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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Permanent Magnet Synchronous Motors for Commercial Refrigeration (Final Report)

This report provides background information on various fractional-horsepower electric motor technologies used for evaporator fan applications in commercial refrigeration and summarizes data from a DOE-sponsored evaporator fan motor laboratory and field demonstration project. This report also extrapolates that data to project the potential economic and environmental benefits resulting from upgrading the current installed base of commercial refrigeration evaporator fan motors to permanent magnet synchronous (PMS) motors.Evaporator fan motors used in commercial refrigeration applications are fractional horsepower in size, responsible for moving air across the evaporator coil, and typically run at one speed. Historically, shaded-pole induction motors have been the most commonly used evaporator fan motors in commercial refrigeration equipment and beverage vending machines. These are the simplest and least expensive type of fractional-horsepower motor, with an efficiency of approximately 20%. Electronically commutated (EC) permanent magnet motors, also known as brushless DC motors, were initially commercialized in the late 1980s, and their use in commercial refrigeration applications has increased within the last 10 to 15 years because of economic incentives and regulatory requirements. State-of-the-art EC motors are approximately 66% efficient. Another induction motor type, the permanent split capacitor (PSC) motor, offers a mid-point between shaded-pole and EC motor price and efficiency levels. PSC motors are typically about 29% efficient.A permanent magnet synchronous (PMS) AC motor that can directly use grid-supplied AC current without the need to rectify to DC has recently been commercialized. This new motor exhibits a peak efficiency of 75% and has the potential to significantly reduce the energy consumption of evaporator fan motors in commercial refrigeration equipment. Laboratory evaluation of evaporator fan motor technologies was performed to quantify and compare the performance of shaded-pole, PSC, EC, and PMS evaporator fan motors in a controlled environment, so as to minimize the influence of external factors and anomalies. The laboratory evaluation included dynamometer testing of the fan motors and airflow testing of the motor/fan assemblies. It was found that the 6–12 W PMS motor exhibited a peak efficiency of 75% with a power factor of approximately 0.9 at a power output of 11 W. It was also found that a 38–50 W PMS motor exhibited a peak efficiency of 82% with a power factor of approximately 0.9 at a power output of 35 W.Airflow testing of shaded-pole, PSC, EC, and PMS motor/fan assemblies was performed using an airflow test chamber, which was designed in accordance with ANSI/AMCA Standard 210-16/ASHRAE Standard 51-16, to measure the performance of the subject motor/fan assembly and to determine the incumbent display case system impedance (AMCA 2016). A family of fan curves (static pressure vs airflow rate and electrical power input vs airflow rate) was generated for the 6–12 W PMS motor/fan assemblies with 8-inch fan blades pitched from 17 to 32 degrees. A similar set of curves was generated for the 38–50 W motors paired with 10 and 12-inch blades. Various incumbent motor/fan assemblies were also tested in the laboratory airflow test chamber and their fan curves were generated.Field evaluation of refrigerated display case evaporator fan motors was accomplished by performing side-by-side comparisons of 6–12 W PMS motors to 6–12 W shaded-pole and EC evaporator fan motors. It was found that, on average, a PMS motor consumes 79% less power and draws 82% less current than a shaded pole motor, and on average, 34% less power and 49% less current than an EC motor. In addition, the PMS motor exhibits an average power factor of approximately 0.82, which is on average 40% greater than that of existing evaporator fan motors.Two field test sites were selected to evaluate the performance of the larger 38 to 50 W PMS evaporator fan motors in walk-in cooler/freezer applications. At each supermarket, two walk-in units were selected for investigation: one walk-in dairy cooler and one walk-in freezer. A 61% decrease in fan motor power was measured when retrofitting existing evaporator fan motors with PMS motors in the walk-in cooler. In addition, a 48% decrease in fan motor power was measured when retrofitting existing evaporator fan motors with PMS motors in the walk-in freezer.The culmination of the field evaluation of fan motor technologies was a whole-store retrofit conducted at a supermarket. Pre- and post-retrofit measurement of evaporator fan motor power in medium- and low-temperature refrigerated display cases and walk-in coolers/freezers was performed. Overall for the whole-store retrofit, the current supplied to all monitored evaporator fan motors was reduced by 52%, the real power was reduced by 46% and the apparent power was reduced by 51% following the retrofit of the 262 evaporator fan motors that w

