Typical Office Research Articles

A Corneal Surface Reflections-Based Intelligent System for Lifelogging Applications

Corneal Surface Reflections, or reflections on our eye-surface, have been shown as a valid and more socially acceptable source of information for passive lifelogging applications by prior work. However, automatic analysis of corneal surface reflections from a single RGB camera to support passive lifelogging is not extensively investigated in prior work. To address this, we developed a synthetic and self-supervised learning-based two-stage pipeline of deep learning models to detect objects in these reflections. Our prototype only consists a single RGB camera looking into the eye. We collected data from different users in uncontrolled environments using the prototype and trained our system to detect multiple classes of objects present in a typical office environment. We then evaluated our model in partially-controlled and in-the-wild scenarios. In addition, based on the findings from a follow up user study and prior work, we discuss strengths and weaknesses of our system and using corneal surface reflections for passive lifelogging. Finally, we opensource our source codes and trained checkpoints.

A CFD approach to reduce the risk of Covid-19 airborne transmission in a typical office

The Covid-19 virus can spread rapidly in the air and cause the epidemic to rage around the world. This study takes a typical office as the research object and proposes four different partition settings to suppress the spread of the virus in the air based on displacement ventilation. And these strategies are verified by DPM model simulations of two daily situations of indexed person for coughing and talking. This study then employed a modified Wells-Riley model to evaluate the effectiveness of these strategies in mitigating the risk of viral infection. As expected, in the absence of a partition, a susceptible person at the other end of the seat greatly increased the risk of infection. Partitions can significantly reduce the risk of infection (100% → 20%), while partitions with a full-wrapped structure can reduce the risk of infection to less than 1%. For the instantaneous release scenario of coughing, the barrier can capture a large particle diameter (>50 μm) particles, and the smaller particle diameter can be discharged out of the room with the thermal plume. The strategies provided in this study can provide recommendations for indoor epidemic prevention and control in the context of the Covid-19 pandemic.

Performance of Concrete Building Structure Exposed to Localized Fire

Concrete structures have a favorable position in the building industry with regard to their performance of fire resistance. The understanding of their behavior is essential for reliable analysis and design. This paper is mainly concerned with concrete building performance subjected to localized fire arrangement. Special attention has been given to the finite element model of a seven-story concrete building representing a typical commercial office building designed to European Standard. Very large displacements happened on horizontal direction of the floor slabs due to thermal expansions. The large displacement induced lateral movement of the floor slabs and created additional moments to external columns. Design engineers should ensure that the external columns have ability to accommodate lateral displacements during fire. Although, the thin external columns of the model can withstand these movements due to beneficial effect of membrane action developed to the floor slabs. Present analysis indicates that the performance of the whole structure is substantially different from the single isolated structural member behavior during fire. Although the current design procedures are conservative, design engineers have to consider the detrimental and beneficial effects of lateral slabs' thermal expansion in complete structure.

Economic comparison of cool and grey roofs of a small office building in the USA

EnergyPlus V9.0 simulations of a typical small office building prototype in five USA cities (Albuquerque, Atlanta, Buffalo, San Diego, Rochester) indicate that adding a cool roof (albedo 0.6) for an aged grey roof (albedo 0.2) would reduce the annual energy and annual energy cost in all hot dry or humid cities (Albuquerque, Atlanta, San Diego) and in severe cold or mixed humid cities (Buffalo, Rochester). The CO2, SO2, and NOX savings are positive in all selected cities. This work considers the economics of using cool roofs of an office building in the USA by performing a 20-year life-cycle cost analysis that compares each type of roof to a grey roof. The 20-year net present values (NPVs) of annual conditioning (heating + cooling) energy cost savings were calculated. The life cycle cost savings (NPV of annual streams – initial cost premium) of cool roofs have both positive and negative values. The NPV with the cool roofs is from -17.3 USD/m2 in Rochester to 6.5 USD/m2 in San Diego. Among the five cities in the USA, Albuquerque, Atlanta, and San Diego were able to apply the cool roofs since they all have positive NPV, while Buffalo and Rochester were unsuitable to apply the cool roofs methods because of the negative NPV. Owners concerned with urban heat island mitigation and slowing climate change may prefer cool roofs

