Improve Indoor Thermal Comfort Research Articles

Moisture buffer value for hygroscopic materials with different thickness

Moisture buffering is the capacity of hygroscopic building materials or adsorbents to mitigate the humidity fluctuations in the indoor environment through the adsorption/desorption phenomenon. NORDTEST proposed the moisture buffer value to quantitively characterize the moisture buffering capacity of porous materials. Materials with high moisture buffer values have a higher ability to passively control indoor humidity conditions and thus reduce building energy consumption and improve indoor thermal comfort. However, the ideal moisture buffer value theory is based on the assumption that the thickness of the studied materials should exceed the penetration depth of that material. This assumption significantly limits the application of moisture buffer value theory to thin-layer materials, such as textiles, desiccant coating, wallpaper, wood wall panels, etc, which represent a large proportion of moisture buffering in the built environment. In this study, we developed a new numerical model to calculate moisture buffer values for hygroscopic materials with different thicknesses. Experimental measurements were also carried out to validate the solutions. The moisture buffer value of a new kind of desiccant (metal-organic frameworks) under different thicknesses were measured by climatic chamber tests. Simulated results showed agreement with both the measurements and theory. The results indicate that the new moisture buffer value model can be used to find the optimal thickness of desiccant coating or hygroscopic materials for autonomous indoor humidity control.

Green roofs and thermal comfort: a comparative study of soil layers’ seasonal thermal performance integrated with ventilation in hot climate

ABSTRACT Green roofs’ (GR) positive impact on indoor thermal conditions in hot areas may have possible negative impacts during hot and cold weather. Most previous studies have focused on GR’s positive effects as a standalone strategy without mitigating these side effects of GR application. This study contributes to a more comprehensive understanding of the impact of GR and how to mitigate the negative aspects by integrating it with other passive techniques (natural ventilation and thermal insulation). Therefore, this study experimentally compares the seasonal impact of various soil layer configurations, integrated with natural ventilation, on improving Indoor Thermal Comfort (ITC) throughout the day in summer and winter. Field experiments were conducted using two identical validated test boxes. The results revealed that clay soil reduced Indoor Air Temperature (IAT) during the daytime in summer by up to 4.7 and 4°C for low and high soil thickness, respectively. Increasing clay soil thickness improved average IAT during the daytime in summer and winter by up to 6.49% and 2.61%, respectively. Additionally, adding thermal insulation is preferred in winter, while uninsulated soil had a slight positive effect on IAT and Indoor Relative Humidity (IRH) in summer. The use of natural ventilation at night and closed-ventilated systems during the daytime in summer and winter is recommended. Clay soil could save cooling and heating energy by up to 34.8% and 12.18%, respectively. These findings might inform designers by adjusting different GR soil parameters and the importance of natural ventilation in improving multi-seasonal thermal and energy performance.

Evaluating energy generation of a building-integrated organic photovoltaic vertical façade: A case study of Latin America's pioneering installation

Building-integrated photovoltaics play a key role in the reduction of greenhouse gases emission towards sustainability in the building and construction sector. Organic solar technology holds several advantages such as lightweight, flexibility and semitransparency, suiting well for this type of application. When integrated into windows and facades, it provides a dual benefit: it acts as a solar radiation barrier, improving indoor thermal comfort, while also generating off-grid power. Besides that, organic devices are known to be more efficient than traditional photovoltaics based in silicon in diffuse and low light conditions. Nevertheless, only a few studies have been conducted in the area employing large-area commercial modules, in real operational conditions and for a long-term period. This work has the purpose of reducing this gap and shine a light on this debate bringing an analysis based on real data of a set of organic panels laminated in glass in a vertical pioneer installation in Latin America. For this, several linear regression models were tested to predict the energy generation from meteorological data and solar position throughout four years of operation, and the best models developed achieved 0.76 and 0.81 values for R2 with validation data, respectively for simple and multiple regressions. A visual analysis showed that the OPV system produced more energy in winter due to lower solar altitude, despite lower global radiation levels. The most significant variables in the models were the global solar radiation and the solar altitude. The use of glass lamination and vertical orientation likely preserved the performance of the panels, keeping energy generation consistent over four years, akin to the first year.

