Indoor Conditions Research Articles

Soil Color Comparison Using Munsell Soil Color Chart and Calibrated Smartphone Camera

Soil color is a crucial property in soil fertility assessment and monitoring. However, the subjective nature of the Munsell Soil Color Chart (MSCC) can lead to uncertainty in the analysis. To address this issue, a study was conducted to develop a soil color classification model from smartphone digital imagery based on color analysis and MSCC. The study involved taking 26 soil samples from various soil types and locations in the Special Region of Yogyakarta, Indonesia. Digital images of the soil were taken through a smartphone camera and compared with observations using MSCC to compare color differences (ΔE) based on Lab values. Soil images obtained from indoor studio conditions and calibration using spydercheckr in indoor and outdoor conditions are compared with MSCC and Chromameter values. The L*a*b color space was found to be superior to RGB for predicting and detecting small differences in color. The study also found that the Munsell soil color chart (MSCC) had a lower color difference than the chromameter in all lighting conditions, indicating that the MSCC or visual assessment can better detect the main soil color or soil matrix, while chromameter readings may have errors due to soil impurities.

Wide‐Gap Perovskites for Indoor Photovoltaics

Organic–inorganic halide perovskite semiconductors have revolutionized next‐generation photovoltaics (PV) due to several characteristics such as solution‐processability, gap tunability, and excellent charge generation and transport properties. This has made them very adaptable for various applications in light harvesting and photodetection. One such rapidly growing application is indoor photovoltaics (IPV) which have the potential to power standalone Internet of Things devices. IPV requires wider optimal bandgaps than solar cells (1.8 vs 1.3 eV) due to the differences between the spectra of artificial lights versus solar radiation. For IPV applications, the active layer wide‐gap perovskite must be developed systemically considering all other components of the device, such as interlayers, electrodes, and scaling. This perspective provides an overview of the potential and challenges facing perovskite‐based IPV from a theoretical, material, and experimental perspective. Furthermore, accurate characterization of perovskite IPVs under simulated indoor conditions is discussed and candidate perovskite PV (PPV) systems are presented to provide insight into IPV development. These include IPV‐optimized formamidinium cesium‐based perovskite, wide‐gap p‐i‐n devices, and 2D perovskite devices, tested under spectrophotometrically calibrated LED illumination at various indoor‐relevant illuminances and benchmarked against thermodynamic predictions. Finally, strategies required to create stable, optimized PPV devices for indoor applications are discussed.

Power quality assessment and compliance of grid-connected PV systems in low voltage networks using microinverters

AbstractSolar PV has experienced unprecedented growth in the last decade, with the most significant additions being utility-scale solar PV. The role of grid inverters is very critical in feeding power from distributed sources into the grid. With the increasing growth of grid-tied solar PV systems (both rooftop and large-scale), the awareness of power quality issues has risen with new regulations and standards to ensure the stability of the power grid. The power quality of microinverters has been investigated under steady solar irradiation and PV power source and also under real outdoor conditions in compliance with the accepted solar PV integration requirements. The current total harmonic distortion (THD) measured for the studied microinverter under outdoor conditions far exceeded the current THD for the study under steady indoor conditions and was beyond the accepted standard. However, the voltage THD outputs for the two studied cases were in good agreement with the grid codes. The voltage and current THD for the 400 Wm−2 (60 Wp) and the 1000 Wm−2 (146 Wp) scenarios under the steady solar irradiation (solar PV power) were 2.24%, 13%, and 2.27, 6.93%, respectively. The voltage and current THDs for the outdoor study were 2.03% and 14.28% for Solarex (pc-Si module), 1.94%, and 27.43% for Juta (mc-Si modules), and 1.97% and 33.6% for Dunasolar (a-Si glass module). Results showed a strong correlation between the intermittence of solar radiation and the current THD. 67%, 54%, and 37% of the recorded power factor for Dunasolar, Juta, and Solarex modules, respectively, exceeded the limits prescribed by the standards.