Effects of shape-stabilized phase change materials in cementitious composites on thermal-mechanical properties and economic benefits

• The effects of PCMs to save building energy consumption was investigated. • Physical-thermal-mechanical testing and cost analysis were conducted. • Energy saving efficiency was calculated via computational modeling. • Findings infer the potential application of coconut oil as an engineered PCM. Phase change materials (PCMs) have been utilized to improve the thermal properties of cementitious composites by using their latent heat capacity. Applying them to building components can reduce their heating and cooling loads through energy absorption during the phase change period. The shape-stabilized method using porous lightweight aggregates can prevent PCM leakage during the phase transition process. While many attempts have been made to develop and improve shape-stabilized PCM composites to achieve a high level of energy savings, their economic benefits have not been fully investigated, as most analyses are based on initial material costs with a limited linkage of their thermal-mechanical properties. This study used an integrated experimental-computational method to evaluate the effects of different PCMs in building components by considering the core thermal-mechanical properties with an economic benefit analysis. Toward that end, two different PCMs (PureTemp® and coconut oil) were selected to fabricate Thermal Energy Storage Aggregates (TESA) using the vacuum impregnated method: TESA-P (with PureTemp®) and TESA-C (with coconut oil). The thermal-mechanical properties were experimentally determined and used for building energy simulation for a typical small office in Houston, Texas. The cementitious composites incorporated with PCM showed lower thermal conductivity and heat transfer than the non-PCM specimens. The TESA-P specimens showed a more prolonged time lag and better energy-saving performance than the TESA-C specimens due to better thermal properties of PCM itself. In contrast, the costs of TESA-C applications could be less with a shorter pay-back time. The findings of this study infer the potential application of coconut oil as an engineered PCM in building construction.

Influence of External Surface Radiation Properties on Thermal Performance of Walls——Take a typical office building in Chengdu as an example

In this paper, taking a typical office building in Chengdu as an example, the coupling relationship between the radiation properties (short-wave absorption coefficient and long-wave emission coefficient) of the external surface materials of the wall and the insulation types and the insulation performance is studied by using software simulation method. The results show that the internal insulation wall is beneficial to reduce the heating load while the external insulation wall is beneficial to reduce the cooling load. And the external surface material's radiative properties hardly affect the wall insulation type choice. Still, in the case of Chengdu office buildings, interior insulated walls are more conducive to year-round building energy efficiency. In summer, the radiation characteristics of the outer surface material will affect the choice of the best heat transfer coefficient (U-value) of the wall. When the short-wave radiation absorption coefficient is small, the wall with good insulation performance will appear anti-energy-saving phenomenon. Therefore, it is recommended that the regions with high cooling loads fully consider the influence of the external surface material's radiation properties on the wall's thermal performance in the design of the thermal performance of the wall.

Performance evaluation of ventilative cooling systems for buildings under different control parameters and strategies

Ventilative cooling is an energy-saving technology to diminish thermal discomfort and overheating risk of buildings, meanwhile achieving high indoor air quality (IAQ). However, there is still no optimal control strategy in practice, which considerably limits its application. This study developed a typical office building model to evaluate the performance of ventilative cooling systems with different control parameters and strategies for five typical cities in different climatic zones of China. Results showed that, when the control parameter was selected as the upper limit of satisfied comfortable zone by 90% of the occupants, the adaptive thermal comfort (ATC) model, which outperformed the other models in terms of outdoor air utilization, was not necessarily optimal in terms of energy efficiency. The outdoor air utilization potential based on the indoor dry-bulb air temperature (Td) and indoor operative temperature (Top) control was similar, but the energy usage varies considerably, especially in the hot climatic zones. When the overheating period controlled based on the thermal comfort models was the same, the energy usage would be underestimated by 16%–38% without considering the effect of radiant temperature. The ATC-based control could have up to 37% of energy-saving compared to thermostatic control, but inappropriately low limits could make it less advantages to achieve energy-saving. The energy-saving potential associated with the PMV and ATC controls showed a completely opposite trend in the different climatic zones. The analysis results indicate that eliminating the drawbacks of the lower limit in the ATC model is an effective way to demonstrate energy-saving effectiveness. The findings of this study will contribute to the effective improvement of the application potential of ventilative cooling in different climatic zones.