Handling fault detection and diagnosis in incomplete sensor measurements for BAS based HVAC system

Due to the development of sensor networks, Building Automation System (BAS) based heating, ventilation, and air conditioning (HVAC) has gradually replaced traditional HVAC to improve indoor thermal comfort and decrease energy consumption. Because of inevitable faults in sensors or networks, the real-time sensor data may be incomplete with corrupted, lost or undetected missing values. Therefore, Improved Fireworks Algorithm (IFWA)-Long Short-Term Memory (LSTM) is proposed to recover incomplete measurements in BAS HVAC sensors. Because sensor data loss mostly results from incorrect control commands from the BAS system or sensor damage, there is a high probability of concurrent sensor fault. Therefore, Independent Component Analysis (ICA)-K-Nearest Neighbors (KNN) is proposed to monitor the sensor's healthy state under the measurements recovered. This paper discusses the possible causes of incomplete measurement in BAS HVAC sensors and simulates the distribution by experiment. The experiment analyzes the data recovery capability of IFWA-LSTM for different types of missing sensor data in different sensor measurement loss scenarios. The result shows that compared to the comparative methods, IFWA-LSTM achieves a 6.45 %–86.92 % improvement in recovery accuracy and a 0.0041 to 0.6340 improvement in correlation coefficients. Subsequently, it discusses the fault diagnosis rate of ICA-KNN under full measurements and incomplete measurement recovered by IFWA-LSTM. Overall, ICA-KNN achieves an average fault diagnosis rate of 99.86 % and an average fault alarm rate of 0 % under full measurement. When applied to incomplete measurement recovered by IFWA-LSTM, ICA-KNN exhibits an average fault diagnosis rate of 92.18 % and an average fault alarm rate of 1.22 %.

Identifying bioclimatic techniques for sustainable low-rise high-density residential units: Comparative analysis on the ventilation performance of vernacular dwellings in China

Vernacular dwellings equipped with bioclimatic techniques, used to form low-rise high-density communities in most Asian regions, are of great value for the development of modern sustainable residential units. Natural ventilation is a major concern mainly because of its climate-related characteristics of improving indoor thermal comfort at extremely low ecological costs. Therefore, this study applies a comparative analysis coupled with field investigations and numerical simulations to the ventilation technologies of vernacular dwellings in different areas of China. Geometric prototypes of typical vernacular dwellings in six climate zones were generated based on field measurements. Computational Fluid Dynamic (CFD) simulations were conducted in OpenFOAM with the Reynolds Averaged Navier-Stokes (RANS) modeling approach and the RNG k-ε turbulence model. A correlation analysis of the building elements and climate factors was also performed to determine the relevant parameters affecting ventilation performance. The results revealed different emphases and verified strategies for wind environment regulation based on different local climates. Six physical parameters, namely wind projection angle, orientation, wind inclination angle, window-to-wall ratio, top-to-bottom ratio, and height-to-width ratio of the atrium, are considered to be closely related to ventilation efficiency. The findings from the current research provide quantitative evidence of the effectiveness of natural ventilation technologies of vernacular dwellings and contribute to comprehensive knowledge for designing sustainable low-rise high-density residential units with optimum ventilation functions.

Development of personalized predicted mean vote based on a real-time clothing insulation recognition system

As people’s standards for indoor environmental quality and life are getting higher and higher, many studies try to find ways to improve indoor thermal comfort through experiments and simulations. Predictive mean voting (PMV) is a widely used indicator, but personal factors used to calculate PMV are not easy to monitor. This study aimed to develop a real-time clothing insulation identification (R-CLO) system to estimate personal PMV. This study is mainly divided into three stages. The first stage is to issue questionnaires to obtain the value of the personal clothing level and analyze the correlation between different external temperatures and the clothing insulation (Icl). The second stage is to build a real-time clothing recognition model and analyze its recognition accuracy. The third stage is to use ANN to establish a clothing insulation transition model and use the outdoor temperature and the results of clothing recognition to estimate Icl. This research also established an experimental environment to verify the system’s feasibility. The results show that the system has more than 80% accuracy rate for clothes recognition, and the accuracy rate of short-sleeved tops, shorts, trousers, and skirts is more than 90%. Moreover, most of the Icl estimated by the ANN have less than 0.1 differences from the value reported by occupants. In the future, this system can also combine occupant behavior recognition to strengthen PMV prediction results to achieve more precise, comfortable air-conditioning control.

