Multi-storey Office Building Research Articles

Configuration optimization and performance analysis of hybrid PV/wind systems in building groups

Distributed hybrid renewable energy is a promising technology for addressing environmental and energy issues, and its performance and system configuration play an essential role in the application. However, the contribution of energy sharing among buildings in building groups to the matching performance has yet to be fully explored. This study established a joint MATLAB-TRNSYS optimization model for the hybrid PV/wind building system to investigate the matching performance of energy consumption in building groups and energy production in PV/wind systems. The optimal system configuration for three objectives, technical, economic, and environmental, was also studied using the multi-objective particle swarm algorithm. Several factors influencing system performance and configuration were considered: renewable energy hybrid, a hybrid of different buildings, intensity of energy use and energy resource, and economic parameters. The results reveal that a hybrid system outperforms a single system, particularly a PV system with a smaller roof area and less installed capacity. Additionally, wind turbines contribute more to system performance than PV panels. Mixing buildings with different heights and functions could also improve system performance by renewable energy sharing in most instances, except multi-story office buildings. Increasing wind resources improves system performance more than solar resources, and increasing energy use intensity negatively impacts system performance for residential buildings but is beneficial for office buildings. Higher grid prices and feed-in tariffs can bring more economic benefits. This study revealed the contribution of energy sharing among different buildings, which could support better application of distributed hybrid renewable energy systems in complex urban environments.

Towards net-zero embodied carbon: Investigating the potential for ambitious embodied carbon reductions in Australian office buildings

Embodied carbon is recognised as a major contributor to building-related greenhouse gas (GHG) emissions. In response, ambitious targets have been posed to reduce embodied carbon in the built environment, including the aspiration of ‘net-zero embodied carbon’. This research uses a life cycle assessment (LCA) methodology to explore the magnitude of embodied carbon reductions viable within a multi-storey office building in Australia. It compares a typical building with more ambitious design scenarios to determine if net-zero embodied carbon is feasible in the current context and how design, material and methological decisions impact this. The results show that upfront embodied carbon reductions of 17–45% are achieveable with ambitious design and material changes, including a full timber structure, hybrid timber-aluminium façade, reduced columns grids, straw insulation, and more. However, the magnitude of reductions is highly influenced by material data sources and methodology. Net-zero embodied carbon was achievable when considering biogenic emissions stored in timber and other biomaterials, although only temporarily, for a period of up to 19 years. In response, we propose a new term ‘temporal net-zero embodied carbon’ to identify the point in time during a building's life cycle when it can no longer be considered a temporary carbon sink. The paper concludes by highlighting the opportunties and challenges temporal net-zero embodied carbon presents in terms of transparency and reliability of metrics, the need for consistent approaches to measurement and benchmarking, and the challenges of achieving large-scale embodied carbon reductions in the office sector.

Thermal regulation enhancement in multi-story office buildings: Integrating phase change materials into inter-floor void formers

Addressing the thermal loss from building envelopes is a crucial challenge and requires the exploration of various mitigation strategies. This study employs comprehensive 3D computational fluid dynamics simulations to investigate the incorporation of various bio-based Phase Change Materials (PCMs) including CrodaTherm (CT) 19, CT21, and CT24W, within inter-floor void formers between the roof-floor boundary in multi-story office buildings to optimize energy management during inactive periods in one of the adjacent units. Aside from the PCM type, the void former shape, its placement, and the combinations of PCMs and insulating layers are examined through heat flux and solid fraction plots as well as liquid fraction contours. Results highlight the exceptional performance of CT24W-integrated void formers, achieving a remarkable 36.74 % reduction in the 48-h average heat flux in comparison with the case without void formers, and offering lower heat flux values than the scenario with insulating layers for 89.38 h (endurance time). Based on the findings, with identical PCM volumes, the semi-ellipsoid PCM-integrated void former provides 11.07 % lower heat flux and 27.56 % longer endurance time compared to the one with a spherical shape. The results underscore PCM integration as a superior strategy over standalone insulation for managing thermal loss between apartment floors.

