Energy Star Research Articles

Smart Building Energy Inefficiencies Detection through Time Series Analysis and Unsupervised Machine Learning

The climate of Houston, classified as a humid subtropical climate with tropical influences, makes the heating, ventilation, and air conditioning (HVAC) systems the largest electricity consumers in buildings. HVAC systems in commercial buildings are usually operated by a centralized control system and/or an energy management system based on a fixed schedule and scheduled control of a zone setpoint, which is not appropriate for many buildings with changing occupancy rates. Lately, as part of energy efficiency analysis, attention has focused on collecting and analyzing smart meters and building-related data, as well as applying supervised learning techniques, to propose new strategies to operate HVAC systems and reduce energy consumption. On the other hand, unsupervised learning techniques have been used to study the consumption information and profile characterization of different buildings after cluster analysis is performed. This paper adopts a different approach by revealing the power of unsupervised learning to cluster data and unveiling hidden patterns. In this study, we also identify energy inefficiencies after exploring the cluster results of a single building’s HVAC consumption data and building usage data as part of the energy efficiency analysis. Time series analysis and the K-means clustering algorithm are successfully applied to identify new energy-saving opportunities in a highly efficient office building located in the Houston area (TX, USA). The paper uses 1-year data from a highly efficient Leadership in Energy and Environment Design (LEED)-, Energy Star-, and Net Zero-certified building, showing a potential energy savings of 6% using the K-means algorithm. The results show that clustering is instrumental in helping building managers identify potential additional energy savings.

Research of the Negative Influence of Dimmed LED Luminaires in Context of Smart Installations

This article deals with the investigation of the negative impacts of dimmed public, industrial and office LED (light emitting diode) light installations. This approach is required due to the uncertain design of LED ballasts, while manufacturers do not implement the required PFC (power factor correction) function. Therefore, the focus is on a brief description of the principles of negative influences such as: low power factor, high inrush current and high total harmonic distortion based on direct confrontation with actual standards (IESC EN, NEMA, ENERGY STAR). Further, the behavior of LED drivers is explained under nominal load and dimmed up to critical level. Presented findings confirm issues reported by users from larger installations where LED fittings are dimmed over a certain level. The article includes recommendations for consumers and producers of LED fittings about main issues from the scientific and user points of view. Presented facts conclude on the necessity of studying the marginal operating state of LED fittings aiming at THD (total harmonic distortion), PF (real power factor) and inrush currents.

Improving awareness of energy conservation: Rocky Mountain City

Purpose The purpose of this research project was to improve public awareness to improve public awareness of the importance of energy conservation and to improve the use of simple conservation strategies. A thorough evaluation of the net gain from the numerous energy campaigns rolled out to the public every year is lacking. This study conducted pre- and post-campaign surveys and focus groups to evaluate one campaign’s impact on self-reported energy behaviors. Design/methodology/approach The campaign used television public service announcements and a website to improve awareness of the city’s efforts to conserve energy and to increase individual energy conservation practices. Focus groups (n = 40) were used to identify common barriers to conservation, and pre- and post-surveys (n = 533, 479) were conducted to evaluate the campaign’s effectiveness. Findings Results indicated that the campaign increased positive changes in changing light bulbs and confidence in taking action to turn down thermostats, unplug devices and turn off lights. While follow-up research is needed on the precise mechanism of the psychological process at work, the findings are consistent with the concepts of self and response efficacy as needed components of any behavior change. The authors advocate the adoption of research-informed message design to maximize communication campaign effects. Originality/value This paper demonstrates how the combination of three prominent persuasion theories can be used to develop behavior change campaigns. Also, it is one of the few studies to evaluate the effectiveness of the Energy Star campaign.

