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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Measure Guideline: Deep Energy Enclosure Retrofit for Interior Insulation of Masonry Walls and Flat Roofs

Measure Guideline: Deep Energy Enclosure Retrofit for Zero Energy Ready House Flat Roofs BSC TO5 Task 7.4 Deep Energy Enclosure Retrofit (DEER) for Interior Insulation of Masonry Walls Lawrence, MA 01840 This Measure Guideline describes a deep energy enclosure retrofit solution for insulating mass masonry buildings from the interior. It describes the retrofit assembly, technical details, and installation sequence for retrofitting masonry walls. Interior insulation of masonry retrofits might adversely affect the durability of the wall. This guideline includes a review of decision criteria pertinent to retrofitting masonry walls from the interior and the possible risk of freeze-thaw damage. This Measure Guideline is intended to support contractors who are implementing an interior insulation-based high-performance enclosure retrofit for masonry buildings and designers who are looking to design such retrofits. It may also be helpful to building owners who wish to learn more about strategies that are available for deep energy enclosure retrofit of masonry residential buildings on the interior. This Measure Guideline is important to the high-performance retrofit industry because the solution described here provides an opportunity to retrofit masonry buildings with ambitious energy performance goals by insulating them from the interior without disturbing their exterior appearance. BSC TO5 Task 7.4 Deep Energy Enclosure Retrofit (DEER) for Zero Energy Ready House (ZERH) Flat Roofs House Jamaica Plain, MA 02130 This Measure Guideline provides design and construction information for a deep energy enclosure retrofit solution of a flat roof assembly. It describes the strategies and procedures for an exterior retrofit of a flat wood-framed roof with brick masonry exterior walls using exterior and interior (framing cavity) insulation. The approach supported in this guide could also be adapted for use with flat wood-framed roofs with wood-framed exterior walls. Designers, contractors, and building code officials will benefit from the information contained in this Measure Guideline. The guide may also be helpful to building owners who wish to learn more about strategies for deep energy enclosure retrofit of flat roofs. This Measure Guideline is important to the high-performance retrofit industry because it demonstrates techniques for retrofitting flat roofs from the exterior, which is less disruptive to the living space and allows the structure to remain occupied during the project. It also illustrates a solution for preparing homes to become zero energy ready.

Array↗
DOE OSTI2016

Impact Study of Metal Fasteners in Roofing Assemblies using Three-Dimensional Heat Transfer Analysis

Heat transfer analysis was performed on typical roofing assemblies using HEAT3, a three-dimensional heat transfer analysis software. The difference in heat transferred through the roofing assemblies considered is compared between two cases - without any steel fasteners and with steel fasteners. In the latter case, the metal roofing fasteners were arranged as per Factor Mutual Global (FMG) approvals, in the field, perimeter, and corner zones of the roof. The temperature conditions used for the analysis represented summer and winter conditions for three separate Climate Zones (CZ) namely Climate Zone 2 or CZ2 represented by Orlando, FL; CZ3 represented by Atlanta, GA; and CZ6 zone represented by St. Paul, MN. In all the climatic conditions, higher energy transfer was observed with increase in the number of metal fasteners attributed to high thermal conductivity of metals as compared to the insulation and other materials used in the roofing assembly. This difference in heat loss was also quantified in the form of percentage change in the overall or effective insulation of the roofing assembly for better understanding of the practical aspects. Besides, a comparison of 2D heat transfer analysis (using THERM software) and 3D analysis using HEAT3 is also discussed.