Investigation on the cross-infection control performance of interactive cascade ventilation in multi-scenario of winter

With the wide spread of COVID-19, numerous cases demonstrate that proper ventilation method can reduce the cross-infection risk obviously. Interactive cascade ventilation (ICV) as a recently proposed ventilation method, the advantage of indoor environment construction has been proven. However, few studies are conducted to investigate the virus prevention and control characteristics of ICV, which is particularly important under epidemic normalizing. Hence, this study explored and compared the cross-infection control performance of three ventilation strategies, namely mixing ventilation (MV), stratum ventilation (SV), and interactive cascade ventilation (ICV), with a validated CFD model. A typical office was selected as the background scene, where an infected person coughs, sneezes with standing or sitting at different positions. Exposure doses, health infection risk, and disease burden (DB) were employed as the evaluation indicators under different ventilation methods of multi-scenario. The research results indicated that the average aerosol exposure dose among the human respiratory region under ICV was 0.29 g/day, which was reduced by 67 % and 50 % compared with MV and SV. In addition, only in ICV can the health infection risk meets the EPA standard. The average disease health burden for exposed persons under ICV was 0.93 × 10−6 DALYs pppy, which was 37 % and 70 % lower than SV and MV. The findings obtained from this study confirm that ICV performs excellently in reducing the cross-infection risk, providing the theoretical basis for future epidemic prevention and control.

Numerical analysis for the optimization of multi-parameters stratum ventilation and the effect on radon dispersion

To reduce hazards due to the radon dispersion on occupants, careful consideration of multi-parameters of stratum ventilation is necessary, including air supply velocity, temperature, angle and air outlet position. In this study, the radon dispersion in a typical office with stratum ventilation was evaluated based on experimental measurements and computational fluid dynamics (CFD) modelling. Besides, the ventilation performance of each scheme was evaluated by using a technique of order preference by similarity to the ideal solution (TOPSIS) method. Results showed that the mentioned factors and their interactions could pose important impacts on the indoor environment. Combining with TOPSIS, the optimal operation of the stratum ventilation was determined. Compared with the worst ventilation scheme, the ventilation effectiveness was increased by 77.4%, the air distribution performance index (ADPI) was increased by 38.1% and the radon radiological effective dose rate was reduced by 63.4%. The findings may form an important mitigation control strategy to effectively minimize radioactive exposure in indoor environments. • Operation of stratum ventilation for cooling and reducing radon in a typical office is optimized. • Parameter impact on stratum ventilation performance for cooling is analyzed. • Compared with the worst ventilation scheme, the maximum ventilation effectiveness was increased by 77.4%, the air distribution performance index (ADPI) was increased by 38.1% and the annual effective dose of radon exposure was reduced by 63.4%.

Local room‐side heat transfer of an office room with different heating strategies

AbstractThe room‐side heat transfer of a building is essential for calculating and simulating heat loss through radiation and convection in interior spaces, and also for preventing mould growth and condensation. By means of Computational Fluid Dynamics (CFD) simulations, this study investigates the effect of floor heating, mixing ventilation, furniture, room geometry, and their combinations on the interior heat transfer coefficient (HTC) of a typical office room. The results show an inhomogeneous distribution of the HTC on the exterior walls. HTC values are generally below the German standardised value for thermal protection, which means an overestimation of the heat loss when the standardised value is applied. However, compared to the standardised value for preventing mould growth, the minimum surface‐averaged HTC behind closets is 63 % lower, potentially leading to mould growth and condensation.

The environmental impact of the new version of the Interior Lighting European Norm in Lighting and Circadian Design

The new version of the European Standard of Interior Lighting (EN 12464-1) considers LED technology for energy saving and minimizing environmental impact by giving new criteria for quantitative and qualitative lighting, including those that concern the “non-image-forming effects” (NIF) of light. In addition, it takes into account normal aging as an assumption for proposing increased light levels in indoor workplaces. In real applications, this seems to create lighting conditions that do not fully support human well-being based on the criterion of WELL Building Standard v2 (2021) for Circadian Lighting Design. Therefore, in offices, it is proposed to increase the light levels by at least one step from the minimum provided by the EN Standard. In order to examine this hypothesis, a typical office space is examined. In addition to the main requirements, the Mean Ambient Illuminance (Ēamb) and the Mean Room Surface Luminous Exitance (Mrs) are calculated according to the EN Standard but also the Equivalent Melanopic Lux (EML) and the Melanopic Equivalent Daylight Illuminance (M-EDI) as proposed by the WELL Standard. The comparison between EN 12464-1 and Well Standard has shown that the qualitative lighting design criteria are stricter in WELL than in EN Standard.

