Sound-absorbing barriers and screens are commonly employed to mitigate one of the most annoying noises in workplaces: intelligible speech. However, isolating their acoustic contribution from all the other elements (ceilings, wall treatment, or carpets) is challenging. This study uses a wave-based room acoustic modeling approach to explore the acoustic function of desk screens in a virtually reconstructed open-plan office. Analytical models, finite-element simulations, and experimental data from 3D-printed samples allowed defining a multi-resonator unit cell, attenuating the voice signal's main formants. The sound-absorbing panels composed of the unit modules iteration are assessed in the full-scale digital model, starting from the calibrated version on in-field measurements. The wave-based engine employed in this study grants the crucial aspect of computing the acoustic performance of the potential multi-resonator screens, including the edge diffraction due to their desk installation. In the virtual workplace, the acoustic role of such screens in increasing the speech level decay is outlined in comparison with the calibrated scenario and the traditional screens' option.

Heat, air and moisture (HAM) models allow efficient simulation of the building components’ hygrothermal behavior. However, specific model assumptions, simplifications and approximations, as well as users’ preferences, biases and mistakes in the implementation of material properties, boundary conditions, etc., may yield divergences among results from different models. The lack of a standard framework for HAM model quality assessment results in inconsistent benchmark cases and assessment methods in previous studies. Thus, this state-of-the-art empirical round robin validation targets to test the robustness and the reliability of HAM models in predicting one-dimensional hygrothermal responses of building components under controlled boundary conditions. It ran from 2023 to 2024, was coordinated by KU Leuven, and achieved participation of 38 groups from 19 countries. A comprehensive experimental dataset serves as the “correct answer”, and simulation results from other participants form “reference answers”. Since the boundary conditions are simple and explicit, the material properties’ implementation has the main impact on the simulated hygrothermal responses. Most models prove to be robust, particularly in the heat transfer prediction. The moisture transfer prediction, on the other hand, looks more challenging. Reliability is also achieved by most models, as the deviations between simulation and experimental results are reduced when actual measured material properties are implemented as inputs. However, inappropriate and/or incorrect implementations are also observed. More in-depth investigations are performed for a better understanding of HAM-simulation tools and achieving their better performance in predicting and interpreting the hygrothermal behavior of building components.

Binnenisolatie is vaak de enige mogelijke na-isolatietechniek om historisch baksteenmetselwerk thermisch te verbeteren. Helaas brengt deze techniek ook schaderisico’s met zich mee, zoals bijvoorbeeld vorstschade, schimmelgroei of houtrot van ingewerkte houten elementen. Verder onderzoek is nodig, in het bijzonder rond biobased isolatiesystemen. In dit artikel tonen we een in-situ meetcampagne van het landgoed de Grote Noordijk te Wilp, waarbij het hygrothermische gedrag van massieve metselwerkwanden na-geïsoleerd met kalkhennepisolatie werd opgevolgd. Vervolgens vergelijken we de meetresultaten met de resultaten van numerieke simulaties. De studie werd uitgevoerd in het kader van het onderzoeksproject ‘Energetische prestaties van massieve bakstenen gevels in woonhuismonumenten’, gesubsidieerd door de Rijksdienst voor het Cultureel Erfgoed.

Sustainable development requires efficient planning and management of both natural and built resources. The identification of urban forms that best balance exposure to solar radiation and urban noise, ensuring compliance with residential construction regulations and European directives may be carried out through simulations. The proposed methodology involves simulating various scenarios and adjusting parameters of selected urban forms to evaluate the availability of solar radiation and the noise exposure on building façades within a specific context. In addressing the requirements for solar and noise optimization, predictive models (solar and noise) were employed, utilizing urban form indicators to relate these three variables. The case study demonstrates the inverse behavior of these variables in relation to the same urban forms. The findings highlight the optimal urban forms for each scenario. The enclosed form was identified as the most suitable for minimizing noise exposure, while the linear form is optimal for maximizing solar radiation exposure. This approach allows the designer to make informed decisions that balance these competing requirements, achieving a compromise between optimizing thermal and acoustic performance. The ultimate goal is to enhance the overall comfort of the building, reduce energy consumption, and promote a sustainable building solution.

