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At least 145 records · Page 8

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DOE OSTI2017

Building America Case Study: Impact of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps, Cocoa, Florida

A new generation of central, ducted variable-capacity heat pump systems has come on the market, promising very high cooling and heating efficiency. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they vary their cooling and heating output over a wide range (approximately 40 to 118% of nominal full capacity); thus, staying 'on' for 60% to 100% more hours per day compared to fixed-capacity systems. Current Phase 4 experiments in an instrumented lab home with simulated occupancy evaluate the impact of duct R-value enhancement on the overall operating efficiency of the variable-capacity system compared to the fixed-capacity system.

BA-PIRC↗

DOE OSTI2017

Building America Case Study: Impact of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps, Cocoa, Florida

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DOE OSTI2017

Building America Case Study: Assessment of a Hybrid Retrofit Gas Water Heater

ARBI↗

DOE OSTI2017

Building America Case Study: Energy Efficient Management of Mechanical Ventilation and Relative Humidity in Hot-Humid Climates, Cocoa, Florida

In hot and humid climates, it is challenging to energy-efficiently maintain indoor RH at acceptable levels while simultaneously providing required ventilation, particularly in high performance low cooling load homes. The fundamental problem with solely relying on fixed capacity central cooling systems to manage moisture during low sensible load periods is that they are oversized for cooler periods of the year despite being 'properly sized' for a very hot design cooling day. The primary goals of this project were to determine the impact of supplementing a central space conditioning system with 1) a supplemental dehumidifier and 2) a ductless mini-split on seasonal energy use and summer peak power use as well as the impact on thermal distribution and humidity control inside a completely furnished lab home that was continuously ventilated in accordance with ASHRAE 62.2-2013.

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DOE OSTI2016

Building America Case Study: Columbia County Habitat for Humanity Passive Townhomes, Hudson, New York

Columbia County (New York) Habitat for Humanity built a pair of townhomes to Passive House criteria with the purpose of exploring approaches for achieving Passive House performance and to eventually develop a prototype design for future projects. The project utilized a 2x6 frame wall with a structural insulated panel curtain wall and a ventilated attic over a sealed OSB ceiling air barrier. Mechanical systems include a single head, wall mounted ductless mini-split heat pump in each unit and a heat recovery ventilator. Costs were $26,000 per unit higher for Passive House construction compared with the same home built to ENERGY STAR version 3 specifications, representing about 18 percent of total construction cost. This report discusses the cost components, energy modeling results and lessons from construction. Two alternative ventilation systems are analyzed: a central system; and, a point-source system with small through-wall units distributed throughout the house. The report includes a design and cost analysis of these two approaches.

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DOE OSTI2017

Building America Case Study: Occupant Comfort from a Mini-Split Heat Pump, San Antonio, Texas

IBACOS worked with builder Imagine Homes to evaluate the performance of an occupied new construction test house following construction of the house in the hot, humid climate of San Antonio, Texas. The project measures the effectiveness of a space conditioning strategy using a multihead mini-split heat pump (MSHP) system in a reduced-load home to achieve acceptable comfort levels (temperature and humidity) and energy performance. IBACOS collected long-term data and analyzed the energy consumption and comfort conditions of the occupied house after one year of operation. Although measured results indicate that the test system provides comfort both inside and outside the ASHRAE Standard 55-2010 range, the occupants of the house claimed both adequate comfort and appreciation of the ease of use and flexibility of the installed MSHP system. IBACOS also assisted the builder to evaluate design and specification changes necessary to comply with Zero Energy Ready Home, but the builder chose to not move forward with it because of concerns about the 'solar ready' requirements of the program.

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DOE OSTI2016

Building America Case Study: The Impact of Thermostat Placement in Low-Load Homes in Sunny Climates, Denver, Colorado

Modern, energy-efficient homes conforming to the Zero Energy Ready Home standard face the challenge of meeting high customer expectations for comfort. Traditional heating, ventilation, and air conditioning (HVAC) sizing and control strategies may be insufficient to adequately condition each zone due to unique load patterns in each room caused by a number of factors. These factors include solar heat gains, occupant-related gains, and gains associated with appliances and electronics. Because of shrinking shell loads, these intermittent factors are having an increasingly significant impact on the thermal load in each zone. Consequently, occupant comfort can be compromised. To evaluate the impact of climate and house geometry, as well as HVAC system and control strategies on comfort conditions, IBACOS analyzed the results of 99 TRNSYS multiple-zone simulations. The results of this analysis indicate that for simple-geometry and single-story plans, a single zone and thermostat can adequately condition the entire house. Demanding house geometry and houses with multiple stories require the consideration of multiple thermostats and multiple zones.

