Reflective Paint Research Articles

A comparative study on the optical performance of retro-reflective coatings before and after the aging process

Retro-reflective (RR) materials are largely included among the strategies to mitigate Urban Heat Island (UHI) phenomenon in the urban spaces thanks to their optical directional properties. As materials potentially used in the building exterior envelope, RR materials are subjected to outdoor aging and soiling processes, which could alter their optical behaviour. In this perspective, the investigation focuses on the characterization of the optical performance of several types of RR plaster coatings after outdoor aging and soiling processes. The RR plaster coatings were previously developed and studied, before undergoing the outdoor exposure. The RR samples were developed covering the support with a reflective white paint and glass beads. Five different microsphere diameter ranges and three different microsphere superficial density ranges have been employed. In this paper, the RR plaster coatings were tested in terms of optical properties after outdoor aging and soiling and results were compared with data of the same plaster coatings pre-aging. Generally, all RR aged samples show a lower solar reflectance in the Vis region with respect to the pre-aging conditions. The RR behaviour is qualitatively maintained after aging and soiling. The RR sample made of glass beads of 200–300 μm diameter range could represent the best solution both in pre- and post-conditions and both in terms of solar reflectance and retro-reflective behaviour, regardless of the density of microspheres used.

Minor Modification in Asbestos Roof of Cow Shed for Reduction of Heat Stress in Dairy Cows during Summer Season

Thermo neutral zone (TNZ) is the range of ambient temperature & humidity in which animals feel comfortable and their production level is optimum. When temperature humidity index (THI) goes above 72, the dairy cows begin to show symptoms of mild heat stress, which affects the milk production in dairy animals during summer season in India. Asbestos and GI sheet are commonly used as roofing material in many cattle farms throughout the world. This experiment was carried out on apparently healthy cross bred jersey cows receiving balanced ration during the month of May in the livestock farm of OUAT, Bhubaneswar for one week. The existing cattle shed was partitioned into three compartments by raising brick walls, each having the dimension of 30 x 25 ft size. The asbestos roof of first one was covered with 90 % grade green shed-net. Over the asbestos roof of second compartment, heat reflective white colour was painted and asbestos roof of third one was left as such. From 8.00 AM to 5.00PM, the THI of the normal asbestos roof shed varied from mild to moderate heat stress range. But THI of both shed-net covered shed and heat reflective colour painted shed was found to be within the mild heat stress range i.e. 72-79 during noon indicating a comfortable ambient condition for the animals in summer season when the outside ambient temperature went up to 40 0C during noon. No significant (P>0.05) change in the milk production was observed among the groups during the week. However, a decrease (P<0.05) of 0.43, 0.25 and 0.38 L in milk yield of the cows was observed when they were kept under normal asbestos shed, heat reflective colour painted shed and shed-net covered shed, respectively. From the study, this can be concluded that the impact of heat stress on milk production can be reduced by painting the rood of the shed with heat reflective colour paint.

Study of Roof and Ceiling Surface Temperatures in Coastal Area (Case Study: Pasar Bengkulu Village)

Abstract The majority of residential roofs in Pasar Bengkulu Village are constructed using corrugated iron and galvalum metal. These coastal areas often grapple with high levels of solar heat radiation. Both corrugated zinc and galvalum roofing materials are known for their high heat conductivity and excellent heat-reflecting capabilities. To combat this, solar reflectance paint is often used to reflect solar radiation heat, thereby reducing heat absorption. This research is a qualitative research with a focus on the description and analysis of measured data which aims to compare the surface temperature of the roof and ceiling before and after being coated with reflective solar paint. This research was conducted to determine the difference in roof and ceiling surface temperatures before and after the application of solar reflective paint. The results of the roof surface temperature measurements revealed that galvalum metal roofs exhibited the most significant reduction in roof surface temperature, with a decrease of 9.1°C.

