Life cycle efficiency of solar shading systems: a proof-of-concept

Solar control strategies are essential for the glare control and decreasing cooling needs or overheating risks (in the absence of active cooling system), however, they come with their own embodied energy. With the carbon neutrality objective looking at the 2050 horizon, life-cycle assessment (LCA) approach is needed to evaluate the impact of decisions made on the different building components, including solar shading systems. To that end, this paper applies a relatively new concept defined as the Life-Cycle Efficiency Ratio (LCER) to quantify the trade-off between operational and embodied energy. Results based on a low-carbon case study suggests that adding solar shadings does not reduce the life cycle carbon emissions of this project. Also, analyses show that the ratio between operational benefits and embodied impacts of external fabric blind is the highest, while this ratio is the lowest for the internal fabric blinds in this case study.

Active renovation strategies with building-integrated photovoltaics (BIPV). Application on an early 20th century multi-family building

Sergi Aguacil Moreno

Tomorrow's cities are already largely built, as much of the existing building stock – with a low level of energy performance – will still be standing in 2050. Urban renewal processes therefore play an essential role towards the sustainable transition of European cities. In this context, building-integrated photovoltaic (BIPV) systems can potentially provide a crucial response to achieve current energy and mid- to long-term carbon targets. Functioning both as envelope material and electricity generator, BIPV systems can simultaneously reduce the use of fossil fuels and greenhouse gas (GHG) emissions, while providing savings in materials and electricity costs. These are precisely the objectives of most European energy directives, from zero- to positive-energy buildings. However, despite continuous technological progress and increasingly favourable economic conditions, the significant assets of BIPV remain broadly undervalued in the current practice. Focusing on the architectural design, this paper presents the results of a multi-criteria evaluation in terms of Life-Cycle Assessment (LCA) and Cost (LCC) of different renovation and energy-use scenarios, showing which strategies can allow to achieve the ambitious targets for the 2050 horizon by integrating into the design process: (1) Passive strategies, to improve the envelope through low-embodied energy materials and construction systems; (2) BIPV strategies, using innovative photovoltaic products as a new construction material for façades and roofs, and by selecting the BIPV surfaces in order to synchronize on-site generation with the building consumption profile; (3) Active strategies, adapting the HVAC system to improve its efficiency and maximize PV self-consumption, thus reducing the dependence on feed-in-tariffs to ensure the profitability of investments. The research methodology, presented in this paper through the comparison of different renovation scenarios applied on a 1900’s archetype building in Neuchâtel (Switzerland), proposes a new way to address rehabilitation projects of existing buildings in urban environments towards Low Carbon Buildings. The main outcome provides - to architects and engineers - advanced BIPV renovation strategies depending on the building typology, the architectural design goals, and the level of intervention.

2020

Application of the Cradle to Cradle paradigm to a housing unit in Switzerland: Findings from a prototype design

Marilyne Andersen, Shady Galal Mohamed Attia, Jean François Bernard Beney

The Cradle to Cradle (C2C) paradigm is emerging as an important regenerative design approach. C2C is aiming to create a positive footprint of the built environment, beyond carbon neutrality. However, there are very few studies that address the application of the C2C concept in building design. More importantly, there is hardly any documentation processes on methods or tools currently being used to design and evaluate C2C buildings. Therefore, the purpose of this paper is to design, model and assess a C2C building prototype with a focus on energy and materials. The research methodology is based on literature review, case study design and performance (energy/materials) evaluation (DesignBuilder/SimaPro). The paper articulates the values, principles and goals of the C2C paradigm and translates them through the prototype design in the Swiss context. The results of the prototype design point to a 74% independence from non-renewable energy resources, compensating the operating and embodied energy during the building’s life. On the other hand only 8% of the building materials were totally recyclable according to the C2C principles. The design process delivers insights on the application of the C2C concept in the built environment reporting on the limitation and means of improvement.

2013

LCA as key factor for implementation of inertia in a low carbon performance driven design: the case of the smart living building in Fribourg, Switzerland

Marilyne Andersen, Arianna Brambilla, Endrit Hoxha, Thomas Bernard Paul Jusselme

The building sector is known as a major contributor to greenhouse gas (GHG) emissions and energy consumption. These impacts are commonly evaluated by life cycle assessment (LCA), which assess the potential impacts of a building from the construction to the end of life. LCA considers: the operating impacts (OI) occurring during the service life of buildings, and the embodied impacts (EI) occurring during the other lifecycle. Materials usually increase EI, but some of them, such the ones used for thermal inertia (TI), concur to energy efficiency and can reduce OI. This makes it difficult to understand the role of such materials in low carbon building strategies. The aim of this study is to understand how to weigh the overall environmental benefits of TI. Four building models were used to assess LCA with either low, medium, high or very high levels of TI. These are reached using materials characterized by different embodied impacts, such as concrete and earth. The difference with the low inertia case, taken as the base case, is evaluated for each model regarding OI and EI. The comparison between OI and EI determines which scenario brings the lowest impacts on LCA. To evaluate how the results are influenced by climate change, the analysis is made with two different scenarios: one with the typical meteorological year (TMY, Meteonorm) and the other with the weather conditions for 2050 (IPCC, International Panel on Climate Change). The paper shows a methodology to evaluate the effects of a design strategy on the LCA, applied to the case of TI. It demonstrates that TI is not very relevant in the frame of this case study because the EI related to the added materials is higher than the induced operating savings. Furthermore, it has been demonstrate that in the future when the carbon content of the energy may be lower, TI can change its effects and influence negatively the lifecycle environmental impacts.