Reduce Building Energy Research Articles

Planning and design of an architectural energy supply system based on photovoltaic-thermal technology

China’s building energy consumption is growing and the energy consumption of the whole process of buildings accounts for more than 46.5% of the country’s total energy consumption, of which the proportion of energy consumption used for heating, ventilation and air conditioning is as high as 50%. Solar energy has the greatest potential to achieve energy conservation in buildings. Buildings are the best carrier for solar energy utilization because of the advantages of local collection and local application. The combination of solar energy and buildings can meet a variety of energy and health needs in buildings, among which solar photovoltaic and CSP building integration technology is an important way to reduce building energy consumption and improve indoor air quality. This article presents a PV/T-based thermal storage wall system that efficiently utilizes solar energy. It outlines the PV/T technology’s fundamental principles and provides a detailed description of the system’s construction and operation, highlighting critical components like the solid thermal storage medium and heat transfer via a heat pump. The analysis indicates improved energy utilization and favorable economic feasibility. This technology offers a practical solution for the construction industry, promoting sustainable energy practices and environmental conservation.

A novel heating strategy and its optimization of solar–air source heat pump heating system for rural buildings in northwest China

In the rural areas of Northwest China, the utilization of clean and renewable energy is deemed a crucial measure for reducing building energy consumption and environmental pollutant emissions. This paper focuses on constructing a simulation platform for a solar-assisted air source heat pump heating system. A rural residential building in Yongshou County, Shaanxi Province, serves as an illustrative example. A novel flexible temperature control method with a feedback controller in sub-area and period is proposed in this paper, alongside the selection of three distinct objective functions aimed at optimizing the heating system. The simulation results indicate an average temperature of 17.0 °C throughout the heating cycle, with a peak temperature of 18.7 °C. Moreover, the solar fraction is measured at 25.11%, underscoring the significance of collector area and heat storage tank volume as primary factors in system design. The results also demonstrate that across various optimization objectives, the life cycle cost optimization scheme yields greater economic benefits, while the target building unit heating cost optimization scheme boasts the shortest static payback period and lowest unit heating cost. Conversely, the solar fraction optimization scheme stands out for its superior environmental benefits. These findings offer valuable insights for the design of heating systems tailored to diverse objectives.

Controlling the Size of Hydrotalcite Particles and Its Impact on the Thermal Insulation Capabilities of Coatings.

This study focuses on the development of high-performance insulation materials to address the critical issue of reducing building energy consumption. Magnesium-aluminum layered double hydroxides (LDHs), known for their distinctive layered structure featuring positively charged brucite-like layers and an interlayer space, have been identified as promising candidates for insulation applications. Building upon previous research, which demonstrated the enhanced thermal insulation properties of methyl trimethoxysilane (MTS) functionalized LDHs synthesized through a one-step in situ hydrothermal method, this work delves into the systematic exploration of particle size regulation and its consequential effects on the thermal insulation performance of coatings. Our findings indicate a direct correlation between the dosage of MTS and the particle size of LDHs, with an optimal dosage of 4 wt% MTS yielding LDHs that exhibit a tightly interconnected hydrotalcite lamellar structure. This specific modification resulted in the most significant improvement in thermal insulation, achieving a temperature difference of approximately 25.5 °C. Furthermore, to gain a deeper understanding of the thermal insulation mechanism of MTS-modified LDHs, we conducted a thorough characterization of their UV-visible diffuse reflectance and thermal conductivity. This research contributes to the advancement of LDH-based materials for use in thermal insulation applications, offering a sustainable solution to energy conservation in the built environment.

Development of ReShadS, a climate-responsive shading system: Conception, design, fabrication, and small-scale testing

Integrating computational technologies to produce dynamic and intelligent architecture that can enhance building thermal performance and meet users' requirements and routines is broadly classified as responsive architecture. This seems to be a viable solution for façades, reducing energy demand during the building operational phase. However, scientific content regarding responsive components' fabrication, operation, and performance evaluation is not yet consolidated. This paper comprehensively presents the design and fabrication processes of a low-cost responsive shading system prototype, accounting for materials' characterization, software, responsive functionality, and its performance evaluation regarding thermal and illuminance management. The analysis is based on the Adaptive Comfort Model and Useful Daylight Illuminance parameters. Preliminary results indicate the system's feasibility in managing temperature and illuminance within the comfort zone by 58 % and 82 % of data points, respectively. The resulting prototype and the responsive management strategy contribute to the emerging responsive architecture field toward reducing building energy consumption.