AN INTEGRATING SPHERE SPECTROPHOTOMETER PROTOTYPE

Spectroscopy is essential for research in the qualitative and quantitative analysis of samples. In recent years, the need to develop portable and accessible equipment for sample characterization has reduced real-time analysis. The objective is to design and build a prototype of a portable spectrophotometer with an integrating sphere using tools such as Rhinoceros and Trace-Pro for its theoretical design and radiation simulation. The result is an integrating sphere 3D printed with PLA material and an internal coating with a 95% high reflectance paint. The AS7265 Triad module is the detector, along with signal processing to obtain spectra from control samples. The spectral profiles obtained were comparable with commercial equipment, validating the viability of the measurement system as the first spectroscopic instrument in the field, in complement to other spectroscopic techniques. This breakthrough promises to facilitate research in the field and in environments where mobility and accessibility are priorities. Keywords: Integrating sphere, High reflectance coating, simulation Trace Pro, Manufacturing integrating sphere, spectroscopy.

State-of-the-Art Review: Effects of Using Cool Building Cladding Materials on Roofs

Cool roofs are roofing systems designed to reflect significant solar radiation, reducing heat absorption and subsequent cooling energy demands in buildings. This paper provides a comprehensive review of cool roof technologies, covering performance standards, material options, energy-saving potential, and hygrothermal considerations. The review examines provisions in current codes and standards, which specify minimum requirements for solar reflectance, thermal emittance, and solar reflectance index (SRI) values. These criteria often vary based on factors like roof slope, climate zone, and building type. Different cool roof materials are explored, including reflective paints and coatings that can be applied to existing roofs as cost-effective solutions. Several studies have demonstrated the energy performance benefits of cool roofs, showing significant reductions in cooling loads, indoor air temperatures, peak cooling demand, and overall cooling energy consumption compared to traditional roofs. However, hygrothermal performance must be evaluated, especially in cold climates, to optimize insulation levels and avoid moisture accumulation risks, as reduced heat absorption can alter moisture migration patterns within the building envelope. While cool roofs provide substantial energy savings in hot climates, further research is needed to validate modeling approaches against real-world studies, investigate the impact of seasonality and green spaces on cool roof efficacy and urban heat island mitigation, and explore energy-saving potential, moisture control, and condensation risks in cold and humid environments.

A detailed investigation on thermal performance and energy savings of cool roof systems for composite climates of India

ABSTRACT The rising worldwide temperatures leading to a spike in air conditioning to ensure thermal comfort in buildings is the root cause of the increase in energy demand in India's building sector. The roof of a building significantly adds to the heat gained on the top floor, accounting for 50–60% of the total heat gain. One sustainable way to reduce this heat gain is via cool roofing technology. Through examination and dynamic simulations with the Energy-Plus-based Design Builder software tool, this study explores different cool roof solutions. An experimental setup of a Reinforced Cement Concrete (RCC) roof with cement plaster, solar reflective paint, solar reflective tiles, and earthen pots have been created on the institute campus. Recordings were taken during the peak summer days and peak winter days, alongside simulations carried out to determine various factors such as Albedo, Surface Temperatures, Air Temperatures, Diurnal Heat Ingress, and the Building's Thermal Energy Consumption. The experiments have demonstrated that cool roof layers can considerably improve interior thermal comfort by minimizing heat transfer, which maintains a constant temperature over the bottom surface of the roof. By reducing heat gain by 33–71%, they can save energy by 21-26% compared to traditional RCC roof slab.

The Painting in Front of Itself: Frank Stella’s Atypical ‘Projective’ Spaces through Canvas, Paint and Colour

Abstract Frank Stella’s early works tend to be characterised as displaying the flatness of painted surfaces and an ambition to negate pictorial illusionism. However, beyond their emphasis on flatness, these early series of paintings generate new forms of illusions and, in some cases, initiate another type of pictorial space — one that bodies forth, coming toward the viewer, appearing as if in front of the canvas. We consider the materials of the painting format in Stella’s early work (1959 to 1986) that create or facilitate the emergence of such a protruding or ‘projective’ space: mainly canvas, types and colours of paint. After introducing notions of flatness and illusionism and our respective approaches, we focus on Stella’s use of unprimed, raw, canvas, on the one hand, and his use of reflective and fluorescent paint skins, on the other, and how paint and canvas relate to each other. We focus on the material conditions that Stella sets up to manifest his intentions regarding the perception of space in painting and where he believes painting ‘should’ go. Indeed, in a book published in 1986, Stella describes projective effects from painters who use different tactics than his, but he does not reveal how he achieves his own. We analyse precisely which elements in Stella’s early paintings trick the eye of the viewer into seeing a painting, as it were, in front of itself, and we demonstrate the aesthetic impact of Stella’s chosen materials. Or how colour, paint and canvas, working together in a sort of symbiosis, generate a protruding effect in a new, previously unseen manner, and challenge Stella’s assertions against illusionism.

