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A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.
In January 2013 SMUD, the electric utility of Sacramento Calif., began the conceptualization and pre-engineering for a small steam energy augmentation project that would use high temperature (1000 F) Concentrating Solar Power collection technology and thermal storage to increase output of its existing 527 MWe gas fired combined cycle power plant. SMUD generation technology planners worked together with NREL and the DOE SunShot Program to try to complete such a project. Though technical challenges ultimately prevented the project from going forward, several important lessons were learned along the way. This report is a summary of lessons learned and other information which may be of help for others contemplating an Integrated Solar Combined Cycle (ISCC) retrofit.
A multi-year pilot energy efficiency retrofit project has been undertaken by Greenbelt Homes, Inc, (GHI) a 1,566 co-operative of circa 1930 and '40 homes. The three predominate construction methods of the townhomes in the community are materials common to the area and climate zone including 8” CMU block, wood frame with brick veneer and wood frame with vinyl siding. GHI has established a pilot project that will serve as a basis for decision making for the roll out of a decade-long community upgrade program that will incorporate energy efficiency to the building envelope and equipment with the modernization of other systems like plumbing, mechanical equipment, and cladding.
The improvement of existing homes in the United States can have a much greater impact on overall residential energy use than the construction of highly efficient new homes. There are over 130 million existing housing units in the U.S., while annually new construction represents less than two percent of the total supply (U.S. Census Bureau, 2013). Therefore, the existing housing stock presents a clear opportunity and responsibility for Building America (BA) to guide the remodeling and retrofit market toward higher performance existing homes. There are active programs designed to improve the energy performance of existing homes. Home Performance with ENERGY STAR (HPwES) is a market-rate program among them. BARA's research in this project verified that the New Jersey HPwES program is achieving savings in existing homes that meet or exceed BA's goal of 30%. Among the 17 HPwES projects with utility data included in this report, 15 have actual energy savings ranging from 24% to 46%. Further, two of the homes achieved that level of energy savings without the costly replacement of heating and cooling equipment, which indicates that less costly envelope packages could be offered to consumers unable to invest in more costly mechanical packages, potentially creating broader market impact.
A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).
Energy improvements in a home are often approached as one concerted effort, beginning with a simple walk-through assessment or more in-depth energy audit and followed by the installation of recommended energy measures. While this approach allows for systems thinking to guide the efforts, comprehensive energy improvements of this nature are undertaken by a relatively small number of U.S. households compared to piecemeal remodeling efforts. In this report, the U.S Department of Energy Building America Retrofit Alliance research team examines the improvement of a home’s energy performance in an opportunistic way by examining what can be done to incorporate energy efficiency measures into general remodeling work and home repair projects. This allows for energy efficiency upgrades to occur at the same time as remodeling projects. There are challenges to this approach, not the least of which being that the work will take place over time in potentially many separate projects. The opportunity to improve a home’s energy efficiency at one time expands or contracts with the scope of the remodel. As such, guidance on how to do each piece thoughtfully and with consideration for potential future projects, is critical.
In 2010, natural gas provided 54% of total residential space heating energy the U.S. on a source basis, or 3.5 Quadrillion Btu. Natural gas burned in furnaces accounted for 92% of that total, and boilers and other equipment made up the remainder. A better understanding of installed furnace performance is a key to energy savings for this significant energy usage. In this project, the U.S. Department of Energy Building America team Partnership for Advanced Residential Retrofit examined the impact that common installation practices and age-induced equipment degradation may have on the installed performance of natural gas furnaces over the life of the product, as measured by steady-state efficiency and annual efficiency. The team identified 12 furnaces of various ages and efficiencies that were operating in residential homes in the Des Moines, Iowa, metropolitan area and worked with a local heating, ventilation, and air conditioning contractor to retrieve furnaces and test them at the Gas Technology Institute laboratory for steady-state efficiency and annual efficiency. Prior to removal, system airflow, static pressure, equipment temperature rise, and flue loss measurements were recorded for each furnace as installed in the house.
Durability of the building envelope is important to new homes that are increasingly built with improved levels of airtightness. It is also important to weatherized homes such that energy savings from retrofit measures, such as air sealing, are persistent. This paper presents a comparison of air leakage measurements collected in November 2013 through March 2014, with two sets of prior data collected between 2001-2003 from 17 new homes located near Atlanta, GA, and 17 homes near Boise, ID that were weatherized in 2007-2008. The purpose of the comparison is to determine if there are changes to the airtightness of building envelopes over time. The air leakage increased in all but one of the new homes, with a mean increase of about 25%. A regression analysis was performed to describe the relationship between prior and current measurements in terms of normalized leakage (NL).
