Annual Energy Use Research Articles

Low energy consumption form of the U-shaped plan office building in the Yangtze River Delta

The significance of form in green building design is well recognized, as it has a substantial impact on both energy performance and construction cost. This study investigates the impact of the U-shaped plan on the energy demand, which can be flexibly applied to irregular site forms and clustered building blocks, and is widely used in existing office buildings. Specifically, we select the U-shaped plan as the object of study and collect related case data primarily from Hangzhou and Shanghai. Using Python, we generate plans based on two lengths, two angles, and depth, which serve as basic parameters and boundary conditions. The EnergyPlus platform is utilized for dynamic simulation of the energy consumption of each model, and correlation analysis using the Spearman coefficient method identifies two planar factors (depth-length ratio and modified length) that have the most significant influence on energy consumption, including five basic parameters. Regression fitting and regression evaluation of the model further identify morphological critical information in the plan. Our research reveals that the critical interval of depth-length ratio (M1) is in (0.48, 1.02), and the critical point of the modified length (M2) is 109.38 m. Furthermore, the contour plot of M1–M2–E1 is obtained, illustrating the mutual trend between morphological parameters (M1 and M2) and annual energy use intensity, which serves as a useful aid for designing low energy consumption solutions.

Comparison of shading design between the northern and southern hemispheres: using the NSGA-II algorithm to reduce building energy consumption and improve occupants' comfort

PurposeThis paper aims to investigate the optimization of window and shading designs to reduce the building energy consumption of a standard office room while improving occupants' comfort in Tehran and Auckland.Design/methodology/approachThe NSGA-II algorithm, as a multi-objective optimization method, is applied in this study. First, a comparison of the effects of each variable on all objectives in both cities is conducted. Afterwards, the optimal solutions and the most undesirable scenarios for each city are presented for architects and decision-makers to select or avoid.FindingsThe results indicate that, in both cities, the number of slats and their distance from the wall are the most influential variables for shading configurations. Additionally, occupants' thermal comfort in Auckland is much better than in Tehran, while the latter city can receive more daylight. Furthermore, the annual energy use in Tehran can be significantly reduced by using a proper shading device and window-to-wall ratio (WWR), while building energy consumption, especially heating, is negligible in Auckland.Originality/valueTo the best of the authors' knowledge, this is the first study that compares the differences in window and shading design between two cities, Tehran and Auckland, with similar latitudes but located in different hemispheres. The outcomes of this study can benefit two groups: firstly, architects and decision-makers can choose an appropriate WWR and shading to enhance building energy efficiency and occupants' comfort. Secondly, researchers who want to study window and shading systems can implement this approach for different climates.

Energy use and energy efficiency in cruise ship hotel systems in a Nordic climate

In light of climate change, the shipping industry is committed to reducing its greenhouse gas emissions. When transitioning from fossil fuels to low-carbon fuels, it is crucial to also reduce the ships' energy need. For cruise ships, the hotel system is a major energy consumer and the focus of this paper. This study aims to investigate the energy use of an existing fossil-fuelled cruise ship operating in a Nordic climate, and evaluate the effectiveness of various passive and active energy-saving measures. For this purpose, a dynamic energy model of the hotel system was developed in the building simulation tool IDA Indoor Climate and Energy (IDA ICE), including a customised weather file. Validation of the model was achieved through comparison with literature and some operational data from the actual cruise ship. Simulation results showed a total annual energy use of 55 MWh/passenger, with the hotel system accounting for 20%. The passive measures, such as increased insulation and improved windows, each resulted in less than a 1% reduction in the hotel's annual energy use. Larger energy savings were achieved by using heat pumps (38%), improved ventilation system (8–24%), and heating setback in port and during the night (5%). A hot water storage tank, charged with the engines' waste heat during sea operation, could reduce the use of auxiliary boilers, especially in port. A hot water tank of 600 m3 could cover 97% of the heating demand in port, thereby minimising the use of fuel-fired boilers.