Technical note: Visual, rapid, scintillation point dosimetry for in vivo MV photon beam radiotherapy treatments.

While careful planning and pre-treatment checks are performed to ensure patient safety during external beam radiation therapy (EBRT), inevitable daily variations mean that in vivo dosimetry (IVD) is the only way to attain the true delivered dose. Several countries outside the US require daily IVD for quality assurance. However, elsewhere, the manual labor and time considerations of traditional in vivo dosimeters may be preventing frequent use of IVD in the clinic. This study expands upon previous research using plastic scintillator discs for optical dosimetry for electron therapy treatments. We present the characterization of scintillator discs for in vivo x-ray dosimetry and describe additional considerations due to geometric complexities. Plastic scintillator discs were coated with reflective white paint on all sides but the front surface. An anti-reflective, matte coating was applied to the transparent face to minimize specular reflection. A time-gated iCMOS camera imaged the discs under various irradiation conditions. In post-processing, background-subtracted images of the scintillators were fit with Gaussian-convolved ellipses to extract several parameters, including integral output, and observation angle. Dose linearity and x-ray energy independence were observed, consistent with ideal characteristics for a dosimeter. Dose measurements exhibited less than 5% variation for incident beam angles between 0° and 75° at the anterior surface and 0-60 at the posterior surface for exit beam dosimetry. Varying the angle between the disc surface and the camera lens did not impact the integral output for the same dose up to 55°. Past this point, up to 75°, there is a sharp falloff in response; however, a correction can be used based on the detected width of the disc. The reproducibility of the integral output for a single disc is 2%, and combined with variations from the gantry angle, we report the accuracy of the proposed scintillator disc dosimeters as ±5.4%. Plastic scintillator discs have characteristics that are well-suited for in vivo optical dosimetry for x-ray radiotherapy treatments. Unlike typical point dosimeters, there is no inherent readout time delay, and an optical recording of the measurement is saved after treatment for future reference. While several factors influence the integral output for the same dose, they have been quantified here and may be corrected in post-processing.

ANALISIS DAMPAK PERUBAHAN PENGGUNAN LAHAN PERKOTAAN TERHADAP URBAN HEAT ISLAND DI KECAMATAN KEDATON

The Urban Heat Island phenomenon is defined as a form of local climate change. In the formation of the Urban Heat Island phenomenon, there are several factors, namely changes in land use, vegetation density, building density, and vehicle emissions. Dense development areas that have caused changes in land use, settlements, and transportation activities have begun to accumulate in Kedaton District. Kedaton District is included in the activity center area so that changes in land use from 2017 to 2022 occur significantly, which can cause an increase in urban temperatures. This study aims to analyze the impact of changes in urban land use on Urban Heat Island in Kedaton District. The variables used are land use, surface temperature, vegetation density, building density, motor vehicle intensity, and motor vehicle emissions. The analytical methods used are LST, NDVI, NDBI, road service level analysis, vehicle emission analysis, and correlation analysis. The results of the analysis show that the impact of changes in land use will result in a 76% decrease in vegetation density in 2022, a 95% increase in building density, and a 99% increase in vehicle emissions. The impact of changes in land use has contributed to the distribution of urban heat islands in Kedaton District. To minimize the impact of changes in use on the Urban Heat Island in Kedaton District, mitigation efforts based on the resilient city concept are needed, namely the addition of private green open spaces, reflective roof paint in densely populated areas, and optimizing public transportation.

Solar Spectrum Reflectometer Measurements on Profiled and Small Samples: Design and Testing of Adapters