Type-II Weyl Semimetal versus Gravastar

The boundary between the type I and type II Weyl semimetals serves as the event horizon for the "relativistic" fermions. The interior of the black hole is represented by the type II Weyl semimetal, where the Fermi surface is formed. The process of the filling of the Fermi surface by electrons results in the relaxation inside the horizon. This leads to the Hawking radiation and to the reconstruction of the interior vacuum state. After the Fermi surface is fully occupied, the interior region reaches the equilibrium state, for which the Hawking radiation is absent. If this scenario is applicable to the real black hole, then the final state of the black hole will be the dark energy star with the event horizon. Inside the event horizon one would have de Sitter space time, which is separated from the event horizon by the shell of the Planck length width. Both the de Sitter part and the shell are made of the vacuum fields without matter. This is distinct from the gravastar, in which the matter shell is outside the "horizon", and which we call the type I gravastar. But this is similar to the other type of the vacuum black hole, where the shell is inside the event horizon, and which we call the type II gravastar. We suggest to study the vacuum structure of the type II gravastar using the $q$-theory, where the vacuum variable is the 4-form field introduced for the phenomenological description of the quantum vacuum.

Bridging the energy gap of India’s residential buildings by using rooftop solar PV systems for higher energy stars

Abstract The residential-building sector in India consumes >25% of the total electricity and is the third-largest consumer of electricity; consumption increased by 26% between 2014 and 2017. India has introduced a star-labelling programme for residential buildings that is applicable for all single- and multiple-dwelling units in the country for residential purposes. The Energy Performance Index (EPI) of a building (annual energy consumption in kilowatt-hours per square metre of the building) is taken as an indicator for awarding the star label for residential buildings. For gauging the EPI status of existing buildings, the electricity consumption of residential buildings (in kWh/m2/year) is established through a case study of the residential society. Two years of electricity bills are collected for an Indian residential society located in Palam, Delhi, analysed and benchmarked with the Indian residential star-labelling programme. A wide EPI gap is observed for existing buildings for five-star energy labels. Based on existing electricity tariffs, the energy consumption of residential consumers and the Bureau of Energy Efficiency (BEE)’s proposed building ENERGY STAR labelling, a grid-integrated rooftop solar photovoltaic (PV) system is considered for achieving a higher star label. This research study establishes the potential of grid-connected rooftop solar PV systems for residential buildings in Indian cities through a case study of Delhi. Techno-economic analysis of a grid-integrated 3-kWp rooftop solar PV plant is analysed by using RETScreen software. The study establishes that an additional two stars can be achieved by existing buildings by using a grid-integrated rooftop solar PV plant. Payback for retrofit of a 3-kWp rooftop solar PV plant for Indian cites varies from 3 to 7 years. A case study in Delhi, India establishes the potential of grid-connected rooftop solar PV systems for residential buildings. Techno-economic analysis of grid integrated, 3 kWp rooftop solar systems estimates a payback period from 3 to 7 years.

ENERGY STAR Appliance Market Shares: Do They Respond to Electricity Prices, and Does It Matter?

We address an apparent paradox that the market shares of four ENERGY STAR appliances in the United States do not respond to within-state changes in electricity prices. We resolve the paradox by showing that market shares do respond to between-state variation in electricity prices. We also suggest an economic explanation for the paradox through the timing of appliance purchases. Using the estimation results, we find that the four ENERGY STAR appliances reduce carbon emissions by 1.9 million megawatt-hours per year, equivalent to removing 0.1% of all U.S. vehicles, and that the addition of a $100/ton CO2 price would increase these figures to 2.1 million megawatt-hours and 0.11%.