Economic optimization of exterior wall insulation in Chinese office buildings by coupling artificial neural network and genetic algorithm

Envelope insulation is an essential measure to reduce building energy consumption and is the focus of many building energy codes. In China, the current standard (GB 55015-2021) only specified limit values for the thermal conductivity (U) of the exterior walls, and it ignored variations in building characteristics and internal parameters. Therefore, it is difficult for architects to quickly determine the exterior wall U-value in building design and retrofit. To address this issue, the exterior wall U-values of office buildings in China were economically optimized by TRNSYS, ANN, and GA. To begin with, the effect of enhancing exterior wall insulation on the heating and cooling energy consumption of office buildings was investigated by TRNSYS software, taking into account variations in building characteristics. Moreover, the exterior wall U-values of office buildings were optimized by coupling ANN and GA. The results showed that the design values of the GB 55015-2021 did not achieve the optimal results in China, and the most economical exterior wall U-value was 0.24 W/(m2·K) in Harbin, 0.24 W/(m2·K) in Beijing, 0.42 W/(m2·K) in Changsha, 1.82 W/(m2·K) in Guangzhou, 0.66 W/(m2·K) in Kunming. Compared with the pre-optimization, the annual life cycle cost of building heating and cooling reduced by 0.96 % in Harbin, 2.07 % in Beijing, 1.44 % in Changsha, 1.68 % in Guangzhou, and 7.37 % in Kunming. In addition, variations in building parameters should be considered in the design phase of new buildings or in the renovation of old buildings, such as internal heat gain, which may lead to different optimal results.

Thermochromic Hydrogels with Adjustable Transition Behavior for Smart Windows.

With the fast economic development and accelerating urbanization, more and more skyscrapers made entirely of concrete and glass are being constructed. To keep a comfortable indoor environment, massive energy for air conditioning or heating appliances is consumed. A huge amount of heat (>30%) is gained or released through glass windows. Using smart windows with the capability to modulate light is an effective way to reduce building energy consumption. Thermochromic hydrogel is one of the potential smart window materials due to its excellent thermal response, high radiation-blocking efficiency, cost-effectiveness, biocompatibility, and good uniformity. In this work, polyhydroxypropyl acrylate (PHPA) hydrogels with controllable lower critical solution temperature (LCST) were prepared by photopolymerization. The transition temperature and transition rate under "static transition" conditions were investigated. Unlike "static" conditions in which the transition temperature was not affected by the initial and final temperature and heating/cooling ramp, the transition temperature varied with the rate of temperature change under dynamic conditions. The "dynamic" transition temperature of the PHPA hydrogel gradually increased with the increase of the heating rate. It was the result of the movement of the molecular chains lagging behind the temperature change when the temperature change was too fast. The results of the solar irradiation experiment by filling PHPA hydrogels into double glazing windows showed that the indoor temperature was about 15 °C lower than that of ordinary glass windows, indicating that it can significantly reduce the energy consumption of air conditioning. In addition, a wide range of adjustable transition temperatures and fast optical response make PHPA hydrogels potentially applicable to smart windows.

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.

Sensitivity Analysis and Optimization of Energy-Saving Measures for Office Building in Hot Summer and Cold Winter Regions

To effectively reduce building energy consumption and enhance indoor thermal comfort, this study developed a sensitivity analysis and multi-objective optimization method for an office building in Hangzhou considering the effects of parameter interactions. We utilized Latin hypercube sampling (LHS) to sample the parameters and subsequently simulated the energy consumption and discomfort hours for the building’s four orientations. Following this, Gaussian process regression models were established, and the feature importance ranking method (FIRM) alongside an interaction effects method were employed to quantify the sensitivity of 10 parameters. Lastly, a multi-objective optimization was performed for total energy consumption and discomfort hours, yielding a set of Pareto-optimal solutions. Through the VIKOR method, the optimal solution within the Pareto set was identified, resulting in three sets of optimal solutions.

