Evolution of energy standards led to high-performance buildings requiring very low energy for their operation. Occupancy is the variable with the greatest impact on nearly Zero Energy Building (nZEB) energy performance because both constructive and technical characteristics have been improved over time. Occupants influence energy use in buildings as they contribute to internal gains, interact with systems and modify indoor conditions with their behaviour. Assumptions about occupancy schedules are usually adopted in energy models for compliance calculation and when experimental data are not available. These theoretical profiles might be far from real conditions and frequently generate a mismatch between expected and actual performance. The present work analyses six months of monitored data from an nZEB in Denmark. A simulation model is used to analyse the effect of three different occupancy profiles on the final energy use: the ‘Compliance profile’, defined on the basis of regulations, the ‘Standard profile’, built on average data obtained from surveys, and the ‘Actual profile’, customized on measured data from the actual building case. Significant differences are detected in the three different occupancy profiles as well as in the results achieved by applying the three occupancy models in performance prediction.

The number of buildings experiencing humidity problems and fungal growth appears to be increasing as energy-saving measures and changes in construction practices and climate become more common. Determining the cause of the problem and documenting the type and extent of fungal growth are complex processes involving both building physics and indoor mycology. New detection and identification methods have been introduced, and new fungal species have been added to the list of building-related fungi. However, the lack of standardised procedures and general knowledge hampers the effort to resolve the problems and advocate for an effective renovation plan. This review provides a framework for building inspections on current sampling methods and detection techniques for building-related fungi. The review also contains tables with fungal species that have been identified on commonly used building materials in Europe and North America (e.g., gypsum wallboard, oriented strand board (OSB), concrete and mineral wool). The most reported building-associated fungi across all materials are Penicillium chrysogenum and Aspergillus versicolor. Chaetomium globosum is common on all organic materials, whereas Aspergillus niger is common on all inorganic materials.

A growing focus on occupant comfort, health and wellbeing has resulted in attempts to quantify indoor environmental quality (IEQ) and to determine the relative contributions of single IEQ aspects to an overall IEQ index. The recently developed IV20 tool assesses potential IEQ to label overall IEQ, and assign separate scores for the main indoor environment (IE) areas: thermal, visual, acoustic and air quality. In the absence of objective, universally applicable IEQ weights, this paper develops and executes a methodology asking regional experts with different backgrounds to make relative comparisons between related IE aspects. The authors hypothesize that wide-ranging subjective evaluations can be combined into useful relative weights (best operational solution based on the current status of IE literature). This paper presents results from an IE expert survey on relative IE aspect weights using simple percentile prioritization and the Analytic Hierarchy Process pairwise comparison. Results are compared to expert panel judgements to ensure validity. The advantages of this combined weight determination method are (1) that the expert survey ensures a broad spectrum of opinions and allows for input from different built environment disciplines, and (2) that the expert panel has tool-specific insight, methodology awareness and state of the art knowledge.

Research on nearly zero-energy buildings has addressed mainly the aspects of energy saving or technical and economic optimization, while some studies have been conducted on comfort and indoor air quality. However, the potential problems that may arise in low-energy buildings during the operational phase, and especially the risk of fungal growth, which can deteriorate the indoor environment and pose a health risk to the occupants, are yet to be extensively investigated. The present work intends to analyze previous research on microbial contamination in zero-energy buildings in order to identify the possible risks that may lead to fungal formation and the possible strategies to prevent the proliferation of molds. The methodology is based on a systematic literature review and subsequent critical analysis to outline perspectives on this topic. The main results indicate that high envelope insulation and inadequate ventilation are the leading causes of fungal growth in energy-efficient buildings. The need for more detailed regulation in this area is also highlighted. The study’s outcomes underline the need for more attention to be paid to the design and management of zero-energy buildings, aiming to achieve the reduction in energy demands while ensuring the occupants’ well-being.