Residential thermostat usability: Comparing manual, programmable, and smart devices

Residential thermostats were originally very simple devices. Any energy saving practices, such as nighttime setbacks, were entirely dependent on the occupants and required diligent setpoint adjustment. Programmable thermostats were endorsed by Energy Star in the 1990s, but later studies showed they failed to realize expected savings due to a lack of usability. New, ‘smart’ thermostats promise to address the downfalls, while offering increasingly complex features. This study examines the relationship between thermostat usability and interface characteristics in Ottawa, Canada, with a focus on devices currently installed in homes. To compare manual, programmable, and smart interfaces, human computer interaction methods, including participant interviews and think-aloud analysis, were employed. A sample of 51 participants were interviewed in their homes and attempted six usability tasks on their thermostat interface(s). Interviews were recorded and each thermostat type (manual, programmable and smart) was evaluated based on the time to complete, required interactions and qualitative observations. An averaged time and success usability metric was assigned to each category and contrasted with previous literature. In general, smart thermostats were found to be significantly more useable than their programmable counterparts. Participants expressed a desire for more feedback regarding energy consumption and half (51%) noted they either wanted or enjoyed thermostat control through a smartphone application.

STUDY THE NEED OF BASELINE ENERGY USE BENCH MARKING OF BUILDINGS IN DIFFERENT CLIMATE ZONES OF INDIA

The aim of research is to identify a need of a baseline energy use for benchmarking the minimum energy performance of the buildings for different climate zones of India. Its objective is to provide information and create awareness among customers on energy performance so that consumers can make informed decisions while purchasing appliances, selecting the ECMs and in creating a sustainable home. This study will help in the identification of underperforming buildings to target for efficiency improvements, identify best practices from efficient buildings, set investment priorities, verify savings and prevent snapback, share and report performance, earn recognition, continuous monitoring and implement a comprehensive management program. There are rating system available in India i.e. BEE Star Labelling program and GRIHA Baseline Energy Use to support these requirements. However, there are some limitation in the terms of Climate Zones and Standardization. The baseline energy use differs with each other on a certain parameter, which can create a misinterpretation for the building owners to rely on any standard. There is a need of knowing the current status/performance of the building as comparison to the similar type of buildings in India in respective climate zones. There is a further need to getting recognized by the authority at national level providing the status of the building energy performance. Enormous studies have been made and have suggested to follow the best Energy Conservation Measures (ECM’s) in the buildings. However, there is no portal or tool which can guide what further energy performance is needed to choose the ECMs accordingly. There is an online portal called Energy Star Portfolio Manager in USA which looks closer to the need and for the same a research has been carried out including all the stakeholders, engineers, architects, consultants to come up with the need of online benchmarking tool, accessible for all the building holders. Further, the expertise of BEE Certified Energy Auditors and Energy Managers can be helpful in the identification of this eco system of energy use benchmarking for the different climate zones of India. KEYWORDS: Energy Use; Green Buildings; Climate Zones; Energy Performance Benchmarking; Energy Star Portfolio Manager

Does Eco-Certification Correlate with Improved Financial Performance? Evidence From a Longitudinal Study in the US Hospital Industry.

Health care-based negative production externalities, such as greenhouse gas emissions, underscore the need for hospitals to implement sustainable practices. Eco-certification has been adopted by a number of providers in an attempt, for instance, to curb energy consumption. While these strategies have been evaluated with respect to cost savings, their implications pertaining to hospitals' financial viability remain unknown. We specify a fixed-effects model to estimate the correlation between Energy Star certification and 3 different hospitals' financial performance measures (net patient revenue, operating expenses, and operating margin) in the United States between 2000 and 2016. The Energy Star participation indicators' parameters imply that this type of eco-certification is associated with lower net patient revenue and lower operating expenses. However, the estimated negative relationship between eco-certification and operating margin suggests that the savings in operating expenses are not enough for a hospital to achieve higher margins. These findings may indicate that undertaking sustainable practices is partially related to intangible benefits such as community reputation and highlight the importance of government policies to financially support hospitals' investments in green practices.

