Retrofit Actions Research Articles

Retrofits of multi-storey office building facade

The city of Jakarta is the 7th big city in the world that has the most high-rise buildings. High-rise buildings in Jakarta were built from 1971 until now and in the 90s it was the peak of the construction of high-rise buildings such as offices and apartment. Tall Buildings with glass facade, concentrating plans are the most typology of office high-rise buildings in Jakarta. Buildings with the dominance of glass facade that reflect heat cause an increase in temperature in the microclimate and a decrease in building performance resulting in the amount of energy used by buildings, especially air conditioners. Building facade play an important role in reducing the improvement of the microclimate and energy use in buildings. Therefore, an analysis was carried out on the BRI II building on Jalan Sudirman Jakarta as a case study that represents the typology of the most office buildings in Jakarta. It turns out that this building has a high OTTV (Overall Thermal Transfer Value) value, so the largest AC cooling load comes from the building casing. Therefore, facade retrofit is one of the alternatives that can be done to reduce energy use, especially air conditioning. After that, a simulation of the casing retrofit to obtain a significant retrofit action can reduce the AC energy used through ottv value reduction analysis.

Energy performance analysis of alternative building retrofit interventions for the four climatic zones of Greece

Climatic conditions determine which retrofit strategy can result in a satisfactory improvement of a building's thermal performance. This study systematically investigates alternative retrofit actions, as standalone and in combination, and assesses their energy performance. The retrofit actions include i) insulation on the external walls, ii) the incorporation of phase change material (PCM) on the roof and the increase of the building thermal inertia, iii) a mechanical ventilation system with a summer period operation, and iv) a cool roof coating. The energy analysis concerns a typical two-story family building and the four climatic categories of Greece and is conducted with the INTEMA.building tool, a dynamic energy analysis software developed in Modelica language. The importance of the present study is that it serves as a guideline for the selection of the energetically optimum single retrofit or multiple-retrofit strategy regarding a building's location climatic data, and provides calculations concerning the annual heating and cooling loads, and the corresponding heat pump electricity consumption. The retrofit actions of external wall insulation and PCM roof addition are characterized as more effective in reducing a building's heating energy loads, while the mechanical ventilation system and cool roof coating are more effective in reducing a building's cooling loads. The quadruple retrofit strategy results in the maximum electricity savings for Heraklion (28.01%), Athens (21.15%), and Thessaloniki (16.54%), while the triple retrofit strategy which does not include the cool roof coating, results in the maximum electricity savings for Kastoria (10.79%). Lastly, an economic analysis of the energetically optimum renovation strategies is conducted.

Identification of residential building typologies by applying clustering techniques to cadastral data

Building typologies are usually classified according to their shape, distribution and construction features depending on the time period they were built. As a result, a subjective classification arises which highly depends on the criteria used to differentiate buildings. When this analysis is carried out at the urban scale, data sets become bigger, making patterns difficult to uncover. Mistakes in deciding the variables to classify buildings lead to incorrect typologies and, consequently, wrong results. The aim of this study is to test a new methodology based on clustering techniques to identify typologies related to energy retrofitting, which would allow obtaining a more objective classification and better pattern recognition by reducing human intervention. To that end, a data set from the Spanish cadastre is used, with additional information to reflect the influence of existing standards on constructive solutions. By applying three clustering techniques (Ward's method, Partitioning Around Medoids, and a combination of both), new proposals of building typologies are obtained and discussed in comparison to traditional classifications. The results show that the Ward's method produces building typologies with significantly high quality metrics and meaningfulness. The agglomeration coefficient is 99.8%, which indicates that hardly another hierarchical method could generate a better clusters structure. Six clusters comprise 86% of the dwellings as most occupants do not declare retrofitting works, thus not being reflected in the cadastre database. This research provides a new classification method that can notably influence the estimation of costs, environmental impact and cost effectiveness of energy retrofitting actions at urban scale.