Layer-stacked polyaniline/silver nanowire composite film for multicolor electrochromic smart windows with dual-band optical modulation

Dual-band electrochromic smart windows (DESWs) have attracted widely concern for their potential in significantly reducing building energy consumption by selectively controlling near-infrared (NIR) and visible light (VIS) transmittance. However, its monotonous color changes limit its large-scale application. In this study, we designed a DESW based on the layer-stacked polyaniline (PANI)/silver Nanowires (Ag NWs) composite films. When PANI films is stacked layer by layer with Ag NWs, it not only performs dual band regulation, but also exhibits impressive electrochromic performance with rich color conversions (light yellow, yellow-green and blue-black). The four-layer PANI/Ag NWs composite film outperformed the pure single-layer PANI film because of the faster electron transfer, its coloring time and bleaching time at 525 nm were shortened to 6.7 s and 18.0 s, respectively, and the coloring efficiency was increased to 45.5 cm2 C-1. After 2500 cycles, the PANI/Ag NWs films tend to have better cycle stability. Therefore, the incorporation of Ag NWs enhances the electrochromic performance of PANI films, providing valuable insights for advancing single-component organic electrochromic materials.

Preparation and performance study of a novel radiant panel for thermal and cooling storage with phase change materials

Phase change radiant panels (PCRPs) with thermal storage can enhance the heat capacity of buildings, and reduce building energy consumption. In this paper, a composite phase change material (CPCM) was prepared by paraffin wax-lauric acid/expanded graphite (PW-LA/EG) and applied to radiant panels. This CPCM exhibits a broad temperature range for phase change (10°C - 40°C), with EG at the optimal mass fraction of 14% and PW-LA at the optimal ratio of 1:1. It has a moderate latent heat capacity, a thermal conductivity of 1.692 W/mK, and excellent thermal stability. Furthermore, the simulations were performed in this paper, and the year-round comfort, thermal storage/release characteristics, and the influencing factors of PCRPs were evaluated by TRNSYS software. The results show that the PCRP can enhance indoor comfort throughout the year and exhibit excellent thermal storage and release properties. The analysis of influencing factors indicates that the thickness of the PCM has a small impact on the PCRP. It is recommended that a radiant panel coverage rate of at least 70% and a water supply time of 10 h in summer and 8 h in winter. These optimized parameter values can offer valuable guidance for the design and practical application of PCRPs. Practical application Phase change materials have been widely studied as materials used for thermal energy storage. The radiant panel with phase change materials can enhance the heat capacity of buildings, and reduce building energy consumption. This paper proposes a phase change radiant panel that can be used to solve the problem of year-round energy storage of radiant panels in hot summer and cold winter areas. Furthermore, this paper uses TRNSYS software to study the performance of the phase change radiant panels and offers valuable guidance for the design and practical application of PCM radiant panels.

Effect of Orientation and Skylight Area Ratio on Building Energy Efficiency in the Qinghai–Tibet Plateau

The Qinghai–Tibet plateau, with an average altitude of over 4000 m, has low annual average temperatures and a high demand for building heating. This region’s abundant solar energy resources hold substantial practical significance for improving the indoor heat environment and reducing building energy consumption. This paper investigates the impact of orientation and skylight area ratio on building heat load and indoor temperature, using both actual measurement and simulation methods, with a case study of the comprehensive building at Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment (Beiluhe Station), located in the Qinghai–Tibet Plateau region. Initially, a model was established using the EnergyPlus 9.4 software, with orientation variables set from east to west in 15° increments, to simulate the variations in building heat load resulting from orientation changes; simulations were then conducted for three different skylight area ratios under the optimal orientation to evaluate their influence on heat load and indoor temperature. The results show that for the architectural style examined in this paper, the optimal building orientation within the region is 30° south by east, with the optimal orientation range spanning from 45° south by east to due south. Heating load is negatively correlated with the skylight area ratio, and beyond a certain threshold, the rate of decrease in heat load diminishes or even stabilizes. The conclusions of this paper offer guidance for the orientation and skylight design of new buildings on the Qinghai–Tibet Plateau.

Long-term assessment of energy consumption reduction in a building ventilation system with passive particulate matter control technology in the fresh air intake

A particulate matter (PM) control device known as aspiration efficiency reducer (AER) has been developed as an attachment to the fresh air intake in building ventilation systems to reduce building energy consumption and improve the fresh air intake’s quality. Ambient particle laden air is drawn into the fresh air inlet of a mechanically ventilated building via the air handling unit (AHU). The ventilation system particle filters become loaded and clogged with PM, increasing the load on the fan’s motor. Three novel AER devices were tested against an AHU inlet rainhood, and their long-term energy performance assessed. Furthermore, an AER attached to an AHU incorporating single-stage filtration (SSF) was compared against an AHU fitted with rainhoods employing two-stage filtration (TSF). The findings showed AER technology resulted in a 6.6–11.4 % reduction in the AHU’s energy consumption. Finally, the impact of the AER with SSF compared to a rainhood with TSF led to a lowering of the system pressure throughout the entire testing period, reduced filter and labour costs resulting in a 36.5 % reduction in the total costs. AER technology and a ventilation filtration system design tailored to the local environment will result in lower building energy consumption and CO2 emissions.