Indoor thermal comfort comparison between passive solar house with active solar heating and without active solar heating in Tibetan

Passive solar house technology has been spread for many farmers and herdsmen to improve the indoor thermal environment in Tibetan. However, due to lackage of fuels and arid cold in winter, dry cow dung and coal are popularly fired in stove in passive solar houses, which leads to indoor air pollution and poor indoor comfort. For improving indoor thermal comfort of Tibetan, an active solar heating system which consists of 7 sets of tandem solar water heaters with 30 glass evacuated solar tubes, low temperature floor heating and circulation controller was developed and tested for a common house without insulation in Gan-nan Tibetan area. Its indoor environment was compared and evaluated by PMV-PPD and LPD method to that of the same passive solar house heated by coal stove. On sunny, cloudy and snow days, the active solar heating system provided 113.1, 46.4 and 26.3 kWh of heat to room. The indoor humidity and wind speed of the experimental building were better. The indoor temperatures were 17.2-20.7, 14.9-20.5 and 11.0-14.8°C, while the compared building were 8.9-14.8, 10.1-12.1 and 7.2-10.5°C. The maximum temperature difference between head and ankle were 1.7, 1.6 and 0.9℃, and the compared building were 4, 4 and 4.7℃. The PMV-PPD on sunny day were class I and II; on cloudy day were class I, II and III; on snow day was class III. On sunny and cloudy days, the LPD were class I, on snow day was class I, II and III. The PMV-PPD and LPD for typical days of the compared building were class III. During the 179 days, the mean indoor temperature exceeded 14 ℃ for 81 days, the solar active heating system provided 12471 kWh of heat to room. The CO2 emission reduction was 12905 kg. The system's dynamic payback period were 2.57 years.

Enhancement of Indoor Thermal Comfort Using Alternative Building Materials and Construction Technology in Low Income Housing - A Case of Trivandrum, Kerala

In India, rapid urbanisation followed by increased demand for housing has led to higher energy consumption in the building sector and a larger percentage of which is contributed by the housing sector. And the population using affordable housing is higher compared to other developed countries (MOUHA, 2013). The occupants tend to achieve the desired level of thermal comfort by personal adjustments and mechanical means. Using energy intensive methods for comfort is not feasible for a country, like India, with a low energy economy. This study analyses the indoor thermal comfort in low income housing with respect to the building materials and construction technology used. Two typologies of housing were studied which includes a row housing constructed using conventional materials, with hollow brick cement plastered walls and RCC roof slabs, and a vertical stacking multi dwelling constructed using Laurie Baker’s alternative construction technology, with rat-trap bond brick walls and filler slabs. The study explored the current scenario of housing based on a thermal comfort field study using questionnaire survey and onsite measurements (following ASHRAE class II protocol) which was then simulated using Design Builder software changing the wall material used to understand the improvement in indoor thermal comfort. An adaptive thermal comfort model and neutral temperature was generated for both types of housing which was then compared with IMAC Model ranges. The adaptive comfort ranges obtained for both housing were too warm than the acceptable ranges and the PMV values in row housing are hot, while that in vertical stacking is slightly warm to warm. The neutral temperature obtained in vertical stacking housing (28 deg C) is within the acceptable range, whereas that of row housing (28.8 deg C) is greater than the upper limit range of neutral temperature under the IMAC model. The results showed that building material with good thermal performance can cause a significant reduction in indoor temperatures thus improving indoor thermal comfort. Thus indoor thermal comfort in low income housing can be improved by using alternative construction technology, without compromising cost-effectiveness and affordability, and thus contributing to energy efficiency.

