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At least 865 records · Page 48

Effective Training for Flight in Icing Conditions

The development of a piloted flight simulator called the Ice Contamination Effects Flight Training Device (ICEFTD) was recently completed. This device demonstrates the ability to accurately represent an iced airplane s flight characteristics and is utilized to train pilots in recognizing and recovering from aircraft handling anomalies that result from airframe ice formations. The ICEFTD was demonstrated at three recent short courses hosted by the University of Tennessee Space Institute. It was also demonstrated to a group of pilots at the National Test Pilot School. In total, eighty-four pilots and flight test engineers from industry and the regulatory community spent approximately one hour each in the ICEFTD to get a "hands on" lesson of an iced airplane s reduced performance and handling qualities. Additionally, pilot cues of impending upsets and recovery techniques were demonstrated. The purpose of this training was to help pilots understand how ice contamination affects aircraft handling so they may apply that knowledge to the operations of other aircraft undergoing testing and development. Participant feedback on the ICEFTD was very positive. Pilots stated that the simulation was very valuable, applicable to their occupations, and provided a safe way to explore the flight envelope. Feedback collected at each demonstration was also helpful to define additional improvements to the ICEFTD; many of which were then implemented in subsequent demonstrations.

Barnhart, Billy P.↗

The Fastrack Suborbital Platform for Microgravity Applications

The FASTRACK suborbital experiment platform has been developed to provide a capability for utilizing 2.5-5 minute microgravity flight opportunities anticipated from the commercial suborbital fleet (currently in development) for science investigations, technology development and hardware testing. It also provides "express rack" functionality to deliver payloads to ISS. FASTRACK fits within a 24" x 24" x 36" (61 cm x 61 cm x 91.4 cm) envelope and is capable of supporting either two single Middeck Locker Equivalents (MLE) or one double MLE configuration. Its overall mass is 300 lbs (136 kg), of which 160 lbs (72 kg) is reserved for experiments. FASTRACK operates using 28 VDC power or batteries. A support drawer located at the bottom of the structure contains all ancillary electrical equipment (including batteries, a conditioned power system and a data collection system) as well as a front panel that contains all switches (including remote cut-off), breakers and warning LEDs.

Levine, H. G.↗

Computational and Physics-Based Modeling for the Development of in-Space Welding Technology

Welding will be an enabling technology for in-space assembly and manufacturing (ISAM) and in-space repair operations in support of the growing Space Economy. Prospective use cases of welding include metal repair on long-duration lunar surface missions and assembly of large structures that exceed dimensions of the currently available launch vehicle envelopes such as space arrays, tall lunar transmission towers, or even large transit vehicles powered by nuclear propulsion. There is a brief history of beam welding for in-space use. Soviet and NASA astronauts performed electron beam welds (EBW) in space in the late-1960s through mid-1980s and several parabolic flights of laser beam welding (LBW) were undertaken in the USA and Canada in the early-1990s. Work has since stagnated until the recent boom of the in-space economy has demonstrated need for continued development of EBW and LBW processes, which are desirable for their compactness, low mass, low power consumption, and high wall plug efficiency. No space-based manufacturing laboratory capable of demonstrating, developing, and applying welding processes exists, and costs are high to develop and fly individual space-based trials. This drives the current approach to develop welding technology with computational and physics-based models in tandem with earth-based experiments. Several approaches are taken to complement and drive the selection of instrumentation for planned parabolic and suborbital flights. First, a thermal model of Skylab EBW experiments is established and compared to empirical data. Next, the model is used to show variation between Earth-based and in-space weld structure and properties through exploration of key variables that define the Low earth orbit and lunar surface space environments, namely temperature (40 – 400 K), pressure (10-10 to 104 Pa), and gravity (10-6 g to 1 g). Finally, physical processes associated with heat and mass transport during welding are evaluated through several case studies across the above variable ranges demonstrating need for further research.

in-space welding↗

Advancements in the H-Canyon Exhaust Ventilation System Inspections at the Savannah River Site - 16030

