US Residential Sector Research Articles

Searching for Suitable Binary Fluid for an Ejector Heat Pump for Domestic Water Heating

Abstract Water heating is a major source of energy consumption in the U.S. residential sector. Heat pumps can significantly increase the energy efficiency of water heating. An ejector heat pump (EHP) is a novel, thermally driven heat pump that uses an ejector as a thermocompressor. Choosing suitable working fluids is critical in developing high-performance EHPs. Therefore, this research screens binary fluid pairs (BFPs) for EHPs to produce domestic hot water at a high coefficient of performance (COP). The criteria for screening BFP candidates for EHP water heaters (EHPWHs) are established, and BFP candidates are shortlisted. This study identifies HFE7000, Novec649, HFE7100, HFE7200, and HFE7500 for the primary fluids and RE170, R600a, R600, and R1234ze(Z) for the secondary fluids. The thermodynamic model is employed to investigate the performance of EHPWHs using the shortlisted BFPs under various operating parameters, including the evaporation pressure of the primary working fluid in the high-temperature evaporator and the condensation temperature. The highest heating-cycle COP of 1.328 is achieved by an EHPWH operating with HFE7000/R600 at a condenser temperature of 50 °C and a pressure of 1.69 MPa in the high-temperature evaporator.

Decarbonization pathways for the residential sector in the United States

Residential GHG emissions in the United States are driven in part by a housing stock where onsite fossil combustion is common, home sizes are large by international standards, energy efficiency potential is large and electricity generation in many regions is GHG intensive. In this analysis, we assess decarbonization pathways for the US residential sector to 2060, through 108 scenarios describing housing stock evolution, new housing characteristics, renovation levels and clean electricity. The lowest emission pathways involve very rapid decarbonization of electricity supply alongside extensive renovations to existing homes, including improving thermal envelopes and heat pump electrification of heating. Reducing the size and increasing the electrification of new homes provide further emission cuts and combining all strategies enables reductions of 91% between 2020 and 2050. The potential of individual mitigation strategies shows great regional variation. Reaching zero emissions will require simultaneous deployment of multiple strategies and greater reduction of embodied emissions. Residential sector decarbonization is an essential part of mitigation, especially in the United States where per capita energy use is high by global standards. This article shows the emission reduction potential from individual and combined strategies applied to existing and new homes and to electricity supply.

Energy efficiency and the role of energy-related financial literacy: evidence from the European residential sector

In this paper, we analyze the level of efficiency in the use of electricity in the European residential sector relying on a cross-sectional data set comprised of 1375 households located in Italy, the Netherlands, and Switzerland and observed in 2016. To do this, we estimate an electricity demand frontier function using a stochastic frontier approach. The empirical results show that the residential sector in these three European countries could save approximately 20% of its total electricity consumption on average if it improves the level of efficiency in the use of electricity. These figures are in line with recent studies for Switzerland and for the US residential sector. Moreover, we link energy efficiency to energy-related financial literacy. We find that while energy-relevant knowledge per se does not play a significant role, stronger cognitive abilities are associated with higher levels of energy efficiency.

Application of Prevention through Design (PtD) to improve the safety of solar installations on small buildings

As a viable, clean and renewable energy resource, solar energy has gained a significant interest in the US residential sector. Most solar systems are installed on rooftops to take advantage of available space and reduce land use. However, this installation environment also exposes workers to unique safety hazards related to existing roof conditions such as slippery roofing materials, irregular roof layouts, and steep roof slopes. Although Prevention through Design (PtD) has been widely considered as an effective way to address safety issues during the design phase, little to no studies have applied PtD to improve safety in solar energy installations. To fill this knowledge gap, this research aimed to investigate how, during the design phase, to address the safety concerns of solar workers when installing solar energy systems on residential buildings. Through a series of interviews, four case studies, and a seminar, seven solar PtD attributes were identified: roofing materials, roof slopes, roof accessories, panel layouts, fall protection systems, lifting methods and electrical systems. Based on the attributes, a PtD protocol was developed that can serve as guidance for implementing PtD in solar installations. This paper presents the research activities and findings, and feedback gained from solar contractors through a seminar on the study. The study is expected to contribute to reducing safety hazards by implementing PtD, help improve safety performance in solar installations on small residential buildings and support the promotion of safety in sustainable construction.