3D modeling↗
DOE OSTI2023

Observations and Lessons Learned in Residential Roofing Integrated Photovoltaics

The data file includes field observations of residential roofing integrated photovoltaics installation that happened between July 2021 and June 2022 in California. There are 21 observations - 2 in the re-roofing category and 19 in the new construction category. The file includes two time and motion forms (Re-Roofing & New Construction) we used to capture the time it takes for each activity in the rooftop solar and electrical installation process. You will see the duration for detailed steps along with activities that are included for total installation time for the paper. There are three parts to the time and motion form - Part 1 has project and crew characteristics, product information, and inspection and permitting data and can be filled before the installation. Part 2 has the actual installation time stamps and related notes. Part 3 has the crew information and can be filled on-site or off-site, but this section is optional. The re-roofing form has pre-solar activities and gutters and vents section in Part 2 of the form, whereas new construction form includes a section for capturing the time it took for rough wiring. The re-roofing form does not include rough wiring but instead includes the final electrical wiring process. These are the key differences in both the forms. Each day/step/installation activity needs to include the crew break time as they happen and there is space available to capture the crew breaks duration. In Table 1 below, the different terms used in the time and motion form are defined and their corresponding unit of measurement stated. We also highlight the optional sections. The data is captured in total mins, total hours, person mins, person hours. You can use this form or make edits to the form to recreate the study or make your own observations. The data herein was reviewed but may not be comprehensive. NREL invites questions and inputs to improve the data, including to: Correct erroneous information Fill in missing/updated information Clarifications on data and variables Updated information may be submitted to Sushmita Jena at sushmita.jena@nlr.gov.

14 SOLAR ENERGY↗
DOE OSTI2016

Investigation of the proposed solar-driven moisture phenomenon in asphalt shingle roofs

We report that unvented, sealed or conditioned attics are an energy efficiency measure to reduce the thermal load of the home and decrease the space conditioning energy consumption. This retrofit is usually done by using spray polyurethane foam underneath the roof sheathing and on the gables and soffits of an attic to provide a thermal and air barrier. Unvented attics perform well from this perspective but from a moisture perspective sometimes the unvented attic homes have high interior humidity or moisture damage to the roof. As homes become more air tight and energy efficient, an understanding of the hygrothermal dynamics of the home become more important. One proposed reason for high unvented attic humidity has been that moisture can come through the asphalt shingle roof system and increase the moisture content of the roof sheathing and attic air. This has been called solar driven moisture. Oak Ridge National Laboratory (ORNL) investigated this proposed phenomenon by examining the physical properties of a roof and the physics required for the phenomenon. Results showed that there are not favorable conditions for solar driven moisture to occur. ORNL also conducted an experimental study on an unvented attic home and compared the humidity below the roof sheathing before and after a vapor impermeable underlayment was installed. There was no statistically significant difference in absolute humidity before and after the vapor barrier was installed. Finally, the outcome of the theoretical and experimental study both suggest that solar driven moisture does not occur in any significant amount.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS1979

Feasibility of determining flat roof heat losses using aerial thermography

The utility of aerial thermography for determining rooftop heat losses was investigated experimentally using several completely instrumented test roofs with known thermal resistances. Actual rooftop heat losses were obtained both from in-situ instrumentation and aerial thermography obtained from overflights at an altitude of 305 m. In general, the remotely determined roof surface temperatures agreed very well with those obtained from ground measurements. The roof heat losses calculated using the remotely determined roof temperature agreed to within 17% of those calculated from 1/R delta T using ground measurements. However, this agreement may be fortuitous since the convective component of the heat loss is sensitive to small changes in roof temperature and to the average heat transfer coefficient used, whereas the radiative component is less sensitive. This, at this time, it is felt that an acceptable quantitative determination of roof heat losses using aerial thermography is only feasible when the convective term is accurately known or minimized. The sensitivity of the heat loss determination to environmental conditions was also evaluated. The analysis showed that the most reliable quantitative heat loss determinations can probably be obtained from aerial thermography taken under conditions of total cloud cover with low wind speeds and at low ambient temperatures.

Bowman, R. L.↗
NASA NTRS1998

The Successful Transfer of Space Derived Convergent Spray: An Application for Industrial Roof Coatings and Interstate Bridge Repair

