Improving summer energy performance of highly insulated buildings through the application of a thermal analysis by numerical simulation

The work presented in this paper is aimed at deepening the optimisation of the energy performance of highly insulated buildings in summer conditions through the application of an original methodology of thermal analysis. The methodology, already presented in a previous work (Ballarini et al., 2011), allows us to investigate the building energy balance and identify the most important parameters affecting the energy performance under certain conditions. The analysis is developed through the application of a dynamic simulation tool (EnergyPlus). The methodology consists of analysing the different contributions to the convective energy balance on internal air and their interrelations with different boundary conditions. Each contribution is split according to the dynamic driving forces of outdoor and indoor environment, i.e. external air temperature, solar radiation, internal air temperature and internal heat sources, and it is referred separately to the specific groups of components that exchange heat with internal air. This work focuses on the application of the above thermal analysis to a highly insulated single-family house in summer conditions, in two different Italian climatic zones. The methodology provides the mean values and the standard deviations of the contributions to the convective energy balance on internal air, and allows both to identify the main causes of low energy performance and to quantify the effects of possible retrofit or operational measures. As an exemplification, the effect of increasing the air change rate by natural ventilation during the night is investigated. The results show how the energy performance could be improved also in highly insulated buildings located in warm climate

Improving summer energy performance of highly insulated buildings through the application of a thermal analysis by numerical simulation

The work presented in this paper is aimed at deepening the optimisation of the energy performance of highly insulated buildings in summer conditions through the application of an original methodology of thermal analysis. The methodology, already presented in a previous work (Ballarini et al., 2011), allows us to investigate the building energy balance and identify the most important parameters affecting the energy performance under certain conditions. The analysis is developed through the application of a dynamic simulation tool (EnergyPlus). The methodology consists of analysing the different contributions to the convective energy balance on internal air and their interrelations with different boundary conditions. Each contribution is split according to the dynamic driving forces of outdoor and indoor environment, i.e. external air temperature, solar radiation, internal air temperature and internal heat sources, and it is referred separately to the specific groups of components that exchange heat with internal air. This work focuses on the application of the above thermal analysis to a highly insulated single-family house in summer conditions, in two different Italian climatic zones. The methodology provides the mean values and the standard deviations of the contributions to the convective energy balance on internal air, and allows both to identify the main causes of low energy performance and to quantify the effects of possible retrofit or operational measures. As an exemplification, the effect of increasing the air change rate by natural ventilation during the night is investigated. The results show how the energy performance could be improved also in highly insulated buildings located in warm climates

La riqualificazione energetica del patrimonio edilizio residenziale europeo: il progetto di ricerca EPISCOPE

L’articolo illustra metodologie e risultati di analisi energetiche condotte su alcuni parchi edilizi residenziali europei nell’ambito del progetto IEE-EPISCOPE. La finalità della ricerca è verificare se l’attuale tendenza della riqualificazione sia sufficiente per conseguire le riduzioni di emissioni fissate dall’UE. I risultati mostrano che gli obiettivi saranno difficilmente raggiungibili senza l’applicazione di interventi più efficaci e l’incremento del tasso annuo di ristrutturazione

A comparative analysis of different future weather data for building energy performance simulation

The building energy performance pattern is predicted to be shifted in the future due to climate change. To analyze this phenomenon, there is an urgent need for reliable and robust future weather datasets. Several ways for estimating future climate projection and creating weather files exist. This paper attempts to comparatively analyze three tools for generating future weather datasets based on statistical downscaling (WeatherShift, Meteonorm, and CCWorldWeatherGen) with one based on dynamical downscaling (a future-typical meteorological year, created using a high-quality reginal climate model). Four weather datasets for the city of Rome are generated and applied to the energy simulation of a mono family house and an apartment block as representative building types of Italian residential building stock. The results show that morphed weather files have a relatively similar operation in predicting the future comfort and energy performance of the buildings. In addition, discrepancy between them and the dynamical downscaled weather file is revealed. The analysis shows that this comes not only from using different approaches for creating future weather datasets but also by the building type. Therefore, for finding climate resilient solutions for buildings, care should be taken in using different methods for developing future weather datasets, and regional and localized analysis becomes vital