In many residential building retrofit programs, air tightening to increase energy efficiency is often constrained by safety concerns with naturally vented combustion appliances. Tighter residential buildings more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spill combustion exhaust into the living space. Several measures, such as installation guidelines, vent sizing codes, and combustion safety diagnostics, are in place with the intent to prevent backdrafting and combustion spillage, but the diagnostics conflict and the risk mitigation objective is inconsistent. This literature review summarizes the metrics and diagnostics used to assess combustion safety, documents their technical basis, and investigates their risk mitigations. It compiles information from the following: codes for combustion appliance venting and installation; standards and guidelines for combustion safety diagnostics; research evaluating combustion safety diagnostics; research investigating wind effects on building depressurization and venting; and software for simulating vent system performance.
GATEWAY demonstration report of LED wall washer retrofit lighting at the University of Maryland Clarice Smith Performing Arts Center.
Insulating roofs with dense-pack cellulose (instead of spray foam) has moisture risks, but is a lower cost approach. If moisture risks could be addressed, buildings could benefit from retrofit options, and the ability to bring HVAC systems within the conditioned space. Test houses with unvented roof assemblies were built to measure long-term moisture performance, in the Chicago area (5A) and the Houston area (2A). The Chicago-area test bed had seven experimental rafter bays, including a control vented compact roof, and six unvented roof variants with cellulose or fiberglass insulation. The interior was run at 50% RH. All roofs except the vented cathedral assembly experienced wood moisture contents and RH levels high enough to constitute failure. Disassembly at the end of the experiment showed that the unvented fiberglass roofs had wet sheathing and mold growth. In contrast, the cellulose roofs only had slight issues, such as rusted fasteners and sheathing grain raise. The Houston-area roof was an unvented attic insulated with spray-applied fiberglass. Most ridges and hips were built with a diffusion vent detail, capped with vapor permeable roof membrane. Some ridge sections were built as a conventional unvented roof, as a control. In the control unvented roofs, roof peak RHs reached high levels in the first winter; as exterior conditions warmed, RHs quickly fell. In contrast, the diffusion vent roofs had drier conditions at the roof peak in wintertime, but during the summer, RHs and MCs were higher than the unvented roof (albeit in the safe range).
There has never been a better time to launch initiatives to promote residential energy efficiency savings. Over the past several decades, residential retrofit programs have demonstrated that energy efficiency measures contribute to achieving multiple benefits, including but not limited to reductions in home energy consumption, stabilization improvements for the grid by shaving peak loads, saving consumers millions on utility bills, and significantly reducing carbon emissions. Although a number of barriers to widespread uptake of home energy upgrades persist, the lessons learned as a result of the 2009 stimulus funding1 have resulted in a set of policy approaches that create new strategies for taking residential energy efficiency to scale.2 The identification of these approaches is well timed; energy efficiency is often the least expensive and most cost effective way to comply with a variety of federal, state and local policies. This Guide is designed to help state and local policymakers to take full advantage of new policy developments by providing them with a comprehensive set of tools to support launching or accelerating residential energy efficiency programs. It is written primarily for state and local policymakers, including state and local executives, legislators, public utility commissioners, and the staff who advise them.
The purpose of the Daemen Alternative Energy/Geothermal Technologies Demonstration Project is to demonstrate the use of geothermal technology as model for energy and environmental efficiency in heating and cooling older, highly inefficient buildings. The former Marian Library building at Daemen College is a 19,000 square foot building located in the center of campus. Through this project, the building was equipped with geothermal technology and results were disseminated. Gold LEED certification for the building was awarded. 1) How the research adds to the understanding of the area investigated. This project is primarily a demonstration project. Information about the installation is available to other companies, organizations, and higher education institutions that may be interested in using geothermal energy for heating and cooling older buildings. 2) The technical effectiveness and economic feasibility of the methods or techniques investigated or demonstrated. According to the modeling and estimates through Stantec, the energy-efficiency cost savings is estimated at 20%, or $24,000 per year. Over 20 years this represents $480,000 in unrestricted revenue available for College operations. See attached technical assistance report. 3) How the project is otherwise of benefit to the public. The Daemen College Geothermal Technologies Ground Source Heat Pumps project sets a standard for retrofitting older, highly inefficient, energy wasting and environmentally irresponsible buildings that are quite typical of many of the buildings on the campuses of regional colleges and universities. As a model, the project serves as an energy-efficient system with significant environmental advantages. Information about the energy-efficiency measures is available to other colleges and universities, organizations and companies, students, and other interested parties. The installation and renovation provided employment for 120 individuals during the award period. Through the new Center, Daemen will continue to host a range of events on campus for the general public. The College does not charge fees for speakers or most other events. This has been a long-standing tradition of the College.
