The construction industry in the Baltic countries has undergone significant transformation since the 1990s, driven by advancements in construction technologies and the introduction of new materials. However, despite these developments, most buildings constructed during this period fail to meet modern energy efficiency standards, falling far short of the nearly Zero-Energy Building (nZEB) requirements.

This study analyzes the energy performance of multi-apartment buildings constructed between the 1990s and the 2020s. The research is based on an in-depth evaluation of multiple databases, incorporating real measured data from the past five years. The analysis leverages the national energy performance certification database to compare theoretically planned energy performance with actual measured data. Additionally, data from a municipal energy agency was included for further comparison.

The findings reveal that energy consumption for heating in these buildings can reach up to 110 kWh/m² per year, which is comparable to the consumption levels of non-renovated multi-apartment buildings constructed prior to the 1990s.

Energy efficiency is a key indicator of sustainability in buildings. Buildings are affiliated with over a third of energy consumption and carbon emissions. Prefabricated buildings play a crucial role in fulfilling the transition to higher energy efficiency standards through production, construction, waste generation, and the total life cycle impact. Prefabrication is an integral part of the modular building systems that have recently gained attention, especially for their deployment to residential buildings.

This paper explores innovative approaches to sustainable architectural design by integrating universal ecological strategies and advanced energy design principles. The study combines low-tech and high-tech passive concepts with aerodynamic and bionic design to optimize natural ventilation, cooling, and energy efficiency. A novel combinatorial building optimization method, supported by building physics simulations, is introduced to identify optimal building configurations for comfort and energy performance. The methodology involves modular space unit systems, enabling diverse mass form configurations tailored for single-family housing. These configurations are analyzed through a sensitivity analysis of roof geometry, glazing ratios, and orientation. Dynamic thermal simulations evaluate thermal and visual comfort alongside energy efficiency. The findings highlight 72 massing configurations (54 STANDARD and 18 EMELT), which are further refined for architectural feasibility and sustainability. This work contributes to the field by demonstrating a scalable and adaptable design framework, enhancing both environmental performance and practical applicability in the residential building sector.

This study examines the effectiveness of Morocco’s Thermal Regulation for Construction (RTCM) and France’s Environmental Regulation (RE2020) in reducing building energy consumption and carbon emissions. With buildings contributing significantly to global energy use and greenhouse gas emissions, effective regulatory frameworks are crucial for meeting climate goals. France and Morocco represent two distinct climatic and regulatory contexts. France addresses both heating and cooling needs across varied climatic zones, while Morocco faces rising cooling demands due to urbanization and arid conditions. Although both countries aim to enhance energy efficiency, their regulations differ in scope, implementation, and alignment with international standards. This study compares RTCM and RE2020 based on envelope performance, energy use, indoor and outdoor environmental quality, renewable energy integration, and smart building technologies. It uses a qualitative synthesis of regulatory texts and benchmark assessments, referencing global standards such as ASHRAE, ISO, and EPBD. Findings show that Morocco’s RTCM lacks enforceable limits on energy consumption and IEQ parameters, relying heavily on international standards for guidance. France’s RE2020, in contrast, offers a comprehensive, enforceable framework aligned with carbon neutrality goals, though it could benefit from more adaptive comfort modeling and occupant behavior integration. The study proposes optimal baseline benchmarks for key performance indicators such as U-values, energy limits, IAQ thresholds, and renewable integration. These benchmarks provide a framework for evaluating building performance within each country's regulatory system. Policy recommendations support stronger enforcement in Morocco and more flexible, occupant-aware, and smart management approaches in France.

The increasing demand for sustainable building practices highlights the need for energy-efficient options for conventional air conditioning systems, particularly in regions characterized by extreme climatic conditions. One promising solution is the Earth-Air Heat Exchanger (EAHE) system, which uses the ground’s stable temperature to cool air through underground pipes, significantly reducing cooling demands in hot climates. This study investigates the performance of EAHE systems, focusing on optimizing design parameters, improving operational efficiency, and integrating them into modern sustainable building practices.

The TRNSYS simulation tool is used to evaluate the system’s thermal and airflow performance during the peak cooling months of May to September, with Saudi Arabia as a case study. Key metrics such as heat transfer efficiency, airflow rates, and energy savings are analyzed. The study refines crucial design parameters to maximize system effectiveness, including tube length, diameter, and burial depth. It also considers site-specific factors, such as soil thermal properties and climate conditions, to improve model accuracy. An economic and environmental assessment compares the cost and carbon reduction potential of EAHE systems to traditional cooling methods, highlighting their benefits.

The findings reveal that EAHE systems achieve a 70% reduction in cooling capacity during peak operational periods, with a maximum energy saving of 25% recorded in August. These reductions underscore the system’s potential to minimize energy-intensive mechanical cooling reliance, yielding operational cost benefits and substantial carbon emissions reductions. Integrating EAHE systems into sustainable building practices also aligns with decarbonization objectives, contributing to climate change mitigation efforts.

However, the analysis identifies implementation challenges such as soil variability, system complexity, and regulatory requirements, which may require tailored solutions for different locations. It highlights the potential of combining EAHE systems with advanced technologies like IoT-based controls to improve monitoring and performance. Additionally, integrating renewable energy sources like solar panels could enhance efficiency and sustainability. This research demonstrates that EAHE systems are a practical, energy-efficient cooling solution for hot climates. The findings provide valuable insights for integrating these systems into sustainable urban development and support the broader adoption of low-energy building technologies to address environmental challenges.

Energy refurbishment of historic buildings plays an important role in the mitigation of climate change particularly as winter conditions remain significant in moderate climates, even under future scenarios. Internal insulation is commonly used in historic buildings, as external insulation is often impractical due to conservation requirements or spatial constraints. However, the hygrothermal performance of internal insulation is typically assessed using present or past climate data, with future climate scenarios often overlooked. Furthermore, internal insulation is deemed of worsening the summer discomfort.

This study explores the impact of internal insulation on winter comfort and heating demand while addressing common concerns about its potential to worsen summer discomfort and cooling energy demand. Particularly, this study compares three insulation strategies—internal, external, and hybrid solutions—under present and future climates.

Hygrothermal simulations were conducted on an 18th-century residential building in Valle dei Laghi, Northern Italy. The building features stone masonry walls, a wooden roof, attic openings, and stone window cornices. Renovated in 1996, the original 60 cm thick stone walls were insulated internally with 4 cm expanded polystyrene (EPS), a vapor barrier, and an 8 cm brick counter wall. Considering this, three renovation scenarios were simulated: 1) adding 10 cm of insulation plaster externally to the existing structure, 2) replacing the internal stratigraphy with 16 cm of wood fiber insulation, and 3) adding 16 cm of EPS insulation externally. The analysis was conducted across seven climate scenarios, including 10 years of past/present climate using measured data and 10 years of near- and far-future climates modeled under three Representative Concentration Pathways (RCP 2.6, RCP 4.5, and RCP 8.5).

The results show that all three strategies are hygrothermally effective under present and future climates. Insulation position minimally affects summer discomfort but influences the timing of overheating. Internal insulation aids in night cooling by keeping wall heat mass outside, whereas external insulation provides more stable indoor temperatures throughout the day. However, the thermal mass of internal brick partitions mitigates these differences, making their impact less pronounced.

This research highlights the importance of considering future conditions when planning a retrofit strategy and demonstrates that internal insulation does not inherently worsen summer discomfort.