A partnership was formed between the National Aeronautics and Space Administration (NASA), the Environmental Protection Agency (EPA), and United Technologies USBI Company to develop, demonstrate, and evaluate a technology that uses a solventless spray process for depositing a lightweight, highly filled roof coating on low-sloped commercial roofs. Although the levels of volatile organic compound (VOC) emissions from industrial roof coating's and paint operations have been reduced in recent years, this partnership,was an effort to further reduce VOC emission levels and to also demonstrate the use of reclaimed automobile tire rubber as a filler material in roof coating systems. Different materials and coatings were evaluated and tested before the final selection used to coat the roofs of two small buildings at NASA's Marshall Space Flight Center during fiscal year 1997. The project successfully leveraged the investment of EPA, NASA and private sector resources to demonstrate a pre-commercial roofing coating process. This process utilizes the Convergent Spray Technologies process, which was initially developed by USBI to apply highly-filled, thermal protection coatings to the Space Shuttle Solid Rocket Boosters. A second partnership between the NASA, Federal Highway Administration, Alabama Department of Transportation and USBI Company was formed to develop and demonstrate the Convergent Spray Technology as a method of applying a skid resistant coating to interstate roads and concrete bridge decking's. Again, different materials and coatings were evaluated and tested before the final selection of ground flint and resin. Two field demonstrations were performed during fiscal year 1997 for the purpose of evaluating the coating system under actual highway conditions. These coatings were applied on Interstate 65 near Huntsville Alabama, and in the Mobile Bankhead tunnel. The system performed this task without the use of harmful solvents, and accomplished the process in a single application. This project successfully leveraged the investment of NASA, Federal Highway Administration, the Alabama Department of Transportation, and private sector funding.

McMillan, Vernotto C.↗
DOE OSTI2016

Office-like Test Chambers to Measure Cool Roof Energy Savings in Four Indian Climates

Selecting a high albedo (solar reflectance) waterproofing layer on the top of a roof helps lower the roof’s surface temperature and reduce the air conditioning energy consumption in the top floor of a building. The annual energy savings depend on factors including weather, internal loads, and building operation schedule. To demonstrate the energy saving potential of high albedo roofs, an apparatus consisting of two nearly identical test chambers (A and B) has been built in four Indian climates: Chennai (hot & humid), Bangalore (temperate), Jhagadia (Hot & dry) and Delhi (composite). Each chamber has well-insulated walls to mimic the core of an office building. Both chambers have the same construction, equipment, and operating schedule, differing only in roof surface. The reinforced cement concrete roof of Chamber A is surfaced with a low-albedo cement layer, while that of Chamber B is surfaced with a high-albedo water proof membrane (change in solar reflectance of 0.28). The experiment will be carried out for one year to explore seasonal variations in energy savings. Initial results in the month of July (post summer) shows that savings from high albedo roof ranges from 0.04 kWh/m2/day in temperate climates, to 0.08 kWh/m2/day in hot & dry climate.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Monitoring of Unvented Roofs with Fibrous Insulation, Diffusion Vents, and Interior Vapor Control in a Cold Climate

This research involved construction of a conditioned test hut in a cold climate (Climate Zone 5A) with multiple side-by-side instrumented roof rafter bays. This work examined seven experimental unvented roofs and one code-compliant control hybrid ccSPF-cellulose roof over three winters and following summers. Examined variables included insulation material (fiberglass and cellulose), the presence or absence of a ridge diffusion vent (vapor-open material at the roof ridge to promote drying), the effect of various interior vapor control membranes (fixed and variable permeance), the effect of interior relative humidity, and the effect of interstitial airflow (from the interior into the cavity). This experiment was run over three winters, changing variables of interior conditions, roof configurations/materials, and the addition of intentional air leakage.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

NorthernSTAR Project Overcoat: Exterior Insulation Strategies for 1.5-Story Roof Applications in Cold Climates

This is a repository for all NorthernSTAR Overcoat insulation retrofit projects. Both houses received Overcoat insulation retrofit on roof only, performed by Cocoon Insulation. 1 - St. Louis Park house - St. Louis Park, MN 2 - Edina house - Edina, MN In this second study, the team wished to analyze the before and after air-tightness data from roof only ETMMS retrofits on 1.5-story homes in cold and very cold climates. To identify homes to analyze, we reached out to our national network of energy professionals, home performance contractors, and general contractors who had expressed interest in promoting roof-only External Thermal Moisture Management System (ETMMS) to clients. Five projects by three contractors were submitted for consideration as they were being done to mitigate severe ice dams for homeowners. Only two of the five projects followed a roof only ETMMS protocol. Data from the other three projects, however, were reviewed with the air-tightness data of 250 roof-only, interior-applied energy retrofits on 1.5-story homes provided by three NorthernSTAR industry partners. These data represent homes in the general market as well as homes that were part of the state of Minnesota weatherization program.