42 ENGINEERING↗
DOE OSTI2022

Energy Performance of Awnings in Residential Buildings

Residential buildings consume approximately 20% of the total primary energy in the United States. More than 50% of this energy is spent in heating, cooling, and lighting these buildings. Solar heat gain is one of the largest and most variable sources of cooling load in these buildings, while it can also provide passive heating during the heating season. Shading devices can be used to control the amount of solar heat gain in buildings. Various studies have considered how different shading devices and their applications affect energy and occupant comfort in buildings. However, most of these studies were limited to planar shading devices such as roller shades, cellular shades, and blinds. Although some theoretical studies have been performed for awnings, the energy performance of awnings has rarely been studied via either energy simulation or field measurement. In this study, the authors evaluated the energy performance of typical operable awnings by using field data, aided by simulation. Awnings were installed on a real house, and measurements were performed to evaluate the thermal performance of the awning. The measured data were then used to develop a calibrated energy model and evaluate the awning’s energy performance. The annual simulation of the building model used showed that awnings left in the closed position from April to September can reduce annual HVAC energy consumption by 15% compared with a building without any shades. The validated model was used in US Department of Energy prototype buildings to evaluate awning energy performance in climate zones 1A through 4B via energy simulation. For these prototype buildings, energy savings of up to 1,034 kWh were achieved for a building with a conditioned floor area of 2,377 ft 2 .

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Influence of Vegetation Canopy Architecture on Dynamics of Spatiotemporal Light Distribution and its Effect on Land-Biosphere-Atmosphere Fluxes of Energy, Carbon, and Water

The dynamic spatiotemporal distribution of light and micro climatic variables (wind speed, atmospheric CO 2 concentration, humidity, pressure, and air temperature) within the plant canopy as determined by the canopy architecture play a critical role in land-biosphere-atmosphere (LBA) photosynthetic carbon uptake, transpiratory water loss and energy partitioning. Vegetation models that include effects of sun and shade flecks, leaf temperature and energy balance partitioning between sensible and latent heat fluxes, and reduced turbulent mixing in dense vegetation canopies can accurately predict canopy performance, particularly its shaded leaves, which can constitute 80% of leaf area and contribute up to 50% of carbon update and 65% of water loss. However, current vegetation models with their bulk characterization of shaded leaves poorly represent the complex three dimensional (3D) canopy architecture are insufficient to capture the spatiotemporal dynamics of shaded leaves. Here, we propose to employ an x-ray computed tomography (XCT) imaging technique in combination with an automated, high throughput, image processing pipeline (3DArch, to be developed) to obtain an explicit 3D triangulated surface mesh of a plant canopy (Fig 1). 3DArch would provide a much needed technological jump in 3D LBA modeling where computer generated artificial 3D models suffer from lack of high resolution detailed canopy architecture parameters. The 3D canopy surface mesh output from 3DArch is coupled with an explicit 3D forward ray tracing model (fastTracer) to obtain a high resolution representation of the dynamic spatiotemporal light environment within the canopy over the course of a day (Fig 1). The results from the light attenuation model are then coupled with a process based multi-scale bio-physical canopy and leaf model of photosynthesis (PlantGro) to get fluxes of carbon, water and energy at the leaf and canopy scale, in addition to estimating whole plant carbon uptake, and water loss. Our proposed model framework would be the first of its kind to provide a breakthrough capability in the field of process-based plant modeling that bridges the key technological gap in shaded leaf modeling through explicit representation of 3D canopy architecture. Computer generated artificial 3D model canopy simulations on grasses show that the canopy light distribution does not follow an exponential behavior as assumed in most 1D vegetation models, but rather exhibits a heterogeneous behavior, with a small but significant portion of interior canopy leaves experiencing peak light levels due to sun flecks while the rest of the canopy receives substantially lower light levels. These results indicate a bias in traditional models that overestimates shaded leaf contribution towards whole canopy photosynthesis by up to 15% and underestimate transpiration by up to 12% with an associated increase in sensible heat fluxes since photosynthesis, transpiration and energy partitioning are tightly coupled processes. However, these test results need to be validated using the 3D architecture obtained from a real plant imaged in 3D using 3DArch, rather than an artificial model plant. Our proposed model framework would allow us to identify inefficiencies in canopy light distribution and prescribe optimal canopy architectures (leaf optical properties, leaf area, leaf angles, row spacing, planting density, etc.) to traditional and genetic engineering based crop breeders, for maximizing target functions such as light use efficiency, water use efficiency, drought tolerance, crop yield, crop resilience etc., with important applications in biofuel crops such as sorghum, and switchgrass. Our model can also be applied for designing optimal canopy architecture that increase surface albedo as a mitigation strategy for global warming and projections of crop yield for future food and water security under climate change.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2007