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DOE OSTI2015

Building America Case Study: Field Performance of Inverter-Driven Heat Pumps in Cold Climates - Connecticut, Massachusetts, and Vermont

New inverter-driven ASHPs are gaining ground in colder climates. These systems operate at sub-zero temperatures without the use of electric resistance backup. There are still uncertainties, however, about cold-climate capacity and efficiency in cold weather and questions such as measuring: power consumption, supply, return, and outdoor air temperatures, and air flow through the indoor fan coil. CARB observed a wide range of operating efficiencies and outputs from site to site. Maximum capacities were found to be generally in line with manufacturer's claims as outdoor temperatures fell to -10 degrees F. The reasons for the wide range in heating performance likely include: low indoor air flow rates, poor placement of outdoor units, relatively high return air temperatures, thermostat set back, integration with existing heating systems, and occupants limiting indoor fan speed. Even with lower efficiencies than published in other studies, most of the heat pumps here still provide heat at lower cost than oil, propane, or certainly electric resistance systems.

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DOE OSTI2017

Building America Case Study: Assessment of a Hybrid Retrofit Gas Water Heater

This project completed a modeling evaluation of a hybrid gas water heater that combines a reduced capacity tankless unit with a downsized storage tank. This product would meet a significant market need by providing a higher efficiency gas water heater solution for retrofit applications while maintaining compatibility with the half-inch gas lines and standard B vents found in most homes. The TRNSYS simulation tool was used to model a base case 0.60 EF atmospheric gas storage water, a 0.82 EF non-condensing gas tankless water heater, an existing (high capacity) hybrid unit on the market, and an alternative hybrid unit with lower storage volume and reduced gas input requirements. Simulations were completed under a 'peak day' sizing scenario with 183 gpd hot water loads in a Minnesota winter climate case. Full-year simulations were then completed in three climates (ranging from Phoenix to Minneapolis) for three hot water load scenarios (36, 57, and 96 gpd). Model projections indicate that the alternative hybrid offers an average 4.5% efficiency improvement relative to the 0.60 EF gas storage unit across all scenarios modeled. The alternative hybrid water heater evaluated does show promise, but the current low cost of natural gas across much of the country and the relatively small incremental efficiency improvement poses challenges in initially building a market demand for the product.

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DOE OSTI2016

Building America Case Study: Southern Energy Homes, First DOE Zero Energy Ready Manufactured Home, Russellville, Alabama

Three side-by-side lab houses were built, instrumented and monitored in an effort to determine through field testing and analysis the relative contributions of select technologies toward reducing energy use in new manufactured homes.The lab houses in Russellville, Alabama compared the performance of three homes built to varying levels of thermal integrity and HVAC equipment: a baseline HUD-code home equipped with an electric furnace and a split system air conditioner; an ENERGY STAR manufactured home with an enhanced thermal envelope and traditional split system heat pump; and a house designed to qualify for Zero Energy Ready Home designation with a ductless mini-split heat pump with transfer fan distribution system in place of the traditional duct system for distribution. Experiments were conducted in the lab houses to evaluate impact on energy and comfort of interior door position, window blind position and transfer fan operation. The report describes results of tracer gas and co-heating tests and presents calculation of the heat pump coefficient of performance for both the traditional heat pump and the ductless mini-split. A series of calibrated energy models was developed based on measured data and run in three locations in the Southeast to compare annual energy usage of the three homes.

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DOE OSTI2014

Building America Case Study: Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes (Fact Sheet)

This guide provides information and recommendations to the following groups: Insulation contractors, General contractors, Builders, Home remodelers, Mechanical contractors, and Homeowners as a guide to the work that needs to be done. The order of work completed during home construction and retrofit improvements is important. Health and safety issues must be addressed first and are more important than durability issues. And durability issues are more important than saving energy. Not all techniques can apply to all houses. Special conditions will require special action. Some builders or homeowners will wish to do more than the important but basic retrofit strategies outlined by this guide. The following are best practice and product recommendations from the interviewed contractors and home builders who collectively have a vast amount of experience. Three significant items were discussed with the group which are required to make taped insulating sheathing a simple, long term, and durable drainage plane: 4. Horizontal joints should be limited or eliminated wherever possible 5. Where a horizontal joint exists use superior materials 6. Frequent installation inspection and regular trade training are required to maintain proper installation Section 5 of this measure guideline contains the detailed construction procedure for the three recommended methods to effectively seal the joints in exterior insulating sheathing to create a simple, long term, and durable drainage plane.