The Review of the Application of the Heat Pipe on Enhancing Performance of the Air-Conditioning System in Buildings

An air-conditioning system (ACS), which consumes large amounts of high-grade energy, is essential for maintaining the indoor thermal environment of modern buildings. However, an ACS consumes almost half of the total energy of the building. Therefore, it is necessary to reduce the energy consumption of the ACS to promote energy conservation and emission reduction in the building sector. In fact, there is an abundance of waste heat and low-grade energies with the potential to be utilized in ACS in nature, but many of them are not utilized efficiently or cannot be utilized at all due to the low efficiency of thermal energy conversion. Known as a passive thermal transfer device, the application of a heat pipe (HP) in the ACS has shown explosive growth in recent years. HPs have been demonstrated to be an effective method for reducing building cooling and heating demands and energy consumption in ACS with experimental and simulation methods. This paper summarizes the different HP types applied in the ACS and provides brief insight into the performance enhancement of the ACS integrated with HP. Four types of HPs, namely tubular HP (THP), loop HP (LHP), pulsating HP (PHP) and flat HP (FHP), are presented. Their working principles and scope of applications are reviewed. Then, HPs used in natural cooling system, split air conditioner (SAC), centralized ACS (CACS) and cooling terminal devices are comprehensively reviewed. Finally, the heat transfer characteristics and energy savings of the above systems are critically analyzed. The results show that the performance of the HP is greatly affected by its own structure, working fluid and external environmental conditions. The energy saving of ACS coupled with HP is 3–40.9%. The payback period of this system ranges from 1.9–10 years. It demonstrates that the HP plays a significant role in reducing ACS energy consumption and improving indoor thermal comfort.

Thermal performance research on a novel coupled heating system combined solar air heater with ventilation PCM wall

Solar heating technology is increasingly recognized as a prominent option for clean building heating. However, challenges such as intermittent thermal energy supply and supply–demand mismatch hinder its widespread adoption. To address this issue, this paper introduces a novel coupled heating system that combines a solar air heater with a ventilation Phase Change Material (PCM) wall. A rural residential house in Tianjin was chosen as an experimental platform and comparative experiments was conducted to compare the advantages of the ventilation PCM wall with the conventional wall. Additionally, numerical simulations were utilized to address the non-uniform heat transfer in the direction of the Heat Transfer Fluid (HTF) flow by employing cascaded PCM. The experimental results demonstrated that the coupled heating system exhibited high thermal storage and release efficiency, significantly improving indoor thermal comfort. Under optimal operating conditions (air supply temperature: 35-45℃, air supply speed: 3–4 m/s), the system achieved rapid thermal storage within 4 h, reaching a maximum thermal storage efficiency of up to 87.6 %. The test room maintained a nighttime temperature of 15.7 °C, exhibiting temperatures 6.3–10 °C higher than the control room. Numerical results revealed that the cascaded PCM enhanced the thermal storage rate, particularly at the first 2.8 h of the thermal storage period, contributing to the overall efficiency and flexibility of the system. This research provides theoretical guidance for the optimal design and practical application of the ventilation PCM wall.

The Impact of Public Green Space Views on Indoor Thermal Perception and Environment Control Behavior of Residents - A Survey Study in Shanghai

To reduce energy consumption while meeting the indoor thermal comfort requirements of residential buildings, this survey study explores the visual-thermal cross-modal effect of public green space window view on residents’ indoor thermal perception, and how this effect regulates residents’ environment control behavior. Based on an online questionnaire, 424 valid data were collected from Shanghai residents during the lockdown period during which the window view is the only accessible connection to the outside. The result shows that public green space views, while not significantly changing the physical thermal sensation of residents, made a greater proportion of participants feel thermal neutral, and significantly improved the participants' environmental evaluation, thermal comfort, and thermal acceptance, resulting in a 7% decrease in using air conditioning and 7% increase in natural ventilation. Path analysis reveals that public green space window view can improve indoor thermal comfort by enhancing subjective environmental evaluation, and thus encourage passive environmental regulation behavior, reducing energy consumption. Complementing previous studies, this research provides direct evidence for the energy-saving potential of public green space in residential areas from a different angle.
 Keywords: Visual-thermal interaction; cross-modal perception; Environment control behavior; Environmental psychology;
 Sustainable design

