Evaluation of daylighting strategies based on their embodied carbon emissions: a first methodological framework and case study

Abstract

The impact of daylighting strategies on a building's carbon emissions have so far been assessed mostly based on the building's use phase and their resulting operational benefits, overlooking embodied carbon emissions of material production, construction, maintenance and end of life. This paper proposes a new methodological framework that combines different techniques including sensitivity analysis, target cascading and a method called Design Space Exploration. The framework was tested on a case study, namely the winning entry of Solar decathlon 2012, to evaluate daylighting strategies based on both daylight availability and embodied carbon emissions. . This study allowed to show through a formal process that while choices made on window head height, glazing type, interior surface reflectance and window-to-wall ratio (WWR) basically define daylight access potential, they only have a minor impact on embodied carbon emissions. Key Innovations• First multi-criteria platform to explore a design space with a focus on illuminance and embodied carbon; • Uncover relationships between Daylight Factor (DF) targets and induced embodied Global Warming Potential (GWP) of influential building components; • Ability to rank design parameters based on their influence on daylight access and embodied carbon emissions through sensitivity analysis; • Weighing of embodied carbon impact per façade element (wall, frame and glazing) thanks to target cascading techniques. Practical ImplicationsThe methodology proposed in this article aims to offer useful guidance to practitioners by helping them identify which design parameters may impact daylighting performance or GWP or -most interestingly -both of them. Recent approachesThe impact of daylighting strategies on a building's carbon emissions have been assessed mostly based on the

Dynamic LCA methodology to support post-occupancy decision-making for carbon budget compliance

“…Sensitivity analysis Coupled with LCA, SA assists in the DM process by identifying which parameters have the largest impact in the results [23] and thus, are able to focus on the decisions that matter most. In buildings, SA has seen a plethora of applications, such as finding which daylight strategies have major impact in EE [24], finding the design decisions that matter the most in energy needs, EE and construction costs [25] and for identifying the biggest sources of uncertainty in building LCA [26]. Depending on the method applied however, a great number of samples is necessary, indeed in a variance-based method, such as Sobol SA, a sample size a thousand times larger than the number of parameters is recommended [27].…”

Carbon budgets at the component scale and their impacts on design choices: the façade as a case study

“…The composition of all components, whether variable or fixed, are based on the SIA 2032 [9]. The whole life carbon emissions of building elements were calculated using equation (1), in which I Wi (kg CO2-eq/ERA.y) is the whole life global warming potential (GWP) of variant i amortised over 60 years of building life span, IEi (kg CO2-eq/ERA.y) is the embodied carbon emissions of variant i, Mj represents the material quantity of component j in variant i (extracted thanks to a parametric model previously developed by the authors [10]), IFj (kgCO2-eq) is the carbon impact factor of the component j based on the KBOB [11], RSPB (year) is the building reference study period, LMj (year) is the component j's lifetime, ERA (m 2 ) is the energy reference area and IOi (kg CO2-eq/ERA.y) indicates the operational impacts of variant i, which is calculated thanks to the dynamic energy simulations and KBOB impact conversion factors [11].…”