Abstract
Today, strict insulation requirements apply. Nevertheless, the inverse correlation of thermal conductivity with insulation thickness leads to decreasing energy savings with increasing insulation packages. Therefore, a balance between potential energy savings and environmental impact due to additional materials using Life Cycle Assessment (LCA) needs to be strived for. This balance is sought for a case study called ‘The Mobble’ i.e. a flexible, modular, and circular building system developed by a student team from Ghent University. Through an iterative design process supported by LCA, comfort and dynamic energy simulations efforts are made to design an energy-efficient and low impact module with an agreeable indoor environment. First, material choices are made based on LCA and the material impact of a 5-module home is calculated. Second, energy calculations are executed in Modelica/Dymola. For this, three possible energy reductions are explored: insulating the building, altering the working regime of the HVAC system and lowering the setpoint temperature while maintaining comfort by using personal comfort systems (PCS). The results support PCS as a possible energy conservation measure and indicate that reducing operational energy does not shift the environmental burden to the additional materials’ production. However, these environmental saving effects decrease as the operational share decreases.
Highlights
A shift is detected for new low-energy dwellings for which all phases but the use phase can result in an impact of 68%, which in turn argues for an analysis of the entire life cycle and indicates the importance of system efficiency on the balance between material impact and operational energy
The materials are equivalent by considering an equal functional unit in the life cycle assessment i.e. 1m2 of insulation material with a heat resistance value of 4 m2K/W (R-value) for a building lifespan of 60 years
The results show that there is an optimal insulation thickness from which the energy saving is superseded by the additional insulation materials needed
Summary
The European building sector is responsible, among other factors, for no less than 40% of all greenhouse gas emissions, 50% of all raw material extractions and 50% of all energy use [1]. These numbers undeniably indicate the need for action. The optimal insulation degree in these studies differs according to the boundary conditions (e.g. insulation material, HVAC system, service life, chosen impact indicators, climate, ...), this limit clearly indicates the need to search for a balance between material impact and operational energy for a building design. A shift is detected for new low-energy dwellings for which all phases but the use phase can result in an impact of 68%, which in turn argues for an analysis of the entire life cycle and indicates the importance of system efficiency on the balance between material impact and operational energy
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