Influential factors to occupy green residential building among green building occupants

Green building has been proven having higher occupancy rate than conventional building. The occupancy rate of ENERGY STAR and LEED-certified green office building are 8% to 18% higher than conventional office building. Previous research has proved that occupants prefer to occupy green office building due to various green benefits. However, most of these researches were conducted on green office building. Therefore, this study is motivated to identify the influential factors for occupants to occupy green residential building. The aim of this study is to evaluate factors that influence occupants to occupy green certified residential building. 75 questionnaires were distributed among occupants of green certified residential building namely Molek Pine 4 and Ponderosa Lakeside Apartment in Johor Bahru. The results were analysed using frequency analysis. Location and good environment quality are the most significant factors that influence occupants to occupy the green certified residential building in Johor Bahru. This research is noteworthy for property industry players especially property developer in guiding the direction of green residential building development in accordance with occupants’ and market preferences.

Dark energy stars with a phantom field

Dark energy is the constituent with an enormous abundance in the present Universe, responsible for the Universe's accelerated expansion. Therefore, it is plausible that dark energy may interact within any compact astrophysical object. The author in [S. S. Yazadjiev, Phys. Rev. D 83, 127501 (2011)] constructs an exact star solution consisting of ordinary matter and a phantom field from a constant density star (CDS) known as the Schwarzschild interior solution. The star denotes a dark energy star (DES). The author claims that the phantom field represents dark energy within the star. So far, the role of the phantom field as dark energy in a DES is not systematically studied yet. Related to this issue, we analyze the energy condition of a DES. We expect that DESs shall violate the strong energy condition (SEC) for a particular condition. We discover that a SEC is fully violated only when the compactness reaches the Buchdahl limit. Furthermore, we also investigate the causal conditions and stabilities due to the convective motion and gravitational cracking. We also find that those conditions are violated. These results indicate that DES is not physically stable. However, we may consider DES as an ultracompact object of which we can calculate the gravitational wave echo time and echo frequency and compare them to those of CDS. We find that the contribution of the phantom field delays the gravitational wave echoes. The effective potential of the perturbed DES is also studied. The potential also enjoys a potential well like CDS but with a deeper well. We also investigate the possibility that DES could form a gravastar when $C=1$. It is found that a gravastar produced from DES possesses no singularity with a dS-like phase as the interior. These results could open more opportunities for the observational study of dark energy in the near future, mostly from the compact astrophysical objects.

Modelling of dark energy stars with tolman IV gravitational potential

The present study explores the properties of dark energy star with high density under the dark energy equation of state (EOS) (pr=ωρ) with anisotropic fluid distribution, where ω describes the dark energy parameter. The relativistic dark-energy stellar structures are studied by adopting Tolman IV-type gravitational potential. In this relation we examine many physical properties through graphical plots and mathematical calculation, such as energy condition, compactness, mass-radius ratio, anisotropic nature and surface redshift. It is observed that the strong energy condition is violated whereas all other energy conditions are satisfied. We have also fitted radius corresponding to observed mass value for observed neutron stars, namely, PSRJ1416−2230,VelaX−1,4U1608−52,HerX−1 and PSRJ1903+327, which are compatible with the predicted values.

ENERGY EFFICIENCY LABELLING: INVESTIGATING STUDENTS’ PREFERENCES AND AWARENESS ON THE ENERGY-EFFICIENT ELECTRICAL APPLIANCES IN HOSTEL

The significant role of energy efficiency labelling should not be ignored as it provides various information that serve as a guideline when people make purchasing decision. It indicates projection energy consumption of an electrical equipment according to energy efficiency rating system. This study applied choice experiment (CE) method in which the conditional logit (CL) model was valued to determine students' willingness to pay (WTP) based on their preferences of the energy label attributes of table fans. A questionnaire survey was distributed to 151 on-campus students in Terengganu, Malaysia. The attributes were speed of fan, energy consumption and energy star and price of fan. The study found that the students mostly preferred energy consumption attribute with WTP estimation of RM123.538 (USD29.66) at level two and RM42.88 (USD10.30) at level three. These findings illustrate how people place value on monetary and non-monetary attributes based on their preferences. A label with energy-efficient standard makes it easier for utility companies and government energy-conservation organizations to offer consumers incentives to purchase energy-efficient products. The usefulness of energy efficiency label is very reliant in terms of how it portrays information to the people and promote energy conservation.Keywords: Choice Experiment, energy label, energy efficiency, energy conservation, table fan Willingness to Pay.JEL Classifications: D1, Q0, Q4, Q5DOI: https://doi.org/10.32479/ijeep.10824