Assessing the Potential of Integrated Shading Devices to Mitigate Overheating Risk in University Buildings in Severe Cold Regions of China: A Case Study in Harbin

Creating a comfortable indoor environment in education buildings is an important design objective. Climate change has resulted in rising summer indoor temperatures in the severe cold regions of China, and evidence of summer overheating risk in these regions has not yet been fully investigated. This study presents evidence of overheating in a university building in a severe cold region of China, discusses the potential of integrated shading devices for mitigating overheating, and proposes design ideas for the application of shading devices. Temperature monitoring and simulation were performed in a university building with natural ventilation located in Harbin, and various configurations of integrated shading devices were simulated using IES Virtual Environment software. The results demonstrate that 69% of classrooms were overheated; furthermore, south-facing classrooms could be overheated for up to 152 h during summer occupancy hours. This study finds that integrated shading devices reduce overheating hours by up to 59.2%. The design of appropriate parameters for shading devices can effectively improve indoor thermal comfort while maintaining daylight levels and controlling the increase in energy consumption. The methodology and results presented in this study offer a reference point and practical guidance for mitigating regional overheating, aiming to promote the improvement of regional standards and optimisation of thermal environments in the severe cold regions of China.

Assessment of thermal comfort in the traditional and contemporary houses in Byblos: A comparative study

This paper presents a comparative study on the thermal comfort of traditional and contemporary houses in Byblos, Lebanon. With climate change affecting indoor environments and potentially leading to increased energy consumption, achieving optimal thermal comfort is a crucial issue for building research. The study analyzes several environmental parameters and conducts an occupancy survey to assess thermal comfort in both types of houses. The questionnaire used in the survey consists of 46 questions divided into three parts: “Who are you?”, “The environment of your house?”, and “Architectural characteristics of the house.” The results show that traditional houses perform better than contemporary ones in terms of thermal comfort, due to their use of natural and passive methods. However, both types of houses have room for improvement in terms of energy efficiency. This study provides insights into potential solutions for improving indoor thermal comfort while reducing energy consumption in traditional and contemporary houses.

The advancement of research in cool roof: Super cool roof, temperature-adaptive roof and crucial issues of application in cities

Cool roofs play a significant role in mitigating urban heat islands, improving indoor thermal comfort, and saving energy. In recent years, with advances in the manufacturing of nanophotonics and metamaterials, researchers have developed super cool roofs where the surface temperature remains below the air temperature in direct daylight and temperature-adaptive roofs where the solar reflectance or thermal emissivity can change with temperature. This paper reviews the research progress and status of conventional cool roofs, super cool roofs, and temperature-adaptive roofs. This paper affirms the role of cool roofs in mitigating urban heat islands and energy conservation. And this paper also summarizes some of the crucial issues that cool roofs may face when used in cities. The effects of cool roofs on urban wind fields, planetary boundary layer heights, and pollutants above cities as well as the effects of sky view factor, atmospheric humidity, dust, and aging on the performance of cool roofs are discussed. The results show that the use of cool roofs is limited by geography and climate. The net cooling power can reach 150 W/m2 in dry, rainless, and clear sky areas. Cool roof technology is less effective in hot and humid climates because the first atmospheric window is affected to varying degrees by the increased radiation medium in the atmosphere, while the second atmospheric window is nearly closed in hot and humid climates, weakening the terrestrial long-wave radiation entering space. The use of cool roofs in warm and humid climates (over 80% relative humidity, with temperature over 24 °C) for most summer nights may limit the radiative cooling performance of the cool roof. The large-scale use of cool roofs in cities near huge lakes or seas may affect the urban wind field, causing a cooling island effect and a local build-up of pollutants. Finally, an outlook on the research prospects of cool roofs was given to provide ideas for further research.