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DOE OSTI2016

Building America Case Study: Supplemental Ductless Mini-Split Heat Pump in the Hot-Humid Climate, Brevard and Volusia Counties, Florida

"The BAPIRC team and Florida Power and Light (FPL) electric utility pursued a pilot phased energy-efficiency retrofit program in Florida by creating detailed data on the energy and economic performance of two levels of retrofit - simple and deep. For this Phased Deep Retrofit (PDR) project, a total of 56 homes spread across the utility partner's territory in east central Florida, southeast Florida, and southwest Florida were instrumented between August 2012 and January 2013, and received simple pass-through retrofit measures during the period of March 2013 - June 2013. Ten of these homes received a deeper package of retrofits during August 2013 - December 2013. A full account of Phase I of this project, including detailed home details and characterization, is found in Parker et al, 2015 (currently in draft). Phase II of this project, which is the focus of this report, applied the following additional retrofit measures to select homes that received a shallow retrofit in Phase I: supplemental mini-split heat pump (MSHP) (6 homes), ducted and space coupled heat pump water heater (8 homes), exterior insulation finish system (EIFS) (1 homes), window retrofit (3 homes), smart thermostat (21 homes: 19 NESTs; 2 Lyrics), heat pump clothes dryer (8 homes), and variable speed pool pump (5 homes).

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DOE OSTI2016

Building America Case Study: Philadelphia Housing Authority Energy-Efficiency Turnover Protocols, Philadelphia, Pennsylvania

Over one million HUD-supported public housing units provide rental housing for eligible low-income families across the country. A survey of over 100 public housing authorities (PHAs) across the country indicated that there is a high level of interest in developing low-cost solutions that improve energy efficiency and can be seamlessly included in the refurbishment process. Further, PHAs, have incentives (both internal and external) to reduce utility bills. ARIES worked with four PHAs to develop packages of energy efficiency retrofit measures the PHAs can cost-effectively implement with their own staffs in the normal course of housing operations at the time when units are refurbished between occupancies. The energy efficiency turnover protocols emphasized air infiltration reduction, duct sealing, and measures that improve equipment efficiency. ARIES documented implementation in 18 housing units. Reductions in average air leakage were 16 percent and duct leakage reductions averaged 23 percent. Total source energy consumption savings due to implemented measures was estimated at 3-10 percent based on BEopt modeling with a simple payback of 1.6 to 2.5 years. Implementation challenges were encountered mainly related to required operational changes and budgetary constraints. Nevertheless, simple measures can feasibly be accomplished by PHA staff at low or no cost. At typical housing unit turnover rates, these measures could impact hundreds of thousands of units per year nationally.

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DOE OSTI2017

Building America Case Study: Indoor Heat Pump Water Heaters During Summer in a Hot-Dry Climate, Redding, California

Heat pump water heaters offer a significant opportunity to improve water heating performance for the over 40% of U.S. households that heat domestic hot water using electric resistance storage water heaters. Numerous field studies have also been completed documenting performance in a variety of climates and applications. More recent evaluation efforts have focused attention on the performance of May through September 2014, with ongoing winter monitoring being sponsored by California utility partners. Summer results show favorable system performance with extrapolated annual water heating savings of 1,466 to 2,300 kWh per year, based on the observed hot water loads. Additional summer space cooling benefits savings of 121 to 135 kWh per year were projected, further increasing the water heating savings by 5-9%. Given the project schedule for 2014 completion, no heating season impacts were able to be monitored. May through September 2014, with ongoing winter monitoring being sponsored by California utility partners. Summer results show favorable system performance with extrapolated annual water heating savings of 1,466 to 2,300 kWh per year, based on the observed hot water loads. Additional summer space cooling benefits savings of 121 to 135 kWh per year were projected, further increasing the water heating savings by 5-9%. Given the project schedule for 2014 completion, no heating season impacts were able to be monitored.