Performance assessment of RBFMOpt, NSGA2, and MHACO on the thermal and energy optimization of an office building

Simulation-based Optimization processes (SBO) can be valuable methods in searching for efficient buildings. This study evaluates the performance of the multi-objective algorithms RBFMOpt, NSGA2, and MHACO facing the same SBO problem. The goal is to maximize thermal comfort while minimizing the energy consumption with HVAC systems for a typical Brazilian office building. We proposed a scoring method based on four algorithms’ performance metrics: hypervolume, variability, IGD+, and coverage. We also applied a Kruskal–Wallis test to determine whether the SBO process needs multiple runs to obtain the average performance of each algorithm. The results show that RBFMOpt presents the best performance, reaching a higher score, especially in situations with low budgets for the simulation and optimization process. The results also pointed out that the number of cycles for RBFMOpt impacts directly the quality of solutions, and a higher number of cycles provided better results.

Smart Dimmable LED Lighting Systems.

This paper proposes energy-efficient solutions for the smart light-emitting diode (LED) lighting system, which provides minimal energy consumption while simultaneously satisfying illuminance requirements of the users in a typical office space. In addition to artificial light from dimmable LED lamps, natural daylight coming from external sources, such as windows, is considered as a source of illumination in an indoor environment. In order to reduce total energy consumption, the smart LED system has the possibility to dim LED lamps, resulting in reduced LED output power. Additionally, various LED lamps' functionality, such as semi-angle of the half illuminance and LED tilting, are introduced as an additional parameter to be optimized to achieve greater energy saving of the designed system. In order to properly exploit external lighting, the idea to reduce overall daylight intensity at a users' location is realized by the option to dim the windows with a shading factor. Based on the users' requirements for a minimal and desired level of illumination, the proposed optimization problems can be solved by implementing different optimization algorithms. The obtained solutions are able to give instructions to a smart LED system to manage and control system parameters (LEDs dimming levels, semi-angles of the half illuminance, orientation of LEDs, the shading factor) in order to design total illumination, which ensures minimal energy consumption and users' satisfaction related to illuminance requirements.

Photovoltaic windows cut energy use and CO2 emissions by 40% in highly glazed buildings

<h2>Summary</h2> Buildings account for 30% of global energy use. The architectural trend across building sectors is toward more glass despite higher energy use and carbon emissions than opaque cladding alternatives. Numerous window technologies—low-emissivity coatings, triple glazing, dynamic tinting, and the more recently developed photovoltaic glass—have emerged in the last two decades as approaches to reduce building energy. However, a comprehensive understanding of where and how these window technologies can be installed to enable optimal energy savings under different climate conditions remains limited. Here we test window technologies using thousands of macroscale building-energy simulations for different climate zones and building designs to evaluate the associated net energy use and carbon-emissions reduction potential. Novel window technologies, especially photovoltaic windows with high thermal performance, offer energy savings in all climates, ranging from 10,000–40,000 GJ per year over substandard windows for a typical office building, resulting in up to 2,000 tons of annual CO₂ emissions reduction. Highly glazed, net-zero buildings are achievable via photovoltaic windows when combined with careful geometric considerations.

