Climatic potential for natural ventilation

Naturally ventilated buildings have been widely adopted, because they may increase user satisfaction and well-being while reducing energy consumption due to HVAC systems. Analysis and simulation tools are required at different design stages to support the usage of natural ventilation. Three main levels of analysis/design are identified: climatic analysis, building/system design, and comfort assessment. Focusing on the first level of analysis, this paper proposes a methodology to evaluate the climatic potential for natural ventilation. The methodology does not address a particular ventilation strategy or system. It includes adaptive comfort models and introduces an approach that integrates humidity constraints. The methodology can be applied at the conceptual building design stage to orient designers by providing them with a benchmark for the proceeding design phases or as a tool to contrast different climates. Calculation examples are reported

The effect of weather datasets on building energy simulation outputs

Results of dynamic energy simulations of buildings are affected by many uncertainties, which are the main reason of the performance gap registered between simulated and operational performance. They depend mostly on the incorrect modelling of building components and their properties, the inadequate characterization of operational schedules, the limitations in the simulation algorithms used by energy simulation software, the quality and reliability of data contained in weather files. The first three limiting factors are somehow under the control and capacity of the person in charge of the simulation, that, nevertheless, may not always be able to get detailed building specifications to identify the correct set-points and schedules, or to choose an alternative simulation software. The information contained in weather datasets are, however, completely out of the control of the person in charge of the simulation that may only assume them as a boundary condition. Unfortunately, not all the weather databases show the same level of data accuracy; moreover, they may refer to a climate that substantially changed in the last decades. The effects on building energy simulation results, played by different weather files referred to the city of Milan, is showed and discussed, highlighting the substantial performance difference depending on them

Estimation models of heating energy consumption in schools for local authorities planning

Large building stocks should be well managed, in terms of ordinary activities and formulating strategic plans, to achieve energy savings through increased efficiency, It is becoming extremely important to have the capability to quickly and reliably estimate buildings' energy consumption, especially for public authorities and institutions that own and manage large building stocks. This paper analyses the heating energy consumption of eighty school buildings located in the north of Italy. Two estimation models are developed and compared to assess energy consumption: a Multiple Linear Regression (MLR) model and a Classification and Regression Tree (CART). The CART includes interpretable decision rules that enable non-expert users to quickly extract useful information to benefit their decision making. The output of MLR model is an equation that accounts for all of the major variables affecting heating energy consumption. Both models were compared in terms of Mean Absolute Error (MAE), Root Mean Square error (RMSE), and Mean Absolute Percentage error (MAPE). The analysis determined that the heating energy consumption of the considered school buildings was mostly influenced by the gross heated volume, heat transfer surfaces, boiler size, and thermal transmittance of windows

Modélisation et simulation d'une cellule test en plein air pour l'évaluation énergétique des composants d’enveloppe

The article presents the thermal modelling and simulation work that will constitute the basis for the design of an outdoor test cell. The facility aims at characterizing the thermo-physical properties of transparent and opaque envelope components under real weather conditions, and to study the impact of different air-conditioning configurations on the indoor thermal comfort and indoor air quality. The response delay of the calorimetric measure is particularly critical when trying to achieve a good quality of measurement in rapidly-varying weather conditions. For this reason, the thermal behaviour of the test cell has been described, by means of a lumped parameter model, to simulate a range of operating conditions. The results are used to evaluate the thermal inertia of different solutions, refine the design choices and the most promising control strategies. The article presents the thermal models used to compare the test cell to a traditional installation in terms of calorimetric accuracy under transient external conditions

