Evaluating the impact of Ventilation strategy and Window Opening Area on Overheating Issues

Thermal mass has the benefit of regulating energy in buildings and generates potential savings in energy and CO2 emissions. The result of the effect of climate change will be more intense and longer periods of summer heat waves. Use of the building thermal mass can reduce overheating in summer and minimise the need for cooling energy, reducing energy consumption and CO2 emissions. Night ventilation is one of the key factors to maximise the benefits of thermal mass in buildings but due to issues in security and pollution, in many situations windows can only be effectively opened during occupied hours. Cross ventilation provides gains versus the use of single side ventilation but it is not always possible to have it. The main aim of this study was to evaluate the influence of window opening area and night ventilation on the thermal mass benefits to overheating by exposing the thermal mass. A second aim was to understand the further benefits that could be obtained by using cross ventilation in reducing overheating This study was based on dynamic thermal simulations to analyse the overheating performance of a test room with covered and exposed thermal mass. The testing room was simulated for a range of window openings from 5% to 40% area opening with single-sided and cross natural ventilation. Fifteen building simulation models were performed using the Energyplus plugin in DesignBuilder to evaluate the effect on the thermal mass behaviour to mitigate overheating according to different window opening areas during occupied hours in two different natural ventilation conditions. The simulation results show that by exposing and making use of the room thermal mass, the number of hours above 28ºC can be reduced with the reduction being proportional to the window opening area. The CIBSE TM52 overheating assessment is only passed by using window opening areas above 20% with a cross ventilation strategy, but they could generate occupants discomfort

Impact of Climate Change on the Heating Demand of Buildings. A District Level Approach

There is no doubt that during recent years, the developing countries are in urgent demand of energy, which means the energy generation and the carbon emissions increase accumulatively. The 40 % of the global energy consumption per year comes from the building stock. Considering the predictions regarding future climate due to climate change, a good understanding on the energy use due to future climate is required. The aim of this study was to evaluate the impact of future weather in the heating demand and carbon emissions for a group of buildings at district level, focusing on two areas of London in the United Kingdom. The methodological approach involved the use of geospatial data for the case study areas, processed with Python programming language through Anaconda and Jupyter notebook, generation of an archetype dataset with energy performance data from TABULA typology and the use of Python console in QGIS to calculate the heating demand in the reference weather data, 2050 and 2100 in accordance with RCP 4.5 and RCP 8.5 scenarios. A validated model was used for the district level heating demand calculation. On the one hand, the results suggest that a mitigation of carbon emissions under the RCP4.5 scenario will generate a small decrease on the heating demand at district level, so slightly similar levels of heating generation must continue to be provided using sustainable alternatives. On the other hand, following the RCP 8.5 scenario of carbon emission carrying on business as usual will create a significant reduction of heating demand due to the rise on temperature but with the consequent overheating in summer, which will shift the energy generation problem. The results suggest that adaptation of the energy generation must start shifting to cope with higher temperatures and a different requirement of delivered energy from heating to cooling due to the effect of climate change

Numerical investigation of evaporative cooling strategies on the aero-thermal performance of courtyard buildings in hot-dry climates

In hot and dry urban environments, courtyards help mitigate extreme heat and influence the urban microclimate. These structures not only provide light and private outdoor spaces but also aid in mitigating the urban heat island (UHI) effect through improved airflow and evapotranspiration. Courtyards, being central open-air areas enclosed by buildings, are crucial in creating opportunities for natural ventilation driven by wind and buoyancy-induced forces, thus serving as a microclimatic regulator. This study investigates the role of courtyards in modulating their microclimate and adjacent indoor areas by integrating evaporative cooling strategies to enhance cooling in these spaces. While numerous studies have been conducted on the role of water bodies in evaporative cooling, the aero-thermal impact on adjacent indoor spaces remains less understood. Addressing this gap, the present research explores the effect of an evaporative cooling system on the wind and thermal conditions within a courtyard and examines different natural ventilation modes, namely, single-sided and crossflow ventilation, in indoor spaces. A computational fluid dynamics (CFD) model, validated against wind tunnel experimental data, was employed to simulate various evaporative cooling water spray configurations. The results reveal complex courtyard microclimates with diverse cooling effects influenced by room orientation and floor level. Specifically, in single-sided ventilated courtyards, water sprays significantly improved the indoor thermal environment, with the average temperature across all rooms decreased by 2.06 °C, and humidity increased by 4.29 %. However, in cross-ventilated courtyards, water sprays' cooling and humidifying effects were relatively less effective. This research underscores the potential of evaporative cooling technology in improving the microclimate of courtyards, with practical applications extending to urban design and architecture. By tailoring cooling strategies to specific courtyard configurations, urban planners and architects significantly improve indoor comfort levels and energy efficiency

Evaluating the Influence of Program Type Building Parameters on UBEM: A Case Study for the Residential Stock in Nottingham, UK