A facility safety envelope requires management of activities to ensure no unacceptable radiological or chemical hazards to the public, site worker and environment occur. While appropriate design and construction methods ensure an initial physical plant configuration, what actions must an operating Facility take to ensure the physical plant continues to meet a safety configuration throughout Facility life? While a physical walk down of the plant is a tried and true method to confirm conditions, what other methods must be used when a walk down is not possible? What inspection methods are used when balancing budget pressures against obtaining inspection data? The periodic inspections of the H-Canyon Exhaust Tunnel are performed remotely. The 2015 remote Tunnel inspection has been the most successful inspection to date. This presentation highlights the continued lessons learned with the most recent 2015 remote Tunnel inspection. These lessons learned are applicable to Facilities considering or performing remote inspections. The Recovery Crawler Project was tasked with determining if the 2014 Inspection Crawler could be retrieved, perform the retrieval if feasible and complete the inspection of the remaining sections of the exhaust tunnel that were not previously performed. The objectives for the project were met, the Inspection Crawler was deemed unusable and left in place and the Recovery Crawler performed the complete 143 meters (470 feet) of tunnel inspection and an additional 55 meters (180 feet) of exhaust tunnel inspection not previously completed. The remote inspection of a 60+ year operating Canyon Exhaust tunnel is a complex endeavor requiring close coordination of multiple organizations, adherence to Conduct of Operations, Radiological Safety, Worker Safety, etc. principles as well as alignment with Facility Safety Basis requirements. This paper discusses the challenges, actions required getting ready for the 2015 recovery and continued inspection and the hazards encountered performing the actual recovery/inspection. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Computing Bounds on Resource Levels for Flexible Plans

A new algorithm efficiently computes the tightest exact bound on the levels of resources induced by a flexible activity plan (see figure). Tightness of bounds is extremely important for computations involved in planning because tight bounds can save potentially exponential amounts of search (through early backtracking and detection of solutions), relative to looser bounds. The bound computed by the new algorithm, denoted the resource-level envelope, constitutes the measure of maximum and minimum consumption of resources at any time for all fixed-time schedules in the flexible plan. At each time, the envelope guarantees that there are two fixed-time instantiations one that produces the minimum level and one that produces the maximum level. Therefore, the resource-level envelope is the tightest possible resource-level bound for a flexible plan because any tighter bound would exclude the contribution of at least one fixed-time schedule. If the resource- level envelope can be computed efficiently, one could substitute looser bounds that are currently used in the inner cores of constraint-posting scheduling algorithms, with the potential for great improvements in performance. What is needed to reduce the cost of computation is an algorithm, the measure of complexity of which is no greater than a low-degree polynomial in N (where N is the number of activities). The new algorithm satisfies this need. In this algorithm, the computation of resource-level envelopes is based on a novel combination of (1) the theory of shortest paths in the temporal-constraint network for the flexible plan and (2) the theory of maximum flows for a flow network derived from the temporal and resource constraints. The measure of asymptotic complexity of the algorithm is O(N O(maxflow(N)), where O(x) denotes an amount of computing time or a number of arithmetic operations proportional to a number of the order of x and O(maxflow(N)) is the measure of complexity (and thus of cost) of a maximumflow algorithm applied to an auxiliary flow network of 2N nodes. The algorithm is believed to be efficient in practice; experimental analysis shows the practical cost of maxflow to be as low as O(N1.5). The algorithm could be enhanced following at least two approaches. In the first approach, incremental subalgorithms for the computation of the envelope could be developed. By use of temporal scanning of the events in the temporal network, it may be possible to significantly reduce the size of the networks on which it is necessary to run the maximum-flow subalgorithm, thereby significantly reducing the time required for envelope calculation. In the second approach, the practical effectiveness of resource envelopes in the inner loops of search algorithms could be tested for multi-capacity resource scheduling. This testing would include inner-loop backtracking and termination tests and variable and value-ordering heuristics that exploit the properties of resource envelopes more directly.

