• Energy Research

Abstract The sustainability of the built environment largely depends on its energy and environmental performances. The overall objective, across the different phases of the building life cycle, is to improve building and system performances in terms of economics, comfort, environmental impact and durability. Several modelling methodologies have been developed in order to evaluate the energy performance of buildings. Generally, every modelling methodology responds effectively to some specific tasks, but there exists a lack of integration in particular with respect to the cross-disciplinary role of data. Given the multi-scale and multi-objective nature of the problem of optimization of the energy and environmental performances of the built environment, an appropriate synthesis and integration process in modelling methodologies has to be identified, addressing realistically the uncertainties inherently present in modelling strategies. Visualization and data analysis techniques are successfully used in a wide variety of applications, both in theoretical and applied domains, but questions remains about their robustness, efficiency and applicability to the problems introduced before. The paper aims to analyze critically these topics by means of case studies, showing a possible path to create a multi-scale methodology able to synthesize all the relevant aspects.

Abstract Energy saving is crucial for existing buildings which is present a huge potential of improvement by a strong energy retrofitting. Often, the existing envelope components are not adequately insulated and deep refurbishment is required to comply current regulations to improve energy efficiency and address Nearly Zero Energy Building (NZEB) goals. The strategies to enhance buildings energy performance involve heating and cooling demands strongly dependent by envelope quality (i.e. insulation, thermal mass, internal gain storage capacity and solar heat gains exploitation). Commonly, the suggested main retrofit interventions on envelope are glazed surfaces replacement, Solar Heat Gain Coefficient (SHGC) reduction and thermal transmittance (U value) improvement by additional insulation layers or even components replacement. However, it is worthy to note that the resulting thickness of the external envelope and the payback time of the interventions are important supports for decision-making. The environmental issue related to CO2 emissions during the operational phase of the building is encompassed into the standard energy certification of the asset and the conversion factors to define fuels’ impacts are available and updated. However, the calculation excludes the environmental impact due to energy used for materials’ production and few official information sources provide accredited values, e.g. the Environmental Product Declaration (EPC). Going towards a Zero Energy Building, which reduces its environmental impact during the running phase, embodied energy claims an increasing weight. Thus, materials and components with low embodied energy should be favoured and endorsed. For this reason, the most influential rating systems worldwide available for building sustainability assessment (e.g. LEED, BREEAM, etc.) updated their checklists including criteria related to reduced energy for extraction, production and materials transportation on the field. The technological optioneering of envelope solutions to achieve both energy efficiency and economic affordability is inevitably based on and supported by multicriteria assessment frameworks. These frameworks should include energy, environmental and economic parameters to define the technological suitability in different climate conditions identifying accurate optimization points, e.g. thickness of the insulation layer or heat storage capacity, considering energy saving and management costs in the life cycle. When actual optimization processes are required, computational parametric tools support to ease the options’ performance comparison and to compute different combinations. Nowadays some tools are available into the main authoring software on the energy simulation market. Although different tools could be adopted, the need of transparency and custom workflows is crucial. In the present research, a specific multi-criteria methodological approach enables to outline a synoptic diagram for each considered climate to compare the envelope technological solutions by aggregating LCA (Life Cycle Analysis) and LCC (Life Cycle Cost) factors. For LCA, Embodied Energy (EE) of the envelope materials and Primary Energy (EP) used during the running phase have been considered. For LCC Investment Cost (C) of the materials to enhance a baseline performance and related operational costs of the building based on Net Present Value (NPV) and Discounted Payback Period (DPP) have been adopted. The present study focuses as first on the construction coherency of different technologies used to define the external envelope of a test room, able to manage the energy flows resulting from different external conditions. Subsequently the definition of the technological basket, a parametric analysis based on reducing thermal losses and increase solar gains has been performed defining the most suitable technologies and facade configuration in three representative climate conditions at national level by calculating heating and cooling demand and related primary energy.