Fluorine-doped ATO NCs with enhanced LSPR effect for smart windows with adaptive solar modulation

Smart windows with excellent near-infrared (NIR) light shielding capacity and controlled visible light transmittance are expected to reduce building energy consumption and improve indoor comfort. However, the ability of current thermochromic materials to regulate solar gain with the tunable extinction of phase-change materials is still far from optimum. In this work, an fluorine (F)-doped ATO (FATO) nanocrystals (NCs) are designed as a photothermal material to optimize the solar modulation of thermochromic hydrogels. F ion doping can modify the electronic structure of ATO, resulting in a high concentration of oxygen vacancies and free electrons, thereby enhancing the NIR absorption performance and photothermal conversion performance of the ATO NCs. On this premise, the designed smart window based on FATO NCs and thermochromic hydrogels exhibits the remarkable features of excellent NIR shielding, high initial visible transmittance and fast response speed. The window is capable of shielding 99.5% of the solar radiation from 300 to 2500 nm and permitting 75.0% of initial visible light. Moreover, the simulated indoor temperature of the smart window was 17.2 °C lower compared with the black one, demonstrating potentials in practical application of building energy saving.

GLAZING SYSTEMS WITH SILICA AEROGEL FOR OPTIMIZING ENERGY CONSUMPTION IN HOTEL BUILDING

Due to their high energy consumption hotel buildings have a significant impact on the environment. Such constructions are particularly energy-intensive demanding environments so as to meet the various needs of occupants and ensure their comfort. Guests tend to consume more energy during their stays than they do in their own homes (water, electricity, light, temperature...). In recent years, Algeria has seen a significant increase in the construction of hotels, many of which are concentrated in the Mediterranean region, which experiences particularly high humidity levels in the summer and winter. The new generation of building materials used to enhance comfort and reduce building energy consumption, are progressively sought after all over the world. This work, which studied the performance of silica aerogels for the glazing system of hotel rooms in a Mediterranean climate, can provide a database for hotel designers, an investigation combining experimental work (air and surface temperature measurements and thermography) and numerical simulation (using TRNsys V17) was conducted on an existing hotel building located in Béjaia. The results revealed the insertion of silica aerogel within a 6 mm thick glazing sheet decreases significantly the heating and cooling requirements of the study indoor environment.

Methods to Reduce Building Energy Consumption

Methods to Reduce Building Energy Consumption

USING BIM MODELING FOR THE CALCULATION OF HEAT LOSSES AND GENERAL ENERGY EFFICIENCY AT THE DESIGN STAGE

Problem statement. The issue of energy efficiency is one of the key problems in the construction industry. Increasing attention to this aspect has led to the development of new technologies and tools to improve the energy efficiency of buildings. One of the powerful software complexes for BIM modeling is Revit. The program has built-in tools for analysis. One such tool is Energy Analysis and the My Insight application in Revit software. This tool allows you to calculate the energy consumption of the building and its energy efficiency. With its help, you can perform an analysis of the building's energy consumption in different seasons and under different operating conditions. To achieve energy efficiency of the building in Revit, you can choose materials and change their thermal characteristics or choose materials that have high energy efficiency and durability, develop new material connection nodes and calculate their heat loss. The use of energy-saving technologies, such as energy-efficient windows, solar panels and others, allows you to take into account the contribution of these technologies to the overall energy consumption of the building using the same Insight application that is relevant today. The purpose of this work is to increase the energy efficiency of the house at the design stage using the ВIM model with the help of the Insight cloud service. Conclusions. Energy efficiency improvements in Revit software and its Insight application help reduce building energy consumption and reduce heating and air conditioning costs. This not only helps save the planet's resources, but also reduces costs for building owners. Using these tools allows you to create energy-efficient and climate-resistant buildings, which is an important task in today's world.