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DOE OSTI2014

Building America Case Study: Initial and Long-Term Movement of Cladding Installed Over Exterior Rigid Insulation (Fact Sheet)

Changes in the International Energy Conservation Code (IECC) from 2009 to 2012 have resulted in the use of exterior rigid insulation becoming part of the prescriptive code requirements. With more jurisdictions adopting the 2012 IECC builders are going to finding themselves required to incorporate exterior insulation in the construction of their exterior wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location. However, there has been a significant resistance to its widespread implementation due to a lack of research and understanding of the mechanisms involved and potential creep effects of the assembly under the sustained dead load of a cladding. This research was an extension on previous research conducted by BSC in 2011, and 2012. Each year the understanding of the system discrete load component interactions, as well as impacts of environmental loading has increased. The focus of the research was to examine more closely the impacts of screw fastener bending on the total system capacity, effects of thermal expansion and contraction of materials on the compressive forces in the assembly, as well as to analyze a full years worth of cladding movement data from assemblies constructed in an exposed outdoor environment.

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DOE OSTI2014

Building America Case Study: Lancaster County Career and Technology Center Green Home 3, Mt Joy, Pennsylvania

Transitioning from standard light frame to a thermal mass wall system in a high performance home will require a higher level of design integration with the mechanical systems. The much higher mass in the ICF wall influences heat transfer through the wall and affects how the heating and cooling system responds to changing outdoor conditions. This is even more important for efficient, low-load homes with efficient heat pump systems in colder climates where the heating and cooling peak loads are significantly different from standard construction.This report analyzes a range of design features and component performance estimates in an effort to select practical, cost-effective solutions for high performance homes in a cold climate. Of primary interest is the influence of the ICF walls on developing an effective air sealing strategy and selecting an appropriate heating and cooling equipment type and capacity. The domestic water heating system is analyzed for costs and savings to investigate options for higher efficiency electric water heating. A method to ensure mechanical ventilation air flows is examined. The final solution package includes high-R mass walls, very low infiltration rates, multi-stage heat pump heating, solar thermal domestic hot water system, and energy recovery ventilation. This solution package can be used for homes to exceed 2012 International Energy Conservation Code requirements throughout all climate zones and achieves the DOE Challenge Home certification.

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DOE OSTI2014

Building America Case Study: Advanced Boiler Load Monitoring Controllers, Chicago, Illinois (Fact Sheet)

Beyond these initial system efficiency upgrades are an emerging class of Advanced Load Monitoring (ALM) aftermarket controllers that dynamically respond to the boiler load, with claims of 10% to 30% of fuel savings over a heating season. For hydronic boilers specifically, these devices perform load monitoring, with continuous measurement of supply and in some cases return water temperatures. Energy savings from these ALM controllers are derived from dynamic management of the boiler differential, where a microprocessor with memory of past boiler cycles prevents the boiler from firing for a period of time, to limit cycling losses and inefficient operation during perceived low load conditions. These differ from OTR controllers, which vary boiler setpoint temperatures with ambient conditions while maintaining a fixed differential. PARR installed and monitored the performance of one type of ALM controller, the M2G from Greffen Systems, at multifamily sites in the city of Chicago and its suburb Cary, IL, both with existing OTR control. Results show that energy savings depend on the degree to which boilers are over-sized for their load, represented by cycling rates. Also savings vary over the heating season with cycling rates, with greater savings observed in shoulder months. Over the monitoring period, over-sized boilers at one site showed reductions in cycling and energy consumption in line with prior laboratory studies, while less over-sized boilers at another site showed muted savings.

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DOE OSTI2017

Building America Case Study: Simple Retrofit High-Efficiency Natural Gas Water Heater Field Test, Minneapolis, Minnesota

High performance water heaters are typically more time consuming and costly to install in retrofit applications, making high performance water heaters difficult to justify economically. However, recent advancements in high performance water heaters have targeted the retrofit market, simplifying installations and reducing costs. Four high efficiency natural gas water heaters designed specifically for retrofit applications were installed in single-family homes along with detailed monitoring systems to characterize their savings potential, their installed efficiencies, and their ability to meet household demands. The water heaters tested for this project were designed to improve the cost-effectiveness and increase market penetration of high efficiency water heaters in the residential retrofit market. The retrofit high efficiency water heaters achieved their goal of reducing costs, maintaining savings potential and installed efficiency of other high efficiency water heaters, and meeting the necessary capacity in order to improve cost-effectiveness. However, the improvements were not sufficient to achieve simple paybacks of less than ten years for the incremental cost compared to a minimum efficiency heater. Significant changes would be necessary to reduce the simple payback to six years or less. Annual energy savings in the range of $200 would also reduce paybacks to less than six years. These energy savings would require either significantly higher fuel costs (greater than $1.50 per therm) or very high usage (around 120 gallons per day). For current incremental costs, the water heater efficiency would need to be similar to that of a heat pump water heater to deliver a six year payback.

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