Seismic Performance of Cross-Shaped Partially Encased Steel–Concrete Composite Columns: Experimental and Numerical Investigations

Special-shaped partially encased steel–concrete composite (PEC) columns could not only improve the aesthetic effect and room space use efficiency, but also exhibit good mechanical performance under static load when used in multi-story residential and office buildings. However, research on the seismic performance of special-shaped PEC columns is insufficient and urgently needed. To investigate the seismic performance of cross-shaped partially encased steel–concrete composite (CPEC) columns, three CPEC columns were designed and tested under combined constant axial load and lateral cyclic load. The test results show that the CPEC columns had good load capacity and ductility, and that the columns failed because of concrete crushing and steel flange buckling after the yielding of the steel flange. The plump hysteresis loops indicated that the CPEC column also had good energy dissipation capacity. Due to the constraint of hydraulic jacks, increasing the load ratio would decrease the effective length, thereby increasing the load capacity of the CPEC column and decreasing the ductility. A finite element model was also established to simulate the response of the CPEC columns, and the simulated results agree well with the experimental results. Thereafter, an extensive parametric analysis was performed to study the influences of different parameters on the seismic performance of CPEC columns. For the CPEC column with an ideal hinged boundary condition at the top, its lateral load capacity gradually decreases with the growth of the load ratio and link spacing and increases with the rise of the steel yield strength, concrete compressive strength, flange and web thickness, and sectional aspect ratio. This research could provide a basis for future theoretical analyses and engineering application.

Energy-saving benefits of thermal insulation and glazing in code-compliant office building in cooling-dominated climates

Thermal insulation of wall and roof and high-performance glazing have potential to save energy in cooling-dominated climates. However, lack of careful selection of these options based on the climatic location can adversely affect their energy performance. The local building codes need to be revisited to ensure that the thermal insulation and glazing options fulfil their intended purpose in a given climate. In this context, this study was aimed at assessing the energy performance of thermal insulation (polystyrene) and glazing for different climatic locations. A multistory office building was simulated by using Ecotect software for typical climatic locations of Saudi Arabia. Considering uninsulated wall and roof with single-glazed windows as the baseline, three different cases were studied: insulated wall and roof with single-glazed windows, uninsulated wall and roof with double-glazed windows, and insulated wall and roof with double-glazed windows. In general, the energy-saving benefit of glazing was significantly higher than that of thermal insulation. Also, the collective application of double-glazing and thermal insulation according to the local building code could significantly save the cooling energy demand (ranging from 18 % to 28 %). Conversely, this code-compliance caused an increase of cooling energy demand by 55 % in Abha and by 20 % in Khamis Mushait. However, a sensitivity analysis of these two regions showed that the energy-saving benefit could be positive by proper choice of the heating and cooling setpoints. Besides research interest, the findings of this study will guide for necessary amendments in the building code, eventually contributing to substantial savings in cost and energy and reduction in CO2 emission.

Retrofits of multi-storey office building facade

The city of Jakarta is the 7th big city in the world that has the most high-rise buildings. High-rise buildings in Jakarta were built from 1971 until now and in the 90s it was the peak of the construction of high-rise buildings such as offices and apartment. Tall Buildings with glass facade, concentrating plans are the most typology of office high-rise buildings in Jakarta. Buildings with the dominance of glass facade that reflect heat cause an increase in temperature in the microclimate and a decrease in building performance resulting in the amount of energy used by buildings, especially air conditioners. Building facade play an important role in reducing the improvement of the microclimate and energy use in buildings. Therefore, an analysis was carried out on the BRI II building on Jalan Sudirman Jakarta as a case study that represents the typology of the most office buildings in Jakarta. It turns out that this building has a high OTTV (Overall Thermal Transfer Value) value, so the largest AC cooling load comes from the building casing. Therefore, facade retrofit is one of the alternatives that can be done to reduce energy use, especially air conditioning. After that, a simulation of the casing retrofit to obtain a significant retrofit action can reduce the AC energy used through ottv value reduction analysis.