Effects of sidewall opening areas on the performance of broiler chickens and the indoor climatic conditions of backyard poultry building

Sidewall openings play an important role in the indoor conditions of livestock buildings. It influences airflow patterns, air velocity distribution at the animal-occupied zones and the illumination level in the naturally ventilated animal building. However, there is a paucity of information on the effects of sidewall opening areas on the performance of broiler chickens. Hence, this study investigated the effect of sidewall opening areas on the indoor condition and the body growth of broilers. Two buildings with different sidewall opening areas were developed with broiler chickens reared in them for 28 days. The results showed that air temperatures and relative humidity of the buildings were influenced by the outdoor temperature. The indoor air temperatures of the building exceeded the recommended thermal conditions (18 to 24ºC) for broiler chickens. Similarly, the temperature-humidity index of the building exceeded 21.0ºC recommended for broilers which could result in heat stress and poor performance of broiler chickens during extremely hot weather periods. It was also found in this study that broiler chickens could not perform optimally though they were fed ad libitum. Therefore, further studies are required to ascertain the impact of sidewall opening areas on broiler performance, behaviour and physiological responses.

Indoor photovoltaics: A numerical model of dye-sensitized solar cells based on indoor illumination for the Internet of Things applications

Since dye-sensitized solar cells (DSSC) have a suitable efficiency in the invisible region, they present a promising avenue for sustainable energy generation, particularly in the context of indoor environments where ambient lighting prevails. This paper proposes a novel numerical model tailored to assess the performance of DSSCs under indoor lighting conditions, with a specific focus on their potential application in powering Internet of Things (IoT) devices. By considering factors such as radiation intensity and spectral composition, particularly from common indoor light sources like Light Emitting Diodes (LEDs) and Fluorescent lights, the model offers insights into the efficiency and viability of DSSCs in indoor settings. Since empirical analyses are difficult and expensive, the existence of a numerical model that investigates cell behavior under indoor illumination can be beneficial for developing such cells. In conducting verifying analyses under varying lighting conditions, the study demonstrates notable efficiencies of DSSCs, with LED 3000 K illumination at 1000 lux intensity yielding the highest performance. While DSSCs may appear less economically viable in environments with readily available electricity, their potential significance lies in providing sustainable energy solutions for IoT devices, thus reducing dependency on conventional power sources and contributing to environmental sustainability. The scientific significance of this research lies in its contribution to understanding the behavior of DSSCs under indoor lighting, offering insights into their potential applications in powering IoT devices. By providing a numerical model for evaluating DSSC performance under realistic indoor conditions, this study opens avenues for further research in optimizing DSSC technology for indoor energy harvesting applications, thereby advancing the field of renewable energy and sustainable technology integration.

Super-stable modified wood for enhanced autonomous indoor humidity regulation

The crucial development of materials that automatically adjust indoor humidity, a significant factor in human health and daily life, has gained importance due to the emphasis on energy conservation. Wood, with its natural hygroscopic properties, is effective in this regard but faces challenges of deformation and cracking due to moisture content changes. Herein, we introduced an innovative in-situ wood modification strategy, which integrated deep eutectic solvent (DES) impregnation with heat treatment, producing dimensionally super-stable modified wood for enhanced autonomous indoor humidity regulation. This modification process focused on creating more robust cross-linking structures within the amorphous regions of the wood cell wall. As a result, water-induced deformation of natural wood was significantly reduced, as evidenced by an anti-swelling efficiency exceeding 80%, ensuring the long-term reliability of DES-modified wood in varying humidity environments. Additionally, the introduction of additional pores and hygroscopic sites in the cell wall enhanced the natural wood’s moisture buffering value by 2.5 times, showcasing the superior ability of DES-modified wood to control indoor humidity effectively. Moreover, the DES-modified wood also exhibited commendable flame retardancy and antibacterial properties. Consequently, this novel modified wood emerges as a reliable material for indoor humidity regulation, promoting healthier indoor conditions and offering a sustainable alternative for energy-efficient construction practices.