AbstractTesting solar reflective building materials is mainly performed in laboratories using Solar Spectrum Reflectometer (SSR) or spectrophotometry. To obtain aged materials values, after exposing materials in test farms for natural ageing or applying ASTM-D7897, treated samples shall be tested again using SSR. On-site measurements of new and aged surfaces is allowed using pyranometers or albedometers, which present issues caused both by high-pitched roof and by solar and sky requirements in several locations such as at southern and middle Europe latitudes, where clay tiles are a typical coverage of roof surfaces. The use of battery-powered SSR offsite could be a solution to obtain reliable measurements in every climate, lighting, and slope condition. However, the shape of roof surfaces remains an issue since most of the tiles are characterized by elaborated morphologies that cannot fit the measurement head of the SSR. In this study, two sets of cylindrical adapters for SSR, made via Fused Deposition Modeling and coated with solar reflective white diffuse paint or specular reflective coating were produced and tested to overcome this problem. The adapters were attached to the top of the measurement head and measurements were performed according to ASTM-C1549. These adapters were tested with samples characterized by ASTM-C1549, analyzing the output from all 6 detectors of SSR, and by spectrophotometry according to ASTM-E903, using both AM1GH and ASTM E891-87 irradiance spectra. Aluminum-coated adapters proved ideal due to non-impact on measurements. Solar reflectance showed strong linear correlation for 30–50 mm adapter lengths, indicating minimal signal damping. They will allow testing most of the samples that cannot be tested with standard methods, especially aged ones, without altering their surface.

Determination of intrinsic energy dependence of point-like inorganic scintillation detector in brachytherapy.

Inorganic scintillation detectors (ISDs) are promising for in vivo dosimetry in brachytherapy (BT). ISDs have fast response, providing time resolved dose rate information, and high sensitivity, attributed to high atomic numbers. However, the conversion of the detector signal to absorbed dose-to-water is highly dependent on the energy spectrum of the incident radiation. This dependence is comprised of absorbed dose energy dependence, obtainable with Monte Carlo (MC) simulation, and the absorbed dose-to-signal conversion efficiency or intrinsic energy dependence requiring measurements. Studies have indicated negligible intrinsic energy dependence of ZnSe:O-based ISDs in Ir-192 BT. A full characterization has not been performed earlier. This study characterizes the intrinsic energy dependence of ZnSe:O-based ISDs for kV X-ray radiation qualities, with energies relevant for BT. Three point-like ISDs made from fiber-coupled cuboid ZnSe:O-based scintillators were calibrated at the Swedish National Metrology Laboratory for ionizing radiation. The calibration was done in terms of air kerma free-in-air, , in 13 X-ray radiation qualities, , from 25 to 300 kVp (CCRI 25-250kV and ISO 4037 N-series), and in terms of absorbed dose to water, , in a Co-60 beam, . The mean absorbed dose to the ISDs, relative to and , were obtained with the MC code TOPAS (Geant4) using X-ray spectra obtained with SpekPy software and laboratory filtration data and a generic Co-60 source. The intrinsic energy dependence was determined as a function of effective photon energy, , (relative to Co-60). The angular dependence of the ISD signal was measured in a 25 kVp (0.20mm Al HVL) and 135 kVp beam (0.48mm Cu HVL), by rotating the ISDs 180° around the fiber's longitudinal axis (perpendicular to the beam). A full 360° was not performed due to setup limitations. The impact of detector design was quantified with MC simulation. Above 30keV the intrinsic energy dependence varied with less than 5±4% from unity for all detectors (with the uncertainty expressed as the mean of all expanded measurement uncertainties for individual above 30keV, k=2). Below 30keV, it decreased with up to 17% and inter-detector variations of 13% were observed, likely due to differences in detector geometry not captured by the simulations using nominal geometry. In the 25 kVp radiation quality, the ISD signal varied with 24% over a ∼45° rotation. For 135 kVp, the corresponding variation was below 3%. Assuming a 0.05mm thicker layer of reflective paint around the sensitive volume changed the absorbed dose with 6.3% at the lowest , and with less than 2% at higher energies. The study suggests that the ISDs have an intrinsic energy dependence relative to Co-60 lower than 5±4% in radiation qualities with >30keV. Therefore, they could in principle be calibrated in a Co-60 beam quality and transferred to such radiation qualities with correction factors determined only by the absorbed dose energy dependence obtained from MC simulations. This encourages exploration of the ISDs' applications in intensity modulated BT with Yb-169 or other novel intermediate energy isotopes.