Field Testing of an Acoustic Method for Locating Air Leakages in Building Envelopes

Maintaining the airtightness of building envelopes is critical to the energy efficiency of buildings, yet leak detection remains a significant challenge, particularly during building refurbishment. This study addresses the effectiveness of the acoustic beamforming measurement method in identifying leaks in building envelopes. For this reason, an in-field study employing the acoustic beamforming measurement method was conducted. The study involved testing over 30 rooms across three different multi-story office buildings of varying ages and heterogeneous envelope structures. Numerous leaks were located in the façades, which were subsequently visually confirmed or even verified with smoke sticks. The data, captured using an acoustic camera (a microphone ring array), revealed distinct spectra that indicate the method’s potential for further research. The basic functionality and the significant potential of this methodology for localizing leakages in large buildings were proven.

Collaborative Optimized Design of Glazing Parameters and PCM Utilization for Energy-Efficient Glass Curtain Wall Buildings

Glass curtain walls (GCWs) have become prevalent in office buildings, owing to their lightweight and modular characteristics. However, their lower thermal resistance, compared to opaque walls, results in increased energy consumption. Incorporating phase-change materials (PCMs) provides a viable solution through which to address the susceptibility of GCWs to external conditions, thus enhancing thermal performance and mitigating energy concerns. This study delves into the influences of the glazing solar heat gain coefficient (SHGC), the glazing heat transfer coefficient (U-value), and PCM thickness on the energy performance of buildings. Using Design Builder (DB) software version 6.1.0.006, a multi-story office building was simulated in different climatic zones in China, covering the climatic characteristics of severe cold, cold, hot summer and warm winter, cold summer and winter, and mild regions. The simulation results quantitatively elucidated the effects of the glazing parameters and the number of PCMs on thermal regulation and energy consumption. A sensitivity analysis identified the glazing SHGC as the most influential factor in energy consumption. Additionally, by employing Response Surface Methodology (RSM), the researchers aimed to achieve a balance between minimal building energy consumption and economic cost, ultimately determining an optimal design solution. The results demonstrated significant energy savings, ranging from 20.16% to 81.18%, accompanied by economic savings, ranging from 15.78% to 79.54%, across distinct climate zones in China.

Low-cost gel-polymer electrolytes for smart windows: Effects on yearly energy consumption and visual comfort

The experimental analysis of the main figures of merit of an innovative electrochromic (EC) prototype, based on low cost gel-polymer electrolytes, is at the basis of the numerical simulation exposed hereafter, aiming at the assessment of energy and visual comfort benefits deriving from building integration of smart windows in a multi-storey office building. The effectiveness of the dynamic modulation of glazing properties to improve energy efficiency and users’ comfort was tested comparing the EC windows with a typical law-compliant static commercial glazing system and with a clear windows. To better understand the performances of the proposed EC film, six different locations – ranging from Seville to Helsinki – were selected throughout the European continent to conduct energy and daylighting analyses on three different exposures (east, south, west). The results obtained show reductions of summer cooling and winter heating as well in all the locations considered. Eventually, the effect of electrochromic switching of transmittance on the indoor visual comfort, is considered using a well-established metric: Useful Daylight Illuminance; with regards to daylight analyses, a significant reduction of hours in which excessive illuminance occurs was observed in all the locations considered, confirming that properly controlled EC devices improve both energy efficiency and visual comfort.

Outdoor micro-climate: Air temperature measurements around an office building in Denmark during summer

The outdoor micro-climate caused by the presence of buildings can significantly differ from that around weather stations located outside of urban areas. However, the latter is often used to design buildings and size building systems. This could lead to significant mistakes and performance gaps. To date, there is a certain lack of experimental studies assessing the micro-climate around buildings, especially in Scandinavian countries. The current paper presents the preliminary results and analysis of a measurement campaign of the temperature gradient in the two-meter air layer around the envelope of a multi-storey office building in Denmark in the summertime. Depending on the orientation of the external building surface (South/North façade or rooftop), the distance from the latter and the weather conditions, the temperature in this two-meter air layer can vary significantly and differ from the air temperature measured at nearby open fields or recorded by the reference weather station. During sunny days, a temperature gradient of up to 3.4 °C and 13.6 °C was measured in the air layer around the South façade and the rooftop, respectively. These results could help to validate urban climate models and bridge the gap between building design and real-condition performance. The curated dataset of this measurement campaign is available in open access.

