Reducing Simulation Performance Gap from Hempcrete using Multi Objective Optimisation

Abstract

The impacts of climate change in the built environment is undeniably overwhelming, which highlights the need for a sustainable reduction of carbon from buildings and the built environment. While carbon reduction from the built environment seems ideal for mitigating climate change issues, there are necessary actions to be taken. Especially a shift from the use of conventional construction materials and methods, to using sustainable materials and methods to increase the resilience of buildings to climate change. The technological advancement of the world and built environment has made it possible and necessary to design and simulate buildings for sustainable construction. In this regard, hempcrete is a sustainable construction material increasingly used in the built environment as it provides stable temperature and relative humidity conditions in buildings. In addition to its thermal qualities and low energy operations, it is carbon negative as it possesses carbon sequestration properties. Buildings built from hempcrete also possess negative embodied carbon, which is absorbed into the hemp plant material. However, Hempcrete is hard to represent in design and simulation because standard dynamic simulation tools do not have a built-in capability to accurately simulate it. This is due to hempcrete’s specific material structure and combined heat and moisture transfer, causing a considerable performance gap.

This study investigates the appropriate specification of key parameters to be used in simulation of hempcrete, for reducing simulation performance gap from hempcrete buildings, using multi-objective optimisation, to facilitate hempcrete simulation. To this end, this study uses experimental research method with secondary method of data collection by obtaining monitored data of hempcrete buildings from Zero Carbon Lab. The monitored hempcrete buildings will be simulated and RMSE between the monitored and simulated values will be calculated. The simulation of monitored hempcrete buildings is carried out in IES Virtual Environment and the RMSE is calculated using Microsoft Excel. The results of RMSE between monitored and simulated hempcrete building is the performance gap, which is then investigated in EnergyPlus using the HAMT Simulations coupled into jEPlus+EA for multi-objective optimisation to reduce the performance gap. This study is carried out within simulation tools and the results show a significant reduction in performance gap of temperature and relative humidity, while identifying the accurate parameters to be used for hempcrete simulation. The identified parameters for hempcrete simulation, facilitate the modelling of heat and moisture transfer in hempcrete for optimised simulation.