Polar Lunar Regions: Exploiting Natural and Augmented Thermal Environments

In polar regions of the Moon, some areas within craters are permanently shadowed from solar illumination and can reach temperatures of 100 K or less. These regions could serve as cold traps, capturing ice and other volatile compounds. These potential ice stores have many applications for lunar exploration. Within double-shaded craters, even colder regions exist, with temperatures never exceeding 50 K in many cases. Observed temperatures suggest that these regions could enable equivalent liquid nitrogen cryogenic functions. These permanently shaded polar craters also offer unprecedented high-vacuum cryogenic environments, which in their current state could support cryogenic applications. Besides ice stores, the unique conditions at the lunar poles harbor an environment that provides an opportunity to reduce the power, weight, and total mass that needs to be carried from the Earth to the Moon for lunar exploration and research. Reducing the heat flux of geothermal, black body radiation can have significant impacts on the achievable temperature. With a few manmade augmentations, permanently shaded craters located near the lunar poles achieve temperatures even lower than those that naturally exist. Our analysis reveals that lightweight thermal shielding within shaded craters could create an environment several Kelvin above absolute zero. The temperature ranges of both naturally shaded and thermally augmented craters could enable the long-term storage of most gases, low-temperature superconductors for large magnetic fields, devices and advanced high-speed computing instruments. Augmenting thermal conditions in these craters could then be used as a basis for the development of an advanced thermal management architecture that would support a wide variety of cryogenically based applications. Lunar exploration and habitation capabilities would significantly benefit if permanently shaded craters, augmented with thermal shielding, were used to facilitate the operation of near absolute zero instruments, including a wide variety of cryogenically based propulsion, energy, communication, sensing, and computing devices. The required burden of carrying massive life-supporting components from the Earth to the Moon for lunar exploration and research potentially could be reduced.

Ryan, Robert E.↗
NASA NTRS2012

The Photochemical Reflectance Index from Directional Cornfield Reflectances: Observations and Simulations

The two-layer Markov chain Analytical Canopy Reflectance Model (ACRM) was linked with in situ hyperspectral leaf optical properties to simulate the Photochemical Reflectance Index (PRI) for a corn crop canopy at three different growth stages. This is an extended study after a successful demonstration of PRI simulations for a cornfield previously conducted at an early vegetative growth stage. Consistent with previous in situ studies, sunlit leaves exhibited lower PRI values than shaded leaves. Since sunlit (shaded) foliage dominates the canopy in the reflectance hotspot (coldspot), the canopy PRI derived from field hyperspectral observations displayed sensitivity to both view zenith angle and relative azimuth angle at all growth stages. Consequently, sunlit and shaded canopy sectors were most differentiated when viewed along the azimuth matching the solar principal plane. These directional PRI responses associated with sunlit/shaded foliage were successfully reproduced by the ACRM. As before, the simulated PRI values from the current study were closer to in situ values when both sunlit and shaded leaves were utilized as model input data in a two-layer mode, instead of a one-layer mode with sunlit leaves only. Model performance as judged by correlation between in situ and simulated values was strongest for the mature corn crop (r = 0.87, RMSE = 0.0048), followed by the early vegetative stage (r = 0.78; RMSE = 0.0051) and the early senescent stage (r = 0.65; RMSE = 0.0104). Since the benefit of including shaded leaves in the scheme varied across different growth stages, a further analysis was conducted to investigate how variable fractions of sunlit/shaded leaves affect the canopy PRI values expected for a cornfield, with implications for 20 remote sensing monitoring options. Simulations of the sunlit to shaded canopy ratio near 50/50 +/- 10 (e.g., 60/40) matching field observations at all growth stages were examined. Our results suggest in the importance of the sunlit/shaded fraction and canopy structure in understanding and interpreting PRI.