adhered applied membrane↗
DOE OSTI2016

Fuel consumption impacts of auto roof racks

The after-market roof rack is one of the most common components attached to a vehicle for carrying over-sized items, such as bicycles and skis. It is important to understand these racks' fuel consumption impacts on both individual vehicles and the national fleet because they are widely used. We estimate the national fuel consumption impacts of roof racks using a bottom-up approach. Our model incorporates real-world data and vehicle stock information to enable assessing fuel consumption impacts for several categories of vehicles, rack configurations, and usage conditions. In addition, the model draws on two new data-gathering techniques, on-line forums and crowd-sourcing. The results show that nationwide, roof racks are responsible for 0.8‰ of light duty vehicle fuel consumption in 2015, corresponding to 100 million gallons of gasoline per year. Sensitivity analyses show that results are most sensitive to the fraction of vehicles with installed roof racks but carrying no equipment. Here, the aerodynamic efficiency of typical roof racks can be greatly improved and reduce individual vehicle fuel consumption; however, government policies to minimize extensive driving with empty racks--if successful--could save more fuel nationally.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2024

Validation Study of Experimental Insulating and Air-Sealing Technology for Enclosed Roof Cavities

Validation Study of Experimental Insulating and Air-Sealing Technology for Enclosed Roof Cavities, explores a new minimally invasive system known as Pinhole Insulation ® for retroft insulation of cathedral ceilings, flat roofs, dormer roofs, and other enclosed roof cavities. It also explores the validation of the associated equipment, software, and materials used in this application. The Pinhole Insulation process essentially consists of drilling a ¼” hole in the ceiling surface and then injecting closed cell polyurethane foam such that the foam is deposited on the interior surface of the exterior roof sheathing. In a typical cathedral ceiling with R19 batts, the R value will be improved by at least 60% and the cavity will become completely air sealed. The system is quick, minimally invasive and at least an order of magnitude less expensive than alternatives such as removing the ceiling surface and spraying closed cell foam.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Modeling Green Roof Potential to Mitigate Urban Flooding in a Chinese City

The Middle and Lower Reaches of the Yangtze River (MLRYR) region, which has humid subtropical climate conditions and unique plum rain season, is characterized by a simultaneous high-frequency urban flooding and reduction in groundwater levels. Retrofitting the existing buildings into green roofs is a promising approach to combat urban flooding, especially for a densely developed city. Here, the application potential of the Green Roof System (GRS) and the Improved Green Roof System (IGRS) designed to divert overflowing water from green roofs to recharge groundwater were analyzed in a densely developed city, Nanchang, China. For the first time, the influence of GRS on the hydraulic condition of Combined Sewage System/Storm Water System (CSS/SWS) is analyzed, which is a direct reflection of the effect of GRS on alleviating urban flooding. The simulation results show that GRS can retain about 41–75% of precipitation in a 2-hour timescale and the flooding volumes in the GRS/IGRS region are 82% and 28% less than those of the Traditional Roof System (TRS) in 10- and 100-yr precipitation events, respectively. In the continuous simulations, GRS also enhances Evapotranspiration (ET), which accounts for 39% of annual precipitation, so that reduces the cumulative surface runoff. Considering the IGRS can provide more hydrological benefits than the GRS under the same climate conditions, we may conclude that the widespread implementation of both the GRS and the IGRS in Nanchang and other densely developed cities in the MLRYR region could significantly reduce surface and peak runoff rates.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Optimal planning of the joint placement of photovoltaic panels and green roofs under climate change uncertainty

Photovoltaic (PV) panels directly convert sunlight into electricity; but, sunlight also heats the panels, negatively impacting their efficiency. Green roofs are vegetative layers grown on rooftops, mainly to provide added insulation on the roof to save energy. Green roofs also cool near-surface air temperature. Hence, the joint installation of PV panels and green roofs may potentially lead to higher efficiency of PV panels in certain climates. We develop a two-stage stochastic programming model to optimally place PV panels and green roofs under climate change uncertainty to maximize the overall profit from energy generated and saved. We calibrate the model using the literature, industry reports, and the data from different, at times conflicting, climate projections. We then conduct a case study for a mid-size city in the U.S., perform extensive sensitivity and robustness analyses and provide insights.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2017