Comparative cost analysis of traditional and industrialised deep retrofit scenarios for a residential building

In this paper, the economic competitiveness for deep retrofit actions between the industrialised off-site and the traditional on-site approaches are discussed by using a comparative Life Cycle Costing (LCC) analysis. This assessment was based on a deep analysis of all renovation-related cost and timing processes, from design to operation and maintenance phases. The study was based on three retrofit scenarios for an existing building in Italy undergoing a deep renovation. The Life Cycle Inventory (LCI) was developed starting from real costs and a list of bills collected by the design team and the industrialised technologies developers. Afterwards, the LCC modelling was performed for all scenarios. The results show that the two deep retrofit approaches (traditional and industrialised) are comparable in terms of investment costs, even if a gap of around -7% and +16% still exists. This highlights a potential for technological optimisation. Moreover, the operation and maintenance phase has shown to be key to transforming the expected higher quality of the industrialised components into a prolonged life expectance, hence highly impacting the whole cumulated Net Present Value. Finally, the analysis of the End of Life (EoL) phase in case of possible reusing of some dismantled components in the industrialised scenario resulted in contributing in a relevant way to increase the final value of such an approach.

Neural network-based energy signatures for non-intrusive energy audit of buildings: Methodological approach and a real-world application

Energy Signatures (ES) are highly informative gray-box regression models. Thanks to their simplicity and interpretability, to their data-driven approach, and to their effectiveness in describing a building response to external weather variables, they are employed for (i) the determination of the Balance Point (BP) temperature of a building, (ii) the ranking of the efficiency of heating or cooling systems, (iii) the provision of building diagnostic information, and (iv) the development of strategies for more energy-efficient buildings and the estimation of potential savings. In this work, we propose an innovative energy audit tool, based on a Feed-Forward Neural Network (NN) to determine ES from aggregated (meter-level) electric load profiles of buildings. Multiple NN-based regression models are defined for each building and compared to provide the most accurate and informative one, by considering proper fit and significance indexes. This allows the eventual existence of multiple cooling regimes to be detected. Moreover, the energy audit methodology defines and applies an innovative Key Performance Indicator (KPI), called Temperature Unstandardized Beta Weight (βTemp∗), to account not only for the thermal behavior of buildings but also for the efficiency of the conditioning system and the internal heat generation. This ES approach has been applied to a dataset of electric consumption patterns from about eighty industrial buildings from a telecommunication (TLC) service provider in Italy. The useful outputs from the proposed methodology, together with its simplicity, effectiveness and applicability, are intended to support the diffused understanding of the thermal behavior of buildings and the analysis of their inefficiencies, in order to enhance energy retrofit actions and reduce consumption.

A study on how efficient measures for secondary district heating system performance can be encouraged by motivational tariffs

BackgroundDistrict Heating (DH) is a technology that provides heating and domestic hot water to buildings and is an important technology for supporting the European energy transition. As such the heating systems increasingly resort to renewable heat sources and waste heat, it is even more important that they operate in the most efficient way possible. DH companies have access to the primary network of which they can impact system performance. To maximize the efficiency of the system, however, it is important that the system at the building level, known as the secondary system, is also efficient; otherwise, overall system efficiency is reduced. To increase system efficiency, return temperatures from the secondary system into the primary system have been targeted through motivational tariffs. There is limited information on how to establish a motivational tariff that motivates the customer to improve both the primary and secondary systems, which is a gap that this paper aims to fill.ResultsIn this paper, the impacts of retrofit actions in secondary systems are assessed through simulations. The identified relevant refurbishment measures to lower the return temperature to the primary system are variable flow pumps, low-temperature radiators, parallel heat exchangers, and a pass-through DHW system. Apart from simulated refurbishments, we also identify that the secondary system sometimes generates excess heat, which is valuable to recover, especially during peak load periods for the primary system. Hence, motivational tariffs targeting secondary system efficiency should also encompass an incentive for the customer to make use of waste heat in the secondary circuit to lower peak demand for the DH system.ConclusionsTo date, the most commonly used parameters introduced to customers are linked to the flow of water through the customer’s asset and the bonus malus principle. The results from simulations show that DH companies can introduce additional parameters to support customers in guiding their secondary system to perform more efficiently. Increased overall system efficiency has a positive impact on both costs and emissions.

