Energy Savings In Buildings Research Articles

Building energy savings by green roofs and cool roofs in current and future climates

The global energy demand has greatly impacted greenhouse gas emissions and climate change. Since buildings are responsible for a large portion of global energy consumption, this study investigates the energy-saving potential of green roofs and cool roofs in reducing building energy consumption. Using an integrated approach that combines climate change modeling and building energy simulation, the study evaluates these strategies in six global cities (Cairo, Hong Kong, Seoul, London, Los Angeles, and Sao Paulo) under current and future climate change scenarios. The results show that in future climates, the implementation of green and cool roofs at the city level can lead to substantial annual energy reductions, with up to 65.51% and 71.72% reduction in HVAC consumption, respectively, by 2100. These findings can guide the implementation of these strategies in different climatic zones worldwide, informing the selection and design of suitable roof mitigation strategies for specific urban contexts.

Multifunctional and recyclable aerogel/fiber building insulation composites with sandwich structure

Fire, electromagnetic (EM) pollution, and sustainability require building insulation with fire resistance, EM interference shielding, and recyclability. However, fewer building insulation materials can fulfill these multifunctional requirements. Here, we report a multifunctional building thermal insulation material with a sandwich structure that uses SiO2 aerogel powder as the insulating filler phase, α-Al2O3 fiber as the refractory reinforcing phase, and carbon fiber mat (CFF) as the electromagnetic interference shielding layer prepared by the mixing-pressing-drying method. The effects of different SiO2 aerogel power contents on fire resistance, thermal insulation, and hydrophobicity, the effects of different carbon fiber contents on EMI performance, and the effects of CFF as an interlayer on compressive strength and recyclability were investigated. The results demonstrated exceptional fire resistance properties and low thermal conductivity (0.0529 W/m·K) with a SiO2 aerogel powder content of 11.2 wt%. Specifically, the structure of the aerogel/fiber composite remains intact and the temperature of the non-heated surface is lower than 75.8 ℃ after 4 min of continuous flame combustion. It can achieve a commercial shielding standard of 20 dB at a carbon fiber content of 5 wt%. In addition, CFF as interlayers can effectively improve the compression strength of the material and solve the problem of difficult recycling of carbon fiber. In conclusion, this sandwich structure of multifunctional aerogel/fiber composites provides new ideas for the manufacture of fire resistance, energy-saving, EM-protection, and recyclable building insulation materials.

Energy Consumption Behavior Analysis in the UAE Educational Buildings for Sustainable Economy: A Case Study of Ras Al Khaimah Schools

Energy-saving in educational building has a significant contribution and a vital role in the economic and social development of nations. In this paper, the energy consumption of some educational buildings in the United Arab Emirates (UAE) are collected and analyzed. Four schools within the region of Ras Al Khaimah were selected to study their buildings’ energy consumption behavior. Key energy, economic and environmental parameters were calculated and investigated such as the total annual energy consumption, energy consumption per person, energy consumption per area, energy consumption by category (AC, lighting, other devices, etc.), energy cost, and the amount of greenhouse gas (GHG) emissions. A detailed energy audit was applied to one of the selected schools in order to identify the major areas of energy usage within the school, and to suggest the appropriate measures for potential energy and cost savings. Results revealed that total annual energy consumption of the investigated schools is very high with a range of 3700 - 3900 MWh. Significantly, in these hot climatic regions, AC systems alone accounts for over 80% of the overall annual energy consumption, standing out as the predominant energy consumers particularly during the summer months. The annual energy consumption per unit area was also excessive with values ranging from 200 to 500 kWh per m2. Total annual cost of energy was relatively substantial for all schools with values in the order of 1.2 - 1.5 million AED ($330,000 - $400,000). The negative effects of the CO2 emissions were estimated to be around 500 - 600 ton of CO2/year per a single school.

