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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Building America Case Study: Standard- Versus High-Velocity Air Distribution in High-Performance Townhomes, Denver, Colorado

IBACOS investigated the performance of a small-diameter high-velocity heat pump system compared to a conventional system in a new construction triplex townhouse. A ductless heat pump system also was installed for comparison, but the homebuyer backed out because of aesthetic concerns about that system. In total, two buildings, having identical solar orientation and comprised of six townhomes, were monitored for comfort and energy performance.

air distribution↗
DOE OSTI2016

Comfort in High-Performance Homes in a Hot-Humid Climate

TO5 2.3.2: Large-Scale Temperature Study Although space-conditioning systems are required to meet standards such as those in the Air Conditioning Contractors of America (ACCA) Manual RS (Rutkowski 1997) and the ASHRAE Standard 55 (ASHRAE 2013) comfort criteria, little is known about how space-conditioning systems are actually operating in the field and if these systems are meeting those standards. Unconventional space-conditioning systems may be necessary for low-load homes in the future. It is important to know how current systems are functioning in existing homes and to what temperatures occupants typically set the thermostats in their homes. The U.S. Department of Energy's Building America research team IBACOS set out to find some answers. By using low-cost data loggers and occupant surveys to monitor 37 single-family homes that have standard heating, ventilating, and air-conditioning (HVAC) equipment, the team gained insight into how sensitive occupants are to comfort in their homes relative to the ACCA and ASHRAE standards. This study focused on one climate zone (hot-humid); however, future studies may find differences among occupants- ideas of thermal comfort in other climate zones. Data were collected from installed sensors during a 2-month period from late August 2014 through late October 2014. The final aspect of this project was to review the business metrics associated with builders involved in a comfort and performance guarantee program. The results of this study-taken as an aggregate-show that the homes provided room-to-room temperature differences less than 6 degrees F 95% of the time. Temperature differences were less than 4 degrees F 80% of the time. Some homes showed better or worse performance. On average, two-story homes had a 3.3 degrees F temperature difference between rooms; single-story homes had an average of a 2.2 degrees F temperature difference between rooms. Occupants who did not use programmable thermostats had an average set point of 75 degrees F. Homes in which the thermostats were programmed with a setback schedule showed a median baseline temperature value of 74 degrees F and had a median afternoon setback of 75 degrees F. System runtime was analyzed and showed that the room-to-room temperature uniformity in some homes worsened during an on cycle, whereas the uniformity improved in other homes. That is, when the system was running, some rooms were receiving too much or too little air relative to the rest of the house, and the temperatures in those rooms were moving away from the temperatures of the other rooms in the house. Finally, analysis of the thermostat data shows a wide degree of variability among homes in the study. Interpretation of the measured data suggests that 21 occupants made no regular adjustments to the thermostats in their homes, seven had regular setbacks, seven showed varying setbacks, and 10 appeared to follow no pattern (with random adjustments). Ultimately, the data show that current systems are maintaining expected levels of comfort. As expected, it is more challenging to maintain a uniform temperature in all rooms of two-story homes, and future systems should address this issue. Furthermore, the data show that the majority of homes maintained relative humidity levels below 60% without any supplemental dehumidification

ACCA Manual RS↗
DOE OSTI2016

Spray Foam Exterior Insulation with Stand-Off Furring - New York

IBACOS and Green Homes America 1 (GHA) collaborated with the New York State Energy Research and Development Authority (NYSERDA) Advanced Buildings Program to research a variation of a commercial curtain wall assembly for residential construction as part of a comprehensive whole-house deep energy retrofit (DER) package. The advantages of this strategy include minimizing the physical connections to each individual existing wall stud, using closedcell spray foam to encapsulate existing siding materials including lead paint, and creating a vented rain screen assembly to promote drying. As Moore (2011) states, "Closed-cell foam acts as air-sealing, insulation, and secondary drainage plane..." Field installations on a limited number of houses indicate that the incremental cost when installed as part of a typical siding and window replacement job adds approximately $10/ft2 of wall area. 2 x 4 framing members were attached to the wall at band joists and top plates using "L" clips, and spray foam was used to insulate the wall after the framing was installed. Windows were installed as the framing was put up, including extension jambs. Key lessons learned include the following: (1) The installed cost of the spray foam system was comparable to the installed cost of the rigid foam and furring strips. (2) Spray foam should be applied in such a way that it locks the framing members in place before the remaining foam is installed in the field of the wall. The spray foam has a tendency to move the new wall framing as it expands. Best practice is to "picture frame" the wall framing with spray foam and then apply the spray foam in the field of each bay. (3) Variations in the existing siding conditions must be accounted for when attaching the ledger boards and wall framing. A best practice is to uniformly shim the ledger boards off the walls so the new framing is a uniform distance from the ledger boards and the inside surface of the interior framing. This is important primarily for window and door installation and the associated extension jambs and trim. (4) From a sequencing perspective, it is advantageous to replace the windows at the same time as the exterior walls are being built. This requires a crew that can perform a number of different tasks (e.g., framing, flashing, window install, trim carpentry) and does not lend itself to subcontracting this approach piecemeal (e.g., framing subcontractor, window installer, drainage plane installer, trim carpenter). (5) Application of the brackets and associated fastener screws was more time consuming than anticipated. (6) It is important for the spray foam contractor to perform all preparatory work, which in this case included placing plastic over the windows and exposed foundation to minimize or eliminate the possibility of damage due to overspray.