Enhancing hurricane risk perception and mitigation behavior through customized virtual reality

Hurricanes are one of the most destructive natural disasters, and proper preparation and mitigation are essential to enhance resilience. However, homeowners may have inaccurate risk perceptions, resulting in inadequate mitigation decision-making. Virtual reality (VR) damage visualization has the potential to communicate hurricane risk effectively and improve disaster resilience. Previous studies utilizing VR for hurricanes have primarily focused on disaster response such as evacuation, and often presented generalized visualization consistent across all users. This study presents a methodology for offering individual users a customized tool to experience the impacts of hypothetical hurricane events on their residential structures and explore the effects of various building retrofit actions in customized 3D virtual environments. The methodology was tested with 25 participants. Participants experienced structural damage and utility disruptions caused by hurricanes in their own residential homes in a customized, immersive virtual environment. Participants’ pre- and post-VR risk perceptions, as well as their choices of mitigation actions were surveyed. The results indicate that customized VR was effective in enhancing risk awareness and that participants were able to reduce their structural damages in hypothetical hurricane events by adopting various mitigation measures after the customized VR experience. The outcomes suggest that customized visualization of potential damages in virtual environments can effectively help disaster preparation and mitigation.

Multi-criteria robust optimization for bridge adaptation strategies targeting superstructure unseating under coastal natural hazards

The life-cycle management of low-lying coastal bridges exposed to coastal natural hazards (e.g., Hurricane Ivan, Katrina, and the recent Ian) has become an ongoing concern due to the detrimental impacts of these extreme events. The uncertain occurrence of multiple climate drivers and their accompanying influence on the frequency and intensity of coastal hazards further complicates the determination of bridge adaptations. Reliable modeling of the failure probability and consideration for the deep uncertainties associated with climate change are essential to determining retrofit action and implementation time. This study proposes a multi-criteria optimization framework for robust adaptation strategies of coastal bridges. The proposed framework can devise bespoke adaptation strategies towards the dominant superstructure unseating failure, which is enabled by: (a) pragmatic bridge vulnerability analysis rooted in the coupled fluid–structure dynamic numerical analysis; (b) multi-criteria optimization assessing the efficiency and priority of different adaptations; and (c) strategy robustness against the unknown occurrence of imminent climate futures. The exogenous uncertainties associated with future economics and climate scenarios are addressed via sensitivity analysis. To the best knowledge of the authors, this is the first time that robust adaptation strategies are developed for coastal bridges targeting hurricane-induced superstructure damages. These results not only measure the feasibility of various adaptation actions from both economic and engineering aspects but also provide a reference basis for decision-makers.

Development of an optimization model for decision-making in building retrofit projects using RETROSIM

ABSTRACT Nearly-zero energy buildings are standard for new constructions in the European Union. The challenge for decarbonized cities is retrofitting the existing buildings. Retrofitting the existing buildings provides considerable opportunities for improving occupants’ comfort and reducing global energy consumption and greenhouse gas emissions. Building retrofit is being considered one of the main approaches to achieve sustainability in the built environment at relatively low-cost and high-uptake rates. Although a broad range of retrofit technologies are readily available, methods to ascertain the most suitable set of retrofit actions for specific projects are still a practical challenge. This article first aims to develop and present a simulation-based multi-objective optimization model, named RETROSIM, to quantitatively assess technology choices in a building retrofit project. RETROSIM is a combination of a building energy simulation model and RETROSIM proprietary optimization engine. Secondly, in this study, RETROSIM is used to evaluate a building retrofit project as a case study to show the functionality of the proposed method. The study initiates with the single optimization of objective functions focusing on the building’s characteristics and performance: primary energy consumption, global costs and thermal discomfort hours. Then this methodology is used to study the interaction between these conflicting objectives and evaluate their trade-offs.

Empirical predictive model for seismic damage and economic losses of Italian school building heritage

Schools should be safe places where children and young people are hosted during their training years to develop their abilities and skills and to receive an education that makes them prepared to become the future of the nations where they live. Even though these aspects are of paramount importance and widespread recognized, the same importance does not seem to be equally ensured to school facilities. Educational institutes, indeed, are often old and realized without recent safety Standards, becoming consequently non-resilient, nor robust structures towards multiple natural hazards. This aspect concerns lots of countries worldwide, without making distinction among their richness level.In this paper empirical models for the prediction of damage and retrofit costs expected after earthquakes are presented. These probabilistic models relate seismic intensity to expected damage and economic losses, through the definition of continuous indexes, and are based on data collected after a recent earthquake occurred in Central Italy. Empirical data, required to define the probabilistic models, have been obtained by combining information coming from shaking maps, provided by the National Institute for Geophysics and Volcanology (INGV), information on the building properties (e.g. locations, dimensions, construction typology), provided by the Ministry of Education, and data about the damage suffered by constructions and funding for retrofit actions including damage repairing and seismic upgrading, provided by the Reconstruction Office. Proposed models provide the opportunity to directly derive fragility curves, to make it possible the use of the research outcomes in risk frameworks based on a discrete description of the damages and losses.Model parameters have been calibrated for the considered set of available data, but the methodology is general and can be also applied to different contexts, given data are available. Finally, the proposed models have been used to simulate the post-earthquake damage and losses scenario following a seismic event. A proposal for the analyses of probabilistic outputs have been developed to provide information useful to decision making purpose.