Split-degree day method: A novel degree day method for improving building energy performance estimation

Degree days have been widely used in different applications in buildings, such as estimating building energy use and climate classification for building energy standards. However, there are limitations with the use of conventional degree days that result in inaccuracies in estimating building energy consumption using degree day-based methods. This paper proposes a new method, the split-degree day method, that shows substantially improved results in the accuracy of the building energy use estimation compared to the conventional degree day methods. The analysis in 801 locations in the U.S. using regression models showed that the new, proposed split-degree day method in this paper, compared to the conventional degree day method, better accounts for the weather parameters and more accurately estimates end-uses. The split-degree days showed an improvement of over 5% in the accuracy of the total annual energy use prediction, 8% for predicting the heating energy use, 0.3% for predicting the cooling energy use, and 33% for predicting the fan energy use. Additionally, the analysis showed improved results for the model with higher thermal mass and the model with a 24-hour operating schedule. These improvements were due to the fact that the split-degree day method includes more information related to the weather characteristics of a location, which is missing in a conventional degree day calculation procedure that relies on aggregated data at daily intervals. Furthermore, as opposed to the conventional degree days, the accuracy of the estimations using the split-degree days are shown to maintain their high accuracy when the base temperature deviates from the optimal base temperature. The proposed method can be used as a more accurate alternative to the conventional degree days in different applications, including but not limited to building climate classification, building energy estimation, and weather normalization for building energy savings calculation.

The over-prediction of energy use by EPCs in Great Britain: A comparison of EPC-modelled and metered primary energy use intensity

This analysis compares the difference between the Energy Performance Certificate (EPC)-modelled and smart-meter measured annual energy use on a like-for-like basis in 1,374 gas-heated British households from the Smart Energy Research Lab (SERL) Observatory. EPCs and metered energy use were converted to primary energy use intensity (PEUI) to provide a comparison of the same quantity for the first time.We show that EPCs predict significantly more energy use than metered in homes in Great Britain. EPC bands A and B show no statistically significant difference, but all other bands show a significant gap which increases as EPC rating worsens. The PEUI gap widens from −26 kWh/yr/m2 (−8%) for band C to −276 kWh/y/m2 (−48%) for bands F and G. Unlike previous research, we show that the difference persists in homes matching the EPC-model assumptions regarding occupancy, thermostat set-point and whole-home heating; suggesting that occupant behaviour is unlikely to fully explain the discrepancy.EPCs are a core tool in the residential energy sector, and the gap between EPC-modelled and metered energy use could have a significant impact on policy, research, and industry. Future research should investigate disaggregated components of energy use, the underlying thermal model, and assumptions regarding building characteristics.

Evaluation of potential capabilities of energy savings and utilization of solar energy in mosques in Hail city, Kingdom of Saudi Arabia