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Information Modelling and Management (IMM) methods for Most Economically Advantageous Tender (MEAT) can promote the adoption of environmentally sustainable practices. Despite the wide regulatory framework and existing drivers, Construction and Demolition Waste (CDW) trends are still growing. The literature review analyzed IMM and CDW management implementation during design phases although few studies focused on Green Public Procurement (GPP) and CDW management integration from the Public Client’s point of view. This research aims at investigating the integration and efficiency of MEAT and IMM to promote the application of sustainable strategies focused on waste reduction and resource valorization. The study investigates the Public Client’s role in promoting sustainable practices, introducing digital material inventory and BIM during the design phases, and including environmental award criteria in the call for tender documents. A Design Build (DB) procurement model was considered in the case study of a brownfield renovation and the construction of a new school in northern Italy. The methodology provided the Public Client and included a method to evaluate the environmental impact of the bids, allowing for proper selective demolition planning, CDW decrease, and organization while promoting their integration in companies’ expertise and procedures. The replicability of the methodology is demonstrated by positive results of present and previous case studies.

Abstract School buildings in Italy are outdated, in critical maintenance conditions and they often perform below acceptable service levels and quality standards. Nevertheless, data supporting renovation policies are missing or very expensive to be obtained. The paper presents a method for evaluating building's energy savings potential, using the Building Energy Certification (Certificazione Energetica degli Edifici - CENED) open database. The aim of the research concerns the development of a data-driven set of methods, based on the use of open data, machine learning (ML) and Geographic Information Systems (GIS) to support regional energy retrofit policies on school buildings. The main advantage concerns the possibility to predict the post-retrofit energy savings, avoiding the expensive on-site Condition Assessment (CA) phase. Data have been first clustered to identify the most common thermo-physical properties of the envelope, then three retrofit scenarios have been defined, to allow the retrofit of homogeneous types of buildings. The energy saving potentials have been evaluated through the implementation of eight Artificial Neural Networks. Ultimately, data have been geolocated and further processed to support the definition of the energy retrofit policies for the most critical regional areas. The Lombardy region has been chosen as case study to test the robustness of the proposed methods. The results of the case study proved that school buildings energy retrofit policies can be supported and defined using available open data, ML and GIS. The future developments of the research concern the further integration of GIS for retrofit cost assessment and scenario analysis.

The increased awareness on sustainability matters is contributing to the evolution of energy and environmental policies for the building sector at the EU level, oriented toward resource efficiency. There exist today several possible strategies to model building performance through the life cycle. The increase of available computational capacity and of data acquisition capability is opening new scenarios for practical applications, which can contribute to the reduction of the gap usually encountered between simulated and measured energy performance. This article aims to investigate an approach for probabilistic building performance simulation to be used across life cycle phases, employing reduced-order models for performance monitoring and energy management. The workflow proposed aims to establish a continuity among design and operation phases. Design phase simulation is generally subject to relevant temporal and economic constraints and a successful workflow should incorporate elements from current design practices but should also add new features, which have to be reasonably automated to reduce additional effort. Therefore, the workflow proposed is automated and tested for robustness using Monte Carlo technique. In the design phase, the approach can be used for identifying probabilistic performance bounds suitable for risk analysis in energy efficiency investments, employing cost-optimal or life cycle cost accounting methodologies. In the operation phase, it can be used for performance monitoring and energy management based on daily energy consumption analysis, similarly to other multivariate regression-based methods at the state of the art, addressing the problem of maintaining energy consumption and related costs constantly under control.

AbstractWith the adoption of the recast EPBD in 2010, EU Member States faced new tough challenges, moving towards new and retrofitted nearly-zero energy buildings by 2020 and the application of a cost-optimal methodology for setting minimum requirements for both the envelope and the technical systems. Attention often is focused on building envelope technologies however nowadays technical systems can be a powerful instrumental factor in achieving high levels of energy efficiency. Thermal systems producing heating and cooling have higher investment costs but it is possible to demonstrate that in a long term they are cost effective related with traditional high efficient technologies. Refurbishment and energy retrofitting in residential buildings is frequently approached with standard and traditional technologies preventing the penetration of different but already consolidated solutions. The paper shows the technical and economical comparison between three technical systems (gas boiler, ASHP and GSHP) as option to replace an oil boiler after a whole refurbishment of an apartment residential building in Milan, Italy. The retrofitting of the envelope was standard nevertheless the most innovative choice was on thermal system.