Muscvettola, Nicola↗

Dynamic Modeling, Trajectory Optimization, and Linear Control of Cable-Driven Parallel Robots for Automated Panelized Building Retrofits

The construction industry faces a growing need for automation to reduce costs, improve accuracy and productivity, and address labor shortages. One area that stands to benefit significantly from automation is panelized prefabricated building envelope retrofits, which can improve a building’s energy efficiency in heating and cooling interior spaces. In this paper, we propose using cable-driven parallel robots (CDPRs), which can effectively lift and handle large objects, to install these panels. However, implementing CDPRs presents significant challenges because of their nonlinear dynamics, complex trajectory planning, and precise control requirements. To tackle these challenges, this work focuses on a new application of established control and trajectory optimization theories in a CDPR simulation of a building envelope retrofit under real-world conditions. We first model the dynamics of CDPRs, highlighting the critical role of damping in system behavior. Building on this dynamic model, we formulate a trajectory optimization problem to generate feasible and efficient motion plans for the robot under operational and environmental constraints. Given the high precision required in the construction industry, accurately tracking the optimized trajectory is essential. However, challenges such as partial observability and external vibrations complicate this task. To address these issues, a Linear Quadratic Gaussian control framework is applied, enabling the robot to track the optimized trajectories with precision. Simulation results show that the proposed controller enables precise end effector positioning with errors under 4 mm, even in the presence of external wind disturbances. Through comprehensive simulations, our approach allows for an in-depth exploration of the system’s nonlinear dynamics, trajectory optimization, and control strategies under controlled yet highly realistic conditions. The results demonstrate the feasibility of CDPRs for automating panel installation and provide insights into their practical deployment.

CDPR↗

Exploration of Domain Aware Machine Learning for Grid Analytics: Transfer-Learnt Energy Models to Assist Buildings Control with Sparse Field Data

Buildings are a primary consumer of energy in the United States and are also increasingly being perceived as providers of grid services such as load shifting, shedding and modulation. High fidelity models of building energy consumption are needed to set appropriate baselines for measurement and verification (M&V) of controllers designed for energy efficient operation of buildings and to enable buildings to provide grid services via. participation in demand response programs. State-of-the-art building energy modeling techniques either rely on Physics based models, or extensive instrumentation of the building envelope to gather “big” data to train machine learning based models such as deep neural networks. While Physics based models are often limited by their accuracy, it is not always feasible to gather a significant amount of field data required to train machine learning based models with sufficient accuracy. In this paper, we explore the use of transfer learning-based strategies to address unsatisfactory accuracy of models for estimating building energy consumption when available field data for training is sparse or of unacceptable quality. In particular, we transfer knowledge in the form of data and parameters, from Physics based simulation frameworks to the field to improve the model accuracy, thus resulting in a Physics-informed Machine Learning framework. We evaluated the efficacy of our approach on field data collected from six commercial buildings and our results indicate that the proposed transfer learning based models provide comparative (and in some cases better) accuracy than state-of-the-art machine learning and deep learning solutions, with just one month of field data.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Cryogenic Quartz Crystal Microbalance

A radiatively cooled Cryogenic Quartz Crystal Microbalance designed to monitor highly volatile contaminants on the shuttle is described. Measurements are made with two 15-MHz microbalances having removable, optically polished sensors mounted in a radiant cooler. One sensor operates below the freezing point of water and monitors contamination including that of water vapor. The second sensor is heated and monitors the contamination background. It provides a reference from which the density of the water vapor cloud enveloping the shuttle is determined. The design incorporates a low-power dissipation oscillator, heaters for ice removal, and a method for attaching second-surface mirrors to the radiator employing an indium type solder instead of a room temperature vulcanizer.

D Mckeown↗

Materials and structures for hypersonic vehicles

Hypersonic vehicles are envisioned to require, in addition to carbon-carbon and ceramic-matrix composities for leading edges heated to above 2000 F, such 600 to 1800 F operating temperature materials as advanced Ti alloys, nickel aluminides, and metal-matrix composited; These possess the necessary low density and high strength and stiffness. The primary design drivers are maximum vehicle heating rate, total heat load, flight envelope, propulsion system type, mission life requirements and liquid hydrogen containment systems. Attention is presently given to aspects of these materials and structures requiring more intensive development.

Tenney, Darrel R.↗

The flight test program for the hydrogen powered NASP/X-30 research aircraft

The NASP/X-30 will be the first U.S. manned aircraft to be powered with hydrogen. Flight testing the X-30 powered with liquid and/or slush hydrogen along with its high speed capability will present unique challenges to the flight test community. The paper describes the overall X-30 flight research program along with some of the key technology challenges. A flight test envelope expansion concept is described along with typical mission profiles. Flight test problems unique to this class of vehicle will be outlined as well as some preliminary thoughts as to solutions to those problems. The X-30 ground operations with hydrogen must be compatible with the normal operations at the flight test site. A concept for the ground support system will be introduced.

