This paper focuses on the modelling of occupant behaviour in the case of a non-residential mixed-mode building on the tropical island of La Réunion. For such areas and types of buildings, occupants can operate passive solutions to achieve comfort while energy-consuming ones can offer alternatives during the hottest months. Yet, compared to other climatic zones, specific knowledge on occupant comfort and behaviour is limited, making the work of engineers difficult during the design phase. In this work, occupants' operations on hygrothermal comfort controls, such as windows and fans, were first measured and analysed. Secondly, these behaviours were modelled using two deterministic methods based on machine learning techniques and a probabilistic graphical model. A model was also implemented to estimate the number of people, using the power demand of the electrical outlets. The estimation ability of the behavioural models was evaluated and led to F1 scores greater than 0.7. A two-classifier model was proposed to estimate the level of ceiling fan use. This combined model slightly improves the F1 scores by more that 2%, which demonstrates the necessity of taking into account the links between the different controls.

In this paper, we present the results obtained by modelling the users' behaviours in a mixed mode office building in a tropical climate, more exactly in La Réunion. Few specific research studies on comfort in tropical climates have been published, and there is little feedback on the users' behaviour in these buildings. In order to improve users' assumptions in the design phase, users' actions on ceiling fans and windows have been measured and analysed. These data have then been modelled by machine learning methods, according to hygrothermal comfort and occupancy. The F1 scores eventually obtained for predicting fan use by random forests, decision trees and Bayesian networks are 99%, 98% and 95% respectively. For windows use, the F1 scores obtained are 92%, 91% and 70%, which demonstrates the ability of the models tested to predict the users' behaviours.

This paper presents the Post Occupancy Evaluation of the first naturally ventilated lecture theatre built in a tropical region. The challenge was to design a bioclimatic amphitheatre of 550 seats, which does not use air conditioning and remains comfortable at the same time. A post-occupancy evaluation has been carried out based on, in parallel, indoor and outdoor measurements, and a user's survey. Airflow measurement is used to check the good performance in terms of natural ventilation. A follow-up of the building's actual consumption has been carried out as well, which showed overall positive results. 92% of the users feel comfortable or slightly comfortable during the hottest days. Nevertheless, 50% of them would prefer to get more air movements. In terms of energy consumption, the lecture theatre consumes four times less than a standard one.

One of the handicaps of the large-scale integration of solar energy is due to its variability and its intermittency. The main way to overcome this issue is the energy storage technology. Knowing the high cost of batteries and their impact on the environment, we simulate a storage system based on compressed air and acting as a battery system. The CAES consists in storing the air at a high pressure in a tank during the period when the energy source is abundant, i.e., cheap, or when the energy demand is low. The compressed air is later expanded through an air turbine which generates electricity during the high demand periods, i.e. when the energy source becomes very expensive for instance. This system could be used for decentralized electricity supply or in an area with no electric grid. In order to evaluate the feasibility of a Compressed Air Energy Storage system coupled to a photovoltaic plant and a building that represents a reduced power demand, a numerical model that reflects the instant behaviour has been built. The system is composed of a photovoltaic power plant, an air compression system, a storage vessel, an expansion module, a power grid and a building. The inputs used are, on the one hand, the climate data such as ambient temperature and the global solar irradiation and, on the other hand, the load curve of a building or of the group of buildings, which has to be supplied by electricity. The overall system optimization has then been performed after having done a sensitivity analysis of the key parameters. This optimization allows us to find the most suitable size for each component of the system: compressor, tank size and photovoltaic area. (C) 2019 The Authors. Published by Elsevier B.V.

This report presents 14 comparisons among the case studies collected in the Task 51/Report C1. The case studies represent new urban areas, existing urban areas and landscapes. The comparisons concern 1) scale and planning process, 2) legislation and technology and 3) targets and goals. Each comparison provides lessons learnt and recommendations for the different target groups, such as urban planners, architects, researchers and urban stakeholders involved in the planning process.

This report (C3) presents lessons learnt drawn from the case studies within Task 51 presented in Report C1 and Report C2. The lessons learnt are divided into ten categories. Each category includes lessons learnt for the environments 1) new urban areas, 2) existing urban areas and 3) landscapes. Target groups are 1) citizens, 2) education actors, 3) professionals and stakeholders and 4) potiticians and decision makers.