21 Moorfields: designing against disproportionate collapse using a performance-based framework

21 Moorfields is an over-station commercial office development, located above Moorgate underground station in the heart of the City of London. The multistorey office building spans 55m between supports using an innovative combination of arches coupled with launching trusses and mega-trusses along the east and west facades. Due to the nature and location of the development, the project brief imposed tight robustness requirements, including designing for dynamic forces derived both from multiple permutations of member-removal and event-specific scenarios. This article discusses a performance-based approach to robustness assessment which was implemented on the project, in which the intent of the relevant building regulations was explicitly checked through realistic physics-based simulations.

Investigating the impact of design criteria on the expected seismic losses of multi-storey office buildings

The Ministry of Building, Innovation and Employment is developing advice on how to deliver Low Damage Seismic Design (LDSD) protection for buildings through their Tū Kahika: Building Resilience platform. The draft LDSD advice is considering a design drift limit for multi-storey buildings of 0.5% as part of new damage control limit state design checks. The potential impact of this design criterion on the expected annual loss due to repair costs is investigated for generic reinforced concrete wall case-study office buildings of 4- and 12-storeys in both Wellington and Christchurch. The equivalent static method, in line with NZS 1170.5 and NZS 3101, was used to design the buildings to conventional and draft LDSD specifications, representing current and future state-of-practice designs. The draft LDSD advice aims to limit the expected annual loss of complying buildings to below 0.1% of building replacement cost. This research tested this expectation. Losses were estimated in accordance with FEMA P-58, using building responses from non-linear time history analyses. Although it is found that the new drift limit alone may not limit seismic losses to the target values owing to damage to acceleration-sensitive elements, the results do support the intentions of the draft design advice to significantly reduce the expected seismic losses of complying buildings. The study also highlighted the importance of using an accurate approximation of RC wall stiffness for LDSD, and provides insight into different design strategies that could be followed to effectively limit losses in RC wall buildings as part of LDSD.

Multi-Objective Optimization Design of Geometric Parameters of Atrium in nZEB Based on Energy Consumption, Carbon Emission and Cost

Through the detailed design of the passive design of the geometric parameters of the atrium, it is beneficial to achieve the design goal of a nearly zero-energy building. In the architectural design stage, the geometric design parameters of the atrium are verified and evaluated with different objectives such as energy consumption, carbon emissions, and costs, and then the most appropriate solution according to different design requirements is selected, which can reduce energy consumption and save costs. This paper proposes a method to optimize the energy consumption of a building’s atrium. Taking Jinan City as an example, this paper conducted 1260 energy consumption simulations for buildings with different geometric parameters of the atrium, based on the investigation of the geometric scale and energy consumption of the multi-story office buildings with near-zero energy consumption in cold areas with atriums. The degree of influence of each parameter on building energy consumption was determined. Finally, the parameter selection combination with the best effect is proposed. The results show that the selected four parameters are significantly related to energy consumption, and a new atrium design parameter was found through the combined analysis of the parameters: the body shape coefficient of the atrium. It was found that the importance of atrium design parameters on building energy consumption is as follows: the body shape coefficient of the atrium, the height-span ratio of the atrium (DSR), the atrium building volume ratio (VR), the skylight area ratio (SR), the atrium width-to-depth ratio (FDR). Seven groups of optimal design parameters were obtained by analyzing the design decisions with energy consumption as the target. Taking carbon emission and cost as the targets, three groups of optimal design parameters were obtained according to the Pareto frontier solution set, such as DSR = 2, VR = 0.13, SR = 0.1, and FDR = 2.5. It provides some references and ideas for the optimization of the energy consumption of the atrium of multi-story nearly zero-energy office buildings in the cold regions of China.