Preparatory meteorological modeling and theoretical analysis for a neighborhood-scale cool roof demonstration

Replacing dark conventional roofs with more reflective “cool” roofs has been proposed as a method to lower urban air temperatures. Many meteorological studies have simulated potential cool roof air temperature reductions. However, economic and logistical challenges make it difficult to perform the large-scale demonstrations needed to verify these model results. This work assesses whether a neighborhood-scale cool roof demonstration could yield an observable air temperature change. We use both an idealized theoretical framework and a meteorological model to estimate the air temperature reduction that could be induced by increasing roof albedo over ~ 1 km 2 area of a city. Both the idealized analysis and model indicate that an air temperature reduction could be detected, with the model indicating a reduction of 0.5 °C and the idealized analysis indicating a larger reduction of 1.3 °C. Follow-on modeling is recommended prior to design of a neighborhood-scale demonstration.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Investigating the Urban Air Quality Effects of Cool Walls and Cool Roofs in Southern California

Solar reflective cool roofs and walls can be used to mitigate the urban heat island effect. While past research has investigated the climate impacts of adopting cool surfaces, few studies have investigated their effects on air pollution, especially on particulate matter (PM). This study for the first time investigates the influence of widespread deployment of cool walls on urban air pollutant concentrations, and systematically compares cool wall to cool roof effects. Simulations using a coupled meteorology-chemistry model (WRF-Chem) for a representative summertime period show that cool walls and roofs can reduce urban air temperatures, wind speeds, and planetary boundary heights in the Los Angeles Basin. Consequently, increasing wall (roof) albedo by 0.80, an upper bound scenario, leads to maximum daily 8-h average ozone concentration reductions of 0.35 (0.83) ppbv in Los Angeles County. However, cool walls (roofs) increase daily average PM2.5 concentrations by 0.62 (0.85) μg m-3. We investigate the competing processes driving changes in concentrations of speciated PM2.5. Increases in primary PM (elemental carbon and primary organic aerosols) concentrations can be attributed to reductions in ventilation of the Los Angeles Basin. Increases in concentrations of semivolatile species (e.g., nitrate) are mainly driven by increases in gas-to-particle conversion due to reduced atmospheric temperatures.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Comparison of different simulation programs in modeling the energy savings of cool roofs

The Roof Savings Calculator is a web-based application first developed in 2010 that uses detailed building energy simulations to calculate the energy savings of cool roofs for different building types in over 200 U.S. locations. Although modeling the heat flows of a roof may be straightforward at first glance, modeling the energy savings due to changes in the roof albedo is complicated because it involves modeling the interzone heat transfer between the attic and the conditioned space below. Since direct measurement of energy savings is also problematic, the authors have decided to compare what several independent detailed simulation programs show for the energy savings from cool roof strategies.

Huang, Yu (Joe)↗
DOE OSTI2021

Consumer Guide to Cool Roofs

Learn how cool roofs can save you energy and money while improving the comfort of your home. This fact sheet from Energy Saver includes information on the benefits of cool roofs, how cool roofs work and can save energy and money, and how to select and buy cool roofing materials.

cool roofs, roofing materials, Energy Saver↗
DOE OSTI2020

Monitoring of Unvented Roofs with Fibrous Insulation, Diffusion Vents, and Interior Vapor Control in a Cold Climate

Unvented roof assemblies have been accepted in North American building codes since 2007; code-compliant construction calls for a minimum thickness of “air-impermeable insulation” (based on climate zone) to avoid cold-weather condensation and moisture risks. This is typically implemented with polyurethane spray foam insulation; however, negatives of this material include high first cost and possible adverse environmental impacts. Implementing unvented roofs in a moisture-safe manner with air-permeable fibrous fill insulations (e.g., fiberglass or cellulose) could potentially reduce the first cost of unvented roof designs, allowing for more widespread use. Building unvented roofs in a cost-effective, airtight, and moisture-safe manner opens up options for high-performance house designers and builders.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