Beyond passive House: use of evolutionary algorithms in architectural design

As buildings are accountable for one-fifth of the total greenhouse gas emissions, improving their energy efficiency is foreseen as a pivotal opportunity towards climate neutrality, answering the UN call for climate action. Thus, this work intends to study to what extent the optimisation of the geometrical characteristics of building envelope can contribute to reducing their energy consumption under different climatic scenarios. The case studies have focused on three single-family houses located in different climatic zones in southern Brazil. Therefore, an evolutionary algorithm was employed in a two-step optimisation approach. First the window area and secondly the shading solutions dimensions, considering the Passive House (PH) concept requirements. The optimisation of the window areas and shading solutions dimensions together with the PH concept resulted in a reduction of energy demand between 76 and 91% and an increase in thermal comfort between 89 and 93%. Regarding window dimensions, all scenarios experienced a significant reduction of glazed areas, from 38.9 to 60.5%. As conclusion, an adequate design of shading elements and windows significantly contribute to improve indoor thermal comfort and to reduce the buildings’ energy demand, an utmost relevant factor to be considered in the early stages of project design pursuing high energy performance buildings.

Heat-health governance in a cool nation: A case study of Scotland

Under climate change, many parts of the world are warming with increasing frequencies and intensities of heatwaves, bringing heat-health risks to places including those that have a historically temperate or cool climate. These places may have extensive experience in managing cold-health risks, while experience is lacking in dealing with heat-health risks due to their lack of historical exposure to high temperatures. This paper explores this overlooked area of the challenges and opportunities of heat-health governance in cool places using Scotland as a case study. Various important themes of heat-health governance in cool places were identified by the study, including socio-cultural barriers to intervention, vulnerable population overlaps, temporal and geographical scales, and governance arrangements. The study found challenges in managing heat-health risks including a perceived lack of heat-health risks and policy priority as well as unsuitable building stock. Meanwhile, it also identified opportunities for governing cold and heat risks holistically within existing institutional systems and creating co-benefits of improving communication and information dissemination, reducing inequality and improving indoor thermal comfort of both cold and heat as well as providing good quality greenspace. Our findings contribute to the development or improvement of national/regional strategies to manage heat-health risks not only in Scotland but also in other places with a historically cool or temperate climate.

THERMAL PERFORMANCE OF DIFFERENT BUILDING TYPOLOGIES IN THIMPHU

The building sector in Bhutan is responsible for 42% of total energy and consumes 242,916 TOE of thermal energy. The maximum thermal energy was used for space heating. As per the studies conducted on the energy efficiency of the buildings in Bhutan, the buildings are found to be the worst performance in terms of thermal and airtightness. Without the proper insulation, lack of choice of the building materials as per the climatic conditions and lacks of awareness in the society about the green building practices has led to poor indoor quality of life. Buildings located inthe high region are found to be uncomfortably cold during winter months.This research focuses on studying the thermal performance of different building typologies. The main findings of this research were on enhancing indoor thermal comfort and reducing heating energy demand by the incorporation of passive measures. The results were achieved by simulating the buildings in EnergyPlus software using the data collected from questionnaires and field surveys. The simulation results showed that among the investigated buildings, a concrete hollow block wall located at Kabesa has the less comfort hour of 15% at the existing condition. When passive interventions were incorporated into the building, the thermal comfort hours were achievable up to 32% with the load reduction potential of 65%.As for the traditional house with the adobe brick wall and timber wall at Changdagang, had more comfort hours than the building located at Kabesa. With the different set of passive intervention, it was found that comfort hour of 38% to 41% and load reduction of 25.9% can be achieved for the building with adobe brick wall and timber wall respectively. Whereas for stone masonry with cement mortar and RCC framed structure located at Begana and Langdru had a thermal comfort hour of more that 30%. However, RCC framed structure was reported to have huge demand for heating energy compared to stone masonry with cement mortar. The passive intervention prepared for RCC and stone masonry had the potential to achieve 41%-57% of thermal comfort hours. The results from all the investigated buildings revealed that the inclusion of passive design could improve indoor thermal comfort and can achieve a reduction in heating energy demand.