Annual evaluation of the visual-thermal comfort and energy performance of thermotropic glazing in a reference office room of China

Hydrogel-based thermotropic glazing, which achieves the dynamic characteristics by maneuvering the light-scattering behaviors, has a great potential in improving building energy performance, visual and thermal comfort. The visual-thermal comfort and energy performance of the thermotropic glazing with different transition temperature was evaluated by using an experimental validated building performance simulation model. The performance of the thermotropic glazing was compared with conventional double-clear glazing and low-emissivity double glazing under five cities within the five major climate zones across China. The objective is to comprehensively understand the applicability of the thermotropic glazing in different climatic conditions of China as well as to determine the optimal transition temperature. The results showed that: (1) The thermotropic glazing with a transition temperature of 30 °C could achieve better energy performance, visual and thermal comfort in Xiamen, Nanjing, and Kunming. (2) Low transition temperature is not an essential requirement for the application of the thermotropic glazing, which could result in increasing energy use intensity and this effect is more significant in colder regions. (3) The thermotropic glazing could contribute to building energy savings (up to 16.3% and 2.3% i.e., in Xiamen) compared with conventional double-clear glazing and low-emissivity double glazing with low SHGC. (4) The thermotropic glazing applied in Xiamen, Nanjing and Kunming could obtain better visual and thermal comfort (i.e., increase of the desired range of illuminance sUDI500–2000lux, is up to 85.19% and a promotion of 29.18% in time proportion of desirable thermal comfort in Kunming) when compared with low-emissivity double glazing and conventional double-clear glazing.

Optimising building envelope and insulation materials for energy efficiency and life-cycle cost in Cypriot residences

ABSTRACT Residential buildings consume approximately 36% of total electricity consumption in Cyprus and this is expected to continue increasing in the coming years. This study explores the potential for energy savings in residential buildings in Cyprus through optimising building envelopes and insulation materials. Using building information modelling and energy modelling software, the study analyses 120 combinations of building envelopes and eight insulation materials, identifying an optimal combination of wall, roof, and flooring materials that could result in 32% energy load reductions and 27% lower life-cycle costs compared to the median scenario. High-density rock wool insulation on roofs and double-glazed windows were also found to offer both monetary and energy performance benefits. A sensitivity analysis revealed that the current high energy prices could provide greater economic incentives to adopt these optimisation strategies. Optimising building materials in Cyprus could play a critical role in climate strategy while also offering significant economic benefits.

Chasing Comfort in the Chill: Simulating the Impact of Opened Streamlines on Microclimatic Conditions, Thermal Comfort and Building Facades in Cold Climate Cities

This project aims to evaluate the impact of water surfaces on urban microclimate change and the presence of water in dense urban areas on the heating and cooling loads of buildings by proposing the rehabilitation of urban water resources. It mainly questions whether favorable outcomes for urban microclimate may be expected at the local level with the rehabilitation of water bodies and the contribution of repaired water lines to energy savings in nearby buildings. The analyses are made for Erzurum, the coldest climate city in Türkiye, by using the ENVI-met program, a dynamic simulation tool widely used for microclimate analysis. The analyses use the meteorological data recorded on the site during the same years’ summer and winter periods. The microclimate change caused by the green areas, which involve the opening of covered streamlines, was estimated, and the change in the energy load of buildings was quantitatively analyzed. The findings show that rehabilitation of water lines in urban areas improved microclimate conditions and provided energy-saving opportunities for buildings. Thus, policy-makers should produce more green spaces, including water surfaces, in urban areas to improve the adaptation capacity of cities and mitigate the negative effects of climate change.

Effective Utilization of Bio and Industry Wastes to Produce Thermal Insulation Concrete: A Novel Solution for Energy-Saving Buildings

The research addressed the effective and sustainable ways to enhance the thermal insulation properties of concrete without compromising its structural integrity. Traditional methods of enhancing thermal insulation in buildings, such as using thick layers of insulation materials, can be costly and may not always be practical in certain settings. Additionally, the disposal of waste materials such as date palm fiber, shopping plastic bags, and thermocol beads presents an environmental challenge. Therefore, this study aims to investigate the potential use of these waste materials as additives in concrete to improve its thermal insulation properties while also providing a sustainable solution for waste disposal. Date palm fiber is a natural material that is widely available in the Gulf region. Plastic bags are a huge waste from the shops every day, and from the packing materials, this thermocol is a huge waste product. We have to recycle it very efficiently to protect the environment. Three types of special materials, such as thermocol beads (30%), date palm fiber (3%) & shopping plastic bag fiber (3%), were tested in this research. Thermocol beads, when used, reduce their strength and increase the thermal resistance of concrete, while date palm fiber and shopping bag waste fiber, when used, increase the strength of concrete and also increase the thermal resistance of concrete, so it is an excellent reinforcing material and thermal barrier for shopping plastic bags fiber and date palm fiber. Based on this research result, when thermocol beads are used, they prevent heat by 42 percent, while when added with date palm fiber and plastic fiber, they also block heat by an average of 30% percent; thus, all three ingredients are considered excellent thermal insulation material. The reduction in thermal conductivity was attributed to the formation of air voids and the low thermal conductivity of the waste materials. The density of the concrete decreased with the addition of the waste materials. The study suggests that the incorporation of date palm fiber, shopping bag waste fiber, and thermocol beads can be an effective way to enhance the thermal insulation properties of concrete while also providing an environmentally sustainable solution for waste disposal. It will boost green energy technology in the construction industry.