Notes on the Economics of Residential Hybrid Energy System

Despite advances in small-scale hybrid renewable energy technologies, there are limited economic frameworks that model the different decisions made by a residential hybrid system owner. We present a comprehensive review of studies that examine the techno-economic feasibility of small-scale hybrid energy systems, and we find that the most common approach is to compare the annualized life-time costs to the expected energy output and choose the system with the lowest cost per output. While practical, this type of benefit–cost analysis misses out on other production and consumption decisions that are simultaneously made when adopting a hybrid energy system. In this paper, we propose a broader and more robust theoretical framework—based on production and utility theory—to illustrate how the production of renewable energy from multiple sources affects energy efficiency, energy services, and energy consumption choices in the residential sector. Finally, we discuss how the model can be applied to guide a hybrid-prosumer’s decision-making in the US residential sector. Examining hybrid renewable energy systems within a solid economic framework makes the study of hybrid energy more accessible to economists, facilitating interdisciplinary collaborations.

Transient and persistent energy efficiency in the US residential sector: evidence from household-level data

In this paper, we measure the energy efficiency implicit in residential energy consumption using a panel dataset comprised of 40,246 observations from US households observed over 1997–2009. We fit a stochastic frontier model of the minimum input of energy needed to meet the level of energy services demanded by the household. This benchmarking exercise produces a transient and a persistent efficiency index for each household and each time period. We estimate that the US residential sector could save approximately 10% of its total energy consumption if it reduced persistent inefficiencies and 17% if it were possible to eliminate transient inefficiencies. These figures are in line with recent economy-wide assessments for the USA. Our results suggest that savings in energy use and associated emissions of greenhouse gases may benefit from both policy measures that attain short-run behavioral changes (e.g., nudges, social norms, display of real-time information about usage, and real-time pricing) as well measures aimed at the long run, such as energy-efficiency regulations, incentives on the purchase of high-efficiency equipment, and incentives towards a change of habits in the use of the equipment.

Co-benefits of global, domestic, and sectoral greenhouse gas mitigation for US air quality and human health in 2050

Reductions in greenhouse gas (GHG) emissions can bring ancillary benefits of improved air quality and reduced premature mortality, in addition to slowing climate change. Here we study the co-benefits of global and domestic GHG mitigation on US air quality and human health in 2050 at fine resolution using dynamical downscaling of meteorology and air quality from global simulations to the continental US, and quantify for the first time the co-benefits from foreign GHG mitigation. Relative to the reference scenario from which Representative Concentration Pathway 4.5 (RCP4.5) was created, global GHG reductions in RCP4.5 avoid 16 000 PM2.5-related all-cause deaths yr−1 (90% confidence interval, 11 700–20 300), and 8000 (3600–12 400) O3-related respiratory deaths yr−1 in the US in 2050. Foreign GHG mitigation avoids 15% and 62% of PM2.5-and O3-related total avoided deaths, highlighting the importance of foreign mitigation for US health. GHG mitigation in the US residential sector brings the largest co-benefits for PM2.5-related deaths (21% of total domestic co-benefits), and industry for O3 (17%). Monetized benefits for avoided deaths from ozone and PM2.5 are $137 ($87–$187) per ton CO2 at high valuation and $45 ($29–62) at low valuation, of which 31% are from foreign GHG reductions. These benefits likely exceed the marginal cost of GHG reductions in 2050. The US gains significantly greater air quality and health co-benefits when its GHG emission reductions are concurrent with reductions in other nations. Similarly, previous studies estimating co-benefits locally or regionally may greatly underestimate the full co-benefits of coordinated global actions.

The indirect role of households in shaping US residential energy demand patterns

About a quarter of US energy demand is for domestic use. Yet an understanding of the processes, determinants, and consequences of household energy demand remains elusive. Conventional energy policy has overwhelmingly focused on improving energy efficiency of the buildings. This research applies a non-linear methodology and an interdisciplinary approach to household energy demand. Using data from the US residential sector (2009 Residential Energy Consumption Survey), this research performs Covariance Structure Analysis to isolate direct and indirect effects of household and housing characteristics on total annual domestic energy use. Outcomes uncover some of households' indirect effects on energy demand, which in this research mainly happen through household effects on building characteristics, highlighting the indirect role of household choices in shaping residential energy demand patterns. To maximize its efficiency in reducing energy demand and GHG emissions, this paper suggests that in addition to investing in energy efficient technologies, energy policy should incorporate indirect effects of household choices on the configuration of their future homes.