Cheng, Yen-Ben↗
DOE OSTI2021

An Investigation of Strategies for Sensing Window Attachment Position: Survey of Candidate Technologies, Evaluation, and Deployment Recommendations

While windows are desirable feature in buildings for views, daylighting, and aesthetics, it is important to recognize that windows are a major contributor to a building’s energy load. Interior window coverings, such as shades and blinds, can help improve the energy performance of windows without sacrificing the benefits; however, while appropriate use of window coverings provide the potential for energy savings, there is little consensus regarding how occupants typically use these window attachments, which sometimes puts into question how much energy they actually save in an occupied home. Automated shading control strategies can reduce the uncertainty of energy savings; however, users can overwrite pre-defined schedules or write their own shade control programs to reach their personal comfort and privacy goals. Because it is difficult to identify how occupants interact with window shades, it is difficult to identify the energy savings potential of blinds. To address this problem, this study was developed to identify a candidate sensor that can be deployed to sense blind position. The intended application for this sensor is deployment in energy efficiency field studies so that shade usage can be measured to better understand results and identify the energy impact of specific window attachment technologies.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Laboratory Validation of Integrated Lighting Systems Retrofit Performance and Energy Savings

Light-emitting diodes (LED) fixtures and lamps have emerged as leading technologies for general illumination and are a well-established energy efficiency retrofit measure in commercial buildings (from around 2% of installed fixtures and lamps in 2013 to 28% by 2020). Retrofit approaches that integrate elements, such as networked controls, daylight dimming, and advanced shade technologies lag in comparison. Integrated retrofits have been shown to increase savings over single end-use retrofits, but are perceived as higher complexity and risk. More validation of integrated lighting system performance is needed. This study presents results from laboratory testing of three packages combining fixtures, networked controls, task tuning, and daylight dimming, advanced shades, and lighting layout changes. We characterize performance in perimeter open-office zones, finding energy savings from 20% for daylight dimming and automated shades (no LED retrofit) to over 70% for LED retrofits with advanced controls and shades or lighting layout changes. We present some implementation details, including lessons learned from installation and commissioning in the laboratory setting. We also discuss cost-benefit analysis approaches for the types of packages presented, including the need to quantify and incorporate energy and non-energy benefits for advanced shades packages, which enhance occupant comfort but add significant cost.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

High planting density induces the expression of GA3-oxidase in leaves and GA mediated stem elongation in bioenergy sorghum

Abstract The stems of bioenergy sorghum hybrids at harvest are > 4 m long, contain > 40 internodes and account for ~ 80% of harvested biomass. In this study, bioenergy sorghum hybrids were grown at four planting densities (~ 20,000 to 132,000 plants/ha) under field conditions for 60 days to investigate the impact shading has on stem growth and biomass accumulation. Increased planting density induced a > 2-fold increase in sorghum internode length and a ~ 22% decrease in stem diameter, a typical shade avoidance response. Shade-induced internode elongation was due to an increase in cell length and number of cells spanning the length of internodes. SbGA3ox2 (Sobic.003G045900), a gene encoding the last step in GA biosynthesis, was expressed ~ 20-fold higher in leaf collar tissue of developing phytomers in plants grown at high vs. low density. Application of GA3 to bioenergy sorghum increased plant height, stem internode length, cell length and the number of cells spanning internodes. Prior research showed that sorghum plants lacking phytochrome B, a key photoreceptor involved in shade signaling, accumulated more GA1 and displayed shade avoidance phenotypes. These results are consistent with the hypothesis that increasing planting density induces expression of GA3-oxidase in leaf collar tissue, increasing synthesis of GA that stimulates internode elongation.

09 BIOMASS FUELS↗
DOE OSTI2022

Vegetation clumping modulates global photosynthesis through adjusting canopy light environment

Abstract The spatial dispersion of photoelements within a vegetation canopy, quantified by the clumping index (CI), directly regulates the within‐canopy light environment and photosynthesis rate, but is not commonly implemented in terrestrial biosphere models to estimate the ecosystem carbon cycle. A few global CI products have been developed recently with remote sensing measurements, making it possible to examine the global impacts of CI. This study deployed CI in the radiative transfer scheme of the Community Land Model version 5 (CLM5) and used the revised CLM5 to quantitatively evaluate the extent to which CI can affect canopy absorbed radiation and gross primary production (GPP), and for the first time, considering the uncertainty and seasonal variation of CI with multiple remote sensing products. Compared to the results without considering the CI impact, the revised CLM5 estimated that sunlit canopy absorbed up to 9%–15% and 23%–34% less direct and diffuse radiation, respectively, while shaded canopy absorbed 3%–18% more diffuse radiation across different biome types. The CI impacts on canopy light conditions included changes in canopy light absorption, and sunlit–shaded leaf area fraction related to nitrogen distribution and thus the maximum rate of Rubisco carboxylase activity ( V cmax ), which together decreased photosynthesis in sunlit canopy by 5.9–7.2 PgC year −1 while enhanced photosynthesis by 6.9–8.2 PgC year −1 in shaded canopy. With higher light use efficiency of shaded leaves, shaded canopy increased photosynthesis compensated and exceeded the lost photosynthesis in sunlit canopy, resulting in 1.0 ± 0.12 PgC year −1 net increase in GPP. The uncertainty of GPP due to the different input CI datasets was much larger than that caused by CI seasonal variations, and was up to 50% of the magnitude of GPP interannual variations in the tropical regions. This study highlights the necessity of considering the impacts of CI and its uncertainty in terrestrial biosphere models.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1973