Energy-Saving Potential Comparison of Different Photovoltaic Integrated Shading Devices (PVSDs) for Single-Story and Multi-Story Buildings

Building-integrated photovoltaic (BIPV) façades are a promising technique for improving building energy performance. This study develops energy simulation models of different photovoltaic-integrated shading devices (PVSDs) in single-story and multi-story office buildings. A cross-region study in China is carried out to explore the energy performance of PVSDs in five climate zones. The shading effect of the upper PVSDs is taken into account. The results show that (1) PVSDs can be applicable in hot and cold climates; shading effects lead to a notable difference in the optimal PVSDs style. The average comprehensive energy saving ratios of different PVSDs ranged from 16.12% (fixed PV louvres in the vertical plane) to 51.95% (lower single panel). The most rewarding PVSDs are for single-story buildings in Kunming and the least suitable are for multi-story buildings in Guangzhou. (2) In climate zones with little air-conditioning energy consumption, avoiding considerably increased lighting consumption by PVSDs is vital. (3) To reduce shading effects, solar panels with smaller widths or vertical placements can be adopted. In addition, the distance of the PV modules from the top edge of the windows is also critical. Building performance evaluation in the early design stage enables maximum benefits for the same input (total area of PV panels). The research methodology and data analysis presented can guide parameters design and the geographical applicability of PVSDs, providing a reference for optimal building energy performance.

ELF-MF Exposure, Actual and Perceived, and Associated Health Symptoms: A Case Study of an Office Building in Tel Aviv-Yafo, Israel

Empirical studies link exposure to extremely low frequency magnetic fields (ELF-MFs) to several health symptoms. However, it is unclear whether these symptoms are associated with actual or perceived exposure. In this study we attempted to answer this question by studying the health complaints of employees working in a multi-story office building located near a major high-voltage power line. ELF-MF measurements were conducted in the building using a triaxial sensor coil device on all 15 floors. In parallel, questionnaires were administered to evaluate the prevalence of various health symptoms among the employees. Multivariate logistic regressions were used next to quantify the associations between actual and perceived ELF-MF exposure and the employees’ health complaints. The analysis revealed that feelings of weakness, headache, frustration, and worry were associated with both measured and perceived ELF-MF exposure (p < 0.01), while perceived ELF-MF exposure was also found to be associated with eye pain and irritation (OR = 1.4, 95% CI = 1.2–1.6), sleepiness (OR = 1.3, 95% CI = 1.1–1.5), dizziness and ear pain (OR = 1.2, 95% CI = 1.0–1.4). We conclude that high-voltage power lines produce both physiological and psychological effects in nearby workers, and, hence, proximity to such power lines should become a public health issue.

Progressive Collapse Assessment and Retrofit of a Multistory Steel Braced Office Building

The progressive collapse of the building structures due to abnormal loads has attracted global attention in recent years. Many studies in the literature have been dedicated to the analysis and design procedures for progressive collapse resistance, and several technological solutions have been developed for progressive collapse retrofit. However, many studies are based on simple models and their validity and possibility to generalize the research results to current practice are rather limited. Moreover, there are still not many case studies developed based on full-scale real buildings. The present paper contributes to filling this gap by investigating the robustness of a quite complex real case study, namely a steel braced frame building erected in the early ‘60 s in Naples-Italy to house the Civil Engineering Authority. To this aim, different column removal scenarios have been considered and both nonlinear static and dynamic analyses have been carried out. The results have highlighted that the simple braced frames are susceptible to progressive collapse due to the weak brace connections. However, joint strengthening is not a viable solution, because it would prevent the full functionality of this strategic building during the implementation of the progressive collapse retrofit. As an alternative, an outrigger-belt truss system has been developed that applies the concept of Vierendeel truss system to redistribute the loads due to the column removal. The effectiveness of the proposed retrofit strategy to improve the progressive collapse resistance of the building has been verified through nonlinear dynamic analyses, proving its feasibility for practical applications.

Daylighting evaluation in deep plan office buildings with OPV windows through simulation on Radiance