Array↗
DOE OSTI2016

Moisture Risk in Unvented Attics Due to Air Leakage Paths - Minneapolis Minnesota

IBACOS completed an initial analysis of moisture damage potential in an unvented attic insulated with closed-cell spray polyurethane foam. To complete this analysis, the research team collected field data, used computational fluid dynamics to quantify the airflow rates through individual airflow (crack) paths, simulated hourly flow rates through the leakage paths with CONTAM software, correlated the CONTAM flow rates with indoor humidity ratios from Building Energy Optimization software, and used "Warme und Feuchte instationar Pro two-dimensional modeling" to determine the moisture content of the building materials surrounding the cracks. Given the number of simplifying assumptions and numerical models associated with this analysis, the results indicate that localized damage due to high moisture content of the roof sheathing is possible under very low airflow rates. Reducing the number of assumptions and approximations through field studies and laboratory experiments would be valuable to understand the real-world moisture damage potential in unvented attics.

Array↗
DOE OSTI2016

Measured Performance of a Varied Airflow Small-Diameter Duct System

In this study, researchers with the U.S. Department of Energy's Building America team IBACOS built on research previously done in two new-construction unoccupied test houses-one in Pittsburgh, Pennsylvania (Poerschke and Stecher 2014) and one in Fresno, California (Stecher and Poerschke 2013). Specific traditional central air distribution systems were installed in each of these low-load homes. For this study, the cold-climate new-construction unoccupied test house in Pittsburgh, Pennsylvania, was modified to test the performance of a heating, ventilating, and air-conditioning (HVAC) system with varied airflow and small-diameter ducts. The main goal of the small-diameter duct system is to simplify the task of bringing ductwork inside conditioned space, particularly on the single-story slab-on-grade type of home that is prevalent in the South and Southeast. Guidance is provided here to homebuilders and HVAC contractors on cost and performance tradeoffs between the conventional duct system and the small-diameter duct system. Comparisons were made between variable-capacity heat pump operation modes with three constant airflow rates to determine the ideal tradeoff between maximizing thermal comfort and minimizing fan energy consumption. ASHRAE Standard 55 (ASHRAE 2010a) was used to set limit metrics for temporal temperature variation; Air Conditioning Contractors of America (ACCA) Manual RS (Rutkowski 1997) was used to set a limit on spatial temperature uniformity (room-to-thermostat uniformity). The small diameter duct system was able to meet the temporal temperature variation limits much better than the spatial temperature uniformity limits. TO4 2.1.2: High Velocity Space Cond. Systems

ACCA Manual RS↗
DOE OSTI2016

Mini-Split Heat Pump Evaluation and Zero Energy Ready Home Support

This project was created from a partnership between the U.S. Department of Energy's (DOE's) Building America research team, IBACOS, Inc., and a production builder of high-performance homes called Imagine Homes, which is located in San Antonio, Texas-a hot-humid climate. The primary purpose of this project was to evaluate the performance of a multihead mini-split heat pump (MSHP) space-conditioning system in maintaining uniform comfort in an occupied test house. My Design - PV: Test house design characteristics, with installed PV system DESIGN - Occupied Test House with PV: Design used for one occupied test house including PV STRUCTURE - Platinum Court San Antonio, TX: Occupied test house in 2013

Array↗
DOE OSTI2016

New York State Energy Research and Development Authority Exterior Building Solutions To Insulation

