While the operational energy use of buildings is often regulated in current energy saving policies, their embodied greenhouse gas emissions still have a considerable mitigation potential. The study aims at developing a multi-objective optimization method for design and renovation of buildings incorporating the operational and embodied energy demands, global warming potential, and costs as objective functions. The optimization method was tested on the renovation of an apartment building in Denmark, mainly focusing envelope improvements as roof and exterior wall insulation and windows. Cellulose insulation has been the predominant result, together with fiber cement or aluminum-based cladding and 2-layered glazing. The annual energy demand has been reduced from 166.4 to a range between 76.5 and 83.7 kWh/(m2 y) in the optimal solutions. The fact that the legal requirements of 70 kWh/(m2 y) are nearly met without building service improvements indicates that energy requirements can be fulfilled without compromising greenhouse gas emissions and cost. Since the method relies on standard national performance reporting tools, the authors believe that this study is a preliminary step towards more cost-efficient and low-carbon building renovations by utilizing multi-optimization techniques.
Energy is engaged in the supply chain of many economic sectors; therefore, the environmental impacts of the energy sector are indirectly linked to those of other sectors. Consequential life cycle assessment (CLCA) is an appropriate methodology to examine the direct and indirect environmental impacts of a product due to technological, economic or social changes. To date, different methodological approaches are proposed, combining economic and environmental models. This paper reviews the basic concept of CLCA and the coupling of economic and environmental models for performing CLCA in the energy sector during the period 2006–2020, with the aim to provide a description of the different tools, highlighting their strengths and limitations. From the review, it emerges that economic modelling tools are frequently used in combination with environmental data for CLCA in the energy sector, including equilibrium, input-output, and dynamic models. Out of these, the equilibrium model is the most widely used, showing some strengths in availability of data and energy system modelling tools. The input-output model allows for describing both direct and indirect effects due to changes in the energy sector, by using publicly available data. The dynamic model is less frequently applied due to its limitation in availability of data and modelling tools, but has recently attracted more attention due to the ability in modelling quantitative and qualitative indicators of sustainability.
This paper aims at assessing the embodied energy and greenhouse gas emissions (GHGs) of two building envelopes, designed for a two floors semi-detached house located in the Central Italy. The analysis is performed by applying the Life Cycle Assessment methodology, following a from cradle-to-gate approach. Fixtures (windows and doors), external and internal opaque walls, roof and floors (including interstorey floors) make the building envelopes. Their stratigraphy allows for achieving the thermal transmittance values established in the Italian Decree on energy performance of buildings. The two examined envelopes differ only for the insulation material: extruded expanded polystyrene (XPS) or cellulose fibers. The results shows that the envelope using cellulose fibers has better performance than that using XPS: it allows for reducing the embodied energy and the GHGs of about 13% and 9.3%, respectively. A dominance analysis allows to identify the envelope components responsible of the higher impacts and the contribution of the insulating material to the impacts. The study is part of the Italian research “Analysis of the energy impacts and greenhouse gas emissions of technologies and components for the energy efficiency of buildings from a life cycle perspective” funded by the Three-year Research Plan within the National Electricity System 2019-2021.
Purpose: Current greenhouse gas (GHG) policy aims at reducing emissions from power sector. However, there are some known trade-offs of GHG emission reductions, in terms of other types of environmental impacts and impacts on other economic sectors. Consequential life cycle assessment (CLCA) has been developed to assess the environmental impacts of the power sector in relation with changes in the policy and its indirect impacts on other economic sectors. Methods: A systematic review of CLCA method is conducted in the power sector. CLCA studies since 2005 are reviewed in terms of obtained results and methodology to identify whether CLCA is a more suitable approach for assessing environmental impacts of power sector in the context of GHG policy intervention, compared to attributional life cycle assessment (ALCA). Results and discussion: With CLCA the total environmental impacts/benefits of power system change when indirect impacts are accounted. The variations between the total environmental impacts quantified with CLCA and ALCA range widely from inconsiderable difference (less than 5%) to 200%, depending on the investigated product system. These variations originate from CLCA's modelling principles of expanding the system boundary and the inclusion of socio-economic interactions. With the expansion of system boundary, CLCA covers affected products and accounts for their relevant environmental impacts, which makes the obtained results comprehensively quantified. At the same time, the inclusion of socio-economic interactions in CLCA improves its capability of identifying the connections between environmental impacts and social-economic changes such as economic growth and consumer behaviours.
Ventilated Faç ades integrated with photovoltaic panels have become a popular way to improve both the thermal-physical performances of the existing built environment. The increased usage of not-programmable renewable energy sources implies the adoption of energy storage systems to mitigate the mismatch between the power generation and the building's demand. Aiming at properly integrates a photovoltaic panel and a battery (Lithium based) as a module of an active ventilated faç ade, the prototype design has been carried out in terms of thermo-fluid dynamics performance. Based on experimental setup, a numerical study of flow through the air cavity of the active ventilated faç ade has been carried out by the fluid-dynamics Finite Volume code-Ansys-Fluent. The calibrated model was lastly used to perform a wide range of parametric analyses on different climate and boundary conditions to explore the viability of the prototype.
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