional spaces a field study in three Italian shopping centres

Bottom-up building stock retrofit based on levelized cost of saved energy

Multi-objective optimization algorithm coupled to EnergyPLAN software: The EPLANopt model

Building performance evaluation through a novel feature selection algorithm for automated arx model identification procedures

Energy retrofit and conservation of a historic building using multi-objective optimization

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Scientific Publications

A simulation-based framework for parametric energy renovation strategies in European buildings

Web-based tool to evaluate and compare energy efficient renovation options for buildings

Clustering of Building Stock

European Building Stock Analysis: a country by country descriptive and comparative analysis of the energy performance of buildings

Sensitivity analysis as support for reliable life cycle cost evaluation applied to eleven nearly zero-energy buildings in Europe

Towards integrating occupant behaviour modelling in simulation-aided building design: Reasons, challenges and solutions

Unlocking thermal comfort in transitional spaces a field study in three Italian shopping centres

Bottom-up building stock retrofit based on levelized cost of saved energy

Multi-objective optimization algorithm coupled to EnergyPLAN software: The EPLANopt model

Building performance evaluation through a novel feature selection algorithm for automated arx model identification procedures

Energy retrofit and conservation of a historic building using multi-objective optimization

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