A Zero Energy Concept Building for the Mediterranean Climate

open4siThe Mediterranean climate distinguishes for a mild heating season and a hot (and usually dry) cooling season. All along the year solar radiation is plentiful and the daily range of temperature during the summer is large, due to dry and clear conditions. This environment allowed to design and build a zero energy concept building (a detached single family house) on the basis of passive heating and cooling technologies, supported, when required, by short time active conditioning. The design process was optimized by extensive energy simulations, resulting in an optimal energy balance and favorable thermal comfort conditions along the year. The building is instrumented with an accurate building automation control system, and a number of sensors for a detailed energy and environmental monitoring. The monitoring equipment and framework, have been devised to support further detailed studies to improve the design concept and to provide accurate and comprehensive data to the scientific community.Causone, Francesco; Carlucci, Salvatore; Pagliano, Lorenzo; Pietrobon, MarcoCausone, Francesco; Carlucci, Salvatore; Pagliano, Lorenzo; Pietrobon, Marc

Assessing energy performance of smart cities

The massive urbanization process registered since 1950s and projected to continue for the coming decades is posing a crucial issue for the management of existing cities and the planning of future ones. Smart cities are often envisioned as ideal urban environments where the different dimensions of a city, such as economy, education, energy, environment, finance, etc., are managed in an effective and proactive way. Nevertheless, in order to reach this remarkable and challenging objective, analysis tools are required to create scenarios that are able to inform policy makersâ\u80\u99 decisions. Focusing on energy, this paper proposes an analysis method, based on exergy, to support smart city planning. It may help the decision makers to assess the energy-smartness of different scenarios, and to address urban energy policies. Possibilities and limitations of the analysis method are discussed via the application to the cities of London, Milan, and Lisbon that committed to become smart cities. Practical application: The paper summarizes a study on the possibilities and limitations of adopting an assessment technique, based on exergy, in order to evaluate the energy-smartness of policies in existing and future smart cities. As highlighted in the paper, buildingâ\u80\u99s energy uses have a huge share of many citiesâ\u80\u99 energy breakdown. Thus, professionals in the building industry will be interested in the paper not only because it refers to smart cities, but because the built environment plays a pivotal role in them. Professionals may also refer to this study to perform a similar analysis in other urban environments to support decision makers

Design choices and thermal simulations of a new test cell facility

The paper presents a new test cell facility, named Box Office and under development at the Ecole Spéciale des Travaux Publics (ESTP Paris) for the analysis and characterization of the thermo-physical properties of building envelope components under real climate conditions. The facility will allow to obtain reliable estimates of thermal performance indicators of transparent and opaque building elements. Particular care has been taken in the design phase in order to minimize or to monitor all sources of uncertainty, such as (i) conductive heat losses through the test cell envelope, (ii) time lag of response to transient outdoor conditions, (iii) levels of airtightness and of resistance to vapour or water penetration. Highly variable solar conditions can seriously affect both the correct functioning of outdoor test facilities and the indoor climate conditions in the cell. For this reason, the thermal behaviour of the Box Office was simulated in Matlab environment, implementing a lumped-parameter model, and results are used for refining the design choices and selecting the most promising operative conditions and control strategies. The output of test cell experiments will be beneficial to various target groups, such as designers and manufacturers (to boost the research and development of new products), research centres (to fully understand and model the physical phenomena occurring in a controlled space facing real outdoor conditions) and potential clients, who ask for economically affordable solutions guaranteeing high levels of Indoor Environmental Quality

An Exergy Analysis for Milano Smart City

Cities represent fundamental hubs in the world's energy-flow network, and their role is expected to gain further relevance in the next decades, following the ongoing urbanization process. Reducing energy use and increasing energy efficiency are crucial aspects for both existing and planned cities, and many policies have been established to pursue these objectives. However, in smart cities, as the ones envisioned in many on-going research projects, energy should also be used in a smart way, that is reducing the energy degradation in terms ofcapacity to generate useful work. Starting from the literature, the paper proposes an analysis method, based on exergy, to support smart city planning, with the aim to provide the decision maker with a useful tool to compare and understand the energy-smartness of different scenarios, and to address future energy urban policies. Possibilities and limitations of the analysis method are discussed via the application to the city of Milano that committed to become a smart city