Wierzbanowski, Theodore↗

A Preliminary Motion-picture Study of Combustion in a Compression-ignition Engine

Motion pictures were taken at 1,850 frames per second of the spray penetration and combustion occurring in the N.A.C.A. combustion apparatus arranged to operate as a compression-ignition engine. Indicator cards were taken simultaneously with the motion pictures by means of the N.A.C.A. optical indicator. The motion pictures showed that when ignition occurred during injection it started in the spray envelope. If ignition occurred after injection cut-off, however, and after considerable mixing had taken place, it was impossible to predict where the ignition would start. The pictures also showed that ignition usually started at several points in the combustion chamber. With this apparatus, as the injection advance angle increased from 0 degrees to 40 degrees before top center, the rate of flame spread increased and the duration of the burning decreased.

Buckley, E C↗

Multidisciplinary Optimization of a Transonic Truss Braced Wing Aircraft with Hybrid-Electric Propulsion

Next generation aircraft concepts have subsystems that are increasingly inter-connected. This necessitates advanced design tools using gradient based optimization to properly account for strong subsystem coupling in these aircraft. Additionally, these design tools require accurate modeling capability to support the increased interest in electrified propulsion. Design studies for these aircraft must consider the trade-offs between electric propulsion and turbojet engines at all points in the flight envelope to determine the optimal balance between propulsion options. This paper describes the development of an electric propulsion subsystem model designed to work within Aviary - an open source aircraft design tool. We will demonstrate the electric propulsion model operating with Aviary by showing results from an optimized Transonic Truss-Braced Wing (TTBW) concept using assisted electric propulsion during climb. First, we present results with and without electrification to show the overall system impacts of hybrid electric propulsion during climb. We also present two distinct battery models compatible with this optimization framework, and compare results using both. Next, we ran the same problem using a slightly different cell type, and demonstrate a considerable change in the result. Finally, we vary the cell energy density of the batteries, and provide an illustrative trend for the system-level impact for improving cell technology.

optimization↗

WIPP Certification of the Retrieval Box Assay System at the Advanced Mixed Waste Treatment Plant, Idaho - 16241

The Retrieval Box Assay System (RBAS) at the Advanced Mixed Waste Treatment Plant (AMWTP) is an Imaging Passive Active Neutron system supplemented with a High Purity Germanium (HPGe) gamma system for the quantification of Pu-239 Fissile Gram Equivalent (FGE) and transuranic (TRU) alpha activity of waste containers of various sizes up to 249 cm x 149 cm x 198 cm (Length x Width x Height). The system was originally calibrated in 2002 (with a range of surrogate matrices and radioactive sources in a 213 cm x 122 cm x 122 cm FRP box) and has been operational for over a decade. As of August 2015, the RBAS has measured approximately 18,000 boxes (50,000 m3 of waste) which has subsequently been fed into the facility's treatment process. Its success, and the wide envelope of waste that it can characterize, has led AMWTP to extend the RBAS mission to include WIPP certification. As part of this new project, the instrument must be capable of meeting WIPP's Waste Acceptance Criteria (WAC) which include reporting activities and masses of the 10 WIPP-tracked radionuclides. The system will be required to assay sludge and debris waste streams, shredded waste and large metal items. The container size includes Standard Waste Box (SWBs), Fiberglass Reinforced Plywood (FRPs) and large Shredder Boxes. Sludge matrices will be loaded into 210-liter (55-gallon) drums and placed inside an SWB. After assay, boxes will be over-packed into SLB-II's for shipment to WIPP. The target waste streams will contain mixtures of Weapons Grade plutonium, Heat Source plutonium (high in Pu-238 content) and Mixed Oxide (MOX). The activity of the waste is expected to encompass a wide dynamic range of activity from low-level waste (LLW) to TRU with up to several hundred grams of plutonium. Some packages will have high gamma activity associated with fission and activation products such as Cs-137 and Co-60. The existing RBAS hardware (detectors, electronics, assay chamber etc.) was retained for this project. Two lead filters were provided and installed on the existing filter wheels to attenuate the gamma ray flux from the highest activity boxes to avoid overload of the HPGe detectors. The new software suite includes PC-FRAM (Version 5), which is used for the isotopic analysis of the gamma spectra. Integration of FRAM and neutron results is performed using a software package known as RBAS WIPP Analysis Reporting Software (RWARS). This package also performs matrix dependent background adjustments. Other upgrades provided include automated tests that identify when assay parameters fall outside a predetermined range and a new Quality Checking (QC) application. Minimum Detectable Activity (MDA) values were determined for the active and passive neutron modes as a function of measured matrix correction indices. The resulting Minimum Detectable Concentration (MDC) has been demonstrated to be less than 3700 Bq/g alpha activity (100 nCi/g). Modifications were performed to update the system TMU parameters to accommodate assay of non-standard size boxes and a wider range of matrix materials. A series of calibration confirmation, measurements were performed on site in 2014 using a representative range of surrogate boxes and radioactive sources including Pu. The WIPP WAC performance criteria were successfully demonstrated up to 157 g Pu and the system passed its first Performance Demonstration Program (PDP) cycle in the Spring of 2015. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Non-abelian symmetries in tensor networks: A quantum symmetry space approach