Differences in Residential Energy Use between US City and Suburban Households

Estiri H. Differences in residential energy use between US city and suburban households, Regional Studies. This paper applies path analysis to household-level data from the US residential sector to study differences in energy consumption between self-identified city and suburban households. Results show that, on average, suburban households consume more energy in residential buildings than their city-dweller counterparts. This variation in energy consumption is due to differences in: (1) characteristics of the household and the housing unit, independently, and (2) interactions between the household and housing characteristics in the city and suburban households. Findings of this study provide new insights into how regional policies can be implemented differently in suburbs and cities to reduce energy consumption.

Transient and Persistent Energy Efficiency in the US Residential Sector: Evidence from Household-level Data

In this paper, we measure the energy efficiency in residential energy consumption using a panel dataset comprised of 40,246 observations from US households observed over 1997-2009. We fit a stochastic frontier model of the minimum input of energy needed to meet the level of energy services demanded by the household. This benchmarking exercise produces a transient and a persistent efficiency index for each household and each time period. We estimate that the US residential sector could save approximately 10% of its total energy consumption if it reduced persistent inefficiencies and 17% if it was able to eliminate transient inefficiencies. These figures are in line with the assessment by McKinsey (2008, 2009, 2013) and greater than those indicated by the Electric Power Research Institute (2009). They suggest that savings in energy use and associated emissions of greenhouse gases (and other pollutants) may benefit from both policy measures that attain short-run behavioral changes (e.g., nudges, social norms, display of real-time information about usage, and real-time pricing) as well measures aimed at the long run, such as energy-efficiency regulations, incentives on the purchase of high-efficiency equipment and incentives towards a change of habits in the use of the equipment.

Buying down our carbon footprint: An econometric analysis of the impact of green pricing programs on electricity consumption in the US residential sector

Rising global temperatures caused by carbon dioxide emissions have created environmental and health risks worldwide. Many state governments have rallied around green pricing programs to incentivize energy conservation and reduce CO2 emissions by requiring utilities to make these programs available to their customers. By buying green power, customers increase demand, and in turn supply, for renewable energy production; thereby shifting electricity consumption and generation from carbon to non-carbon energy sources. Green pricing programs show promise particularly in urban areas, where high population density increases energy demand. This study examines whether these programs have the potential to reduce electricity consumption in the residential sector, which accounts for approximately 21% of the total energy consumption in the United States. Employing state- and time-fixed effects regression, the results of this analysis show that participation in GPPs has a statistically significant negative correlation with residential electricity consumption rates; indicating that green pricing programs may reduce electricity consumption, thereby mitigating environmental impacts associated with generating electricity. However, results also show that GPP participation rates would need to increase by over 300% to achieve even relatively small reductions in electricity consumption. Further research and analysis can identify program features to improve participation rates, as well as find ways to strengthen program efficacy in delivering greater energy savings.

Reducing energy consumption in low income public housing: Interviewing residents about energy behaviors

Low-income housing constitutes an important but often overlooked area for energy use reductions within the US residential sector. Given the scarcity of existing information on this subject, this study uses a semi-structured interview format to explore the key behavioral tendencies, energy knowledge gaps, and attitudes among low-income public housing residents, with the goal of demonstrating a process for developing, scoring, and analyzing the interviews that will be useful to other researchers when first engaging complex subjects like behavior in contexts that are not well covered by existing literature. Methods for sampling subjects and iteratively developing an interview guide and response-scoring framework are described, and the usefulness of this approach in allowing both quantitative and qualitative analysis of behavior response data is demonstrated. The paper concludes by illustrating how themes that emerge from the response analysis can be used to inform future surveying and intervention efforts. Key themes include the varying definitions for “comfort” amongst residents; the lack of resident control over the household environment; the tendency for residents to evaluate energy conservation measures (ECMs) in terms of costs, savings, and comfort; the muted differences in behavior between those who do and do not pay energy bills; and the importance of building maintenance and resident energy education to ongoing efficiency efforts.