Scale model testing of drogues for free drifting buoys

Instrumented model drogue tests were conducted in a ship model towing tank. The purpose of the tests was to observe and measure deployment and drag characteristics of such shapes as parachutes, crossed vanes, and window shades which may be employed in conjunction with free drifting buoys. Both Froude and Reynolds scaling laws were applied while scaling to full scale relative velocities of from 0 to 0.2 knots. A weighted window shade drogue is recommended because of its performance, high drag coefficient, simplicity, and low cost. Detailed theoretical performance curves are presented for parachutes, crossed vanes, and window shade drogues. Theoretical estimates of depth locking accuracy and buoy-induced dynamic loads pertinent to window shade drogues are presented as a design aid. An example of a window shade drogue design is presented.

Vachon, W. A.↗
NASA NTRS1982

Aircraft geometry verification with enhanced computer generated displays

A method for visual verification of aerodynamic geometries using computer generated, color shaded images is described. The mathematical models representing aircraft geometries are created for use in theoretical aerodynamic analyses and in computer aided manufacturing. The aerodynamic shapes are defined using parametric bi-cubic splined patches. This mathematical representation is then used as input to an algorithm that generates a color shaded image of the geometry. A discussion of the techniques used in the mathematical representation of the geometry and in the rendering of the color shaded display is presented. The results include examples of color shaded displays, which are contrasted with wire frame type displays. The examples also show the use of mapped surface pressures in terms of color shaded images of V/STOL fighter/attack aircraft and advanced turboprop aircraft.

Cozzolongo, J. V.↗
NASA NTRS1982

Aircraft geometry verification with enhanced computer-generated displays

A method for visual verification of aerodynamic geometries using computer-generated, color-shaded images is described. The mathematical models representing aircraft geometries are created for use in theoretical aerodynamic analyses and in computer-aided manufacturing. The aerodynamic shapes are defined using parametric bi-cubic splined patches. This mathematical representation is then used as input to an algorithm that generates a color-shaded image of the geometry. A discussion of the techniques used in the mathematical representation of the geometry and in the rendering of the color-shaded display is presented. The results include examples of color-shaded displays, which are contrasted with wire-frame-type displays. The examples also show the use of mapped surface pressures in terms of color-shaded images of V/STOL fighter/attack aircraft and advanced turboprop aircraft.

Cozzolongo, J. V.↗
NASA NTRS1987

Sun shield

A shading device which is capable of compactly storing a flexible shade on a biased, window shade type spring roller is disclosed. It is controlled to deliver the shade selectively to either its operative shading or compact storage orientation.

Frank, Arthur M.↗
NASA NTRS1991

The least-squares mixing models to generate fraction images derived from remote sensing multispectral data

Constrained-least-squares and weighted-least-squares mixing models for generating fraction images derived from remote sensing multispectral data are presented. An experiment considering three components within the pixels-eucalyptus, soil (understory), and shade-was performed. The generated fraction images for shade (shade image) derived from these two methods were compared by considering the performance and computer time. The derived shade images are related to the observed variation in forest structure, i.e., the fraction of inferred shade in the pixel is related to different eucalyptus ages.

Shimabukuro, Yosio Edemir↗
NASA NTRS1993

Investigation of lunar base thermal control system options

Long duration human exploration missions to the Moon will require active thermal control systems which have not previously been used in space. The two technologies which are most promising for long term lunar base thermal control are heat pumps and radiator shades. Recent trade-off studies at the Johnson Space Center have focused development efforts on the most promising heat pump and radiator shade technologies. Since these technologies are in the early stages of development and many parameters used in the study are not well defined, a parametric study was done to test the sensitivity to each assumption. The primary comparison factor in these studies was the total mass system, with power requirements included in the form of a mass penalty for power. Heat pump technologies considered were thermally driven heat pumps such as metal hydride, complex compound, absorption and zeolite. Also considered were electrically driven Stirling and vapor compression heat pumps. Radiator shade concepts considered included step shaped, V-shaped and parabolic (or catenary) shades and ground covers. A further trade study compared the masses of heat pump and radiator shade systems.