Analisa Analisa Pencahayaan dan Penghawaan Alami Pada Tourist Information Center (TIC) dan Market Ekonomi Kreatif

Abstract: Natural lighting and ventilation are seen as key elements in supporting environmental sustainability and enhancing occupants’ physical and psychological comfort. The analysis involved measuring light intensity, light distribution and natural ventilation strategies to achieve optimal indoor conditions. The use of natural energy source such as the sun and outside air supports the principle of sustainability in building design. This journal examines natural lighting and ventilation in Tourist Information Center (TIC) and Creative Economy Market buildings which is expected to provide in-depth insight into the effectiveness of natural lighting and ventilation systems. Recommendations for design improvements or enhancements are presented to improve energy efficiency, environmental quality, and user comfort at these locations. Keywords: natural lighting, natural ventilation

Culture of photosynthetic microalgae consortium in artificial produced water supplemented with liquid digestate in closed column photobioreactors and open-pond raceway

Large amounts of produced water are extracted by the Oil and Gas energy sector since the industrial revolution. This available water, often salty, can be used to dilute liquid digestate from the anaerobic digestion process, a promising source of nutrients for microalgae cultivation. The study investigates the growth of halotolerant microalgae and their associated bacteria in column photobioreactors (PBRs) and open raceway pond (RWP), to treat industrial wastewaters while producing biomass for energy valorisation. Microalgae were cultured in mixtures of saline artificial produced water (7–44 %v/v), liquid digestate (5 %v/v using PBRs, 29–63 %v/v using RWP) and seawater. Nannochloropsis oceanica and Tetraselmis suecica strains were firstly cultivated in 70 L PBRs in indoor conditions for 3 months and later in 1.1 m3 RWP operated in outdoor conditions for 5 months in spring-summer period. In PBRs, average productivity was 9.0 ± 4.2 gVSS·m−2·d−1 (102–153 mgVSS·L−1·d−1), with daily removal efficiencies for chemical oxygen demand, nitrogen and phosphorous up to 61.8, 31.6 and 97.2 %, respectively. In RWP, strong changes in the microalgae populations were observed. Productivity was 6.7 ± 5.2 gVSS·m−2·d−1 (30 ± 23 mgVSS·L−1·d−1), with daily removal efficiencies for chemical oxygen demand, nitrogen and phosphorous up to 48.4, 44.4 and 88.1 %, respectively. In parallel with the production of microalgae, a nitrifying microbial population grew in the RWP despite the high salinity (70 g L−1). Over these periods of several months, microalgae production was maintained using a culture medium containing high salt concentration, metals and harmful aromatic compounds.

Exploring the influence of indoor environment and spatial layout on changed behaviours of people with dementia in a nursing home

People with dementia sometimes show changed behaviours such as agitation, hallucination, and wandering during the moderate and severe dementia stages. In addition to individual health factors, contextual factors, such as indoor environment conditions, spatial layout, and human activities, may trigger or influence these behaviours, but there is a lack of solid evidence. We used mixed methods to collect data, including the fly-on-the-wall method to observe the residents' daily lives and deploying environmental sensors to monitor the indoor environments of two central living rooms and ten bedrooms in a nursing home in the Netherlands. A data collection campaign from August to September 2022 focused on the indoor environmental parameters, ventilation control of monitored rooms, the observation of ten participants' locations, activities, clothing levels, and changed behaviours. The data were analysed using Fisher's exact tests and heatmap analysis. The results show that even though the nursing home was well maintained according to existing indoor environmental quality standards, the room conditions of temperature, TVOC, and HCHO levels and contextual factors (main activity and numbers of people in the space) were significantly correlated with locations of changed behaviours. By analysing observation data with spatial layout, participants had larger activity ranges on the days that exhibited changed behaviours than those without. Most of these behaviours were observed at the edge of common spaces, where caregivers need to pay more attention.