Overheating vulnerability assessment of energy retrofit actions in a multi-apartment building in Podgorica, Montenegro

The study aimed to assess the overheating vulnerability of an existing multi-apartment building built in 1971 in Podgorica, Montenegro. The building consists of 80 apartments and is mostly still in its original state. Firstly, the building was modelled in EneryPlus, and a parametric study was performed with jEPlus. The energy need for heating and cooling was simulated using parameters such as thermal insulation level, window properties, external surface solar absorptivity, shading activation set-point, and natural ventilation cooling intensity. Moreover, the energy need was determined for four different climate periods, namely for the current and three future periods up to the end of the 21st century under the RCP8.5 climate change scenario. The total number of building models equalled 648 for each of the four climate scenarios, resulting in 2,592 simulated cases. After that, the overheating vulnerability score was determined using the minimax regret method and cooling energy need as a performance indicator. The best retrofit action was determined by identifying the most favourable combination of the overheating vulnerability and total energy need. The results deliver the appropriate energy retrofit actions to limit the increase in overheating risk and provide for climate change adaptation of the multi-apartment building stock in Montenegro.

Experimental tests for seismic assessment of ventilated façades

Ventilated facades are currently one of the most used technologies for external envelope of buildings. This kind of external cladding offers many advantages in terms of energy saving, sound insulation, protection of the structures, and has also a considerable architectural value. However, these nonstructural components must have suitable features to ensure their integrity in case of earthquakes. Their damage during a seismic event can have relevant consequences, on the safety of human life, on the operability of strategic buildings and can also have a significant economic impact related to post-earthquake retrofit actions. The aforementioned reasons paved the way to several studies referring to the evaluation of seismic behavior of such components, especially by means of experimental tests, even if up to now no standard procedures for seismic assessment of ventilated facades are available in Europe. This paper focuses on an experimental campaign carried out on a ventilated façade sample, 2.4 m wide and 4 m high. An innovative seismic test facility, located at the Construction Technologies Institute (ITC) of the National Research Council of Italy (CNR) in San Giuliano Milanese (Milan), is used to perform both quasi-static and dynamic tests on the sample.Results of the tests performed by using existing experimental procedures for in-plane crescendo tests, i.e. AAMA 501.4 (2009), are compared with those obtained by applying a new loading protocol proposed by the Authors. The innovative aspect of the latter consists in the introduction of test frequencies closer to those of the buildings usually hosting this kind of façades and then obtaining a more realistic behaviour of the tested specimen. The obtained results will be the basis for the definition of harmonized assessment methods for the seismic evaluation of ventilated façades to be possibly introduced in harmonized European technical specifications.

A multi-aspect approach to energy retrofitting under global warming: A case of a multi-apartment building in Montenegro

Global warming will seriously affect buildings, and the Montenegrin building stock is no exception. Since the country is one of the most inefficient energy users in Europe, improving the energy efficiency of buildings is essential. Therefore, the study implemented a novel multi-aspect approach to energy retrofitting, linking building thermal performance, occupant interaction and climate change. A representative existing multi-apartment building in Podgorica was selected, and a survey among occupants was conducted to identify their satisfaction with indoor thermal comfort and to evaluate the acceptability of the proposed energy retrofit measures. Next, the thermal performance of the building was simulated under current and future climate conditions. Finally, a comprehensive parametric analysis was performed by applying different retrofit scenarios. The selected retrofit measures were evaluated based on their impact on energy efficiency and occupant acceptability. The results showed that the most impactful retrofit measure would be thermally insulating the building envelope, followed by a lower shading set-point and natural ventilation cooling. Applying the best retrofit combinations would reduce the total energy demand by 75% under the current climate and by 66% and 59% at the end of the 21st century under the RCP4.5 or RCP8.5 scenarios, respectively. However, the occupant survey results disclosed that beyond thermally insulating the building, occupants have limited awareness about the potential of energy retrofit actions, while summer thermal discomfort is the dominant issue. Therefore, building energy retrofit and climate adaptability actions should also address occupant views.