Energy consumption is one of the most important variables that have an impact on the environment. One of the nations in the world with the highest per capita electrical energy usage is the Kingdom of Saudi Arabia. Many attempts are being made in Kingdom of Saudi Arabia to lower energy consumption and electricity consumption to achieve sustainability. In this work, the data on the energy consumption of two mosques in Hail City were analyzed, and the opportunities for energy conservation and the use of solar energy were studied to make mosques sustainable. Annual energy use intensity was determined to be 100 and 121 kWh/m2 for the Al-Khashil and Al-Jamil mosques, respectively. While Al-Khashil's mosque envelope is insulated, energy efficiency measures implemented to the walls, roof, and windows of Al-Jamil's mosque resulted in reductions in energy consumption of 27%, 13%, and 6%, respectively. The most effective energy efficiency option is a heating, ventilation, and air conditioning system with a high energy efficiency ratio, which can reduce cooling demand by more than 30%. If the condition of Saudi Building Code 601 is met, then it has the potential to cut energy usage by 35.4% and 63.3% for Al-Khashil and Al-Jamil, respectively. Due to coronavirus disease 2019, Al-Khashil's electricity usage was reduced by 58,737 kWh, or 39.9%, in 2020 compared to 2019. When using data from RETScreen and ATLAS, there were inconsistencies of up to 28%, but for DesignBuilder, the findings were the closest to the billing data. The mosques Al-Khashil and Al-Jamil have a combined yearly photovoltaic energy output from the suggested systems of around 135.93 MWh and 33.98 MWh, respectively. For the mosques, Al-Khashil and Al-Jamil, the yearly yield factor and capacity factor were both 1887.9 kWh/kWp/year and 21.9%, respectively. The annual greenhouse gas emission reductions from photovoltaic systems for Al-Khashil and Al-Jamil were 102.9 tCO2 and 25.72 tCO2, respectively. Concerning economics, the following results were obtained: The levelized cost of energy of photovoltaic systems is 0.0901 SR/kWh (0.024 $/kWh); the net present value and internal rate of return for photovoltaic systems are not suitable as a result of the current prices and the system applied in the Kingdom of Saudi Arabia. If the electricity produced from photovoltaic systems is injected into the grid at a rate of 0.32 SR/kWh, which is comparable to the SEC tariff for the mosque or government sector, then the simple payback time is 5.14 years.

Did new electricity progressive tariff system change energy usage pattern in Seoul apartments? Evidence from integrated multisource dataset and combined analytical models

A new electricity progressive tariff (PT) system was introduced to cities in South Korea at the end of 2016 to replace the previous one as a policy response to increased energy demand and costs in hotter summers. Public concerns have been raised over its effects on annual energy use and energy poverty. However, studies on this topic are very few due to the lack of relevant data. In the broader literature on the effect of the PT system, studies are limited in that they mostly focus on household characteristics. This study contributes to the literature and practical discussions by examining how the new PT system influences residential electricity use in 243 sample apartments in Seoul, considering a wide range of factors that impact energy use decisions. An integrated urban dataset was developed based on urban big data from multiple sources, and a combination of two models was used for analysis. The interrupted time series analysis was adopted to find whether the change in household electricity use was significant for each apartment using the dataset. A logistic regression model was then used to examine the relationships between the significance of change and influential factors in energy use and billing, household, apartment, and neighborhood. Results suggest that nearly half of the sample apartments significantly increased electricity usage, and energy and built environment factors significantly influenced the change. Furthermore, higher-income groups were found to benefit more from the new PT system. The findings provide a reference for policymakers to evaluate the new policy and develop strategies toward broad sustainability goals. Given the wicked nature of urban energy policy, suggestions were made on policy implementation design and urban data integration for more rigorous evaluation.

Simulation and Field-Based Study of Thermal Performance of a Building - A Case Study

Concerns about building thermal performance and energy consumption are fast growing as they account for roughly 40% of worldwide annual energy use. Building construction in Nepal is controlled by the National Building Codes (NBC), which focus solely on structural considerations and ignore thermal behaviour. As a result, housing tends to be too much warm and too cold during summer and winter respectively due to the lack of passive heating and cooling mechanisms considered during the construction phase. The Thakle Integrated Settle (TIS), built by the Department of Urban Development and Building Construction (DUDBC) under the National Reconstruction Authority and supported by Oxfam Nepal, was the subject of this research. The building’s performance in the chosen location was analysed using a field and TRNSY simulation-based technique. Using meteorological data from Meteonorm software, the TRNSYS model was created to examine the performance in terms of internal air temperature and heating/cooling load of two buildings with different orientations, e.g., North-East (NE) and South-West (SW). According to simulation results, there is a heating demand that covers roughly 37% of the year, while cooling and comfort conditions were 32% and 31%, respectively. For NE and SW-facing buildings, heating demand was 4.10 MWh and 4.07 MWh, while cooling demand was 1.302 MWh and 1.309 MWh respectively.