Ewart, Michael K.↗
DOE OSTI2015

Discomfort glare with complex fenestration systems and the impact on energy use when using daylighting control

Glare is a frequent issue in highly glazed buildings. A modelling approach is presented that uses discomfort glare probability and discomfort glare index as metrics to determine occupants’ behaviour. A glare control algorithm that actuated an interior shade for glare protection based on the predicted perception was implemented in a building simulation program. A reference case with a state-of-the-art base glazing was compared to the same glazing but with five different complex fenestration systems, i.e., exterior shades. The windows with exterior shades showed significant variations in glare frequencies. Energy use intensity in a prototypical office building with daylighting controls was greatly influenced for the systems with frequent glare occurrence. While the base glazing could benefit from glare control, some of the exterior shades showed significantly greater energy use when discomfort glare-based operation of interior shades was considered.

Hoffmann, Sabine↗
DOE OSTI2021

On the Ambiguity of Using Isc for Analyzing Suns-Voc Data on Modules

In standard silicon solar modules, cells are strung in series with bypass diodes incorporated to reduce the effects of shading. When all of the strings are partially shaded the measured short circuit current is affected and the Isc of the module will be equal to that of the lowest current cell in the least shadowed string. In bifacial modules the ability to assess losses due to shading is especially important. This paper advocates an alternative approach to converting the raw suns-voc data to pseudo IV data in modules where shading may be affecting the suns-voc curve results.

41 EE - Solar Energy Technologies Office (EE-4S)↗
DOE OSTI2018

Greenbuilt Construction Energy Efficiency Retrofit House Demonstration - Sacramento

One of the homes that was part of Sacramento Municipal Utility District's (SMUD) Energy Efficiency Retrofit Demonstration (EERD) project was a 1980's era home in Fair Oaks, California, referred to as the Greenbuilt house, as Greenbuilt Construction completed the retrofit of the home. The home underwent an extensive energy efficiency retrofit with a goal of achieving a 50% reduction in energy use to demonstrate the potential for other builders and homeowners in the area. The retrofit measures included installing: ENERGY STAR appliances high efficiency light roof radiant barrier additional ceiling and wall insulation double-pane, low-e windows external motorized shading and solar tubes a 16 SEER/9.75 HSPF heat pump improved ducts a whole-house fan a heat pump water heater (HPWH) integrated collector storage solar water heater (ICS SWH) and 3.2 kW of PV. In addition, the home was air sealed to reduce infiltration. Researchers from the National Renewable Energy Laboratory (NREL) performed short-term tests on the major systems installed as part of the retrofit to ensure that they were performing as expected. The systems evaluated included the space conditioning heat pump, the air handler and ducts, the HPWH, the ICS SWH, and the PV array. Some ducts were untwisted after testing revealed that two rooms were not getting sufficient airflow. Afterwards, all systems were performing as expected. In addition to testing to confirm adequate performance of all new systems, NREL was given the opportunity to use the Greenbuilt house as a laboratory house for a year. The space conditioning system and home water systems were subjected to a series of tests to determine optimal control strategies for lowering energy consumption and reducing peak (4:00-7:00 p.m.) energy consumption during the summer. The different cooling strategies considered included two different precooling schedules, drawing the external shades during the day and using the whole-house fan at night, and combinations of those. The most effective strategy for reducing overall energy consumption was the use of external shades, which cut the daily cooling load by 34% and reduced the energy use during peak hours by 40%. The different precooling strategies eliminated the peak load entirely but actually increased daily cooling energy use. The use of shades and the advanced precooling strategy increased the daily energy use by 5% but eliminated all peak use and maintained a comfortable home. These results were verified over the entire summer using an Energy Plus model of the home. The hot water system was tested in two configurations: the HPWH alone and the ICS solar water heater paired with the HPWH. Six hot water draw profiles, varying in terms of daily hot water volume, time of day for hot water use, and the duration of the draws, were imposed on the hot water system to test their effects on performance. When operating alone in the summer, the HPWH operated with a COP around 2.2, except for a draw that used a quarter of the averaged daily hot water usage, which had an average COP of 1.6. The combination of ICS and HPWH resulted in larger COPs, but also more variability depending on the draw profile. The standard, hourly draw profile produced the highest COP of 6.4. The quarter volume draw profile had the lowest COP of 2.8 for the combined system. Relative to a standard electric water heater, the HPWH operating alone reduced the peak load by 56% and the combined ICS and HPWH system completely eliminated the peak load.

air sealing↗