Rising temperatures are leading to an increase in cooling energy demand and thermal discomfort due to overheating. Despite dynamic switchable glazing being a promising solution for controlling solar radiation while preserving user access to outdoor views, their cost is currently a barrier to their widespread adoption. The recent development of low-cost inkjet-printed switchable glazing offers a cost-effective alternative; however, its performance remains uncertain concerning its contributions to energy efficiency and user satisfaction in terms of thermal comfort and visual experience. This study presents a multi-domain evaluation of the performance of a novel low-cost inkjet-printed glazing with users in terms of their satisfaction with the environment, personal control and interaction. In comparison to a conventional façade with static glazing and external roller blinds, the EC glazing performed better than the conventional façade if the shading is fully down. In this case, higher satisfaction was measured in terms of view clarity, daylight access and colour in the room with the EC glazing. When comparing the performance of the EC glazing at the clearest state with conventional glazing with blinds raised, users’ satisfaction was not significantly different, except for the satisfaction with view clarity. Despite the long transition time of the EC glazing, users were not significantly dissatisfied with the speed of transition. Overall, these preliminary results show that this novel EC glazing is well-accepted by users especially as an alternative to traditional dark roller blinds, but further research is required to investigate its performance during summer.

Op 18 februari 2025 is Martin Tenpierik benoemd tot hoogleraar Bouwfysica aan de faculteit Bouwkunde van de TU Delft. Dit stuk is geschreven naar aanleiding hiervan en geeft enkele van de belangrijke uitdagingen binnen het vakgebied voor de komende jaren weer. Op 6 maart 2026 om 15 uur zal zijn intreerede plaatsvinden in de Aula van de TU Delft.

The increase in carbon emissions has contributed to rising global temperatures, necessitating higher energy consumption in buildings to maintain thermal comfort during the summer months. The building envelope, as the protective layer of a building, plays a critical role in maintaining indoor comfort and dictating building energy use. However, when assessing the performance of the building envelope, occupant interaction is poorly considered. This study investigates the impact of occupant façade interaction when evaluating alternative façade solutions for thermal comfort in summer season. Occupant behaviour models, specifically window operation models, are identified and implemented to assess their impact on indoor comfort and air quality. This is done by first identifying façade archetypes and generating scenarios with selected occupant behavior models. The results revealed that occupant interaction with windows significantly impact internal air temperatures and thermal comfort, while alternative façade solutions have a relatively lower impact. Largest ventilation areas were associated with lower air temperatures. Consequently, the number of discomfort hours are also lower in scenarios with occupant interaction compared to without. The impact of the façade ventilation area, window-to-wall ratio and thermal mass was more relevant in the scenarios where windows were always closed. The findings of this study can serve as a foundation for the development of strategies that promote occupant interaction with the façade which can lead to reduced building energy demand.

Rising temperatures are leading to an increase in the cooling demand of buildings. Electrochromic (EC) glazing can be a promising solution for controlling solar heat gains while maintaining outdoor views. This paper presents the results of the monitoring of prototype panels of a novel type of inkjet-printed EC glass under real use and weather conditions in a small office building in the Netherlands. This building contained two identical west-facing meeting rooms of which one was equipped with EC triple glass IGUs and the other with normal triple glass IGUs. Each room was equipped with local heating/cooling units of which the energy use was monitored, and with an extensive environmental sensor network. Sensor and calendar data was fed into an energy balance model for each of the rooms for the entire measurement period, allowing to correct for differences between the two rooms with respect to heat losses and gains and use conditions. The results of the monitoring showed that in the meeting room with EC glass IGUs, the heating demand increased by 34% in Jan.-Mar. 2024 while in Sept. 2023 the cooling demand decreased by 3%. The main reason for the increase in heating demand was found to be the lower g-value of the EC glass IGUs in clear state as compared to the normal IGUs. The almost similar cooling demand was a result of a trade-off between the lower direct solar transmittance of the EC glass IGUs and the heating up of the absorptive layer inside the IGUs. Furthermore, an experiment with participants showed that in general in dark state, satisfaction with view clarity, daylight colour and daylight availability was higher for the EC glass IGUs. In transparent state, no significant difference was perceived between the EC glass IGUs and standard IGUs, except for view clarity.