Resilient cooling through geothermal district energy system

Decarbonization and resilience to heat waves have recently become high priorities for building and district energy systems. Geothermal coupled district heating and cooling systems that operate a water loop near ground temperature gain increasing adoption to support decarbonization. In these systems, vapor-compression machines, distributed in the energy transfer stations, lift the temperature up or down to the needs of the particular building. In principle, these systems can provide low-power, free cooling from the geothermal bore field during heat waves when electricity is often scarce. However, the performance of such a resilience operation mode and its implication on the energy system configuration and the sizing of the bore field and HVAC equipment is not yet understood. Consequently, we are assessing their resilience, power use and design implications under a scenario of a heat wave on five working days during which chillers are switched off to reduce electrical consumption. Our analysis is based on high-fidelity, coupled dynamic models of district energy, building-side HVAC and actual control logic, with whole building energy simulation used to assess thermal conditions in a 2004 vintage multi-zone office building in Chicago, IL. The results show that relying only on waterside economizer cooling, the indoor thermal conditions can be maintained in a tolerable range for the majority of the building zones with half the electrical energy compared to standard chiller operation. Thermal comfort in the hottest zones can be further improved by oversizing the cooling coil. However, the waterside economizer has significant implications on the system configuration and sizing: The geothermal bore field needs to be sized about 30% larger than the upper limit of the range observed for conventional geothermal systems. Nevertheless, if a central chiller plant is added, the bore field can be downsized to the typical design range. The latter configuration still allows compressor-less cooling during the heat wave with peak power reduced by 60% compared to the standard design and chiller operation. • Geothermal coupled energy systems improve resilience of buildings during heat waves. • Demonstrated acceptable thermal comfort in typical office building during heat wave. • Integrated waterside economizer in ETS of ambient loop district energy network. • Used model-based HVAC and controls co-design for economic and reliable operation.

On the energy impact of cool roofs in Australia

Urban overheating is a serious environmental issue with a significant impact on cooling loads, peak electricity demand, indoor air temperature, health, pollution, sustainability, and the economy. Cool roofs – which are characterised by high solar reflectance (ρ) or albedo and high thermal emissivity (ε) – are one of the most effective technologies to mitigate the urban overheating effect and its undesirable impacts. The existing literature on the energy impacts of cool roofs in various building types and climate zones is vast but fragmented and predominantly assessed the building-scale and urban-scale benefits separately. Here, we computed the energy conservation potential of cool roofs in 17 building archetypes with different occupation hours, internal heat gains, thermal insulation levels, and building heights under various Australian climates. This study presents a holistic approach to assessing the magnitude and spatial variation of the cooling load savings, the peak electricity demand reductions, and indoor air temperature reductions generated by the building-scale and combined building-scale and urban-scale implementation of cool roofs in all representative building types under various climate conditions in Australia. In Sydney, a city with a warm/mild temperate climate, cool roofs can reduce the cooling loads of a typical low-rise office building without roof insulation by 10.2–13.8 kWh/m2 (37.6–42.0 %) during the summer months of January and February. When cool roofs are implemented in both individual buildings and the whole urban area, the cooling load conservation potential for the same building increases to 14.9–17.4 kWh/m2 (50.3–63.7 %). The corresponding peak electricity demand and indoor air temperature reductions by the combined building-scale and urban-scale application of cool roofs are 53–70 % and 11.2–12.0 °C, respectively. The energy conservation potential of cool roofs can be noticeable even for high-rise buildings with a high level of thermal insulation. We estimated that the cooling conservation potential by combined building-scale and urban-scale application of cool roofs can range between 4.0 and 7.1 kWh/m2 (29.3–48.3 %) in a new high-rise residential building with high levels of thermal insulation to 18.5–24.5 kWh/m2 (23–29.6 %) in an existing low-rise shopping mall centre with low levels of thermal insulation in Sydney. Cool roofs lead to additional savings as the reduced temperature increases the energy efficiency of air conditioning systems, with cooling load savings between 0.6 and 3.7 kWh/m2 (3–11 %) for a typical low-rise office building without roof insulation in Sydney. Also, the heating load penalties induced by cool roofs are negligible compared to the cooling load savings in all building types and Australian cities/climate zones except for non-commercial buildings in the cold climate of Hobart. Policymakers can use the results of this study to obtain a deep knowledge of the expected performance of cool roofs when applied city-wide to mitigate urban overheating and counterbalance its adverse impacts on energy uses and indoor thermal comfort.