Sub-pilot scale sequential microalgal consortium-based cultivation for treatment of municipal wastewater and biomass production

Municipal wastewater (MWW) was treated by a sequential pilot microalgal cultivation process. The cultivation was performed inside a specifically designed low-cost photobioreactor (PBR) system. A microalgal consortium 2:1 was developed using Tetraselmis indica (TS) and Picochlorum sp. (PC) in the first stage and PC:TS (2:1) in the second stage and the nutrient removal efficiency and biomass production and biomolecules production was evaluated and also compared with monoculture in a two-stage sequential cultivation system. This study also investigated the effect of seasonal variations on microalgae growth and MWW treatment. The results showed that mixed microalgal consortium (TS:PC) had higher nutrient removal efficiency, with chemical oxygen demand (COD), total phosphate (TP), and total nitrate (TN) removal efficiencies of 78.50, 84.49, and 84.20%, respectively, and produced a biomass of 2.50 g/L with lipid content of 37.36% in the first stage of cultivation under indoor conditions. In the second stage of indoor cultivation, the PC:TS consortium demonstrated maximum COD, TP, and TN removal efficiencies of 92.49, 94.24, and 94.16%, respectively. It also produced a biomass of 2.65 g/L with a lipid content of 40.67%. Among all the seasonal variations, mass flow analysis indicated that the combination of mixed consortium-based two-stage sequential process during the winter season favored maximum nutrient removal efficiency of TN i.e. 88.54% (84.12 mg/L) and TP i.e., 90.18% (43.29 mg/L), respectively. It also enhanced total biomass production of 49.10 g in 20-L medium, which includes lipid yield ∼15.68 g compared to monoculture i.e., 82.06% (78.70 mg/L) and 82.87% (40.26 mg/L) removal of TN and TP, respectively, and produced biomass 43.60 g with 11.90 g of lipids.

Power Scavenging Microsystem for Smart Contact Lenses.

On-the-eye microsystems such as smart contacts for vision correction, health monitoring, drug delivery, and displaying information represent a new emerging class of low-profile (≤ 1mm) wireless microsystems that conform to the curvature of the eyeball surface. The implementation of suitable low-profile power sources for eye-based microsystems on curved substrates is a major technical challenge addressed in this paper. The fabrication and characterization of a hybrid energy generation unit composed of a flexible silicon solar cell and eye-blinking activated Mg-O2 metal-air harvester capable of sustainably supplying electrical power to smart ocular devices are reported. The encapsulated photovoltaic device provides a DC output with a power density of 42.4 µW cm-2 and 2.5mW cm-2 under indoor and outdoor lighting conditions, respectively. The eye-blinking activated Mg-air harvester delivers pulsed power output with a maximum power density of 1.3mW cm-2. A power management circuit with an integrated 11 mF supercapacitor is used to convert the harvesters' pulsed voltages to DC, boost up the voltages, and continuously deliver ≈150 µW at a stable 3.3V DC output. Uniquely, in contrast to wireless power transfer, the power pack continuously generates electric power and does not require any type of external accessories for operation.

Beyond droplet deposition: Virus transport and deposition modeling in respiratory tract influenced by ambient environment and exhalation activities