Color-flavor locked quark stars in energy–momentum squared gravity

Several attempts have been made in the past decades to search for the true ground state of the dense matter at sufficiently large densities and low temperatures via compact astrophysical objects. Focusing on strange stars, we derive the hydrostatic equilibrium assuming a maximally symmetric phase of homogeneous superconducting quark matter called the \textit{color-flavor-locked} (CFL) phase in the background of energy-momentum squared gravity (EMSG). Theoretical and experimental investigations show that strange quark matter (SQM) in a CFL state can be the true ground state of hadronic matter at least for asymptotic densities, and even if the unequal quark masses. Motivated by these theoretical models, we explore the structure of stellar objects in recently proposed EMSG, which allows a correction term $T_{\mu \nu}T^{\mu \nu}$ in the action functional of the theory. Interestingly, EMSG may be effective to resolve the problems at high energy densities, e.g., relevant to the early universe and dense compact astrophysical objects without invoking some new forms of fluid stress, such as bulk viscosity or scalar fields. Finally, we solve the complicated field equations numerically to obtain the mass-radius relations for strange stars in CFL equation of state.

Selection of modern LED fittings for SMART installations considering THD and PF worseness due to dimming

This article reports an analysis of problematics of negative influences of SMART LED light installations aimed on current distortion and circulation of reactive energy. Article describes main principals of negative influences based on direct confrontation with actual standards (CENELEC, NEMA, ENERGY STAR). Article briefly explains behavior of LED drivers under nominal and dimmed conditions up to critical level. Measurements confirm issues reported by users from larger installations, where LED fittings are dimmed over certain level, or low-quality LED driver is used in LED fitting. Currently used limitations set by EN standards seems to be insufficient along the new generations of LED fitting, with higher lumen output ratings and its “optional dimmability.” Therefore, article sets pre-evaluate method of limiting the negative influences of dimmed LED installation, using combination of experimental methods and gathering information from datasheets of LED drivers.

Theoretical Minimum Thermal Load in Buildings

Summary Building cooling and heating accounts for a large portion of total global energy use and requires commensurate amounts of resources, which contribute significantly to global warming. Traditionally, addressing this issue has meant improving the efficiency of equipment supplying the thermal energy, reducing envelope heat transfer, and reducing air infiltration. However, this approach is already reaching practical limits. In this perspective, we explore (1) how to reduce thermal load in buildings theoretically and (2) how to achieve that reduction and dramatically lower the energy required to support building loads practically. First, we discuss our framework developed for calculating the theoretical minimum thermal load (TMTL) in buildings. Our analysis shows that current thermal loads in buildings are more than an order of magnitude higher than the TMTL. We also introduce an approximate formula to calculate energy savings from zonal control of thermal load, which shows that the majority of zonal control benefits can be achieved with fewer than 10 zones. Then, we discuss pros and cons of various approaches and strategies to achieve the TMTL. We conclude our perspective with some longer-term R&D ideas, such as thermally adaptive clothing and thermal storage to help approach the TMTL, while providing the additional benefit of interacting with the renewable grid of the future.