This study introduces a systematic framework to facilitate decision-making in selecting renovation options for preparing existing Dutch dwellings for utilising lower temperature heat (LTH) supplied by district heating (DH) systems. The framework was applied to an archetype terraced intermediate house built between 1945 and 1975 to identify the renovation options required for transitioning from existing High-Temperature (90/70℃) supply from gas-boilers to Medium Temperature (70/50℃) supply from DH systems. The framework's effectiveness was demonstrated by systematically assessing the readiness of the archetype dwelling for LTH use, reducing the number of viable renovation options, evaluating the financial feasibility using a life cycle costing approach and generating decision support insights through comparative analysis. The framework identified an optimised solution involving cavity wall insulation, exhaust ventilation and switching to low-temperature radiators. This solution incurs low initial investment and global costs while significantly reducing space heating and underheated hours. As a result, the framework provides tangible solutions for the specific use case and can serve as a valuable tool for dialogue among stakeholders during the decision-making process.

Analyzing the impact of aircraft noise on urban areas requires specific consideration of sound propagation over long distances, which is not typically covered by tools designed for indoor acoustics. Although it is unclear to what extent existing parametric tools that combine 3D modeling and acoustic simulation can accurately replicate these spatial scales, they provide a valuable means of exploring design options and optimizing performance. One such tool, Pachyderm, a numerical model based on geometrical acoustics, was used to simulate a field lab near Schiphol Airport to assess its applicability for urban acoustics simulation. The simulation results were compared to in-situ measurements, with a focus on differentiating the effect of air noise attenuation based on varying building shapes and the accuracy of the resulting sound pressure level values. The most decisive factors in reducing noise in the courtyard were found to be the building’s orientation and slope relative to the sound source. However, as the design complexity increased with the addition of features such as shielding, the accuracy of the simulation results decreased.

The Dutch government aims to eliminate natural gas for residential heating in 1.5 million homes by 2030. One strategy is connecting existing dwellings to lower-temperature district heating (DH) systems, although these dwellings might require energy renovations. The heterogeneous dwelling stock causes varying renovation needs that complicate the energy transition. The present study addresses this issue by assessing the building-level parameters affecting the readiness of the Dutch terraced-intermediate and apartment types for lower-temperature heating (LTH) supplied by DH systems. A sampling-based approach was employed to capture variability within these dwelling types, addressing the limitations of archetype-based methods. The findings suggest a sample size of 1300 to represent the variations in these dwelling types. Parametric simulations and machine learning methods were used to identify significant building-level parameters for medium-temperature (MT: 70/50 °C) and low-temperature (LT: 55/35 °C) supply levels. These include heating setpoints (desired indoor temperature) and ventilation-related parameters (ventilation system type and air infiltration rate), followed by fabric-related parameters (roof, glazing, wall, ground, and door insulation) and geometric properties (orientation, compactness ratio, and window-to-wall ratio). Additionally, radiator oversizing also impacts LTH readiness. These results broadly apply to the studied dwelling types, although feature importance varies by supply temperature and dwelling type. The findings can guide stakeholders in assessing current conditions and prioritising renovation measures, aiding the development of targeted renovation solutions. Encompassing the representative variations within studied dwelling types enhances the robustness of the results. However, incorporating more refined data could improve the accuracy of the findings, better supporting the energy transition of these dwellings.

Façade properties influence human responses in a multidomain manner and these interactions needs to be accounted for effective façades design, particularly to increase resilience to extreme heat. From existing research, it remains unclear whether the glazing colour properties can influence occupant thermal sensation, preferences, and acceptance, or whether higher temperatures affect glare sensation or view perception. This study investigates the combined influence of tinted glazing in façades through a preliminary experimental campaign with human participants exposed to varying glazing hues (neutral and blue) and indoor air temperatures. While previous research has examined the impact of coloured daylight on thermal and glare sensation under thermal conditions close to neutrality, this paper compares occupant responses at neutral and warm thermal conditions by performing repeated measurements.

An experiment was conducted to measure potential differences in human thermal sensation, acceptance, preference, and glare sensation under two thermal conditions (operative temperatures of 25°C and 30°C) and two daylight colours (neutral and blue). Thirty-nine participants were exposed to different combinations of temperature and glazing colour in a randomized order. Data were collected using questionnaires and thermal physiological sensors to capture human responses to these varying conditions. In terms of visual perception, the results demonstrate a distinction between the two visual scenarios, particularly regarding obstruction and glare at a neutral temperature. At the level of thermal sensation, the impact of blue-tinted glazing is not statistically significant with this number of participants. However, a slight difference is observed between the two scenarios at both temperature levels.

