An early design stage parametric exploration of integrated concrete funicular floor element and thermal mass performance for carbon footprint reduction
In response to the imperative of reducing material use and carbon footprint, building structural elements can be designed with structural and environmental design considerations for duo-functions. We present an early-stage, parametric design workflow that integrates thermal mass performance with structurally optimized, prefabricated, funicular, concrete floor elements. Thermally massive building structures, like concrete floors, can act as a thermal battery that reduces reliance on and carbon emission associated with mechanical cooling. The proposed co-design workflow forges an integrated structural and building energy simulation framework that assesses the operational carbon saving associated with cooling induced by different building structural thermal mass design options, while constraining the embodied carbon associated with material volume. Polyhedral Graphic Statics (PGS) is utilized as the geometric form-finding method to intuitively design and optimize the discrete floor geometry via Polyframe, a parametric plugin developed in Grasshopper. The floor geometries are then placed in the whole building energy simulation environment to evaluate its thermal mass performance impact on lifecycle carbon emission reduction related to space cooling with Future Typical Meteorological Year (fTMY) weather data. Projected hourly average grid emission factors from 2020 to 2079 are referenced for emission calculations. Using the US Department of Energy Secondary School Reference Building as a case study, the 60 year life cycle cooling carbon emission savings associated with structurally optimized thermal mass floors are investigated in two representative cities in two climate zones and grid emission scenarios (marine climate in San Diego, California, and cold climate in Denver, Colorado). Our results reveal that using co-designed concrete funicular floors as building thermal mass can achieve 25% and 15% annual cooling carbon emission reduction compared to the flat slab of the same material volume in San Diego and Denver respectively from 2020 to 2039. With further grid electrification, a 9% and 10% reduction can be obtained from 2040 to 2059, and 0 and 6% from 2060 to 2079 in the respective locations.
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