Assessing the impacts of urban morphology factors on the energy performance for building stocks based on a novel automatic generation framework

The building sector accounts for an increasing amount of energy and emissions with continued urbanization, and improving the energy performance of building stocks at the early planning stage is cost-efficient and easy to operate. This study presents an automatic generation framework to quantify the impacts of urban morphology factors on the energy performance of neighborhood-scale building stocks. The typical office building shape is firstly determined by a field survey and clustering analysis. Then the building modular cells-based method is introduced to establish a comprehensive energy performance database for building stocks. The impacts of urban morphology factors on energy performance are further prioritized via global sensitivity analysis. A case study in Shanghai, China demonstrated the proposed automatic generation framework which can act as a generalized paradigm to model building stocks and be widely applicable to other climate zones. The urban morphology factors representing buildings’ geometric characteristics tend to have greater impacts on energy performance, among which the top influencing factors are relative compactness, building coverage ratio, and building height distribution. The proposed framework and the findings are expected to generate valuable insights into energy-efficient urban design.

Impact of placement and design of phase change materials in thermally activated buildings

Phase change materials (PCMs) and thermally activated building systems (TABSs) are two candidate technologies for reducing the energy consumption of modern buildings due to their favorable thermal storage features. However, the existing relevant studies do not specify the optimal integration schemes of PCMs when used in radiant cooling systems. Hence, this paper reports the first attempt to parametrically optimize the PCM-TABS system integration, considering typical open office space in the hot and dry climate zone of Cairo, Egypt. Using dynamic system simulations, four system configurations are examined, regarding the relative positions of the activated slab and Bio-PCM layer (ceiling or floor), and compared to active ceiling or floor systems (without PCMs). The results demonstrate the feasibility and favorableness of using PCMs in TABS, with energy and cost saving up to 18.80 and 19.78 %, respectively. The largest cost savings are achieved when PCMs are incorporated into the radiant ceiling, with a melting temperature of 22.0 °C and thickness of 6.0 cm. Energy savings also increase as the volume of PCMs increases, with melting temperatures closer to the building's setpoint. The percentage of comfortable hours decreases slightly from ~100 % to >95.5 % when using some PCM designs due to their thermal inertia, but PCMs result in generally lower variations of indoor thermal comfort. By mapping the performance of such system configurations, the study can be valuable for researchers and practitioners alike to determine the optimal integration scheme of PCMs in radiant cooling systems.

External Shading Devices: Should the Energy Standard Be Supplemented with a Production Stage?

The Israeli Standard SI5282 rates buildings according to the operational energy (OE) used to support their heating, cooling, and lighting needs. When it was proposed, OE was generally considered to be derived from fossil fuels, such as coal. However, at present, Israel is in the process of transitioning to cleaner energy sources, such as natural gas and renewables. In light of this change, the question that guided this study was as follows: should the production (P) stage of external shading devices be taken into account alongside the OE stage? In this study, we aimed to evaluate the P (environmental damage) and OE (environmental benefit) of five external shading devices with equivalently high energy rates that were installed in a typical office building using cleaner OE sources. We evaluated the environmental impacts using the ReCiPe2016 method. The results indicated that the P stage of the five shading devices led to significantly different degrees of environmental damage, thus reducing the environmental benefits related to the OE stage. Therefore, the five similarly rated shading devices could no longer be considered as equivalent sustainable alternatives. As such, we recommend that the energy rating be supplemented with a P stage environmental evaluation.

Effect of progressive deinking and reprinting on inkjet-printed paper

Abstract The main aim of the present research is to examine the effect of progressive deinking and reprinting on the paper properties of inkjet-printed paper. A typical office copy paper was selected as the base paper and printed using an inkjet printer having at least 50 % ink coverage. Thereafter, it was deinked and reprinted thrice, and its paper properties were measured. The paper properties that were measured were roughness, porosity, opacity, brightness, specular gloss, whiteness, bursting strength, tearing resistance, tensile strength, contact angle, deinkability efficiency, visible dirt area, ink elimination factors, and color differences. The results showed that in comparison to the base paper, the progressively deinked and reprinted paper samples showed an increase in roughness, porosity, opacity, tearing resistance, dirt area, and color difference. On the other hand, there was a decrease in brightness, gloss, whiteness, burst strength, tensile strength, contact angle, deinkability efficiency, and ink elimination factors. The experiment shows that the progressively deinked and reprinted papers can be compared to the base paper in the major paper properties.