DMFF: Deep multimodel feature fusion for building occupancy detection

The 2022 Global Status Report for Buildings and Construction (Buildings-GSR) indicates that construction activities have returned to pre-pandemic levels in most major economies, alongside more building energy consumption. To achieve the Net Zero emissions target by 2050, particularly in the post-pandemic era, accurate occupancy information is important to enhance building energy efficiency and improve occupancy comfort. While remarkable progress has been made in existing studies, they struggle to make full use of multi-sensor data to achieve high accuracy. Furthermore, there is a high expectation of the multimodel multi-temporary fusion by Transformer. In this study, we present a Transformer-based multimodal, multi-temporal feature fusion method (DMFF) for occupancy detection. To transfer domain knowledge from artificial intelligence into the building area, DMFF includes a pretrain-finetune pipeline and leverages pre-trained visual and sound models. Multiple pre-trained Transformer encoders are employed to extract features of different modalities. Then, we propose a self-attention mechanism for modality fusion to learn relationships among various sensors. Our DMFF method demonstrates superior performance on a real dataset, outperforming machine and deep learning methods (e.g., Convolutional Neural Networks, Random Forest, and Multilayer Perceptrons). Applied to a room setting, DMFF shows promising potential for building energy savings. The code and demo are accessible at https://github.com/kailaisun/multimodel_occupancy.

Multi-Objective Optimization of Building Energy Saving Based on the Randomness of Energy-Related Occupant Behavior

Given the escalating global energy demand driven by building energy consumption, this study is dedicated to meticulously investigating efficient energy-saving strategies in buildings, with a keen focus on the impact of occupant behavior’s randomness on energy efficiency and multi-objective optimization. The methodology encompassed a thorough analysis of various energy consumption factors, including building envelope and architectural form. We employed Latin Hypercube Sampling for in-depth sampling studies across each factor’s reasonable range. Utilizing Sobol sensitivity analysis, we pinpointed variables of high sensitivity and embarked on multi-objective optimization targeting two primary indicators: energy consumption and thermal comfort. Leveraging the NSGA-II algorithm, we adeptly identified optimal solutions, culminating in the proposition of building energy-saving strategies anchored on the Pareto frontier. Through stochastic modeling simulations of occupant behavior in window opening and air conditioning usage, a comparison was made with models that do not consider occupant behavior. It was found that incorporating occupant behavior into energy-saving designs can reduce energy consumption by up to 20.20%, while ensuring thermal comfort. This approach can achieve improved energy efficiency and indoor comfort.

Displacement field and mechanical analysis of a creeping silo-cave and the evaluation about its popularization potentiality

ABSTRACT As a low-cost green building warm in winter and cool in summer, silo-cave has gradually declined in recent years for its low safety and inconvenient living condition. In the calling of energy-saving buildings worldwide, the popularization potentiality of the silo-cave in the condition of scientific design depends on its safety, comfort, and economy. In view of the lack of safety analysis with creep effect and economy evaluation, the displacement field and mechanical analyses after excavation of the silo-cave are conducted based on its simulated creep, and a series of corresponding reinforcement measures are provided to make it to be a safety silo-cave. Meanwhile, the popularization potentiality of the safety silo-cave is evaluated by budgeting its real building and living costs and comparing with those of the counterpart ground house. The results show that the building cost index and living cost index of the safety silo-cave are just 59.41% and 43.69% of those of the ground house. The research results indicate that the safety silo-cave has a great advantage and potential to be widely popularized in the modern society that advocates eco-friendly and low-carbon, which has a significant meaning for policy makers and architectural designers of green residence in suitable rural region.