РЕКОНСТРУКЦИЯ И ВОССТАНОВЛЕНИЕ ИСТОРИЧЕСКИХ ПАМЯТНИКОВ: МЕЖДУНАРОДНЫЙ ОПЫТ

Introduction: In addition to recognizing and taking into account the vital need for the maintenance and repair of historical structures, this study will focus on their inherent design potential at the intersection of the new and the old. Purpose of the study: The study aims to review the approach to restoring such landmarks as the library in Vyborg and the Arsenal building in the Nizhny Novgorod Kremlin. We will also focus on the restoration of more mundane structures. In addition to historical monuments, this study will look at instances when there is no attempt to return the buildings to some idealized version of the past, but instead, the restoration process is used to celebrate the qualities of the buildings’ age in the here and now, and to recognize that they are living, evolving, and constantly changing entities. Methods: The study uses the method of analysis, which we apply to the standard solutions for various purposes and objects, in the form of structural and technological protection of cultural heritage sites during their restoration and adaptation. The use of modern restoration materials and protective structures’ construction technologies will help protect the environment while taking into account LEED, BREEAM, the Energy Star program (the USA), and the GREEN ZOOM standards. Results: We offer selected examples from contemporary practice in Europe, the United States, and Russia to illustrate these approaches to restoration, including two student-led architectural installations that explore the creative intersection between the new and the old. Discussion: Discussing the execution of specific restoration and reconstruction projects reveals the importance of international cooperation in the development of educational strategies and practices in the field of conserving and restoring the cultural heritage. The growing volume of conservation and restoration work is putting pressure on the development of research approaches and methodologies aimed at solving practical problems. At the same time, the restorer must be mindful of continuity with the past when reconstructing the more mundane and utilitarian structures that can benefit from less restrictive approaches to the intersection of the old and the new.

Equivalent Electric and Heat-Pump Water Heater Models for Aggregated Community-Level Demand Response Virtual Power Plant Controls

Advanced control techniques may be used to establish a virtual power plant to regulate the operation of electric water heaters, which may be regarded as a “uni-directional battery” and a major component of a hybrid residential energy storage system. In order to estimate the potential of regulating water heaters at the aggregated level, factors including user behavior, number of water heaters, and types of water heaters must be considered. This study develops generic water heater load curves based on the data retrieved from large experimental projects for resistive electric water heaters (EWHs) and heat pump water heaters (HPWHs). A community-level digital twin with scalability has been developed to capture the aggregated hot water flow and average hot temperature in the tank. The results in this paper also include the “energy take” in line with the CTA-2045 standard and Energy Star specification. The data from the experiments demonstrated that changing from an EWH to an HPWH reduces electricity usage by approximately 70%. The case study showed that daily electricity usage could be shifted by approximately 14% and 17% by EWH and HPWHs, respectively, compared to their corresponding average power. Another case study showed that both EHWs and HPWHs, coordinated with PV to reduce morning and evening peaks, could shift approximately 22% of the daily electricity.

Detection of large-scale X-ray bubbles in the Milky Way halo

The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection into the halo from past activity in the nucleus of the Milky Way1-4; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova5 but part of a vast Galaxy-scale structure closely related to features seen in γ-rays6. Large energy injections from the Galactic centre7 are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 1056 erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.

Energy Management Practices in State Universities and Colleges (SUCs): An Assessment for an IOT Intervention

Monitoring and analyzing a building’s energy consumption patterns are major components for an effective energy management system, which helps in understanding the building’s operational behavior under different conditions. Energy management teams of universities are responsible for monitoring, analyzing and maintaining energy consumption data of their buildings. The study was conducted to elucidate the status of energy consumption, and to identify and illustrate the potential weak areas found from the energy consumption gap analysis in the context of government HEIs. The gap in this study was addressed by providing a detailed assessment of energy consumption practices and insights in an intra-university context, primarily through the identification of key practices leading to energy-saving measures. The work presented in this paper relied on data obtained from energy audits from the complete set of buildings over several campuses. In the occurrence of disparity between the actual values and the theoretical values, a focused group discussion was conducted to determine the energy consumption practices. The researchers had identified and categorized lists of practices based on the literature and selected those most applicable for government-funded HEIs. The researchers identified the list of key practices anchoring three Energy Management models: ISO 5001, Energy Star and BRECSU Energy Management System. The study determined that addressing specific key practices leading to an effective energy management system helps develop clear and achievable goals and objectives that adopt the SMART concept in the implementation of energy management programs.