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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Retrofitting a 1960s Split-Level, Cold-Climate Home

National programs such as Home Performance with ENERGY STAR® and numerous other utility air-sealing programs have made homeowners aware of the benefits of energy-efficiency retrofits. Yet these programs tend to focus only on the low-hanging fruit: they recommend air sealing the thermal envelope and ductwork where accessible, switching to efficient lighting and low-flow fixtures, and improving the efficiency of mechanical systems (though insufficient funds or lack of knowledge to implement these improvements commonly prevent the implementation of these higher cost upgrades). At the other end of the spectrum, various utilities across the country are encouraging deep energy retrofit programs. Although deep energy retrofits typically seek 50% energy savings, they are often quite costly and are most applicable to gut-rehab projects. A significant potential for lowering energy use in existing homes lies between the lowhanging fruit and deep energy retrofit approaches—retrofits that save approximately 30% in energy compared to the pre-retrofit conditions. The energy-efficiency measures need to be nonintrusive so the retrofit projects can be accomplished in occupied homes.

1960 split level↗
DOE OSTI2022

Capsule network-based semantic segmentation model for thermal anomaly identification on building envelopes

Thermography technology is widely used to inspect thermal anomalies in building façade systems. Computer vision-based techniques provide opportunities to autonomously detect such heat anomalies to significantly improve the efficiency of decision-making for building envelope retrofitting and maintenance. Here, in this work, we propose a novel Capsule Network-based deep learning model – CapsLab – that detects and identifies thermal anomalies by semantic segmentation. CapsLab is built based on our proposed prediction-tuning capsule (PT-Capsule) layer. Different from a traditional capsule layer, which consists of part-whole transformation and capsule-routing process, the proposed layer is composed of a prediction and tuning process, which helps decreasing the number of model parameters significantly. While the applicability of traditional Capsule Networks (CapsNets) has been limited to simpler tasks and smaller datasets due to their scalability issue, we can leverage the lightweight of the proposed PT-Capsule layer, and apply it to the semantic segmentation task. In this work, we also employ our previously presented performance metric, referred to as the Anomaly Identification Metric (AIM) (Kakillioglua et al. 2021), to evaluate the segmentation outputs. Traditional performance metrics do not accurately reflect the true performance of the segmentation models in thermal anomaly identification due to the high subjectivity in the annotation process and higher overlap ratio sensitivity of the standard metrics. AIM, on the other hand, is robust to these drawbacks. Experimental results show, both qualitatively and quantitatively, that our proposed segmentation method can effectively segment the thermal anomalies. Specifically, our model provides 9.38% and 13.53% improvements over the baseline model – DeepLabV3+ – based on traditional mIoU score and the AIM score, respectively, while requiring less model parameters and less computation at the same time. In addition, the scores that the AIM metric generates better align with the scores provided by building performance experts.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Operating-Envelopes-Aware Decentralized Welfare Maximization for Energy Communities

We propose an operating-envelope-aware, prosumer-centric, and efficient energy community that aggregates individual and shared community distributed energy resources and transacts with a regulated distribution system operator (DSO) under a generalized net energy metering tariff design. To ensure safe network operation, the DSO imposes dynamic export and import limits, known as dynamic operating envelopes, on end-users' revenue meters. Given the operating envelopes, we propose an incentive-aligned community pricing mechanism under which the decentralized optimization of community members' benefit implies the optimization of overall community welfare. The proposed pricing mechanism satisfies the cost-causation principle and ensures the stability of the energy community in a coalition game setting. Numerical examples provide insights into the characteristics of the proposed pricing mechanism and quantitative measures of its performance.

distributed energy resources aggregation↗
DOE OSTI2014

Low-cost phase change material as an energy storage medium in building envelopes: Experimental and numerical analyses

A promising approach to increasing the energy efficiency of buildings is the implementation of a phase change material (PCM) in the building envelope. Numerous studies over the last two decades have reported the energy saving potential of PCMs in building envelopes, but their wide application has been inhibited, in part, by their high cost. This article describes a novel PCM made of naturally occurring fatty acids/glycerides trapped into high density polyethylene (HDPE) pellets and its performance in a building envelope application. The PCM-HDPE pellets were mixed with cellulose insulation and then added to an exterior wall of a test building in a hot and humid climate, and tested over a period of several months, To demonstrate the efficacy of the PCM-enhanced cellulose insulation in reducing the building envelope heat gains and losses, side-by-side comparison was performed with another wall section filled with cellulose-only insulation. Further, numerical modeling of the test wall was performed to determine the actual impact of the PCM-HDPE pellets on wall-generated heating and cooling loads and the associated electricity consumption. The model was first validated using experimental data and then used for annual simulations using typical meteorological year (TMY3) weather data. Furthermore, this article presents the experimental data and numerical analyses showing the energy-saving potential of the new PCM.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Operating-Envelopes-Aware Decentralized Welfare Maximization for Energy Communities: Preprint