Improving energy modeling of large building stock through the development of archetype buildings

12th Conference of International Building Performance Simulation Associatio

On the Cost-Optimal Design: Comparison of Quasi-Steady-State and Dynamic Simplified Methods of Calculation of H/C Energy Needs

The Directive 2010/31/EU promotes the improvement of the energy performance of buildings within the European Union, by taking into account indoor climate requirements and cost-effectiveness. Thus, the cost optimisation is one of the main objectives of the EU regulatory framework concerning the energy performance of both new buildings and existing buildings subject to refurbishment actions. When assessing the cost-optimal levels of energy performance, the calculation of the energy needs is usually carried out by means of CEN standards or equivalent national calculation methods, based either on steady-state or on dynamic simplified models. However, many research studies have pointed out the limitations of the steady-state approach, especially for high performance buildings. The aim of this work is to study how the calculation method - quasi-steady or dynamic - of the energy needs for heating and cooling, impacts on the final optimal design. This is done through the application of a cost-optimal procedure to a single-family house located in Milan. The building energy needs for space heating and cooling are calculated by means of the quasi-steady-state monthly method specified by the Italian standards and the simplified hourly dynamic model of ISO 13790. The performance of the thermal systems is then assessed by means of the national standards (UNI/TS 11300), while the global cost is evaluated by means of EN 15459. Several design options with increasing levels of energy efficiency are applied to the case study. The cost-optimal solutions derived from the application of the two methods are compared, and the reasons for the deviations are discussed

Calibrating the Dynamic Energy Simulation Model for an Existing Building: Lessons Learned from a Collective Exercise †

Calibration of the existing building simulation model is key to correctly evaluating the energy savings that are achievable through retrofit. However, calibration is a non-standard phase where different approaches can possibly lead to different models. In this study, an existing residential building is simulated in parallel by four research groups with different dynamic simulation tools. Manual/automatic methodologies and basic/detailed measurement data sets are used. The calibration is followed by a validation on two evaluation periods. Monitoring data concerning the windows opening by the occupants are used to analyze the calibration outcomes. It is found that for a good calibration of a model of a well-insulated building, the absence of data regarding the users' behavior is more critical than uncertainty on the envelope properties. The automatic approach is more effective in managing the model complexity and reaching a better performing calibration, as the RMSE relative to indoor temperature reaches 0.3 degrees C compared to 0.4-0.5 degrees C. Yet, a calibrated model's performance is often poor outside the calibration period (RMSE increases up to 10.8 times), and thus, the validation is crucial to discriminate among multiple solutions and to refine them, by improving the users' behavior modeling

Application of Building Typologies for Modelling the Energy Balance of the Residential Building Stock.

Building typologies can serve as a basis for analysing the national housing sector. During the TABULA project which was introducing or further developing building typologies in thirteen EU countries, six of the European partners have carried out model calculations which aim at imaging the energy consumption and estimating the energy saving potentials of their national residential building stocks (IWU / Germany, NOA / Greece, POLITO / Italy, VITO / Belgium, STU-K / Czech Republic, SBi / Denmark). The results show that the model calculations can provide plausible projections of the energy consumption of the national residential buildings stock. The fit of model calculations and national energy statistics is satisfactory, deviations can often be explained and corrected by adapting standard boundary conditions of the applied calculation models to more realistic values. In general, the analysis shows that building typologies can be a helpful tool for modelling the energy consumption of national building stocks and for carrying out scenario analysis beyond the TABULA project. The consideration of a set of representative buildings makes it possible to have a detailed view on various packages of measures for the complete buildings stock or for its sub-categories. The effects of different insulation measures at the respective construction elements as well as different heat supply measures including renewable energies can be considered in detail. The quality of future model calculations will depend very much on the availability of statistical data. For reliable scenario analysis information is necessary about the current state of the building stock (How many buildings and heating systems have been refurbished until now?) and about the current trends (How many buildings and heating systems are being refurbished every year?). The availability and regular update of the relevant statistical data will be an important basis for the development and evaluation of national climate protection strategies in the building sector