Developing a validated simulation model of micro-zonal air-conditioning to evaluate thermal comfort parameters

ABSTRACT Micro-Zonal Occupant-Centric Control (MZOCC) helps in reducing building energy consumption by conditioning only the occupied regions in a room. For this, MZOCC divides a large room such as open-plan offices into virtual micro-zones to allow independent diffuser level control. But, unplanned MZOCC can lead to heavy thermal gradients and deflection of air jets, leading to thermal discomfort. To evaluate thermal comfort at different regions of a room under MZOCC, there is a need to accurately model parameters of thermal comfort. Field studies, exploring the transient variations in air temperature, humidity and velocity at different regions of the room due to MZOCC, are limited. At the same time, developing validated simulation models or digital twins using experimental data helps in exploring micro-zonal strategies to arrive at the best strategy. The aim of this study is to create a digital twin of an open-plan office and model the parameters required to estimate thermal comfort. This study senses transient variations in air temperature, velocity and humidity using a wireless sensor network and develops a computational fluid dynamic (CFD) model that can accurately model the sensed transient variations. Field data, constituting external surface temperatures captured using thermal images, variations in air-conditioning control strategy, dynamic occupancy and location, are periodically updated in the digital twin. The CFD model accurately predicts the trends in variations in indoor temperature, velocity and humidity at different regions of the room. The developed digital twin can be used in future studies to evaluate thermal comfort and plan MZOCC control strategies.

A Study on the Effect of Dynamic Photovoltaic Shading Devices on Energy Consumption and Daylighting of an Office Building

Photovoltaic shading devices (PVSDs) have the dual function of providing shade and generating electricity, which can reduce building energy consumption and improve indoor daylighting levels. This study adopts a parametric performance design method and establishes a one-click simulation process by using the Grasshopper platform and Ladybugtools. The research focuses on the effect of dynamic PVSDs on daylighting and energy consumption in an office building in Qingdao. The optimal configuration of PVSDs for each month under three dynamic strategies (rotation, sliding, and hybrid) is determined here. Additionally, different control strategies and fixed PVSDs are compared to clarify the impact of various control strategies on daylighting and energy consumption. The findings reveal that, compared to no shading, dynamic PVSDs in the rotation strategy, sliding strategy, and hybrid strategy can achieve energy savings of 32.13%, 47.22%, and 50.38%, respectively. They can also increase the annual average UDI by 1.39%, 2.8%, and 3.1%, respectively. Dynamic PVSDs can significantly reduce the energy consumption of office buildings in Qingdao while improving indoor daylighting levels. A flexible control strategy that adapts to climate change can significantly improve building performance. This research can provide theoretical, methodological, and data support for the application of the PVSD in cold-climate regions in China.

Building Energy Governance: Statutes and Guides on Retro-Commissioning in China and the United States

Reducing building energy use, a linchpin of climate change mitigation, is a daunting challenge across the world. Gaining increasing attention, retro-commissioning (RCx) is a systematic process that can improve building energy performance. Using a techno-legal lens to review statutes and guides on RCx, this study reveals that in China, a national standard on building commissioning has taken effect yet RCx statutes are hitherto not found. The United States has RCx statutes enacted over 14 states; scrutinizing the statutes of five cities unveils similarities and differences in their scope of control and compliance requirements. In the absence of a specific RCx statute, the guide of Hong Kong, China provides detailed guidance for energy saving practices. While these findings can serve as reference for other places planning to formulate laws or guidance on RCx, the need to further study the effectiveness of mandating RCx for reducing building energy use is highlighted. A conceptual analysis of cost variation with statutory control, which could help policymakers consider from an economic perspective whether or to what extent statutory RCx requirements should be imposed, is also illustrated. This not only contributes insights to the pursuit of an optimal balance between statutory control and voluntary action for energy reduction but also adds to the debate on building energy policies.

Application of Building Intelligent Design in Energy Saving and Sustainable Development

With the rapid development of social and economic development, people's living standards to a certain extent has been continuously improved, building energy consumption further shows a trend of sustained growth, the apparent contradiction in the supply of energy resources in our country further aggravated. In order to the sustainable development of mankind, we must effectively reduce the energy consumption, and further implement the building energy conservation measures into practice. To a certain extent, effective control of building energy consumption, and further alleviate the contradiction between China's energy supply and economic and social development. Let building energy-saving design in China's energy saving and emission reduction to make the necessary contribution. China is a populous country, per capita resources are poor, people's overall average standard of living is low. With the deepening of China's reform and opening up, the Chinese people are gradually getting richer and richer, the Chinese people began to continuously improve their material life, especially the living environment, so China's construction business is also rapidly developing, with the increase of a large number of new buildings, the building energy consumption is growing rapidly. However, China's large population, the energy situation is not optimistic, reduce building energy consumption is the implementation of the scientific concept of development, to achieve sustainable development of the major strategic initiatives.