This research aims to evaluate the OPV window (OPVW) potential application in a deep-plan multi-storey office building, in order to verify its contribution to indoor daylighting quality. OPVW is a cost-effective technology with reduced environmental impact, suitable for application in a multi-story office building due to its potential to adapt to different architectural configurations, lightness and transparency, etc. In an earlier study developed by the authors, an experiment was conducted with a generic office room scale model. Three window materials were compared under real sky conditions (overcast and clear): 3 mm single glass (A scenarios); single glass with OPV (B scenarios); and single glass with application of solar control film (C scenarios). In the present study the same parameters from the experiment were used as input for simulations on Radiance, whose results were compared to previous (work plane illuminance, Daylight Factor and model interior photographs). We found similarities between them. Thus, further results were produced: isolux curves, Daylight Glare Index and render images. The rendered images show a brighter view at A scenarios, and at B and C scenarios. Even if average illuminance is reduced, a better daylight distribution and a reduction in glare are achieved. DGI indicates perceptible glare for some of A scenarios. On the other hand, at most of B and C scenarios, glare was below the perceptible range. Furthermore, the scenarios with OPVW (B scenarios) still show one more advantage: the energy production for artificial lighting when illuminance values are not sufficient.

Energy and daylighting performance of building integrated spirooxazine photochromic films

The study of chromogenic materials and systems is particularly promising for innovative, transparent building envelopes, with thermo-optical properties adaptable to surrounding environmental conditions. This work spots light on the multiple effects of photochromic glazing on the energy consumption of buildings and on the impact that such technologies would have on the visual comfort of occupants. To our knowledge, this is the first work dealing with building integration of spirooxazine-based photochromic films. This experimental and theoretical work aims helping to fill this gap by reporting the results of a study concerning the spirooxazine photochromic molecules, integrated in transparent matrices of polymethylmethacrylate. This work discloses the potential of specific photochromic materials, especially as a function of spectral peculiarities. The figures of merit of this technology have been studied by assuming its integration in an ideal multi-storey office building, and by studying the effects in terms of energy consumption and visual comfort and proposing a comparison with several static commercial glazing technologies. The photochromic glazing demonstrated to offer significant reduction of energy use for cooling, compared to a clear glass (with yearly saving of 4079 kWh, on the Southern facade), and for artificial lighting (with a saving of 3711 kWh), if compared to the commercial solar control glazing. Furthermore, the dynamic behaviour of the photochromic glazing represented the best choice in terms of visual comfort.

Factors affecting aerosol SARS-CoV-2 transmission via HVAC systems; a modeling study.

The role of heating, ventilation, and air-conditioning (HVAC) systems in the transmission of SARS-CoV-2 is unclear. To address this gap, we simulated the release of SARS-CoV-2 in a multistory office building and three social gathering settings (bar/restaurant, nightclub, wedding venue) using a well-mixed, multi-zone building model similar to those used by Wells, Riley, and others. We varied key factors of HVAC systems, such as the Air Changes Per Hour rate (ACH), Fraction of Outside Air (FOA), and Minimum Efficiency Reporting Values (MERV) to examine their effect on viral transmission, and additionally simulated the protective effects of in-unit ultraviolet light decontamination (UVC) and separate in-room air filtration. In all building types, increasing the ACH reduced simulated infections, and the effects were seen even with low aerosol emission rates. However, the benefits of increasing the fraction of outside air and filter efficiency rating were greatest when the aerosol emission rate was high. UVC filtration improved the performance of typical HVAC systems. In-room filtration in an office setting similarly reduced overall infections but worked better when placed in every room. Overall, we found little evidence that HVAC systems facilitate SARS-CoV-2 transmission; most infections in the simulated office occurred near the emission source, with some infections in individuals temporarily visiting the release zone. HVAC systems only increased infections in one scenario involving a marginal increase in airflow in a poorly ventilated space, which slightly increased the likelihood of transmission outside the release zone. We found that improving air circulation rates, increasing filter MERV rating, increasing the fraction of outside air, and applying UVC radiation and in-room filtration may reduce SARS-CoV-2 transmission indoors. However, these mitigation measures are unlikely to provide a protective benefit unless SARS-CoV-2 aerosol emission rates are high (>1,000 Plaque-forming units (PFU) / min).

Seismic analysis of multi-story frame office building based on SAP2000

Taking a multi-storey reinforced concrete frame structure office building as an example, the model analysis, response spectrum analysis and time history analysis of the whole structure are carried out by using the finite element software SAP2000, and the output results of y-pillar in different scenarios are analyzed. The results show that the overall seismic performance of the frame meets the design specifications, and the y-pillar structure meets the elastic and non yield characteristics of the large earthquake.