Quantifying virus deposition in the respiratory tract during exposure to various infected environments is crucial for developing effective indoor environmental interventions against airborne infectious diseases. This study presents a novel approach that combines a physical model for virus-laden droplet evaporation, size-independent viral load concentrations, and computational fluid dynamics simulations inside the respiratory tracts. We quantify the impact of exhalation activities and actual vapor pressure on virus deposition fraction (DFv) and droplet deposition fraction (DFd) in the respiratory tract by tracking virus-laden droplets from exhalation to inhalation to deposition. Our findings reveal that virus deposition fraction significantly differs from the droplet deposition fraction in the respiratory tract, as the minimum mean absolute percentage error (MAPE) is 0.65. Moreover, the exhalation activities and indoor conditions play a vital role in virus deposition. Considering exhalation activity is necessary for assessing the potential risk of infection in the lung lobes. The deposition fraction and copies of the virus are nearly 2-fold and over 6000-fold higher during patient speaking compared to breathing, respectively. Actual vapor pressure is also vital for the interception of the upper respiratory tract. The DFv decreases from 66.86% to 46.96% as actual vapor pressure changes from low to high. Additionally, our study quantifies the difference in virus deposition fraction between size-dependent and size-independent viral load concentrations, showing the necessity of considering size-dependent viral load concentration. Our findings improve the predictability of infection risks and can refer to the development of effective non-pharmaceutical interventions in indoor environments in the post-pandemic.

Robust hyperspectral image classification using generative adversarial networks

This paper introduces Sill-Rgan, a novel Generative Adversarial Network (GAN) designed to improve hyperspectral image (HSI) classification under varying lighting conditions. Sill-Rgan uniquely maps different light condition domains, enhancing sample classification robustness and generating new virtual samples. Addressing challenges like high spectral dimensionality and noise in HSI classification, our approach utilizes a deep proxy-based learning framework. It integrates and improves advanced GAN models and multitask networks for optimal training stability and loss function optimization. The model's mapping network is adept at generating domain-specific latent codes, enabling the transformation of original hyperspectral data into enhanced versions. Extensive experiments conducted on hyperspectral datasets of agricultural products under diverse indoor and outdoor lighting conditions confirm the effectiveness of Sill-Rgan. The results highlight the model's adaptability in both supervised and semi-supervised learning scenarios, yielding exceptional classification accuracy and enhanced data quality. The versatile potential of Sill-Rgan extends its applicability to a broad range of spectral data classifications, underlining its significant contribution to hyperspectral imaging. This advancement opens new avenues in machine vision systems, particularly in scenarios with dynamic lighting challenges.

IoT Based Real Time Monitoring System for Data Center Indoor Conditions

İnternet çağını yaşadığımız şu günlerde veri merkezleri, kullanıldığı işletmeler veya kurumlar için bilginin erişilmesi, saklanması ve kullanılması için hayati önem taşımaktadır. İçerisinde sunucu sistemleri ve sunucu bilgisayarları barındıran veri merkezleri sürekli gözetim altında tutulması gereken kritik öneme haiz bilgisayar sistemleridir. Bu bakımdan veri merkezlerinin kurulumlarının yapıldığı odalarda veya merkezlerde bazı iç ortam parametrelerin ele alınması ve bu parametrelerin kontrol altında tutulması gerekmektedir. Bu çalışmada, veri merkezinin bulunduğu bir oda içerisindeki iç ortam parametrelerinin izlenmesi ve herhangi bir sorun tespit edilmesi durumunda e-posta yoluyla ilgili kullanıcıların uyarılmasına imkân sağlayan IoT tabanlı bir sistem gerçekleştirilmiştir. Geliştirilen sistemde Raspberry Pi 3 mini-bilgisayar kartı kullanılmış ve veri merkezi içerisindeki sıcaklık ve nem değerleri, ses şiddeti, hareket tespiti, yangın tespiti, sıvı tespiti gibi parametreler ele alınmıştır. Ele alınan parametreler, geliştirilen web arayüzü ile anlık ve gerçek zamanlı olarak izlenmektedir. Sistem, veri merkezindeki iç ortam koşullarında meydana gelen anormal durumları tespit etmede başarılı olmuş ve hızlı bir şekilde önlemler alınabilmesi için ilgili kullanıcılara uyarılarda bulunmuştur.

Influences of Indoor Air Temperatures on Empathy and Positive Affect.