Triggering Deep Renovation of Buildings in Portugal

EU and national buildings related regulations are moving towards policies that improve indoor thermal comfort, reduce energy consumption and its environmental impact by establishing very ambitious targets in the emissions reduction in the decades to come. In this context, improving energy efficiency through deep energy renovations is a key action line because of its potential to meet long-term climate and energy targets. However, deep renovations need to become more environmentally friendly, more reliable in terms of performance and more attractive to all concerned stakeholders, in addition of enabling the implementation of the Near Zero-Energy Building (nZEB) assumed by the Energy Performance of Building Directive in 2010. This paper highlights the key aspects related to the strategic pillars of deep renovation and explore ongoing related funding schemes to meet Portugal´s carbon neutrality and related sustainability goals.

Energy, Thermal, and Economic Benefits of Aerogel Glazing Systems for Educational Buildings in Hot Arid Climates

The high cost of air conditioning during the summer makes it crucial to develop strategies to reduce energy use in buildings, especially in hot arid climates. Nanomaterial-based external window insulation is considered an effective method for achieving this goal. This research examines the effectiveness of using aerogel-based glazing systems combined with passive design techniques to improve energy efficiency in buildings in hot arid regions. This study presents various scenarios, including building orientation and aspect ratio, utilizing field measurements and energy simulations with aerogel-filled windows. This study is two-phased. The first phase compares two rooms with aerogel and conventional glazing in Aswan. The new glazing system made the room 0.3–1.9 °C cooler. The second phase simulated the Egyptian Japanese School in Aswan to assess the effects of aerogel glazing systems and altering the enclosed semi-open courtyard’s building orientation and aspect ratio. Results show that using aerogel glazing systems and altering the building orientation and aspect ratio can significantly reduce energy consumption and improve indoor thermal comfort. The results reveal that Scenario 1, which represents using aerogel glazing in the northern façade, could reduce the average air temperature between 0.30 and 1.49 °C below the base case (BC). Scenario 3, which used aerogel glazing on the southern facade, reduced annual energy consumption by 26.3% compared to the BC. Meanwhile, Scenario 5, a semi-open courtyard with an aerogel glazing system and an aspect ratio of 2.40, could save 25.7% more energy than Scenario 1. The economic viability of the scenarios was also analyzed using a simple payback period analysis, with Scenario 3 having the second-shortest payback period of 4.13 years. By insulating the exterior panes of windows, this study proposes that adopting aerogel glazing systems can make windows more cost-effective and ecologically sustainable.

The indoor environmental quality and energy savings potential of room ventilation units compared to exhaust-only ventilation systems in France

Humidity-controlled mechanical exhaust ventilation (RH-MEV) has been widely used in France for over 35 years, demonstrating high durability and robustness. This exhaust-only ventilation strategy is widely used as an energy-saving measure, replacing constant mechanical exhaust ventilation (Constant-MEV) systems in residential buildings. It demonstrates energy savings due to the restricted airflows, but as a downside, the building’s indoor air quality (IAQ) often deteriorates. Moreover, it is impossible to recover heat with exhaust-only ventilation systems, which means that energy consumption for space heating is still quite significant and cold supply air temperatures are frequently introduced to the heated spaces. Room ventilation units (RVUs) with heat recovery represent an alternative ventilation solution allowing simple installation through the façade and providing fresh outdoor air and exhaust ventilation to each room. This study investigates these units’ energy saving potential and indoor environmental quality performance as an alternative solution to centralized exhaust-only ventilation systems. The dynamic simulations were performed for a reference residential building under various French climatic conditions for a heating season. The three ventilation strategies investigated were Constant-MEV, RH-MEV and room-based ventilation with RVUs. The results demonstrated 61–85% savings in space heating demand with the RVUs, compared to Constant-MEV under all climatic conditions. Compared to RH-MEV, the RVUs saved 44–75% energy for space heating while the CO2 concentration and relative humidity levels were decreased due to RVUs’ constant air exchange rate. In all cases, RVUs provided considerably higher supply air temperatures due to the implemented heat recovery, which can potentially improve indoor thermal comfort.