We propose an operating-envelope-aware, prosumer-centric, and efficient energy community that aggregates individual and shared community distributed energy resources downstream of a regulated distribution system operator's (DSO) net energy metering revenue meter. Due to the elevated risk of grid constraint violations and to ensure safe network operation, the DSO imposes dynamic export and import limits, known as dynamic operating envelopes, on end-users' revenue meters. Given the operating envelopes, the proposed community market mechanism maximizes the community's social welfare in a decentralized fashion while every community member abides by its own operating envelopes. We show that the proposed market mechanism conforms with the cost-causation principle and guarantees community members a surplus level no less than their maximum surplus when they autonomously face the DSO. Lastly, a numerical study is implemented to showcase and compare the community's welfare under the proposed operating-envelopes-aware mechanisms to others, including the welfare of customers under the DSO's regime.

distributed energy resources aggregation↗
DOE OSTI2026

Transformative Efficiency and Automation in Modular Homes (TEAMH)

This report documents the Transformative Efficiency and Automation in Modular Homes (TEAMH) project, which evaluates the integration of advanced building envelope technologies and automation-assisted modular construction to improve residential energy performance and construction efficiency. The study investigates high-performance insulation systems, including vacuum insulation panels (VIPs), combined with light gauge steel (LGS) modular construction and factory automation. Laboratory testing, whole-building energy modeling across multiple climate zones, and factory demonstrations were conducted to assess thermal performance, energy savings, and production efficiency. Results indicate that upgraded envelope assemblies can achieve up to ~50% heating and ~34% cooling energy savings relative to IECC 2018 code-compliant homes, while automation-assisted construction can reduce wall assembly time by 24%–46% compared to conventional wood framing. The findings demonstrate the potential for scalable, high-performance modular homes that deliver significant energy savings with competitive projected costs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

GIANT IMPACT: AN EFFICIENT MECHANISM FOR THE DEVOLATILIZATION OF SUPER-EARTHS

Mini-Neptunes and volatile-poor super-Earths coexist on adjacent orbits in proximity to host stars such as Kepler-36 and Kepler-11. Several post-formation processes have been proposed for explaining the origin of the compositional diversity between neighboring planets: mass loss via stellar XUV irradiation, degassing of accreted material, and in situ accumulation of the disk gas. Close-in planets are also likely to experience giant impacts during the advanced stage of planet formation. This study examines the possibility of transforming volatile-rich super-Earths/mini-Neptunes into volatile-depleted super-Earths through giant impacts. We present the results of three-dimensional hydrodynamic simulations of giant impacts in the accretionary and disruptive regimes. Target planets are modeled with a three-layered structure composed of an iron core, silicate mantle, and hydrogen/helium envelope. In the disruptive case, the giant impact can remove most of the H/He atmosphere immediately and homogenize the refractory material in the planetary interior. In the accretionary case, the planet is able to retain more than half of the original gaseous envelope, while a compositional gradient suppresses efficient heat transfer as the planetary interior undergoes double-diffusive convection. After the giant impact, a hot and inflated planet cools and contracts slowly. The extended atmosphere enhances the mass loss via both a Parker wind induced by thermal pressure and hydrodynamic escape driven by the stellar XUV irradiation. As a result, the entire gaseous envelope is expected to be lost due to the combination of those processes in both cases. Based on our results, we propose that Kepler-36b may have been significantly devolatilized by giant impacts, while a substantial fraction of Kepler-36c’s atmosphere may remain intact. Furthermore, the stochastic nature of giant impacts may account for the observed large dispersion in the mass–radius relationship of close-in super-Earths and mini-Neptunes (at least to some extent)

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Single rotating stars and the formation of bipolar planetary nebula

We have computed new stellar evolution models that include the effects of rotation and magnetic torques under different hypotheses. The goal is to test whether a single star can sustain the rotational velocities needed in the envelope for magnetohydrodynamical(MHD) simulations to shape bipolar planetary nebulae (PNe) when high mass-loss rates take place. Stellar evolution models with main sequence masses of 2.5 and 5 M {sub ☉} and initial rotational velocities of 250 km s{sup –1} have been followed through the PNe formation phase. We find that stellar cores have to be spun down using magnetic torques in order to reproduce the rotation rates observed for white dwarfs. During the asymptotic giant branch phase and beyond, the magnetic braking of the core has a practically null effect on increasing the rotational velocity of the envelope since the stellar angular momentum is efficiently removed by the wind. We have also tested the best possible case scenarios in rather non-physical contexts to give enough angular momentum to the envelope. We find that we cannot get the envelope of a single star to rotate at the speeds needed for MHD simulations to form bipolar PNe. We conclude that single stellar rotators are unlikely to be the progenitors of bipolar PNe under the current MHD model paradigm.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Modeling, Testing, and Analysis of Volvo Truck Tractor Cabins (Final Report)