TO4 8.2.2: Space Cond. for Deep Energy Retrofits The purpose of this project for the New York State Energy Research and Development Authority (NYSERDA) is to find new or improved strategies for exterior building solutions in regard to insulation that will provide extensive energy-savings benefits for homeowners. Deep energy retrofits (DER) is one of the solutions. In the past, DERs have been expensive and hard for the average homeowner to budget. The DER solutions that IBACOS and GreenHomes America (GHA) are proposing will be market friendly, affordable, and easily repeatable. The insulation strategies that will be used on nine test homes include the following: - Rigid foam insulation - Four homes will have approximate center-of-wall R-values of R-28, including furring strips for siding, with additional systems approach work to supply the complete integrated DER solution. - Spray foam insulation - Four homes will have approximate center-of-wall R-values of R-30, with additional systems approach work to supply the complete integrated DER solution. - HPwES upgrade - One home will include criteria from the Home Performance with ENERGY STAR (HPwES) program, including dense pack walls and window upgrades for this retrofit strategy. In addition to the insulation, the strategies will include treatment where needed in the attic, mechanical systems, ventilation and basement band joist, walls, and floors.

acca manual rs↗
DOE OSTI2016

Brookfield Homes Passive House Performance Evaluation

TO4 3.1.3: Brookfield Homes Short-Term Results TO5 3.1.3: Brookfield Passive House Monitoring To further define its market position on high performance homebuilding, Brookfield worked with IBACOS and the Building America program to design and construct a Passive House (PH) certified model home in Denver, CO to evaluate advanced building technologies and to use as a marketing tool for potential homebuyers. Brookfield used a new architect and a new floor plan as a standard production model and constructed it to the PH standard as an upgrade option. This PH was completely built and certified in August 2013.

Array↗
DOE OSTI2023

Carbon Emissions in a Typical New Production Home: A Case Study

This report, prepared by IBACOS, is intended to serve as a foundational document for the residential construction industry to understand how a typical home currently performs relative to building decarbonization goals set for 2030 and 2050. The intent is to help homebuilders benchmark their current performance and better understand the largest sources of carbon emissions in their homes.

Carbon Emissions↗
DOE OSTI2026

A Simple Panel System to Overcome Interface Challenges for Retrofits: Preprint

Retrofitting buildings is usually an expensive and labor-intensive process. Weatherization measures can improve comfort and energy affordability to some extent, but deep energy retrofits are needed to optimize performance and comfort, and to achieve significant energy cost savings. Barriers to deep energy retrofits include a limited supply of skilled labor, different building types, planning complexity, split incentives, and a long or non-existent ROI horizon. The "Simple Panel System" (SPS) workflow developed and demonstrated in this effort streamlines deep energy retrofits by applying advanced site capture, machine learning, and mixed reality to panelized construction. The result is a one-stop, product-independent solution for rapidly scalable retrofits with the potential to reduce construction time and project costs by 50%. Soft costs are reduced by more than 66%, total costs by more than 50%, and field construction time by more than 50% - not to mention the reduction in construction waste, improvement in working conditions, and the ability to scale without an influx of skilled labor. This paper presents the SPS and the preliminary results and findings from the pilot project.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Strategy Guideline: Energy Retrofits for Low-Rise Multifamily Buildings in Cold Climates

This Strategy Guideline explains the benefits of evaluating and identifying energy efficiency retrofit measures that could be made during renovation and maintenance of multifamily buildings. It focuses on low-rise multifamily structures (three or fewer stories) in a cold climate. These benefits lie primarily in reduced energy use, lower operating and maintenance costs, improved durability of the structure, and increased occupant comfort. This guideline focuses on retrofit measures for roof repair or replacement, exterior wall repair or gut rehab, and eating system maintenance. All buildings are assumed to have a flat ceiling and a trussed roof, wood- or steel-framed exterior walls, and one or more single or staged boilers. Estimated energy savings realized from the retrofits will vary, depending on the size and condition of the building, the extent of efficiency improvements, the efficiency of the heating equipment, the cost and type of fuel, and the climate location.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Strategy Guideline: Compact Air Distribution Systems

This Strategy Guideline discusses the benefits and challenges of using a compact air distribution system to handle the reduced loads and reduced air volume needed to condition the space within an energy efficient home. Traditional systems sized by 'rule of thumb' (i.e., 1 ton of cooling per 400 ft 2 of floor space) that 'wash' the exterior walls with conditioned air from floor registers cannot provide appropriate air mixing and moisture removal in low-load homes. A compact air distribution system locates the HVAC equipment centrally with shorter ducts run to interior walls, and ceiling supply outlets throw the air toward the exterior walls along the ceiling plane; alternatively, high sidewall supply outlets throw the air toward the exterior walls. Potential drawbacks include resistance from installing contractors or code officials who are unfamiliar with compact air distribution systems, as well as a lack of availability of low-cost high sidewall or ceiling supply outlets to meet the low air volumes with good throw characteristics. The decision criteria for a compact air distribution system must be determined early in the whole-house design process, considering both supply and return air design. However, careful installation of a compact air distribution system can result in lower material costs from smaller equipment, shorter duct runs, and fewer outlets; increased installation efficiencies, including ease of fitting the system into conditioned space; lower loads on a better balanced HVAC system, and overall improved energy efficiency of the home.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Imagine Homes New Construction Occupied Test House