Aircraft noise is a major stressor for communities in the vicinity of airports. Aircraft noise prediction models omit the built environment, based on an implicit assumption that the impact of buildings on the propagation of aircraft noise is neglectable. In this article a study is presented in which aircraft noise levels were measured near walls facing towards and away from aircraft flyovers in an urban test environment near Amsterdam Schiphol Airport. The test environment comprises three adjacent courtyards, each enclosed by stacked shipping containers. To examine the influence of street geometry on aircraft noise, specifically for slanted roofs and building insets, the shipping containers were stacked in a different pattern around each courtyard. In total, sound levels for 2383 aircraft flyovers were analysed across five months at ten microphone positions within the courtyards, for both arrivals and departures. Depending on the geometry of the courtyards, mean differences (L_A,max) between facades with- and without a line of sight towards the aircraft ranged between −1,3dBA and 5,0dBA for arrivals, and 8,7dBA and 13,6dBA for departures. SEL values ranged between between −0,8dBA and 4,3dBA for arrivals, and 8,1dBA and 11,6dBA for departures. The results suggest that slanted roofs perpendicular to the flight direction deflect incident sound, substantially reducing the sounds levels inside courtyards. Contrarily, building insets at building sides facing away from the flight paths did not reduce sound levels underneath the overhangs significantly. The findings stress the importance of architectural and urban design to mitigate aircraft noise.

Accurate knowledge of solar radiation data or its estimation is crucial to maximize the benefits derived from the Sun. In this context, many sectors are re-evaluating their investments and plans to increase profit margins in line with sustainable development based on knowledge and estimation of solar radiation. This scenario has drawn the attention of researchers to the estimation and measurement of solar radiation with a low level of error. Various types of models, such as empirical models, time series, artificial intelligence algorithms and hybrid models, for estimating and measuring solar radiation have been continuously developed in the literature. In general, these models require atmospheric, geographical, climatic and historical solar radiation data from a specific region for accurate estimation. Each analysis model has its advantages and disadvantages when it comes to estimating solar radiation and, depending on the model, the results for one region may be better or worse than for another. Furthermore, it has been observed that an input parameter that significantly improves the model’s performance in one region can make it difficult to succeed in another. The research gaps, challenges and future directions in terms of solar radiation estimation have substantial impacts, but regardless of the model, in situ measurements and commercially available equipment consistently influence solar radiation calculations and, subsequently, simulations or estimates. This article aims to exemplify, through a case study in a multi-family residential building located in Viana do Castelo, a city in the north of Portugal, the difficulties of capturing the spectrum of radiations that make up the total radiation that reaches the measuring equipment or site. Three pieces of equipment are used—a silicon pyranometer, a thermopile pyranometer and a solar meter—on the same day, in the same place, under the same meteorological conditions and with the same measurement method. It is found that the thermopile pyranometer has superior behavior, as it does not oscillate as much with external factors such as the ambient temperature, which influence the other two pieces of equipment. However, due to the different assumptions of the measurement models, the various components of the measurement site make it difficult to obtain the most accurate and reliable results in most studies. Despite the advantages of each model, measurement models have gained prominence in terms of the ease of use and low operating costs rather than the rigor of their results.

Changing outdoor conditions, i.e. higher outdoor air temperature, higher occurrence of heatwaves and outdoor air pollution, increase the risk of overheating and accumulation of air pollution in homes. Previous studies showed that high indoor air temperatures and air pollution affect occupants’ health, resulting in cardio-vascular and respiratory diseases, eyes and skin symptoms, and mortality. Measures to increase energy efficiency of renovated and newly built homes can further increase health risks during extreme weather events and can increase the outdoor temperature. Moreover, the rise of the outdoor air temperature in Europe is higher than the global average.

Therefore, understanding of the extent of current overheating and indoor air pollution and of the contributing factors is necessary to identify the required adaptability of dwellings in Europe to changing outdoor conditions. The objective of this study is to systematically review consequences of changing outdoor conditions, building characteristics, and technology on the indoor environment and occupants’ health in homes in European countries during summer.

