Linking thermal risk, energy performance, and building typology: a comparative study of Walloon residential buildings under climate change

The latest research on building performance in the face of climate change has largely focused on new constructions, particularly in the tertiary sector, energy-efficient buildings, buildings meeting minimum regulatory criteria, and renovated buildings (Baglivo et al., 2024; Fernandes et al., 2024; Rahif et al., 2022). Many articles also concentrate on simulating models of new or yet-to-be-constructed buildings to determine their performance in the context of climate change.

However, in some regions, such as Wallonia in Belgium, a significant portion of existing buildings is comprised of aging structures with energy performance far below the regulatory standards set by the government. Wallonia has already established a roadmap to change this paradigm and renovate its building stock through its long-term energy renovation strategy. This strategy commits the region to a thorough renovation of its buildings, aiming for an average A-label by 2050 for its entire residential stock, with a focus on the least performing housing units.

The objective of this paper is to demonstrate the impact of climate change on existing, energy-inefficient residential buildings in Wallonia. The study is conducted using numerical building models with the TRNSYS18 software for dynamic thermal simulation. Two types of buildings are analyzed: detached single-family house (4 free facades) and detached single-family house (2 facades).

This paper investigates the thermal and energy performance of pre-war Walloon residential buildings under projected climate conditions, comparing them with new constructions that comply with current regulations. To assess potential heat-related health risks, the study introduces the Heat Index as a complementary indicator to conventional metrics such as overheating degree hours and annual energy consu