Annual fuel use for sleeper cab truck rest period idling is estimated at 667 million gallons in the United States, or 6.8% of long-haul truck fuel use. Truck idling during a rest period represents zero freight efficiency and is largely done to supply accessory power for climate conditioning of the cab. This project aimed to reduce heating, ventilating, and air conditioning (HVAC) loads and resulting fuel use from rest period idling by using efficient long-haul truck thermal management systems while maintaining occupant comfort. Enhancing the thermal performance of cab/sleepers will enable smaller, lighter, and more cost-effective idle reduction solutions. In addition, if the fuel savings provide a one- to three-year payback period, fleet owners will be economically motivated to incorporate them. This project evaluated several promising candidate technologies through experimentation and modeling to determine their effectiveness in reducing rest period HVAC loads. Load reduction strategies were grouped into the focus areas of solar envelope, occupant environment, conductive pathways, and efficient equipment. Technologies in each of these focus areas were investigated. The most promising of these technologies were then combined with the goal of exceeding a 30% reduction in HVAC loads. These technologies included 'ultra-white' paint, advanced insulation, and advanced curtain design. This project showed more than a 35.7% reduction in rest period idle air conditioning loads using thermal load reduction technologies. Overall heat transfer coefficient testing during cab heating, showed a 43% reduction in heating load using this technology package.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2024

ResStock 2024.2 Dataset [Slides]

In the ResStock 2024.2 dataset, ResStock runs are used to create "what-if" scenarios including energy efficiency measures such as heat pumps, envelope improvements, and electrification of appliances. This dataset release includes 15 measure packages across two weather years and incorporates ResStock improvements in variable speed heat pump modeling, geothermal heat pump modeling, and housing characteristic data updates from RECS 2020.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2012

SUPERNOVAE POWERED BY COLLAPSAR ACCRETION IN GAMMA-RAY BURST SOURCES

The association of long-duration gamma-ray bursts (LGRBs) with Type Ic supernovae presents a challenge to supernova explosion models. In the collapsar model for LGRBs, gamma rays are produced in an ultrarelativistic jet launching from the magnetosphere of the black hole that forms in the aftermath of the collapse of a rotating progenitor star. The jet is collimated along the star's rotation axis, but the concomitant luminous supernova should be relatively-though certainly not entirely-spherical, and should synthesize a substantial mass of {sup 56}Ni. Our goal is to provide a qualitative assessment of the possibility that accretion of the progenitor envelope onto the black hole, which powers the LGRB, could also deposit sufficient energy and nickel mass in the envelope to produce a luminous supernova. For this, the energy dissipated near the black hole during accretion must be transported outward, where it can drive a supernova-like shock wave. Here we suggest that the energy is transported by convection and develop an analytical toy model, relying on global mass and energy conservation, for the dynamics of stellar collapse. The model suggests that a {approx}10 000 km s{sup -1} shock can be driven into the envelope and that {approx}10{sup 51} erg explosions are possible. The efficiency with which the accretion energy is being transferred to the envelope is governed by the competition of advection and convection at distances {approx}100-1000 km from the black hole and is sensitive to the values of the convective mixing length, the magnitude of the effective viscous stress, and the specific angular momentum of the infalling envelope. Substantial masses of {sup 56}Ni may be synthesized in the convective accretion flow over the course of tens of seconds from the initial circularization of the infalling envelope around the black hole. The synthesized nickel is convectively mixed with a much larger mass of unburned ejecta.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