Under an award issued by the U.S. Department of Energy (DE-FE0031535), the Electric Power Research Institute (EPRI) is leading project to examine the technical and economic feasibility of a series of steam cycle upgrades to the two most prevalent types of U.S. coal power plants (including both subcritical and supercritical cycle configurations). The retrofit upgrade options are focused on evaluating increasing main steam and reheat steam temperatures from 1000°F (538°C) to hotter temperatures, ranging from ultra-supercritical (USC) (i.e., 1100°F or 593°C) to advanced USC (AUSC) conditions (≥1300° or 704°C) while maintaining steam pressures at their original values. By maintaining the original operating steam pressures as well as the original boiler and furnace enclosure envelopes, we aim to minimize the modifications required to the existing power plant, while still providing a significant improvement in heat rate. A unique aspect of this study is that the economic value of the heat rate improvement of each technically feasible option will be determined by detailed modeling of unit dispatch, over the remaining future plant life, in several regional power markets, using EPRI’s US-REGEN model. The capital cost estimates will be compared to the increased revenue estimated by the dispatch modeling to determine the overall economic attractiveness of each upgrade option. The results of this study have the potential to be applicable at up to 80% of the existing U.S. coal-fired power generation fleet. The project team, led by the Electric Power Research Institute, has completed the technical feasibility evaluation, and is currently executing the unit dispatch and capital cost evaluation portions of the work scope. This will describe the motivation for the project, explain the project’s structure and schedule, and provide details on the work scope and preliminary results of the technical feasibility evaluation.
Residential photovoltaic (PV) costs have fallen consistently for over a decade (Ardani et al. 2018). DOE has subsequently developed a new residential PV cost target for 2030 of $0.05/kilowatt hour (SETO 2023). Ardani et al. (2018) conclude that integrated roofing and PV (RIPV) products may be key to achieving the residential target for both new construction and retrofit residential PV. In RIPV, the PV product is incorporated into or replaces the roofing material. RIPV systems can use conventional crystalline or thin-film technologies, may be aesthetically attractive alternatives to traditional racked and mounted PV systems, and may increase building property values (Cook et al. 2023). These products also have the potential to provide customer acquisition, labor, and equipment cost savings over traditional, racked and mounted residential rooftop PV and several companies have recently introduced integrated roofing and PV (RIPV) products (Cook et al. 2023). In 2022, Tesla was the market leader, representing 94% of RIPV capacity installed in 2022 through its Solar Roof offering, while GAF Energy and its Timberline Solar product was second capturing 3% (Feldman et al. 2023). In this project, NREL analyzed three research questions: (1) How do current RIPV products compare to racked and mounted PV in terms of costs, install times and processes? (2) How are RIPV products installed and are there opportunities for cost savings? (3) What are the key barriers to expanding market opportunities for integrating solar and roofing products? In this project, we explored residential RIPV cost reduction opportunities by analyzing installation processes. Our study documented residential RIPV installations at two reroofing sites (20.52 kilowatts) and the equivalent of nine new construction sites (71.75 kW) in California through a methodology known as time and motion study. We also conducted 15 interviews with subject-matter experts to identify barriers and solutions to maximize these products' market penetration.
This technical report documents the Advanced Rooftop Unit Control End Use Savings Shapes (EUSS) measure, including providing a description of the technology, modeling methods, and the energy savings calculated from applying the measure to applicable across the US commercial building stock using ComStock to quantify its potential. Advanced rooftop unit controls (ARC) generally consist of a supply fan VFD, and controls to implement demand controlled ventilation (DCV) and air-side economizing, as a retrofit to improve energy efficiency of existing rooftop units (RTUs).
In pursuit of a net-zero-carbon emissions economy in the United States, non-powered dams (NPDs) represent a large opportunity to develop hydropower while leveraging existing infrastructure. With almost 600 NPD sites in the United States identified as having over 1 megawatt (MW) of potential capacity, only a small portion of the total potential capacity at these sites has been developed in recent years. , Conventional NPD retrofit feasibility analysis primarily focuses on the developer’s perspective but fails to consider the broader impacts of developing a dam, including on the neighboring communities. This tool, the Non-Powered Dam Hydropower Development and Ranking Opportunity Tool (NPD HYDRO), allows users to prioritize or rank NPD sites for future development based on user-defined priorities. Benefits can be evaluated in several categories: the grid, community, industry, and environment (referred to as the four impact scores in the tool as discussed in Section 2.2). In addition, the tool provides the user with a qualitative measure for the feasibility of adding energy storage during NPD conversion, specifically battery, hydrogen electrolysis, and pumped-storage hydropower (PSH). By taking a holistic approach to the potential range of benefits provided by NPD conversions with results tailored to the user’s priorities, NPD HYDRO provides the opportunity for national-level screening and enables users to focus on the sites that are most closely aligned with their interests.
This package replaces existing gas and electric resistance rooftop units (RTUs) with standard efficiency heat pump RTUs and improves roof insulation. The purpose is to couple heat pumps retrofits with an improved envelope to investigate the combined effect.