The consequences of climate change are already visible, and yet, its effect on psychosocial factors, including the expression of empathy, affect, and social disconnection, is widely unknown. Outdoor conditions are expected to influence indoor conditions. Therefore, the aim of this study was to investigate the effect of indoor air temperature during work hours on empathy, positive and negative affect, and social disconnection. Participants (N = 31) were exposed, in a cross-over design, to two thermal conditions in a simulated office environment. Questions on empathy and social disconnection were administered before and after the exposure to each condition, while affect was measured throughout the day. Subjective thermal sensation and objective measures of mean skin temperature were considered. The results indicated a significant difference in empathy (F(1, 24) = 5.37, p = 0.03, with an η2 = 0.126) between conditions. Participants reported increases in empathy after exposure to the warm condition compared to the cool condition, in which reductions in empathy were reported. Although the same pattern was observed for positive affect, the difference was smaller and the results were not significant. Thermal sensation had a significant effect on changes in empathy too (F(1, 54) = 7.015, p = 0.01, with an R2 = 0.115), while mean skin temperature had no effect on empathy (F(1, 6) = 0.53, p = 0.89, with an R2 = 0.81). No effects were observed for positive and negative affect and social disconnection. Longitudinal studies are needed to support these findings.

Low-Cost Sensor System for Air Purification Process Evaluation.

With the development of civilisation, the awareness of the impact of versatile aerosol particles on human health and the environment is growing. New advanced materials and techniques are needed to purify the air to reduce this impact. This brings the necessity of fast and low-cost devices to evaluate the air quality from particulate and gaseous impurities, especially in a place where gas chromatography (GC) techniques are unavailable. Small portable and low-cost systems may work separately or be incorporated into devices responsible for air-cleaning processes, such as filters, smoke adsorbers, or plasma air cleaners. Given the above, this study proposes utilising a self-assembled low-cost system to evaluate air quality, which can be used in many outdoor and indoor applications. ESP32 boards with the wireless communication protocol ESP-NOW were used as the framework of the system. The concentration of aerosol particles was measured using Alphasense sensors. The concentrations of the following gases were measured: NO2, SO2, O3, CO, CO2, and H2S. The system was used to evaluate the quality of air containing tobacco smoke after passing through an actual DBD plasma reactor where the purification occurred. A high amount of reduction in aerosol particles and a reduction in the SO2 concentration were detected. An increase in the NO2 concentration was seen as an undesirable effect. The aerosol particle measurements were compared with those using a professional device (GRIMM, Hamburg, Germany), which showed the same trends in aerosol particle behaviour. The obtained results are auspicious and are a step towards producing a low-cost, efficient system for evaluating air quality as well as indoor and outdoor conditions.

Data-driven approach enabling post-operation evaluation of air conditioning performance regarding thermal conditions attained indoors

Data-driven approaches become more and more attractive in building performance analysis including performance assessment of heat, ventilation, and air conditioning (HVAC) systems. Their popularity is associated with the increasing availability of large amounts of high-quality building-related measurement data. The study is focused on a data-driven approach that enables post-operation evaluation of AC performance based on indoor air monitoring. It allows for the identification of the classifying solution which recognizes the monitoring data that is representative of thermal conditions during AC operation. The major novelty consists in proposing the classification performance criterion, which is F1w-Score (the weighted F1-Score), and the procedure of weights selection. The procedure utilizes Hellinger distance (H). It is applied to measure the similarity between the binary empirical probability distribution of T and RH (EPDtr), associated with AC operation, and the prediction of this distribution (EPDes), made by the classifier. The approach was tested on three years of data from continuous indoor air monitoring in the IT engineers' room equipped with an AC unit. The best weights of F1w-Score were wPPV = 0.85 and wTPR = 0.15. The best classifying solution was identified using F1w-Score. It involved: Logistic Regression as the classifier and feature vector being Fourier spectrum of 16 min long fragments of RH and T time series. The performance of the best classifying solution was high as indicated by F1w-Score = 0.89 ± 0.05. The corresponding H(EPDtr, EPDes) = 0.17 ± 0.04 pointed at the capability to identify the measurement data that characterizes indoor conditions during AC operation well. This work contributes to the development of data-driven approaches serving diagnostics of HVAC systems. It draws attention to the problem of defining the classification performance criterion which takes into account the ultimate, domain-specific use of the classification results.