This report gathers and presents approaches, methods and tools that can support and facilitate daylight and solar energy considerations within urban planning processes. The report presents different ways to address existing building stock, new urban environments and landscape environments in relation to use of daylight and active solar. It addresses the need for spatial and energy planning that enhances solar energy while respecting cultural and historical heritage values in urban and landscape contexts.

Cities all over the world are redefining their urban landscapes with new buildings integrated within existing environments. Due to the dearth of climate and context consideration, as well as the lack of interoperability of existing design tools, buildings are mostly designed as stand-alone entities which limits their potential utilisation of natural resources and potentially affect existing buildings' performance and outdoor microclimate conditions. To overcome these limitations, an integrated simulation and parametric design approach was developed. This paper presents the qualitative outcomes of the workshop that investigated the usability and appropriateness of the urban modelling, simulation and design platform prototype which embeds the approach. Workshop participants appraised the integrated features of the prototype and emphasised its potential to promote optimised integrated urban designs that consider the users, the buildings, their surroundings and the microclimate as elements of the same system that sustainably adapt to and mitigate the effects of climate change.

IEA SHC Task 51 Solar Energy in Urban Planning. Subtask C - Case Studies and Action Research. Task 51/Report C1

Net Zero-Energy Buildings have been the object of numerous studies in recent years as various countries have set this performance level as a long-term goal of their energy policies. This book presents a unique study of 30 NZEBs that have been constructed and have had their performance measured for at least 12 months. The study is based upon an international collaborative research initiated by the International Energy Agency the Solar Heating and Cooling Programme (SHC). It is the first book to evaluate building strategies in houses, educational buildings and offices that have been demonstrated to work in practice. It examines how the design challenges of climate and building type have been addressed, and to what extent the various design approaches have been successful.

Meeting the demand in electricity for houses or buildings provided by means of photovoltaic panels is relatively tricky, especially because of the stochastic character of solar radiation. There are some solutions in terms of storage and among them, the one consisting in converting electricity in high-pressure compressed air, seems promising. This option is under investigation in a building of teaching classes at Reunion University (a French island situated in the Indian Ocean, at the east of Madagascar). The aim in terms of consumption is 25 kWh(fe).m(NFA)(-2).year(-1) leading, if possible to a NetZEB (Zero Energy Building). Therefore, it has been envisaged to produce the electricity by means of PV panels, to consume the major part and to store the extra production for use at night and during periods of overcast sky. The solution that has been investigated, consists in compressing air in high-pressure storage tanks and to produce electricity later using a turbine. A dynamic numerical model has been built, taking a specific given load profile and local climatic data into consideration, in order to estimate the production. The whole system depends mainly on the PV panel area, the storage tank volume and the pressure range. The objective is to reduce the amount of energy provided by the external grid to the minimum, leading to the maximum autonomy of this system. First results have been obtained and are explained in terms of pressure and power evolution in the final section of this paper.

This work aims to investigate the application and replicability of parametric solar design to both existing and future development urban areas in two extreme climate conditions: Ovre Rotvoll in Norway (subarctic climate) and Ravine Blanche in Reunion Island (tropical humid climate). The interplay between urban morphology and its potential for passive and active solar energy strategies has been investigated. The methodology combines the parametric modelling software Rhinoceros-Grasshopper, with two Radiance-based solar simulation tools to optimise the solar potential of a district. The application of a new workflow is studied over the computation of various design scenarios in an existing urban environment at both the district and the building scale. The results show differences and similarities between climate-specific interventions that can be used as supportive instruments for the ongoing local planning processes. The study demonstrates how parametric optimisation allows maximising the solar potential of urban areas at different latitudes despite climatic and urban densification constraints.

The conversion of renewable energies such as solar or wind is usually difficult due to their intermittency and their variability. Reunion Island, a tropical French island situated 200 km off the West coast of Mauritius, has no possibilities to be grid connected to other countries. As the island expects to reach the electric autonomy by 2030, Renewable Energy like Photovoltaics has recently encountered a huge increase. Nevertheless, the development of large scale PV farms directly connected to the grid may create instabilities. For the same reasons, it is difficult to supply a building only with intermittent electric sources. Then, making the large-scale integration of PV farms for the decentralized electricity grids becomes a real challenge. One of the solutions for a deployment of intermittent sources such as PV is the integration of an energy storage system. However, the most common technology is based on the use of batteries, which suffer from being not environmentally friendly. A Compressed Air Energy Storage (CAES) appears as a solution to this disadvantage. A model that reflects the instant behavior of a system composed of a photovoltaic plant, an air compressor, a storage tank, a turbine, a building and the power grid is proposed in order to evaluate its feasibility. A sensitivity analysis on key parameters of the system is performed and the simulation results such as the overall efficiency, the load coverage ratio and the energies involved are presented in this paper. This model allows to assess the size of these components by minimizing the solar electricity sold and bought so as to reach autonomy.