The effect of a protective layer on the optical behavior of retro-reflective paintings for building envelopes

Retro-reflective (RR) materials, applied to building envelopes, constitute an option to tackle Urban Heat Island phenomenon, thanks to their capability to reflect the sunlight predominantly towards the solar incidence direction. RR coatings are obtained with the deposition of glass beads on traditional diffusive materials. During their lifetime, outdoor aging and soiling affect their optical behavior. In addition, without a proper protection, some glass beads could detach from the paint and disperse in the environment. Hence, a necessity arises for the application of a safeguarding stratum on RR materials to avert the separation of glass beads in RR coatings following the aging process. In this paper, five RR samples were produced, employing a highly reflective paint as foundation, RR glass beads and a protective layer. A diffusive sample, without glass beads, was made for comparison. Samples underwent spectrophotometric and angular distribution analyses. The effect of the protective layer on the optical behavior was assessed comparing the results with those obtained for the same RR materials without the protective layer. RR samples with a protective layer exhibit a higher reflectance with respect to the same RR sample without a protective layer. In the near-infrared (NIR) region, a lower reflectance occurs for all RR samples with a protective layer. A less concentrated angular distribution of the reflected light was observed for all RR samples with the addition of a protective layer.

EVALUATION AND COMPARISON OF DIFFERENT TIME OF FLIGHT CAMERAS FOR OUTDOOR APPLICATIONS

Abstract. Time-of-Flight (ToF) cameras have gained prominence in robotics, augmented reality, and gesture recognition due to their costeffective direct measurement of 3D environments. However, their outdoor applications remain limited, mainly due to challenges like sunlight interference. Through systematic testing under challenging outdoor conditions, we aim to assess the suitability of ToF cameras, specifically Azure Kinect and Pmd Monstar, in smart city contexts and contribute to the state-of-the-art and future trends of 3D sensing technology. Our experiments focus on three high-reflectivity cases: license plates, reflective road marking paint on cement and asphalt boards, and traffic cones. Results indicated that Azure Kinect offered a longer measurement range but was more susceptible to flying pixels. Pmd Monstar provided more stable depth measurements and was less sensitive to flying pixels. Differences in performance were attributed to their modulation frequencies and the distinct approaches to handling low-confidence points. By addressing the identified limitations and challenges, researchers and engineers can enhance ToF camera capabilities, ultimately improving their performance and expanding their applicability in outdoor transportation, autonomous driving, and other related smart city fields.

NIR reflective Paints as an Alternative for Sustainable Façade Renovation

Several studies of infrared reflective materials used on opaque envelopes have shown that their application can reduce the surface temperature and the cooling energy needs of buildings and help mitigate the urban heat island effect. Some of these studies were carried out by incorporating near-infrared (NIR) reflective materials on new buildings or as part of new construction systems, considering that one of the simpler and most used façade renovation methods is repainting. In a repainting process, the reflectance could change since the reflectance depends on the interaction between the reflective layer and the substrate. A study was carried out on the reflectance of paints with NIR reflective properties applied on the finishing coat of external thermal insulation composite systems (ETICS), simulating a façade renovation. A black NIR reflective paint was applied in one layer over the existing finishing coat of two ETICS samples: one with a grey mortar colour and another with a conventional black colour. A second configuration was considered by adding an intermediate layer of regularisation with white colour. Traditional black colour and the mortars were applied on a transparent acrylic base as a reference. The samples were assessed with a modular spectrophotometer to assess the total and NIR reflectance and the colour coordinates on the CIELab space. The results showed that the reflectance and colour of the new layer are independent of the colour or type of the first layer in the case of conventional paint. Conversely, the substrate affects the NIR paint performance, where a lighter substrate can help improve the reflectance but can also lead to a more significant colour change. Likewise, the results of the paint over a new white layer resulted in a lower reflectance compared to the reflectance of a single paint layer.

Improving Thermo-Energetic Consumption of Medical Center in Mexican Hot–Humid Climate Region: Case Study of San Francisco de Campeche, Mexico

An assessment of the thermal refurbishment of an outpatient medical center in a tropical location, such as the City of San Francisco de Campeche, was presented with the aim to diminish its energy consumption. A year-long energy audit of the facility was conducted to formulate and validate a numerical simulation model while scrutinizing enhancement strategies. The examined improvement alternatives encompass passive adjustments to the roof (utilizing insulating materials, applying reflective coatings, and installing a green roof), modifications to active systems incorporating inverter technology, and alterations to the walls via reflective paint. The outcomes of the simulated enhancement scenarios were assessed utilizing energy, environmental, and economic metrics: key performance index (KPI), equivalent CO2 emission index (CEI), and net savings (NS). These results were subsequently juxtaposed against TOPSIS decision-making algorithms to ascertain the alternative that optimally balances the three options. It was identified that using reflective paint on the roof provides the best energy benefits and contributes to mitigating emissions from electricity use. Furthermore, combining this passive technology with the integration of inverter air conditioning systems offers the best economic return at the end of 15 years. For its part, the TOPSIS method indicated that by prioritizing the financial aspect, the reflective coating on the roof combined with inverter air conditioning is enough. However, adding a wall with insulating paint brings environmental and energy benefits. The results of this work serve as a starting point for the analysis of other post-occupied buildings in the region and others under tropical climatic conditions.