An Assessment of Envelope Measures in Mild Climate Deep Energy Retrofits

Energy end-uses and interior comfort conditions have been monitored in 11 Deep Energy Retrofits (DERs) in a mild marine climate. Two broad categories of DER envelope were identified: first, bringing homes up to current code levels of insulation and airtightness, and second, enhanced retrofits that go beyond these code requirements. The efficacy of envelope measures in DERs was difficult to determine, due to the intermingled effects of enclosure improvements, HVAC system upgrades and changes in interior comfort conditions. While energy reductions in these project homes could not be assigned to specific improvements, the combined effects of changes in enclosure, HVAC system and comfort led to average heating energy reductions of 76percent (12,937 kWh) in the five DERs with pre-retrofit data, or 80percent (5.9 kWh/ft2) when normalized by floor area. Overall, net-site energy reductions averaged 58percent (15,966 kWh; n=5), and DERs with code-style envelopes achieved average net-site energy reductions of 65percent (18,923 kWh; n=4). In some homes, the heating energy reductions were actually larger than the whole house reductions that were achieved, which suggests that substantial additional energy uses were added to the home during the retrofit that offset some heating savings. Heating system operation and energy use was shown to vary inconsistently with outdoor conditions, suggesting that most DERs were not thermostatically controlled and that occupants were engaged in managing the indoor environmental conditions. Indoor temperatures maintained in these DERs were highly variable, and no project home consistently provided conditions within the ASHRAE Standard 55-2010 heating season comfort zone. Thermal comfort and heating system operation had a large impact on performance and were found to depend upon the occupant activities, so DERs should be designed with the occupants needs and patterns of consumption in mind. Beyond-code building envelopes were not found to be strictly necessary for the achievement of deep energy savings in existing uninsulated homes in mild marine climates, provided that other energy end-uses were comprehensively reduced. We recommend that mild climate DERs pursue envelopes in compliance with the 2012 International Energy Conservation Code (IECC) and pair these with high efficiency, off-the-shelf HVAC equipment. Enhanced building envelopes should be considered in cases where very low heating energy use (<1,000 kWh/year or <0.5 kWh/ft2-year) and enhanced thermal comfort (ASHRAE 55-2010) are required, as well as in those situations where substantial energy uses are added to the home, such as decorative lighting, cooling or smart home A/V and communication equipment.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Goode Gym Energy Renovation Project

The Ida H. Goode Gymnasium was constructed in 1964 to serve as a focal point for academics, student recreation, and health and wellness activities. This 38,000 SF building contains a gymnasium with a stage, swimming pool, eight classrooms, a weight room, six offices and auxiliary spaces for the athletic programs. The gym is located on a 4-acre greenfield, which is slated for improvement and enhancement to future athletics program at Bennett College. The available funding for this project was used to weatherize the envelope of the gymnasium, installation of a new energy-efficient mechanical system, and a retrofit of the existing lighting systems in the building’s interior. The envelope weatherization was completed without disturbing the building’s historic preservation eligibility. The existing heating system was replaced with a new high efficiency condensing system. The new heating system also includes a new Building Automation System which provides additional monitoring. Proper usage of this system will provide additional energy savings. Most of the existing interior lighting fixtures and bulbs were replaced with new LED and high efficiency T-8 bulbs and fixtures. Occupancy sensors were installed in applicable areas. The Ida Goode Gymnasium should experience high electricity and natural gas savings as well as operational/maintenance efficiency increases. The aesthetics of the building was maintained and the overall safety was improved.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

New Whole-House Solutions Case Study: Fort Devens: Cold Climate Market-Rate Townhomes Targeting HERS Index of 40, Harvard, Massachusetts

Achieving aggressive energy efficiency targets requires tight coordination and clear communication among owners, designers, builders, and subcontractors. For this townhome project, MassDevelopment, the quasi-governmental agency owner, selected Metric Development of Boston, teaming with Building America team Consortium for Advanced Residential Buildings (CARB) and Cambridge Seven Architects, to build very high performing market-rate homes. Fort Devens is part of a decommissioned army base in working-class Harvard, Massachusetts, approximately one hour northwest of Boston. The team proposed 12 net zero energy-ready townhomes that were also designed to achieve a Home Energy Rating System (HERS) Index Score of 41 before adding renewables. The team carefully planned the site to maximize solar access, daylighting, and efficient building forms.

air tight envelope↗
DOE OSTI2016

Simulation-based coefficients for adjusting climate impact on energy consumption of commercial buildings

This paper presents a new technique for and the results of normalizing building energy consumption to enable a fair comparison among various types of buildings located near different weather stations across the U.S. The method was developed for the U.S. Building Energy Asset Score, a whole-building energy efficiency rating system focusing on building envelope, mechanical systems, and lighting systems. The Asset Score is calculated based on simulated energy use under standard operating conditions. Existing weather normalization methods such as those based on heating and cooling degrees days are not robust enough to adjust all climatic factors such as humidity and solar radiation. In this work, over 1000 sets of climate coefficients were developed to separately adjust building heating, cooling, and fan energy use at each weather station in the United States. This paper also presents a robust, standardized weather station mapping based on climate similarity rather than choosing the closest weather station. This proposed simulated-based climate adjustment was validated through testing on several hundreds of thousands of modeled buildings. Results indicated the developed climate coefficients can isolate and adjust for the impacts of local climate for asset rating.