Net Zero Energy Buildings (NetZEBs) design has become a crucial topic of research in recent years. Due to its complexity, discussion has been done on methodological criteria useful to define and assess NetZEBs (building system boundary, conversion factors, energy balance, interaction with the grid, monitoring, etc.), mainly with the engineering approach, and a number of case studies worldwide have been investigated. In regard to Photovoltaics’ (PV) design, research demonstrated that: PV is an indispensable technology for meeting the net zero energy target; 2: meeting the target of the net zero energy balance at the architectural scale (by using the only surfaces of the building envelope to place renewables) is very difficult and therefore 3. an extension of the balance boundary to a wider scale is needed. That is: the concept of NetZEB should be advanced towards the one of Net Zero Energy Community (NetZEC). In view of such an enlargement of the design domain, this paper investigates architectural and landscape design options (spatial features and outdoor thermal comfort considerations) for PV, based on the analysis of case studies collected and assessed in the framework of the International Energy Agency (IEA) SHC-EBC Task 40-Annex 52 Net Zero Energy Solar Buildings. Considering that the traditional understanding of the use of PV in buildings, mainly rooted in technological and morphological considerations, is not sufficient to describe all the issues emerging from this analysis, this paper is a contribution for setting a new cognitive framework in view of PV design for NetZECs.

This paper deals with new considerations about the design of Net Zero Energy Buildings and Net Zero Energy Neighbourhoods in the future. The perspectives presented here are the results from an international work named Task40/Annex52 “Towards Net Zero Energy Solar Buildings” conducted within the framework of the International Energy Agency (SHC-EBC) and in particular from the sub-group working on Solution Sets and case studies. We will see through case studies in different climates that the design scale to reach the Zero Energy goal is not the building anymore. The design of renewables as well as passive strategies must be extended to the whole neighbourhood.

ABSTRACTThe aim of this report is to present a model of a rigid‐rotor system based on computational fluid dynamics (CFD), which is applied on a vertical axis wind turbine (VAWT) research. Its originality results from the use of the average value of the variable rotational speed method taken in a periodic steady‐state (PSS) of the VAWT rotor instead of the classical fixed rotational speed method. This approach was chosen in order to determine the mechanical and aerodynamic parameters of the wind turbine. The modeling method uses an implicit Euler iterative solution strategy, which resolves the coupling between fixed and moving rotor domains. The main methods that were adopted are based on the three‐dimensional modeling of the interaction of the fluid flow with a rigid‐rotor. The strategy consists of using the Reynolds averaged Navier Stokes (RANS) equations with the standard k‐ ϵ and SST k‐ ω models to solve the fluid flow problem. To perform the rigid‐rotor motion in a fluid, the one degree of freedom (1‐DOF) method was applied. In the present study, the steady‐state and dynamic CFD simulations of the Savonius rotor are adopted to contribute to the validation elements of the VAWT models that are used. The dynamic study allows the investigation of the rotor behavior and the relation between velocity, pressure, and vorticity fields in and around the rotor blades. The flow fields generated by the rotation of the Savonius rotor were investigated in the half revolution period of the rotor angle θ from 0° to 180°. In this range of θ, the focus is on generating and dissipating vortices. Copyright © 2013 John Wiley & Sons, Ltd.

The International Energy Agency (IEA), through the Solar Heating and Cooling programme (SHC) Task 40 and the Energy Conservation in Buildings and Community Systems programme (ECBCS, now named EBC) Annex 52, works towards developing a common understanding and setting up the basis for an international definition framework for Net Zero Energy Buildings (Net ZEBs). One of the subtasks of this programme–SubTaskC focuses benchmarking the Net ZEBs around the world to identify the innovative solutions sets that makes up this new type of building. This paper presents an overview of the work conducted by the participants of Subtask C and of Zero Energy Building projects that have been identified.