Performance testing of nanocomposite based coatings with high dust pickup resistance and solar reflective index for energy efficiency in built environment

Cool paints/coatings are passive solutions which enable reduction in energy loads and impart substantially in buildings owing to their reflective properties. The most common metric to assess their performance is the Solar Reflective Index (SRI). Higher SRI values for paints enable the reflectance of solar radiation and further aid in reducing the cooling load in buildings. This study presents the development and testing of a novel nanocomposite-based coating, NanoDPR, designed to offer high dust pickup resistance and solar reflective index for energy efficiency in the built environment. The research addresses the challenges of dust accumulation affecting the long-term performance of such cool coatings in arid climatic conditions of the UAE. The study includes experimental investigation, conducted over 1000 days, demonstrated that the NanoDPR coating exhibits superior resistance to dust pickup and a lower reduction in SRI values compared to a reference coating. The work further extends to modelling on a residential townhouse for energy savings evaluation. The results revealed a 5% reduction in energy consumption annually and an avoidance of 2.75 kg of CO2/m2 of exterior painted area with the NanoDPR coating in comparison with conventional reflective paints. Results show that the development and adoption of such coatings can significantly impact energy consumption and carbon emissions, ultimately promoting a more sustainable future.

Simulation of the eThekwini Heat Island in South Africa

Abstract The study evaluates the performance of the Conformal Cubic Atmospheric Model (CCAM) when simulating an urban heat island (UHI) over the city of eThekwini, located along the southeast coast of South Africa. The CCAM is applied at a grid length of 1 km on the panel with eThekwini, in a stretched-grid mode. The CCAM is coupled to the urban climate model called the Australian Town Energy Budget (ATEB). The ATEB incorporates measured urban parameters including building characteristics, emissions, and albedo. The ATEB incorporates the land-cover boundary conditions obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite. The CCAM configuration applied realistically captured the orientation of the city and land-cover types. Simulations of meteorological variables such as temperatures and longwave radiation reproduced the spatial distribution and intensity of the UHI. Results show that the UHI is stronger during summer and weaker in all other seasons. The UHI developed because of natural factors (e.g., distribution of longwave radiation) and human factors (e.g., urban expansion, an increase in anthropogenic emissions, and additional heating). Because of the city’s location along the coast, the UHI simulation could be weakened by atmospheric circulations resulting from land and sea breezes. Mitigation methods such as applying reflective paints and revegetation of the city may increase albedo and latent heat fluxes but reduce the sensible heat fluxes and weaken the UHI. However, the UHI may not be completely eliminated since natural factors and emissions constantly influence its development. Significance Statement The outcome of this study could be particularly valuable for municipalities in their disaster management planning since the occurrence of UHIs can cause heat-related diseases such as heatstrokes and even fatalities, especially for the elderly, in cities. Increases in temperatures also lead to higher demand for air conditioners, which in the long term lead to higher demand and pressure on the electricity grid system as well as increased costs for the individual. As higher temperatures increase heatwave events, increases in anthropogenic emissions also result in degraded air quality that impacts health. UHIs impact human lives and can cause deterioration in health when individuals experience high temperatures in summer. Warmer temperatures also reduce energy demand (and in the long term assist with global environmental restoration).