This review focuses on empirical studies, as these enable to capture real world interactions of occupants and buildings in relation to outdoor conditions. Varying outdoor conditions, building-, and occupant-related aspects in different European climate zones are discussed. Main findings are that overheating already occurs in normal summers in temperate and northern European countries, while variation in overheating is related to occupants’ adaptative behaviour and building-related aspects. Based on the review, it is suggested to investigate adaptability of dwellings to changing occupants’ needs, new energy efficient technologies, and changing outdoor conditions.

This study aims to evaluate the impact of different urban building geometries (six courtyards, two canyons, two slabs) on heat mitigation and aircraft noise attenuation, in order to support an evidence-based retrofit plan for future airport neighborhoods. Using ’Pachyderm + ENVI-met simulations + field measurements’, we found that the slanted-roof, low-rise courtyard exhibited optimal acoustic-thermal performance (SPLmin = 71.1 dB(A), σU T CI < 5 ◦C), while the mid-rise canyon demonstrated limited performance (SPLmin = 93.4 dB(A), σU T CI > 10 ◦C). These findings were observed under averaged boundary conditions of a 140 dB(A) aircraft sound source and a diurnal MRT range of 60 ◦C on a heatwave day in July 2022.

Vertical greening can be used to absorb and scatter sound, which may reduce noise levels in street canyons. In this paper, a literature review is presented, which combines results and methods from over 40 individual studies. The article describes the guiding principles behind the acoustic effects of vertical greening and provides an overview of the prevalent research methods. The article shows that vertical greenery is effective for the reduction of mid and high frequency noise, unless air cavities or resonators are introduced inside, or behind, the systems. The review also reflects on studies with an emphasis on the application of vertical greenery in streets and urban blocks. The aim of the article is to set out the key design parameters for noise reduction that can be achieved by vertical greening, focusing on designers and engineers.

Aircraft noise is a major source of noise pollution in areas close to airports. Previous studies showed that the design of the urban and architectural context affects local sound levels. Due to surface reflections and edge diffraction, sound levels are reduced or amplified, depending on building geometry and surface materials. Compared to other traffic sources in cities, aircraft noise is currently neither integrated in sound prediction models, nor validated for such purposes. To validate the results from previous computational studies, a full scale experiment was set up. In the experiment, sound and weather data is collected which is used to identify the influence of building geometry and cladding on the propagation of aircraft noise. A subset of the measurements collected on days without wind was used to validate a method for measurements with scale models in an an-echoic room. Based on a series of discrete mono-pole source positions, three flight paths were simulated. Measurements in the an-echoic room were compared with the measurements in the full-scale field lab. This paper presents the results of the experiment and sets out a method for scale model experiments focusing on the prediction of sound in urban canyons for overhead sound sources.

Due to environmental concerns, bio-based materials are being increasingly investigated and used in buildings. In general, the density of these materials, and thus their thermal inertia, is low. Thermal inertia can be beneficial for reducing the energy use of buildings by damping indoor temperature fluctuations or by reducing and delaying incoming (solar) heat through the façade. This study explores the thermal inertia of regular-sized bricks made of a sugar-beet-pulp/starch mixture (BP/S), and with 17 circular holes inside. The holes were filled either with the BP/S mixture, with air, with a stabilised phase change material (PCM) gel or with a salt-hydrate based PCM. The brick was insulated on all sides but one. Two series of experimental measurements were performed: 1.) a heating film placed at the back (insulated) side of the brick heated the brick until steady-state conditions were reached; 2.) the heated brick was then passively cooled down to ambient temperature by cutting the power to the heating film. Numerical simulations of these experimental measurements were also modelled using the COMSOL Multiphysics® software. In addition, simulations were run to study the thermal inertia of a full brick wall made out of 1 layer and of 4 layers of the BP/S brick with and without PCM, exposed to a combination of a sinusoidal outdoor air temperature fluctuation with an imposed radiation flux on the outdoor surface, representing summer conditions. The results show that the brick in which the holes were filled with phase change material had a slower temperature response and thus higher thermal inertia than the bricks in which the holes were filled with BP/S or with air. The salt-hydrate based PCM with the higher latent heat of fusion led to the slowest temperature response and highest thermal inertia. Furthermore, the calculated simulations could accurately reproduce the experimental measurements. Applying PCM in thick walls (40 cm) made of BP/S bricks however hardly affects the temperature amplitude damping and time delay of the complete wall. The addition of PCM therefore is only effective for thinner walls (10 cm).