An optimization procedure based on thermal discomfort minimization to support the design of comfortable Net Zero Energy Buildings

The European standard EN 15251 specifies design criteria for dimensioning of building systems. In detail, it proposes that the adaptive comfort model is used, at first, for dimensioning passive means; but, if indoor operative temperature does not meet the chosen long-term adaptive comfort criterion in the “cooling season”, the design would include a mechanical cooling system. In this case, the reference design criteria are provided accordingly the Fanger comfort model. However, there is a discontinuity by switching from the adaptive to the Fanger model, since the best building variant, according to the former, may not coincide with the optimal according to the latter. In this paper, an optimization procedure to support the design of a comfort-optimized net zero energy building is proposed. It uses an optimization engine (GenOpt) for driving a dynamic simulation engine (EnergyPlus) towards those building variants that minimize, at first, two seasonal long-term discomfort indices based on an adaptive model; and if indoor conditions do not meet the adaptive comfort limits or analyst’s expectations, it minimizes two seasonal long-term discomfort indices based on the Fanger model. The calculation of such indices has been introduced in EnergyPlus via the Energy Management System module, by writing computer codes in the EnergyPlus Reference Language. The used long-term discomfort indices proved to provide similar ranking capabilities of building variants, even if they are based on different comfort models, and the proposed procedure meets the two- step procedure suggested by EN 15251 without generating significant discontinuities

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

Multi-objective optimization of a nearly zero-energy building based on thermal and visual discomfort minimization using a non-dominated sorting genetic algorithm (NSGA-II)

Multi-objective optimization methods provide a valid support to buildings' design. They aim at identifying the most promising building variants on the basis of diverse and potentially contrasting needs. However, optimization has been mainly used to optimize the energy performance of buildings, giving secondary importance to thermal comfort and usually neglecting visual comfort and the indoor air quality. The present study addresses the design of a detached net zero-energy house located in Southern Italy to minimize thermal and visual discomfort. The optimization problem admits four objective functions (thermal discomfort during winter and summer and visual discomfort due to glare and an inappropriate quantity of daylight) and uses the non-dominated sorting genetic algorithm, implemented in the GenOpt optimization engine through the Java genetic algorithms package, to instruct the EnergyPlus simulation engine. The simulation outcome is a four-dimensional solution set. The building variants of the Pareto frontier adopt diverse and non-intuitive design alternatives. To derive good design practices, two-dimensional projections of the solution set were also analyzed. Finally, in cases of complex optimization problems with many objective functions, optimization techniques are recommended to effectively explore the large number of available building variants in a relatively short time and, hence, identify viable non-intuitive solutions

Energy retrofit of a day care center for current and future weather scenarios

Many scientific evidences have shown that Earth’s climate is rapidly changing. By 2050, European Union is aiming to significantly reduce greenhouse gas emissions (GHG) in the building sector. Achieving this target might help the mitigation of global warming, but the climate change seems inevitable. This means that both new and refurbished buildings should be able to face those conditions that they are going to experience during their lifetime. Therefore, any building design should be checked both for current and future climate scenarios. This study describes the use of a downscaling method named morphing to generate future weather scenarios and intends to support the design process of a deep energy retrofit of a day care center in order to improve the energy and thermal comfort performance of the building under the current and future weather scenarios. The retrofit concept of the building also includes hybrid ventilation, automated solar shading, lighting controls and renewable energy generation systems

A high performance home in the Mediterranean climate: From the design principle to actual measurements

Experience developed in the northern European countries led, in the last decades, to standard and shared procedures for the design and construction of passive houses and similar high performance buildings. These approaches are specifically developed for cold climates, therefore cannot be directly applied to the Mediterranean climate, where substantially different climatic conditions must be challenged. The design and early monitoring of a customized zero energy house, located in Sicily, is proposed as an exemplary case study for the future generation of high performance and nearly-zero energy buildings in the Mediterranean area. The key role played by the control of heat gains, and the correct use of thermal mass is highlighted, showing similarities and differences with passive houses built in the North Europe. The measurements of energy and environmental performance of the building show the effectiveness of the response of the adopted design approach to the specific climatic conditions

Comfort Models and Building design in the Mediterranean Zone

In the presence of renewed research and application efforts towards low or zero energy buildings, the issues of fine-tuning comfort and fully understanding its connection with energy use are becoming increasingly relevant both for research and application, and mostly so in the Mediterranean zone. This paper discusses how the evolution of knowledge on comfort and its incorporation into international Standards, inter alia in the form of comfort categories for different types of buildings, can influence the design, operation and evaluation of buildings in the Mediterranean area. We discuss some of the implications, obtained by the authors via dynamic simulation software complemented by pre and post processing tools purposely prepared to ameliorate and speed the treatment of comfort data. We present an optimization methodology, some results in a choice of climates, and the current limitations and needs for improvement of the indexes defined in the standards. Critical analysis and results presented here have been developed partially under the IEE projects Commoncense and ThermCo