Effect of organically modified titania and zirconia nanoparticles on characteristics, properties of coating based on acrylic emulsion polymer for outdoor applications

AbstractEffect of titania nanoparticles modified with 3 wt% [3‐(methacrylloxy)propyl]trimethoxysilane (m‐TiO2 NPs) and zirconia nanoparticles modified with 3 wt% (3‐glycidyloxypropyl)triethoxysilane (m‐ZrO2 NPs) on properties and morphology of acrylic emulsion polymer coating was investigated. With suitable weight ratio of m‐TiO2/m‐ZrO2 NPs, the acrylic coating could be improved abrasion resistance, weather durability, reflectance index (400–1400 nm) as well as thermal‐oxidation stability in comparison with the coatings having the same content of single modified nanoparticles. The starting thermal degradation temperature of acrylic coating filled by mixture of m‐TiO2 NPs and m‐ZrO2 NPs was approximately 10°C higher than that of the acrylic coating contained separately modified nanoparticles. The mixture of m‐TiO2 NPs and m‐ZrO2 NPs were used in solar reflective paint. Replacement of rutile TiO2 microparticles by 1 wt% mixture of modified nanoparticles, the solar reflective paint (SRP) could be improved water resistance and cooling performance. The water permeability of the SRP coating with mixture of modified nanoparticles was reduced by nearly 50%. The results of cooling performance test indicated that SRP loaded 1 wt% (m‐TiO2 NPs and m‐ZrO2 NPs) (weight ratio of 1/1) replaced 1 wt% TiO2 microparticles could reduce outside temperature of chamber test by nearly 11°C and ambient inside temperature of chamber test by 7.5°C. This novel solar reflective paint is considered as promising material for outdoor applications.

TecSB: An Open Web Tool of Energy Efficiency and Solar Energy Integration in Mexican Buildings

There is a need for stakeholders in the construction sector to evaluate energy efficiency and renewable energy generation alternatives appliable to buildings at early design stages. In this regard, public and private organizations have developed tools to compare different options. It was observed that when the objective was to create nearly Zero Energy Buildings (nZEB), the number of tools was still scarce. With this aim, this work presents a new, free digital tool that can predict, among others, energy consumption, energy generation, emissions savings, and payback time. For this purpose, different alternatives applicable to the roof, such as phase change material (PCM), insulation, and reflective paint, as well as to window-to-wall ratios (WWR), with four different glass technologies, can be evaluated. Furthermore, four renewable energy systems were available for comparison: the solar thermal collector (ST), photovoltaic (PV), flat hybrid solar collector (PVT), and low-concentration parabolic solar collector (LCPVT). Our tool was developed based on the results of transient dynamic building simulations of both residential and non-residential building models located in the hot semi-arid conditions of Monterrey, Mexico. Among the results, the small impact of using only reflective paint, the need to combine PCM with insulating material to obtain the best energy savings, and the large impact on emissions savings when using an LCPVT stand out.

The Potential of Using Passive Cooling Roof Techniques to Improve Thermal Performance and Energy Efficiency of Residential Buildings in Hot Arid Regions

In hot dry regions, the building envelope receives abundant solar radiation, which contributes to heat stress and indoor thermal discomfort. To mitigate overheating inside spaces, cooling is the main basic requirement during most of the year. However, due to the harsh climatic conditions, buildings fail to provide passively the required comfort conditions. Consequently, they are fully dependent on-air conditioning systems, which are huge energy consumers. As roofs are exposed to the sun throughout the daytime, they are estimated to be the main source of heat stress. In return, they can contribute significantly to achieve optimum comfort and energy savings when efficient design strategies are used in an early design stage. To examine the potential for cooling load reduction and thermal comfort enhancement by using cooling roof techniques in residential buildings, a study was performed in the city of Biskra (southern Algeria). Accordingly, an in-field measurement campaign was carried out on test-cells during five days in summer. Three different cooling roof techniques were addressed: (a) cool reflective white paint (CR), (b) white ceramic tiles (CT) and (c) a cool-ventilated roof (C-VR). These roofing alternatives were investigated by monitoring both roof surface temperatures and indoor temperatures. Comparative analysis showed that a cool-ventilated roof is the most efficient solution, reducing the average indoor temperature by 4.95 °C. A dynamic simulation study was also performed based on TRNSYS software to determine the best roofing system alternatives in terms of thermal comfort and energy consumption, considering the hottest month of the year. Simulation tests were run on a base-case model representing the common individual residential buildings in Biskra. Results showed that a double-skin roof combined with cool-reflective paint is the most efficient roofing solution. By comparison to a conventional flat roof, meaningful improvements have been achieved, including reducing thermal discomfort hours by 45.29% and lowering cooling loads from 1121.91 kWh to 741.09 kWh.