A general framework for non-abelian symmetries is presented for matrix-product and tensor-network states in the presence of well-defined orthonormal local as well as effective basis sets. The two crucial ingredients, the Clebsch-Gordan algebra for multiplet spaces as well as the Wigner-Eckart theorem for operators, are accounted for in a natural, well-organized, and computationally straightforward way. The unifying tensor-representation for quantum symmetry spaces, dubbed QSpace, is particularly suitable to deal with standard renormalization group algorithms such as the numerical renormalization group (NRG), the density matrix renormalization group (DMRG), or also more general tensor networks such as the multi-scale entanglement renormalization ansatz (MERA). In this paper, the focus is on the application of the non-abelian framework within the NRG. A detailed analysis is presented for a fully screened spin- 3/2 three-channel Anderson impurity model in the presence of conservation of total spin, particle-hole symmetry, and SU(3) channel symmetry. The same system is analyzed using several alternative symmetry scenarios based on combinations of U(1){sub charge}, SU(2){sub spin}, SU(2){sub charge}, SU(3){sub channel}, as well as the enveloping symplectic Sp(6) symmetry. These are compared in detail, including their respective dramatic gain in numerical efficiency. In the Appendix, finally, an extensive introduction to non-abelian symmetries is given for practical applications, together with simple self-contained numerical procedures to obtain Clebsch-Gordan coefficients and irreducible operators sets. The resulting QSpace tensors can deal with any set of abelian symmetries together with arbitrary non-abelian symmetries with compact, i.e. finite-dimensional, semi-simple Lie algebras. - Highlights: Black-Right-Pointing-Pointer We introduce a transparent framework for non-abelian symmetries in tensor networks. Black-Right-Pointing-Pointer The framework was successfully applied within the numerical renormalization group. Black-Right-Pointing-Pointer Combinations of SU(N{<=}3) and Sp(6) are implemented and discussed in detail. Black-Right-Pointing-Pointer Non-abelian symmetries allow to speed up calculations by orders of magnitude. Black-Right-Pointing-Pointer The framework is equally applicable to other tensor networks such as DMRG or MERA.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Organic Rankine Cycle Integration and Optimization for High Efficiency CHP Genset Systems (Final Technical Report)