Asset Rating↗
DOE OSTI2011

A prototype photovoltaic/thermal system integrated with transpired collector

Building-integrated photovoltaic/thermal (BIPV/T) systems may be utilized to produce useful heat while simultaneously generating electricity from the same building envelope surface. A well known highly efficient collector is the open-loop unglazed transpired collector (UTC) which consists of dark porous cladding through which outdoor air is drawn and heated by absorbed solar radiation. Commercially available photovoltaic systems typically produce electricity with efficiencies up to about 18%. Thus, it is beneficial to obtain much of the normally wasted heat from the systems, possibly by combining UTC with photovoltaics. Combination of BIPV/T and UTC systems for building facades is considered in this paper - specifically, the design of a prototype facade-integrated photovoltaic/thermal system with transpired collector (BIPV/T). A full scale prototype is constructed with 70% of UTC area covered with PV modules specially designed to enhance heat recovery and compared to a UTC of the same area under outdoor sunny conditions with low wind. The orientation of the corrugations in the UTC is horizontal and the black-framed modules are attached so as to facilitate flow into the UTC plenum. While the overall combined thermal efficiency of the UTC is higher than that of the BIPV/T system, the value of the generated energy - assuming that electricity is at least four times more valuable than heat - is between 7% and 17% higher. Also, the electricity is always useful while the heat is usually utilized only in the heating season. The BIPV/T concept is applied to a full scale office building demonstration project in Montreal, Canada. The ratio of photovoltaic area coverage of the UTC may be selected based on the fresh air heating needs of the building, the value of the electricity generated and the available building surfaces. (author)

14 SOLAR ENERGY↗
DOE OSTI2015

Distinct Mechanisms of Recognizing Endosomal Sorting Complex Required for Transport III (ESCRT-III) Protein IST1 by Different Microtubule Interacting and Trafficking (MIT) Domains

The endosomal sorting complex required for transport (ESCRT) machinery is responsible for membrane remodeling in a number of biological processes including multivesicular body biogenesis, cytokinesis, and enveloped virus budding. In mammalian cells, efficient abscission during cytokinesis requires proper function of the ESCRT-III protein IST1, which binds to the microtubule interacting and trafficking (MIT) domains of VPS4, LIP5, and Spartin via its C-terminal MIT-interacting motif (MIM). In this paper, we studied the molecular interactions between IST1 and the three MIT domain-containing proteins to understand the structural basis that governs pairwise MIT-MIM interaction. Crystal structures of the three molecular complexes revealed that IST1 binds to the MIT domains of VPS4, LIP5, and Spartin using two different mechanisms (MIM1 mode versus MIM3 mode). Structural comparison revealed that structural features in both MIT and MIM contribute to determine the specific binding mechanism. Within the IST1 MIM sequence, two phenylalanine residues were shown to be important in discriminating MIM1 versus MIM3 binding. Finally, these observations enabled us to deduce a preliminary binding code, which we applied to provide CHMP2A, a protein that normally only binds the MIT domain in the MIM1 mode, the additional ability to bind the MIT domain of Spartin in the MIM3 mode.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

A NEW ANALYSIS OF THE TWO CLASSICAL ZZ CETI WHITE DWARFS GD 165 AND ROSS 548. II. SEISMIC MODELING

We present the second of a two-part seismic analysis of the bright, hot ZZ Ceti stars GD 165 and Ross 548. In this second part, we report the results of detailed searches in parameter space for identifying an optimal model for each star that can account well for the observed periods, while being consistent with the spectroscopic constraints derived in our first paper. We find optimal models for each target that reproduce the six observed periods well within ∼0.3% on the average. We also find that there is a sensitivity on the core composition for Ross 548, while there is practically none for GD 165. Our optimal model of Ross 548, with its thin envelope, indeed shows weight functions for some confined modes that extend relatively deep into the interior, thus explaining the sensitivity of the period spectrum on the core composition in that star. In contrast, our optimal seismic model of its spectroscopic sibling, GD 165 with its thick envelope, does not trap/confine modes very efficiently, and we find weight functions for all six observed modes that do not extend into the deep core, hence accounting for the lack of sensitivity in that case. Furthermore, we exploit after the fact the observed multiplet structure that we ascribe to rotation. We are able to map the rotation profile in GD 165 (Ross 548) over the outermost ∼20% (∼5%) of its radius, and we find that the profile is consistent with solid-body rotation.

79 ASTRONOMY AND ASTROPHYSICS↗