Indoor environmental comfort in an antarctic research station: A case study

The indoor environmental quality of research stations requires attention and constant improvement due to the harsh polar climatic conditions. We conducted a case study at an Antarctic research station from March 2021 to November 2022. Indoor and outdoor condition monitoring and questionnaire surveys with the occupants were conducted to obtain environmental parameters and subjective evaluations. Twenty-six participants were surveyed, and 355 sets of measurement data and subjective questionnaires were obtained. An analysis of environmental evaluations and adaptation behaviors demonstrated that more than 80% of the participants expected the indoor temperature to remain unchanged, and over 40% desired improvements in humidity, air quality, and overall environmental quality. Opening windows was the most common environmental adaptation behavior made by participants. However, they had high expectations for the overall environment, indicating the demand for diverse and effective environmental adaptive options in interior design. Moreover, we analyzed the weighting coefficients of the influence of various environmental evaluations on overall environmental perceptions and the correlations between them. The results revealed the importance of the thermal environment and air quality on overall evaluations. Regressions yielded thermal neutral temperature ranges of 18.4–21.3 °C and acceptable temperature ranges, at which 90% of participants were satisfied, of 21.6–26.7 °C. These results could guide future assessments of the indoor environmental comfort at Antarctic stations and help create polar building environments suitable for work and life.

Enhancing legibility in educational settings: Optimizing projection illuminance for varied indoor ambient illuminance

Projectors are common display devices in the educational setting. However, dim projector lightbulbs or well-lit classrooms may cause blurriness in the projected image. To determine the optimal projection light under different ambient light conditions, the conjoint effects of projection illuminance and ambient illuminance on the legibility of projection images indoors were investigated. Participants (N = 96) were randomly assigned to one of six indoor ambient light conditions (0, 40, 80, 120, 160, and 200 lx) and performed a visual search task under several projection illuminance conditions (200, 250, 300, 350, and 400 lx). The accuracy and correct response time on the task were collected to evaluate the participants’ visual performance to represent legibility. The optimal projection illuminance (high visual accuracy and fast reaction) was 400 lx (944 ANSI lumen) under all ambient light conditions. To avoid low legibility (accuracy<0.6) and maintain acceptable legibility (accuracy>0.7), the projection illuminance should be increased as the indoor ambient light increases.

Pilot study: Occupational and public health consequences of elevated temperatures in restaurant kitchens

Restaurant kitchens are relatively warm and can be made even warmer when the outdoor temperature is excessive. Hot indoor conditions can lead to workers experiencing health effects such as heat stress as well as negatively impact food storage and food cooling. This study’s objective was to simultaneously identify potential occupational health and public health effects inside restaurant kitchens due to warm conditions. Wet Bulb Globe Temperature (WBGT) measurements were collected and the results were compared to the corresponding Threshold Limit Value and Action Limit. Internal temperatures of refrigerators and freezers were gathered and observations were made of any food being held inside the kitchen. Eight premises in the Greater Toronto Area were included in this study. Five of the sites had average WBGT values at or above the Action Limit, which is when heat stress management programs are recommended. Most sites had refrigerators operating over the required 4°C and three sites had freezers operating above the requisite −18°C. Food was observed to be held at temperatures that can promote bacterial growth in 50% of the sites. This study found that hot kitchen environments could result in both heat stress conditions as well as compromise cold food storage and food holding.