Experimental and numerical investigation of novel light weight concrete panels made with aerogel and phase change materials

Silica Aerogel (SAG) mortar is an ultra-lightweight cementitious composite. It has high heat-insulating properties, which helps to reduce building heating energy consumption. However, it may also increase overheating and peak cooling demand in buildings during summer due to low thermal mass to store thermal energy. Therefore, this study aimed to increase the thermal energy storage capacity of silica aerogel lightweight concrete panels (SAGP) by integrating Capric Acid (CA) Phase Change Materials (PCM). The CA was absorbed in Hydrophobic Expanded Perlite (HEP) porous materials to develop form stable capric acid hydrophobic expanded perlite (CAHEP) composite to prevent PCM leakage when melted. Various lightweight Heat Resistive and Storage Panels (HRSP) panels were developed by replacing sand with SAG and CAHEP composite at different volume fractions. Then, the thermophysical properties and thermal performance of those HRSPs were evaluated using appropriate standards and established methods. The results showed that the integration of 60% CAHEP in SAGP resulted in 43% and 56% higher thermal storage and inertia, respectively, compared to the reference SAGP without CAHEP. The developed HRSPs also have acceptable compressive strength and drying shrinkage for thermal insulating and plastering applications. Numerical simulation showed that the application of HRSPs on the interior surface of a typical Victorian house reduced annual energy use and greenhouse gas emissions by 9.14% and 24%, respectively, in air-conditioned buildings; and reduced summertime thermal discomfort hours by 42 h in a free running house during a heatwave period. Finally, the life cycle assessment revealed that HRSPs have lower environmental impacts than SAGPs. Thus, HRSPs can be a sustainable alternative to lightweight concrete panels.

AutoBPS: A tool for urban building energy modeling to support energy efficiency improvement at city-scale

China has promised to peak carbon emissions by 2030 and become carbon neutral before 2060. Achieving this target requires actions from all sectors, especially the building sector, which accounts for 33 % of the total energy consumption in China. Within this scenario, this paper introduces a new urban building energy modeling tool, Automated Building Performance Simulation (AutoBPS), to calculate urban building energy demands and to analyze energy retrofit and rooftop photovoltaic (PV) potential. AutoBPS uses a building-by-building approach to automatically generate multi-zone (one zone per floor) models based on the city building dataset, considering the shading effect by surrounding buildings. The tool simulates building energy use and PV generation via EnergyPlus. A downtown district of 3633 buildings in Changsha, China, was selected as a case study to demonstrate the features of the tool. Firstly, annual baseline energy uses of 1793 GWh were simulated by inputting Geographic Information System (GIS) data. Then, different energy conservation measures (covering envelope, lighting, cooling system upgrade, etc.) and roof PV generation systems were adopted to explore energy saving potential. The results showed that the window upgrade was the most energy-efficient individual measure for residential buildings, while the lighting upgrade was that one for commercial buildings. Altogether three measures could save 2.7 ∼ 30.7 % of annual site energy use intensity per building. The total energy demand could be reduced by 18.5 % by combining all measures and saved by 38.6 % when PV installation was added. AutoBPS can be easily applied to other cities, supporting urban energy efficiency plans for carbon reduction goal implementation.