Paper: Modeling and scenario analysis of residential building energy conservation in cities of different weather

Building models are used to predict energy consumption and CO2 emissions under current and future conditions and serve as a basis for building design. The most important energy saving potentials in buildings can be achieved by improving the thermal performance of building and the efficiency of the district heating system. This study investigated energy savings in buildings in cold and hot regions of China and Africa and developed a modeling approach for energy savings in heating and cooling of residential buildings. We have provided an overview of long-term scenarios for energy demand and carbon dioxide (CO2) emissions. Using the industry-renowned software RETScreen, parameter simulations and optimizations are performed over the three time periods (currently 2030 and 2050). As a result, it was found that energy consumption has also increased and the comfort level of high-rise houses is about 10–21% higher than that of cold regions. The comfortable temperature range in these different cities is between 20°C and 29°C. We have showed the difference between the observed values and the model simulations (model bias) for HDD and CDD in cold and hot regions of China and Africa. This model represents spatial patterns and scales observed in Harbin, Shenzhen and South Africa. These features are characterized by an increased north-south gradient in eastern China, a topographically dependent distribution in western China and an associated increase in average temperature. The most commonly used types of heating in residential areas are heat pumps (31%) and district heating (21%). This is also the preferred case for condensing boilers (17%). In non-residential areas, heat pumps (32%), district heating (27%) and condensing boilers (11%) are the most commonly used heating systems. The total energy demand in Africa and China will be increased from 2020 to 2050. It is expected that the total demand for primary energy in China will be 8770 Mtoe in 2050, which corresponds to an increase in demand for primary energy of 1.9%, while Africa will see an increase of 2.7%. Final energy consumption in China and Africa will be 5776 Mtoe and 970 Mtoe respectively.

Theoretical study of the synergic relationships between the design parameters in energy-saving building design

With the rapid development of the economy, people have increasingly higher requirements for the comfort of living spaces, and the result is the sharp increase in building energy consumption. Several design parameters influence living space comfort and building energy efficiency. Since the same design standard can include different design parameter combinations, synergic relationships may exist between these criteria for one case. Identifying these synergic relationships requires an inverse problem approach. This paper established a model by combining an improved genetic algorithm (IGA) and numerical calculation to determine the synergic design parameter relationships (e.g. the thermophysical building material properties and energy-saving factors). For Isum=0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{I}}}_{{\ ext{sum}}}= {0} $$\\end{document}, the shading coefficient significantly influenced the linear function between the thermal conductivity and insulation thickness. In this case, the insulation thickness was exponentially related to the shading coefficient, while the thermal conductivity of the insulation material significantly impacted the synergic relationship. For ESR=65%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\ ext{ESR}}{=65}\\%$$\\end{document}, the insulation thickness was a segmented function of the shading coefficient. The results verified that the proposed model was efficient and reliable for identifying the synergic relationships between energy-saving parameters. In engineering applications, designers can select the optimal design parameter combination based on the relationship curve between the parameters in this paper according to the local market conditions and specific design requirements.

Unravelling the role of TiO2 nanoparticles on the optical performance of dark colourants for coatings

The growing concern on energy savings in buildings, particularly related with cooling needs, has led to the search of new constructive solutions. Frequently, darker colour coatings are used in buildings for aesthetics purposes. However, such coatings have low reflectance, absorbing a large portion of the solar radiation. The associated heat gains enhance the building cooling demand and may reduce the service life of renderings owing to the increased thermal stresses in comparison to light colour coatings. The aim of this study was to assess the influence of size (30–5000 nm), optical band gap energy and concentration (0–20%) of TiO2 nanoparticles in a conventional black colourant for building applications. We confirm that the use of TiO2 nanoparticles increases the reflectance of the colourant and demonstrate that 50 nm is the most adequate nanoparticle size for reflectance enhancement. Furthermore, the colourimetric parameters are also affected by TiO2 incorporation, with the colour difference becoming increasingly noticeable to the human eye with increasing TiO2 concentration. Such results can lead to new formulations of solar reflective coatings are able to reduce the overall cooling load, particularly in warm climates with high cooling demands.