This project successfully advanced the integration of Organic Rankine Cycle (ORC) technology with reciprocating engine–based combined heat and power (CHP) systems to improve electrical efficiency, total CHP efficiency, and grid-responsive operation. Over three budget periods, the work progressed from high-temperature ORC component development and thermodynamic model validation to next-generation system design, working fluid transition, and techno-economic analysis. Key technical accomplishments include development and validation of a thermodynamic model capable of accurately predicting ORC performance across an expanded temperature and pressure envelope; successful identification and validation of low-global-warming-potential (GWP) working fluids—most notably R1233zd(E)—as viable replacements for R245fa; and demonstration of scalable ORC architectures suitable for integration with 1–20 MW class reciprocating engines. These advances enable flexible CHP configurations that can increase electrical output while maintaining high overall utilization of available thermal energy. The project also produced a clean-sheet design for a next-generation ORC system targeting substantially higher power output per unit, supported by detailed component selection, heat exchanger evaluation, and system-level modeling. Techno-economic analyses indicate that ORC-enabled flexible CHP systems can meet or exceed Department of Energy (DOE) efficiency targets while providing value to both facility operators and the electric grid.. Late-stage testing of the largest next-generation ORC prototype identified limitations related to pump net positive suction head (NPSH) requirements and condenser flooding under certain operating conditions. Although these issues constrained full validation of that configuration within the project timeframe, they provided clear and actionable design guidance for future system refinements. Importantly, validated modeling, smaller-scale testing, and working fluid evaluations confirmed the technical viability of the overall approach. In aggregate, this project met its core objectives by establishing validated design tools, de-risking key ORC technologies for CHP applications, and defining a credible pathway toward commercialization of flexible, high-efficiency CHP systems. The results form a strong foundation for continued development and deployment beyond the conclusion of the DOE-funded effort.

20 FOSSIL-FUELED POWER PLANTS↗

LVD Experiment: 25 Years of Operation

The current status of the LVD (large volume detector) experiment aimed at search for neutrinos from the gravitational collapse of stellar cores is described. Within the period of observations from June 1992 to February 2017, no gravitational collapse was found in the Milky Way Galaxy and Magellanic Clouds, including hidden ones (not ejecting the envelope). The LVD collects data for 99% of the live time. A limit on the frequency of supernova bursts within a distance of 25 kpc was set at a level of 0.1 event/yr. The most recent results obtained by studying the muon component of cosmic rays are presented.

79 ASTRONOMY AND ASTROPHYSICS↗

A model for the sustainable selection of building envelope assemblies

The aim of this article is to define an evaluation model for the environmental impacts of building envelopes to support planners in the early phases of materials selection. The model is intended to estimate environmental impacts for different combinations of building envelope assemblies based on scientifically recognised sustainability indicators. These indicators will increase the amount of information that existing catalogues show to support planners in the selection of building assemblies. To define the model, first the environmental indicators were selected based on the specific aims of the intended sustainability assessment. Then, a simplified LCA methodology was developed to estimate the impacts applicable to three types of dwellings considering different envelope assemblies, building orientations and climate zones. This methodology takes into account the manufacturing, installation, maintenance and use phases of the building. Finally, the model was validated and a matrix in Excel was created as implementation of the model. - Highlights: • Method to assess the envelope impacts based on a simplified LCA • To be used at an earlier phase than the existing methods in a simple way. • It assigns a score by means of known sustainability indicators. • It estimates data about the embodied and operating environmental impacts. • It compares the investment costs with the costs of the consumed energy.

54 ENVIRONMENTAL SCIENCES↗

Potential benefits of cool walls on residential and commercial buildings across California and the United States: Conserving energy, saving money, and reducing emission of greenhouse gases and air pollutants

Solar-reflective “cool” walls reduce absorption of sunlight by the building envelope, which may decrease cooling load in warm weather and increase heating load in cool weather. Changes to annual heating, ventilation, and air conditioning (HVAC) energy use depend on climate, wall construction, wall orientation, building geometry, HVAC efficiency, and operating schedule. Changes to annual energy cost and energy-related emissions further vary with local energy prices and emission factors. In this work, we used EnergyPlus to perform over 100,000 whole-building energy simulations, spanning 10 different building categories, three building vintages, 16 California climate zones, and 15 United States (U.S.) climate zones. We find that cool walls yielded annual source energy, energy cost, and emission savings in all California climate zones and in warm U.S. (ASHRAE) climate zones. In California, annual whole-building HVAC energy cost savings were 4.0–27% in single-family homes, 0.5–3.8% in medium office buildings, and 0.0–8.5% in stand-alone retail stores. In warm U.S. climates—zones 1A (Miami, FL) through 4B (Albuquerque, NM)—annual HVAC energy cost savings were 1.8–8.3% in single-family homes, 0.3–4.6% in medium office buildings, and 0.5–11% in stand-alone retail stores. California and U.S. fractional source energy and emission savings were comparable to fractional energy cost savings. Per unit surface area modified, cool-wall savings often exceeded cool-roof savings because building codes typically prescribe much less wall insulation than roof insulation.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