Optimization of an office building form using a lattice incubate boxes method

With the increasing demand for sustainable built environments, energy performance is becoming essential in the early design stage. Several previous studies using optimization of building form for energy performance considered simple hypothetical forms. In addition, previous multi-objective optimization (MOO) of building form and envelope did not consider views percentage to the outdoor (VPO) despiteof its importance for human mental health and its conflict with energy performance. This paper proposes a novel lattice incubates boxes (LIB) method that optimizes a cellular office building form. It considers the entire building with 27 thermal zones in an attempt to mimic a real case study. In addition, it considers VPO as an objective in the MOO of building form and envelope. First, the study performs single-objective optimization (SOO) of architectural form and orientation for annual thermal Energy Use Intensity (EUI) in Cairo, London, and Chicago. Second, it performs multidisciplinary MOO of Cairo’s form, window to wall ratio (WWR) and horizontal shading devices (HSD) for annual thermal EUI, annual Useful Daylight Illuminance (UDI-100–2000), and VPO. Third, it develops the LIB method to make it more applicable in professional practice through considering 72 individual thermal zones while adding more constraints. Compared to the initial forms, first part EUI savings were between 16.86% and 12.9 %. EUI, UDI, and VPO savings for Cairo in the second part were 20.16%, 11.5%, and 19.5 %. Scatterplots are developed for the second part that show rows motion has the highest positive impact on UDI and VPO, WWR has a positive impact on all objectives and HSD has high positive impact on EUI only. Savings in the third part are 11 % EUI, 8.77 % UDI, 2.86% Daylight Autonomy (DLA) and 7.8 % VPO. Scatterplots in the third part show that almost all proposed form dynamic parameters have strong impact on all objectives.

An Effective Metaheuristic Approach for Building Energy Optimization Problems

Mathematical optimization can be a useful strategy for minimizing energy usage while designing low-energy buildings. To handle building energy optimization challenges, this study provides an effective hybrid technique based on the pelican optimization algorithm (POA) and the single candidate optimizer (SCO). The suggested hybrid algorithm (POSCO) benefits from both the robust local search power of the single candidate method and the efficient global search capabilities of the pelican optimization. To conduct the building optimization task, the optimization method was developed and integrated with the EnergyPlus codes. The effectiveness of the proposed POSCO method was verified using mathematical test functions, and the outcomes were contrasted with those of conventional POA and other effective optimization techniques. Application of POSCO for global function optimization reveals that, among the thirteen considered functions, the proposed method was best at finding the global solution for seven functions, while providing superior results for the other functions when compared with competitive techniques. The suggested POSCO is applied for reducing an office buildings’ annual energy use. Comparing POSCO to POA procedures, the building energy usage is reduced. Furthermore, POSCO is compared to simple POA and other algorithms, with the results showing that, at specific temperatures and lighting conditions, the POSCO approach outperforms selected state-of-the-art methods and reduces building energy usage. As a result, all data suggests that POSCO is a very promising, dependable, and feasible optimization strategy for dealing with building energy optimization models. Finally, the building energy optimization findings for various climatic conditions demonstrate that the changes to the weather dataset had limited effect on the efficiency of the optimization procedure.

The influence of precipitation on the energy footprint of Denver's water supply: A 20-year analysis and implications for climate change

Denver Water serves 1.5 million people in the metropolitan area of Denver, Colorado, USA. Relying on runoff from mountain watersheds, its water supply is obviously sensitive to precipitation, but so is its energy footprint. We analyzed Denver Water's annual energy use and water use alongside local precipitation over a 20-year period from 1995 to 2014. Energy use generally trended opposite to precipitation: In dry years the system used more energy than in wet years, even when the energy use was normalized by water volume. The data suggest that the system needs to compensate for less precipitation by expending more energy, presumably by supplying water from more distant or more energy-intensive water sources. A regression model indicates that a 1 cm decrease in annual precipitation equates to 275,000 kWh of additional energy use and that typical interannual variability in precipitation accounts for 11% of Denver Water's energy footprint. The analysis highlights implications for altered energy footprints as water utilities respond to new precipitation patterns in a changing climate.