Preparation and Properties of Soft-/Hard-Switchable Transparent Wood with 0 °C as a Boundary

Transparent wood has excellent optical and thermal properties and has great potential utilization value in energy-saving building materials, optoelectronic devices, and decorative materials. In this work, transparent wood with soft-/hard-switchable and shape recovery capabilities was prepared by introducing an epoxy-based polymer with a glass transition temperature of about 0 °C into the delignified wood template. The epoxy resin was well filled in the pore structure of the delignified wood, and the as-prepared wood exhibited excellent transparency; the optical transmittance and haze of the transparent wood with a thickness of 2.0 mm were approximately 70% and 95%, respectively. Because the glass transition temperature of the epoxy-based polymer was about 0 °C, the prepared transparent wood was rigid below 0 °C and flexible above °C; meanwhile, the transparent wood exhibited shape change and shape recovery properties. Incorporating optical transparency and soft-/hard-switchable ability into the transparent wood opens a new avenue for developing advanced functional wood-based materials.

A semi-solid, polychromatic dual-band electrochromic smart window: Visualizing sunlight and solar heat transmission

In this paper, a novel semi-solid, polychromatic dual-band electrochromic smart window was constructed by organically assembling monoclinic WO3-x nanowires (m-WO3-x NWs), AlCl3-polyvinyl alcohol (PVA) and polyaniline (PANI). The device not only presented the independent regulation of “bright”, “cool” and “dark”, but also exhibited excellent comprehensive performance, including large optical modulation (74.9 % and 79.1 % at 700 and 2000 nm, respectively.), short coloring/bleaching times (7.6/2.7 and 6.7/3.9 s at 700 and 1200 nm, respectively), and good stability and reversibility (the capacity decreased by 4.3 % and the coulombic efficiency stabled at 99.2 % after 1000 cycles). In addition, the multi-colored PANI endowed the window with the ability to visually monitor modulation modes, as well as indoor sunlight and thermal transmittance. The transparent, green, and blue represented “bright”, “cool”, and “dark” modes, and the depth of the color stood for the control effect in a certain mode. Moreover, the dual-band modulation and polychromatic conversion mechanisms of individual electrodes and the smart window prototype were also elucidated in detail. The modulation of near-infrared light mainly comes from the localized surface plasmon resonance (LSPR) absorption and the phase transition of m-WO3-x NWs, as well as the generated polarons and bipolarons of PANI. While the selective absorption of visible light was related to the bandgap transition of m-WO3-x NWs and the electronic transition of the quinone unit. Surprisingly, the smart window could achieve a maximum decrease of 4.3 °C by controlling the “bright-dark” mode transition in real application simulations, significantly boosting the process of low carbon environmental protection and the construction of energy-saving buildings.

Thermal Conductivity in Concrete Samples with Natural and Synthetic Fibers.

One crucial property of concrete, particularly in construction, is its thermal conductivity, which impacts heat transfer through conduction. For example, reducing the thermal conductivity of concrete can lead to energy savings in buildings. Various techniques exist for measuring the thermal conductivity of materials, but there is limited discussion in the literature about suitable methods for concrete. In this study, the transient line source method is employed to evaluate the thermal conductivity of concrete samples with natural and synthetic fibers after 7 and 28 days of curing. The results indicate that concrete with hemp fiber generally exhibits higher thermal conductivity values, increasing by 48% after 28 days of curing, while synthetic fibers have a minimal effect. In conclusion, this research opens the door to using natural alternatives like hemp fiber to improve concrete's thermal properties, providing alternatives for thermo-active foundations and geothermal energy piles which require high thermal conductivities.

The Effects of Exterior Glazing on Human Thermal Comfort in Office Buildings

As a major component of the building envelope, the energy-saving design of exterior windows is key to energy savings in office buildings. The conventional design of exterior windows mainly focused on their impact on heating and cooling energy but ignored the indoor thermal comfort problems caused by the direct solar radiation transmitted by windows and the fluctuation of their internal surface temperatures. This study analyzed the influence of exterior windows on the indoor thermal environment of office buildings by carrying out field experiments. The experiments were carried out in a typical office building in Xi’an during December and January. The impact of exterior windows on human thermal comfort was studied from two perspectives: longwave radiation from the surface of window glass and solar shortwave radiation. It was found that solar radiation was the main cause of temperature fluctuations on the internal surface of windows and created non-uniform thermal environments. The mean radiant temperature fluctuations in the near-window area could reach up to 7.8 °C due to outdoor solar radiation in winter. Solar radiation transmitted by windows directly affects thermal sensations. Since conventional thermal comfort models or indices underestimated the thermal sensations of occupants in the presence of solar radiation, the additional thermal loads caused by solar radiation needed to be taken into account. The allowable operative temperature range for maintaining thermal comfort should be reduced by 0.5 °C when occupants are exposed to solar radiation.