Cost estimation models for seismic retrofit of masonry school buildings

Seismic retrofits can significantly reduce the vulnerability of masonry buildings. Multiple seismic retrofit alternatives are often available for a given building. Estimating the cost of each candidate action is essential to selecting and implementing the appropriate seismic retrofit initiatives. This research harnesses the capabilities of various regression models for cost estimation. A dataset from 167 retrofit projects for masonry school buildings was used to develop models. Three main retrofit actions were taken into consideration: shotcrete, steel belt and fiber-reinforced polymer. Various regression methods, including multiple linear regression, ridge regression, lasso regression, and elastic net regression, were applied to develop models that estimate the cost of each of the three retrofit actions based on a set of explanatory variables. Next, the models underwent a reduction process to simplify and increase their prediction precision. In most models, the reduction process eliminated multiple terms and enhanced the model prediction performance. This article identifies the height of the building as the most influential parameter governing retrofit costs. It examines the effect of proxy variables (e.g. lateral area of walls and added lateral strength) on the final retrofit cost by adding them as explanatory variables.

Optimizing the Passive House Planning Package simulation tool: A bottom-up dynamic approach to reduce building performance gap

The Passive House Planning Package (PHPP) simulation tool is the only authorized software in Australia for the Passivhaus (PH) certification. Despite its key role in this certification scheme, previous studies have reported significant gaps between the simulated and actual performance. To address this limitation, this study introduces a bottom-up approach to building performance simulation based on a dynamic method combined with advanced appliance profiles. This study uses two-year monitored data in a PH-certified student accommodation building in Australia and validates the proposed bottom-up approach in both annual and monthly granularity. The results show that the level of reliability and robustness of the PHPP tool is substantially improved for three PH criteria (i.e., overheating frequency, space heating energy demand, and primary energy renewable) and three operational variables (i.e., indoor temperature, plug load, and lighting power density), all within the ranges of error allowed by ASHRAE’s Guideline 14–2014. Based on the proposed approach, a set of stepwise retrofit actions was put in place to further improve the energy efficiency and occupant thermal comfort in the case study building.

Urban regeneration through retrofitting social housing: the AURA 3.1 prototype

As a large proportion of housing stock does not meet the current demands for energy and comfort (leading to high levels of obsolescence and vulnerability), the annual rate of energy upgrades for the existing stock must be increased. The AURA Strategy is an intervention methodology which focuses on the regeneration of neighbourhoods or obsolete urban fabrics which suffer from high levels of architectural, urban and socio-economic vulnerability. Within this context, the AURA 3.1 prototype was developed for the Solar Decathlon Europe 2019 Competition. The project was based around a sustainable construction strategy for the urban regeneration of obsolete residential neighbourhoods, through the reuse of existing buildings considering Mediterranean climate and energy. The Poligono San Pablo neighbourhood was chosen as the case study. This article presents the main retrofit action: the juxtaposition on the existing building of a structural-architectural system which provides new technological and spatial features. Quantitative data regarding the validity and effectiveness of the AURA Strategy could be collected from the monitoring of the Pavilion prototype during the competition. Two first prizes were won in contests with on-site measurements: Comfort conditions and House Functioning. Third place was also obtained in the Sustainability contest, thus confirming the enormous possibilities the AURA Strategy has for sustainable urban regeneration in retrofitting social housing, within the limitations of the competition.

Motivators and impediments to seismic retrofit implementation for wood-frame soft-story buildings: A case study in California.