Sensitivity analysis and optimization of PCM integrated buildings in a tropical savanna climate

Several researchers have reported the importance of early design stage decisions in the building design process. Integrating phase change material (PCM) in buildings is a feasible method for enhancing energy efficiency. However, the following issues have not been addressed yet. (a) What is the most effective combination of early design stage parameters that minimizes the energy consumption of PCM integrated residential buildings? (b) Can the various sensitivity analysis methods generate a similar ranking of early design stage parameters? (c) Can the same set of early design stage parameters be used for tropical savanna climates? (d) Are the optimal solutions economically and environmentally feasible? Hence, this research proposes a multi-stage sensitivity and optimization of the PCM incorporated buildings in tropical savanna climates by considering building layout, envelope thermal characteristics, and energy efficiency measures. For multi-stage sensitivity analysis, at the first stage, global sensitivity methods (Morris, standard rank regression coefficients, partial rank correlation coefficients) were used followed by the utilization of the local sensitivity method. An evolutionary algorithm was used to optimize the key early design stage parameters. Finally, the economic and environmental analysis was performed on optimal solutions. Results showed that all methods generated a different ranking of the importance of early design stage parameters. Due to optimization, the annual energy use decreased by about 18.2–42.7% in comparison to the base case. In addition, the optimal solutions are economically and environmentally pronounced. It is concluded that early design stage parameter selection is crucial in reducing building energy consumption.

The Potential of Static and Thermochromic Window Films for Energy Efficient Building Renovations

The type of glazing implemented in a building plays an important role in the heat management of a building. Solar heat entering through glazing causes overheating of interior spaces and increases building’s cooling load. In this work, the energy saving potential of window films based on Cholesteric Liquid Crystals (CLC) is explored. This emerging technology allows for the fabrication of static and thermochromic solar heat rejecting window films and can provide a simple renovation solution towards energy efficient buildings. Simulations on a model office showed that static CLC-based window films can save up to 29% on a building’s annual energy use in warm climates. In climates with distinct summer and winter seasons, static solar heat rejecting windows films cause an additional heating demand during winters, which reduces the annual energy savings. In these climates, the benefit of thermochromic CLC-based window films becomes evident and an annual energy saving up to 22% can be achieved.

Bireysel Derin Kuyu Sulama İşletmesinde Enerji Kullanımı ve Sera Gazı Emisyonunun Belirlenmesi

This study was conducted to determine the annual energy use and related greenhouse gas (GHG) emissions of individual deep well irrigation enterprise. That study was conducted at deep well farm belonging to one farmer with volunteer preforming farming activities in Konya-Meram-Çarıklar location for the growing season of 2021. In that regard, the activities using alfalfa and dry bean production, and total production inputs with their amounts as well as crop yields were determined separately. By considering unit energy equivalent values and GHG emission factors of each input, annual energy consumption and GHG emission values were calculated. Similarly, by examining energy content and crop yield in accordance of crop production unit (kg), annual produced energy amount was calculated. The evaluation was made using energy used and energy produced as well as GHG emission values indicators at individual deep well irrigation farm. According to the results obtained, annual energy use and energy production were calculated 253035 mega-joule (MJ), and 487960 MJ, respectively for individual well irrigation farm. The electricity used during the irrigation processes resulted around 71% of annual energy consumption. The annual GHG emission amount as an equivalent to the carbon dioxide (CO2eqv) for research farm with GWI was determined as 18575 kg (18575 kgCO2eqv year-1). Almost 52% of annual GHG emission was resulted from electricity used in irrigation.

Holistic methodology to reduce energy use and improve indoor air quality for demand-controlled ventilation

Ventilation control logics are usually based on the control indicators of occupancy. However, strategies including control of contaminants not linked to occupancy are requested and more feasible with the introduction in the market of low-cost sensors (LCS).In this work, a methodology for the improvement of demand-controlled ventilation (DCV) using measurements of IAQ parameters with LCS, correlation analysis, and co-simulation EnergyPlus/CONTAM is presented. Its goal was reduced annual energy use and the fraction of time with room air concentration of IAQ parameters outside thresholds.The ventilation control sequences of supply airflow rates and recirculation of return air focused on the significant parameters chosen by cross-correlation functions in the de-trended measurements.The results revealed that the methodology successfully developed control sequences that simultaneously reduced annual energy use and the number of hours outside the recommended IAQ guidelines compared to the baselines. In cold cities with excellent outdoor air quality, recirculation could reduce energy use and increase the RH in winter. Further simulations demonstrated that the use of recirculation had a protective effect on the indoor concentrations of PM2.5, assuming low outdoor air quality. However, when using recirculation, it is essential to control the IAQ to avoid excessive pollutants, RH, and temperatures.