This report summarizes the research findings of a long-term monitoring plan to evaluate the performance of an energy-efficient home constructed in 2010 in San Antonio, Texas. Monitoring of the energy use, energy generation, and temperature conditions for this project occurred between July 2010 and October 2011. The heating, ventilation, and air conditioning system effectively maintained acceptable temperatures and humidity levels in peak cooling and heating and non-peak operating periods. Discrepancies were found between modeled and actual energy use values, with actual space cooling energy use closest to the corresponding modeled value. Energy consumption predicted for lighting, appliances, and miscellaneous electrical loads was significantly higher than measured amounts, and energy consumption predicted for cooling was significantly lower than measured amounts. A high amount of the 1,600 kWh of PV-generated electricity produced annually was sent to the electric grid every month. The solar thermal DHW system was the main source of hot water for most of the year and performed well; during summer, electrical use by the backup system was rare.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Long-Term Results from Evaluation of Advanced New Construction Packages in Test Homes: Lake Elsinore, California

This report presents the long-term evaluation results from a hot-dry climate project that examines the room-to-room temperature conditions that exist in a high performance envelope, the performance of a simplified air distribution system, and a comparison of modeled energy performance with measured energy use. The project, a prototype house built by K. Hovnanian Homes' Ontario Group, is located in Lake Elsinore, Riverside County, California, and achieves a 50% level of whole house source energy savings with respect to the Building America (BA) Benchmark Definition 2009 (Hendron and Engebrecht 2010). Temperature measurements in three rooms indicate that the temperature difference between the measured locations and the thermostat were within recommendations 90.3% of the time in heating mode and 99.3% of the time in cooling mode. The air distribution system is operating efficiently with average delivered temperatures adequate to facilitate proper heating and cooling and only minor average temperature differences observed between the system's plenum and farthest register. Monitored energy use results for the house indicate that it is using less energy than predicted from modeling. A breakdown of energy use according to end use determined little agreement between comparable values.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Inverted Attic Bulkhead for HVAC Ductwork: Roseville, California (Fact Sheet)

K. Hovnanian Homes constructed a 2,253-ft single-story slab-on-grade ranch house for an occupied test house (new construction) in Roseville, California. One year of monitoring and analysis focused on the effectiveness of the space conditioning system at maintaining acceptable temperature and relative humidity levels in several rooms of the home, as well as room-to-room differences and the actual measured energy consumption by the space conditioning system. In this home, the air handler unit (AHU) and ducts were relocated to inside the thermal boundary. The AHU was relocated from the attic to a mechanical closet, and the ductwork was located inside an insulated and air-sealed bulkhead in the attic. To describe the performance and comfort in the home, the research team selected representative design days and extreme days from the annual data for analysis. To ensure that temperature differences were within reasonable occupant expectations, the team followed Air Conditioning Contractors of America guidance. At the end of the monitoring period, the occupant of the home had no comfort complaints in the home. Any variance between the modeled heating and cooling energy and the actual amounts used can be attributed to the variance in temperatures at the thermostat versus the modeled inputs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Comfort and HVAC Performance for a New Construction Occupied Test House in Roseville, California

K. Hovnanian(R) Homes(R) constructed a 2,253-ft2 single-story slab-on-grade ranch house for an occupied test house (new construction) in Roseville, California. One year of monitoring and analysis focused on the effectiveness of the space conditioning system at maintaining acceptable temperature and relative humidity levels in several rooms of the home, as well as room-to-room differences and the actual measured energy consumption by the space conditioning system. In this home, the air handler unit (AHU) and ducts were relocated to inside the thermal boundary. The AHU was relocated from the attic to a mechanical closet, and the ductwork was located inside an insulated and air-sealed bulkhead in the attic. To describe the performance and comfort in the home, the research team selected representative design days and extreme days from the annual data for analysis. To ensure that temperature differences were within reasonable occupant expectations, the team followed Air Conditioning Contractors of America guidance. At the end of the monitoring period, the occupant of the home had no comfort complaints in the home. Any variance between the modeled heating and cooling energy and the actual amounts used can be attributed to the variance in temperatures at the thermostat versus the modeled inputs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