In the midst of rising concern about the implications of climate change, the European Union and the United Kingdom appears to be on the verge of establishing policies to reduce greenhouse gas emissions. The urban building energy models could inform energy analyzers and decision makers for the future results that specific comprehensive energy refurbishment strategies and energy supply infrastructure changes might have. Nonetheless, the data challenges that emerge are various. The lack of data availability and reliability, the data computing issue and data privacy are, only, some of the challenges of building energy modelling, which are intensified in urban scale. Therefore, the investigation of the influence of building parameters on the energy demand results is deemed necessary, in order both to understand the minimum data requirements for urban energy modelling, and the impact of them before the design phase for the new constructions. Therefore, this Paper’s intention is to inform stakeholders from energy analysts to data capture companies, about the influential building parameters, as regards to the Program Type, such as the infiltration, the domestic hot water and the ventilation. An UBEM physics-based approach, for the estimation of the annual energy demand, is implemented with the use of Grasshopper software, and the visualization of the results is done with the QGIS software. The case study is in Nottingham city, in UK, and the energy demand for the whole year of the dwelling stock is estimated. Then, a sensitivity analysis for the influence of the Program Type building parameters is presented. The results have shown that the most impactful parameter among the three under-tested is the infiltration (airtightness) of a dwellin

Assessing Urban Building Energy Demand in Future Climate Scenarios: A Case Study in Nottingham,UK

The most recent report on climate change from the IPCC (Intergovernmental Panel on Climate Change), in 2023, states that urgent action is needed to tackle global warming. The IPCC points out that by 2040, there is a greater than 50% risk that the temperature worldwide will approach or exceed 1.5 degrees Celsius (2.7 degrees Fahrenheit). On top of that, under high-emissions scenarios, the global temperature could increase to that borderline even earlier, before 2037. Since building stock accounts for 40% of total global energy usage and 33% of greenhouse gas emissions each year, their continuous high demand for energy leads to the rapid growth of CO2 emissions. Accounting for that, the energy performance of buildings in urban scale under the future climate scenarios is a significant factor in immediately assisting with climate change mitigation. The purpose of this project was to estimate the influence of the climate change on the energy demand of two neighbourhoods in Nottingham, in United Kingdom, by comparing their current energy performance to the future. The methodology consists of the use of geospatial data for the building geometric parameters, in combination with energy-related data from the EPC (Energy Performance Certificate) dataset. The datasets were processed with Python programming language and the QGIS software, and the final dataset was imported to an energy model that was constructed with the use of Rhino and Grasshopper, with EnergyPlus simulations on the background. The model was run under 9 different climate scenarios, namely under the present, under 2050s and 2080s for 4 different future scenarios each year. The results have shown that the absence of building stock renovation will lead to an accountable decrease in the heating demand of buildings, while the risk of overheating will be critically escalating. </em

The nonlinear analysis of an innovative slit reinforced concrete water tower in seismic regions

Water towers are widely used in our society as one of water distribution facilities within water network systems. In the event of a severe earthquake, however, a single plastic hinge that occurs in a water tower could cause its total collapse before nonlinear resources of the rest of the tower remains fully utilised. This research presents an innovative technique for the assembly of a water tower using the slits in its reinforced concrete shaft for the purpose of mitigating the seismic response. Slit shafts were designed to have four slits at 90 degree intervals along the full height of the shafts. The shaft parts were connected to each other at the bottom, top and every five meters with coupling beams. The slit width was used as a variable in this study which varied between 50 mm and 2000 mm. The nonlinear seismic performance of the proposed slit towers was analysed by means of a finite element approach with respect to soil types defined in Eurocode 8 and seismic behaviour were compared to the solid water tower. A detailed observation of the compression and tension stress distributions with respect to the slit width was performed. The obtained analytical results revealed that slit width in the reinforced concrete tower affect the failure mode and stiffness of a water tower significantly. With an appropriate design, the conversion of a solid water tower into a slit tower can significantly increase its ductility under seismic action without significantly compromising its bearing capacity. The results showed that contours of tension and compression stress intensity in shafts, which could lead to a failure of water towers, highly depended on the slit width. In the solid water tower, the stress concentration dominated at the base of the shaft, however in the narrow slit water towers the stresses were equally distributed along the height of the shafts. Also, the stresses were mostly concentrated at the top of the shafts in the wide slit water towers. Conclusively, the results provided useful information regarding the compression stress distribution along the slit shafts in the water towers which can be used in obtaining an optimum slit shaft design for different soil types

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Experiment and Numerical Investigation of a Novel Flap Fin Louver Windcatcher for Multidirectional Natural Ventilation and Passive Technology Integration

Natural ventilation devices such as windcatchers are incorporated into the building design to provide fresh air supply, energy consumption reduction and, in some cases, indoor thermal comfort. However, unfavourable weather conditions limit the operation period of windcatchers, and researchers have explored the integration of passive/low-energy heating, cooling and dehumidification technologies to address this issue. While previous works have addressed the cooling or pre-heating of the supply air, most have not investigated the impact of changing wind conditions which, in some cases, render the windcatcher ineffective. Thus, a novel windcatcher with inlet openings equipped with flap fins was proposed to provide a fresh air supply irrespective of the wind direction and allow for passive/low-energy technology integration. Inspired by the check valve device, the flap fin mechanism allows wind to flow only one way into the windcatcher's supply channel. Hence, changing wind directions would not affect the ventilation rate and the location of the supply and return channels, so passive technologies can be applied effectively. The lightweight flap fin operates via gravity and takes advantage of the wind pressure around the openings to control the airflow. An open wind tunnel and test room were developed to experimentally evaluate the ventilation performance of the proposed windcatcher prototype, and a validated Computational Fluid Dynamic (CFD) model was developed. The results showed that the ventilation performance of the flap fin louver windcatcher was independent of the wind direction in the field test and wind tunnel experiment, and the use of lighter and longer fins would enhance the ventilation rate