Despite the efforts to improve the energy efficiency of buildings, the actual energy consumption decreased much less than expected in recent years. Therefore, energy sufficiency is gaining attention as a complementary approach to energy efficiency. It aims to reduce the actual energy consumption of buildings by providing thermal comfort to residents in a sufficient way. This demands for alternative heating practices, such as the application of personal heating systems. Although a review of past studies shows that, in office buildings, thermal comfort can be provided with less energy by using personal heating systems, the application in a residential context is much less explored. Our hypothesis is that an innovative, energy-sufficient personal heating practice also has potential to reduce the overall energy consumption in dwellings. Therefore, this paper presents the results of a one-week case study on personal heating as an energy-sufficient heating practice in three dwellings. During the case study, the ambient temperature was reduced to 18 °C, and residents were allowed to use active and passive personal heating systems to make themselves as comfortable as possible. They were also asked to evaluate their thermal sensation and thermal comfort. The results show that, despite a lower indoor temperature, residents are able to achieve thermal comfort by using personal heating at the locations where they effectively reside. Additionally, a significant energy saving potential was found. The case study proved our hypothesis, leading to the conclusion that an innovative, sufficient personal heating practice in dwellings can be a supplementary step to reduce the energy consumption to meet the global challenges.

Earth architecture during the 21st century has resurfaced worldwide as a sustainable, low environmental impact material with expressive aesthetics and textures. Contemporary projects attempt to modernize the traditional techniques of building with earth in order to adapt them to today’s projecting needs. Examples of such techniques are unfired earth bricks and rammed earth. In order to disclosure and highlight future possibilities of earth construction, advantages and limitations of earth construction in a contemporary Western-European context are reviewed, based on a literature study. Because it is hard to generalise due to the case-specific context and constraints, a case study analysis of earth utilization in two contemporary architectural projects is presented. To assess if these contemporary projects meet the environmental benefits associated with traditional earth construction, several environmental aspects are taken into account, such as material sourcing proximity, production process, reuse potential, etc. Based on the literature study, case study analysis and current evolutions in neighbouring countries, promising applications for future development of earth construction for low impact building in Belgium are highlighted.

In order to meet the energy performance regulations for new buildings and to improve the energy performance of the existing building stock, a high amount of insulation materials will be needed in the coming years. Meanwhile, the demand for renewable materials and materials with a low environmental impact is increasing. In previous research, the ecological and hygrothermal potential of lime hemp as a building material has been shown. Besides incorporating a large share of renewable and fast-growing hemp shives, lime hemp combines thermal insulating properties and a high thermal inertia with a good moisture regulating behaviour. However, despite the growing interest in the material and promising lab results, the thermal performance in real conditions is still uncertain. Due to the lack of validated data for in-situ cast walls, rather conservative λ-values for lime hemp are currently compulsory used in energy performance certification calculations in Flanders, the Flemish region of Belgium. In this paper, the results of a case study analysis of four real-life lime hemp projects are presented. The thermal performance of four dwellings with in-situ cast lime hemp walls (both new construction and renovation) is determined by in-situ measurements of the U-value. The measurements show that the in-situ U-value of the lime hemp walls is significantly better than the U-value that is calculated with the λ-value that is currently accepted by the Flemish Energy Agency. However, drying of lime is a slow process, resulting in initially higher U-values that gradually decrease in the first months after lime hemp application. Once dried, in-situ cast lime hemp walls can meet the Flemish energy performance requirements.

Urbanisation-driven housing demand and the environmental burden of sewage sludge disposal highlight the need for low-carbon, circular construction materials. This study evaluates incinerated sanitary sludge ash (ISSA) as a supplementary cementitious material in stabilised earth blocks, aiming to reduce the use of cement and lime while valorising waste sludge. Lateritic soil blocks were produced with a binder-to-soil ratio of 1:7 by mass, in which ISSA partially replaced the primary stabilising binder (cement or lime) at a replacement level of 10–40% within the binder fraction. ISSA’s mineralogical characteristics were analysed using XRD and XRF. The compressive strength and density of earth blocks were measured at 7 and 28 days under curing conditions (29–36 °C; 60–75% humidity). Cement-stabilised blocks were water-cured to support cement hydration, whereas lime-stabilised blocks were air-cured to promote carbonation and pozzolanic reactions. The results, therefore, compared practical binder-specific curing regimes rather than strictly identical curing environments. ISSA exhibited moderate pozzolanic potential, and its incorporation enabled substantial partial replacement of both binders. Cement-stabilised blocks achieved higher strengths, up to 7.7 MPa, after 28 days of curing, whereas lime-stabilised blocks developed strength more gradually, reaching 4.8 MPa. Optimal mixtures were identified at 40% cement + 60% ISSA and 30% lime + 70% ISSA, balancing mechanical performance and binder reduction. A positive density–strength relationship was observed, but chemical bonding predominated over densification effects. ISSA-based stabilised earth blocks show promising structural performance and reduced binder use, but durability and life-cycle assessment need further evaluation before large-scale implementation.