Motivating property owners to mitigate seismic risks for existing buildings is a major challenge for many earthquake-prone regions. This article identifies primary factors that may affect the adoption of seismic retrofit by owners of commercial and residential buildings, assesses the influence of economic, social, regulatory, and individual factors on retrofit implementation in three California cities, and discusses potential approaches to promoting seismic retrofits. Data for three retrofit programs are utilized to create predictive models for retrofit probability. The results suggest that retrofit probability for multifamily residential buildings may increase with building height, median housing value, educational attainment, and population density in the neighborhood, but may decrease with building age, building size, land value, and housing vacancy rate in the neighborhood. The retrofit decision for commercial buildings is strongly correlated with the number of stories and rooms, land value, vacancy rate, and population density, while the retrofit decision for residential buildings is highly associated with building age, number of rooms, land value, median housing value, median contract rent, and educational attainment. Overall, promoting seismic retrofits requires careful consideration of different motivators and impediments to owner's retrofit actions for commercial and residential buildings, and for older, taller, larger buildings, which tend to be more vulnerable but are associated with higher retrofit costs. In addition, neighborhood characteristics including median housing value and vacancy rate may be strong indicators of the retrofit probability among building clusters.

Passive Strategies for Building Retrofitting: Performances Analysis and Incentive Policies for the Iranian Scenario

A large amount of the Iranian energy demand is related to the building sector, mainly due to its obsolescence. In this paper, a second-skin system has been implemented as a retrofit action for an office building, evaluating the effect of a tensile material as second-skin in terms of primary energy saving, carbon dioxide equivalent emissions, and simple payback period. The analysis was carried out through numerical simulations across a whole year and for four Iranian cities (Tabriz, Teheran, Yazd, and Bandar Abbas) in four different climates (cold, temperate, hot-dry, and hot-wet), and with the building aligned at either north-south or east-west. Moreover, an economic analysis was carried out suggesting different incentive policies to promote building energy refurbishment. The simulation results highlighted a favorable orientation for buildings in Iran, suggesting a guideline for new constructions. Indeed, the best results were achieved for an east-west orientation of the building (up to a primary energy saving of 13.6% and reduction of carbon dioxide equivalent emissions of 45.5 MgCO2,eq, in Yazd), with a decrease of the annual specific total (cooling and thermal) energy demand of 37.9 kWh/m2/year. The simple payback period values were also lower in the east-west orientation than the north-south one.

A New Tool for Building Energy Optimization: First Round of Successful Dynamic Model Simulations

Several tools and pieces of software support building energy modelling for optimization, certification and comparisons of different scenarios and usages. Nevertheless, the consistent rise in accessible computational power and the expansion of ICT are pushing the development of new software functionalities and tools able to support cross-disciplinary work on smart building optimization. This paper introduces a new platform (under development) that combines the EnergyPlus dynamic simulation tool with extra-functionalities and pre-defined usage scenarios based on automatic actions to manage massive simulations and correlation analyses. The tool’s utility was tested in three experiments, with goals that we consider to be fundamental requirements: comparing simple retrofit actions to reduce net energy needs; analyzing the free-running potential of a demo building and the impacts of different low-energy technologies in terms of increasing thermal comfort (shading and ventilative cooling); and comparing measured sensor data indicators with simulated ones under real weather conditions for model verification. The results demonstrate the ability of the tool to automatically generate hundreds of EnergyPlus input building models by acting on building geometry; we focused on the most common uses for parametric dynamic simulations. Additionally, the way in which the tool combines the automatic modification of the building’s design and the parallel launching of multiple simulations allows the labor to be reduced. The user can execute complex tasks without spending any time working with model editing software and aggregating the results from multiple simulations.

The dynamic thermal energy simulation of historic buildings in Mediterranean climate: knowledge and simplification

The European built heritage is strongly characterized by “historic buildings”. This built heritage represents an important cultural resource, constitutes a public good and testifies the community identity. The current challenge to reduce the consumption of energy resources is aimed at the requalification of this built heritage. To meet this challenge, energy analysis is increasingly being used also for historic buildings through complex building energy simulation program. Although their application to modern buildings leads to significant results, in the modelling of historic buildings there are numerous approximations and uncertainties relating to materials, thermal bridge, geometry and construction techniques which can lead to inaccurate results. Furthermore, the lack of input data and the complex geometries make even more difficult to determine the correct energy performance of the simulated built heritage. To the aim of investigates the validity, accuracy and reliability of Open BIM software, widely used by Architects and Engineers, based on the simple hourly method (EN ISO 52016-1), an energy analysis of historic building was performed. The work is intended to provide a calculation method to evaluate energy performance (heating, cooling, lighting, etc) of historic buildings (load bearing masonry structure with vaults) with the use of simple dynamic models, which comply with Italian energy laws and regulations, and to predict the energy saving potentials related to building retrofit actions.