Geothermal Heat Pump Production Sustainability—The Basis of the Swiss GHP Success Story

Geothermal heat pump systems (GHP) are the spearhead of geothermal achievement and development, and one of the fastest growing applications of renewable energy technologies worldwide. When Swiss GHP activities started in the late 1970s, market introduction and penetration needed science-based proof of reliable, stable, long-term GHP operation. A special, extended project, realized in a field-laboratory setting, provided this proof. Detailed measurements, as well as numerical model simulations, proved the sustainable operation of the installed GHP system. The measurement setup, the recording of the various time series, and their interpretation are presented. Furthermore, basic perceptions were elaborated concerning geothermal resources behavior in production and regeneration. The Swiss GHP was developed from nothing. Early GHP installation costs halved within 20 years; GHP growth was nearly exponential from 1980 to 2020 (8.5% annually). Drilled borehole heat exchanger (BHE) meters are today around 300,000 m per year; heat delivery of GHPs in Switzerland amounted to 3280 GWh 2020—over 85% of Swiss geothermal direct uses (among others like thermal spas, district heating). Large installations with hundreds of BHEs are now common, and are also used for heating and cooling. The international ranking of Swiss GHP realizations is excellent in terms of annual energy use (TJ/yr/area), and is number one worldwide. Switzerland is a global GHP leader, and the Swiss success story is well documented.

Projected Effects of Climate Change on the Energy Footprints of U.S. Drinking Water Utilities

Drinking water systems’ energy footprints depend mostly on the source, quality, and volume of water supply, but also on local temperature and precipitation, both of which are changing with the global climate. From a previous survey, we develop an equation for modeling relative changes in U.S. water utilities’ annual energy use, in which their energy use increases with temperature and decreases with precipitation. To demonstrate, we insert gridded projections from three scenarios in the EPA’s Climate Resilience Evaluation and Awareness Tool (CREAT) and compare 2035 and 2060 periods with a 1981–2010 baseline. Averaged over the continental United States, the 2060 central scenario projects 2.7 °C warmer temperatures and 2.9 cm more annual precipitation. For the same water demand, we estimate that these conditions will cause U.S. water systems’ energy use to change by −0.7% to 13.7% depending on the location (average 8.5% across all grid cells). Warming accounts for a general increase, and local changes in precipitation can add to or subtract from it. We present maps showing the spatial variability for each scenario. Water systems are essential infrastructure that support sustainable communities, and the analysis underscores their needs for energy management, renewable energy, water conservation, and climate change resilience.

Vacuum insulation arrays as damage-resilient thermal superinsulation materials for energy saving

<h2>Summary</h2> The building sector, where heating and cooling are the major energy consumers, contributes significantly to global greenhouse gas emissions. Large energy savings can be achieved if buildings are thermally insulated from the environment. Existing high-thermal insulation materials, such as aerogels and vacuum insulation panels, are vulnerable to mechanical forces and damage, making their installation a significant challenge and compromising their long-term performance. Here, we report a vacuum insulation array (VIA) design that combines mechanical robustness and ultrahigh thermal-insulation performance, with local vacuum cells that are hermetically sealed and separated from each other. This design allows the material to be punctured, cut, or reassembled, with a long-term thermal conductivity of less than 0.007 W/m-K even after puncture damage. Our insulation material can potentially realize a 20%–40% reduction in the annual energy use for the existing building-space heating and cooling with only 2 cm of added thickness.