Quadruple Control Electrochromic Devices Utilizing Ce4W9O33 Electrodes for Visible and Near-Infrared Transmission Intelligent Modulation.

Electrochromic smart windows are promising for building energy savings due to their dynamic regulation of the solar spectrum. Restricted by materials or traditional complementary device configuration, precisely and independently controlling of visible (VIS) and near-infrared (NIR) light is still on the drawing board. Herein, a novel Zn2+ electrochemically active Ce4W9O33 electrode is reported, which demonstrates three distinct states, including VIS and NIR transparent "bright and warm" state, VIS and NIR opaque "dark and cool" state, VIS transparent and NIR opaque "bright and cool" state. A dual-operation mode electrochromic platform is also presented by integrating Ce4W9O33/NiO complementary device and Zn anode-based electrochromic device (Ce4W9O33/Zn/NiO device). Such a platform enables an added VIS opaque and NIR transparent "dark and warm" state, thus realizing four color states through individually controlling Ce4W9O33 and NiO electrodes, respectively. These results present an effective approach for facilitating electrochromic windows more intelligent to weather/season conditions and personal preferences.

WiSOM: WiFi-enabled self-adaptive system for monitoring the occupancy in smart buildings

There has been extensive research on building energy saving (BES), which aims to reduce energy consumption inside buildings. One of the key solutions for energy saving in buildings is to reduce energy consumption in areas that are not occupied by inhabitants. However, effective monitoring of occupants for energy-saving purposes can be challenging due to unpredictable variations in the indoor environment, such as variations in space size, furniture arrangement, the nature of occupants’ activities (e.g., varied intensities and instances), and penetration losses of walls. Unfortunately, the existing solutions for occupancy monitoring in smart buildings, such as PIR sensors, CO2 sensors, and cameras, etc., are expensive, require excessive maintenance, and are not adaptable to the complex variations in indoor environments. This paper introduces WiSOM, for occupancy detection that utilizes the channel state information (CSI), of commodity WiFi. The method is self-adaptive and designed to handle complex variations in indoor environments. We conducted a thorough analysis of WiSOM and evaluated it under various indoor conditions, including the impact of multipath effects, the detection of different intensities and instances of activities of daily living (ADL), and the impact of wall absorption in a real-home scenario. Our evaluation demonstrated an average detection rate of 98.25% for multipath effects, 96.5% and 98.1% for different intensities and instances of ADL, and 94.4% for wall absorption. Additionally, we assessed WiSOM’s resilience to temporal variation in the CSI and achieved a false alarm rate of less than 2%. In comparison to recent baselines, WiSOM outperformed, achieving up to a 21% improvement in detection rate within real-house scenarios.

Porous vanadium dioxide thin film-based Fabry−Perot cavity system for radiative cooling regulating thermochromic windows: experimental and simulation studies

Abstract Radiative cooling in smart windows using VO2 – a dynamic thermal management material, is of potential interest for enhancing energy savings in buildings due to its both solar and emittance tuneability in response to changing temperatures. However, studies related to the effects of VO2 thin film microstructure in a multilayer system on emissivity regulation are currently lacking. The present study addresses the thermochromic and emissivity performance of VO2/ZnSe/ITO/Glass Fabry−Perot (F–P) cavity thin film system, by manipulating the porosity in VO2 thin film. The device is fabricated by commercially feasible physical vapor deposition methods such as sputtering and thermal evaporation, most suitable for mass production. The optimized sample with porous VO2 delivers an enhanced long-wave infrared (LWIR) emissivity contrast of Δɛ LWIR ≥ 0.4 preserving a high visible transparency T lum(avg) of ∼41 % compared to dense VO2. Then finite difference time domain (FDTD) simulation is performed to further understand the effects of varying VO2 porosity and ZnSe thickness on the F–P cavity properties. The reduced low-temperature ɛ LWIR (0.1–0.2) gives this film better energy saving in regions where warming demand is dominant as simulated by EnergyPlus.