Towards Future-Proof Buildings in Belgium: Climate and Life Cycle Modelling for Low-Impact Climate Robust Office Buildings

There is a twofold interaction between our built environment and climate change. On the one hand, the building sector contributes to an important extent to the emission of greenhouse gases and, by extension, the total environmental impact. On the other hand, building performance is strongly influenced by climate change. This dissertation links climate and life cycle modelling and aims to develop a methodology to identify climate robust office buildings with low environmental impact. A climate robust building is defined in this research as a building whose life cycle environmental impact is minimally affected by extreme climate conditions and which meets thermal comfort requirements under typical and extreme conditions. The developed methodology is based on the Belgian Life Cycle Assessment (LCA) methodology TOTEM and extends it by including two dynamic aspects. A first dynamic aspect is the integration of changing energy use due to climate change by means of dynamic energy simulations using future climate model data. Based on a high-resolution (2.8 km) climate model for Belgium, weather files are created for a realistic high-end climate change scenario for the end of the 21st century. A second dynamic aspect is the integration of the evolution of the electricity mix in the Belgian context. To this end, different scenarios are defined, ranging from business-as-usual policy to a policy that aligns with the Paris agreement (i.e. limiting warming to 1.5°C). In addition, the methodology is combined with an analysis of thermal comfort and robustness. The methodology was validated for a Belgian office building and applied to identify low-impact climate robust office buildings based on a parametric study. The office building showed a decrease in energy use for heating of about 20% (i.e. -5.1 kWh/m²), while the energy use for cooling increased by a factor of 2.5 (i.e. +3.8 kWh/m²), by the end of the 21st century. The dynamic modelling of the energy use has a limited effect on the total impact of this building because the increase in electricity use almost compensates the reduction in gas use. If only electricity is used as an energy source or the balance between or change in energy demand for cooling and heating is different, this total effect changes. Different electricity mixes resulted in a difference in total environmental impact between -4% and +7% compared to keeping the current electricity mix. If only the environmental impact of 1 MJ electricity over 60 years is compared, differences between -29% and + 34% are found in the cumulative impact. A parametric study showed an average decrease of 30% in energy demand for heating and an increase of 67% in energy demand for cooling. Independently of the office configuration, buildings with limited glazing (20%), north-south oriented windows with triple high-efficiency glass and fixed blinds are identified as climate proof buildings with a low environmental impact. Depending on the landscape or cellular offices and the electricity mix, the insulation level complies with the current EPB standard or passive standard. Besides the integration of high-resolution climate models in dynamic building simulations, within this PhD research, a first step has been taken to use future climate model data in simplified energy calculation for the early design phase by means of mapping degree days. The high resolution of the climate model allows to consider the influence of local effects (e.g. urban heat island effect) on the degree days. The average number of heating degree days (HDD) for Belgium decreases by 27% (from 3189 to 2337 HDD), while the average number of cooling degree days (CDD) increases by a factor of 2.4 (from 167 to 401 CDD). Urban areas show lower HDDs and higher CDDs while their change towards the future is larger for HDDs and smaller for CDDs. In addition, contextual features such as the distance to the sea, altitude or natural elements such as rivers play a role.

Publication year:2021

Accessibility:Open