Household energy consumption: a study of the role of occupants

To what extent is energy performance determined by interactions between occupants, behaviour and buildings systems, as well as building and climate characteristics? The purpose of this paper is to establish which factors, and to what extent, affect the energy performance of a housing stock. The US residential sector is used to test the relative roles of socio-economic and behavioural aspects of occupants, as compared with climatic and physical building characteristics. Household heating and cooling energy consumption is investigated using an existing extensive survey, the Residential Energy Consumption Survey (RECS) by the US Department of Energy. This data set consists of information on actual energy consumption along with detailed energy-related characteristics of the housing units and their occupants. The paper presents a statistical analysis of the housing stock and assesses the relative roles of variables on energy use. Regression models and path analysis are used to determine the significance of parameters and their interrelationships. Results reveal that apart from climate, occupant behavioural aspects and socio-economic aspects are critical, partly directly and also significantly indirectly through their influence on choices and decisions about the physical characteristics of buildings and systems. Models are created for the analysis of heating and cooling energy that can be used to explore energy-related policies. Dans quelle mesure la performance énergétique est-elle déterminée par les interactions entre les occupants, le comportement et les systèmes des bâtiments, ainsi que par les caractéristiques de la construction et du climat? L'objet de cet article est de déterminer les facteurs qui ont une incidence sur la performance énergétique d'un parc de logements, et ce, dans quelle mesure. Le secteur résidentiel américain est utilisé pour tester les rôles respectifs des aspects socioéconomiques et comportementaux des occupants, par comparaison avec les caractéristiques climatiques et physiques des bâtiments. La consommation énergétique domestique utilisée pour chauffer et refroidir les logements est étudiée en utilisant une vaste enquête existante du Ministère de l'Energie américain, l'Enquête sur la Consommation d'Energie du Secteur Résidentiel (RECS). Ce jeu de données consiste en des informations portant sur la consommation réelle d’énergie, ainsi que sur les caractéristiques détaillées, liées à l’énergie, des unités d'habitation et de leurs occupants. L'article présente une analyse statistique du parc de logements et évalue les rôles respectifs des variables sur l'utilisation d’énergie. Des modèles de régression et une analyse des pistes causales sont utilisés afin de déterminer l'importance des paramètres et leurs interrelations. Les résultats révèlent que, le climat mis à part, les aspects comportementaux et les aspects socioéconomiques des occupants sont cruciaux, pour partie directement, mais également indirectement, de manière significative, par leur influence sur les choix et les décisions touchant aux caractéristiques physiques des bâtiments et des systèmes. Il est créé des modèles permettant d'analyser l’énergie servant au chauffage et au refroidissement, qui peuvent être utilisés afin d’étudier les politiques énergétiques pouvant être menées. Mots clés: comportement, parc bâti, consommation d’énergie, logement, habitant, résidentiel, États-Unis

Reducing greenhouse gas emissions by inducing energy conservation and distributed generation from elimination of electric utility customer charges

This paper quantifies the increased greenhouse gas emissions and negative effect on energy conservation (or “efficiency penalty”) due to electric rate structures that employ an unavoidable customer charge. First, the extent of customer charges was determined from a nationwide survey of US electric tariffs. To eliminate the customer charge nationally while maintaining a fixed sum for electric companies for a given amount of electricity, an increase of 7.12% in the residential electrical rate was found to be necessary. If enacted, this increase in the electric rate would result in a 6.4% reduction in overall electricity consumption, conserving 73 billion kW h, eliminating 44.3 million metric tons of carbon dioxide, and saving the entire US residential sector over $8 billion per year. As shown here, these reductions would come from increased avoidable costs, thus leveraging an increased rate of return on investments in energy efficiency, energy conservation behavior, distributed energy generation, and fuel choices. Finally, limitations of this study and analysis are discussed and conclusions are drawn for proposed energy policy changes.

Projected regional impacts of appliance efficiency standards for the US residential sector

Minimum efficiency standards for residential appliances have been implemented in the US for a large number of residential end-uses. This analysis assesses the potential energy, dollar, and carbon impacts of those standards at the state and national levels. We explicitly account for improvements in efficiency likely to occur in the absence of standards, but because our method for characterizing these exogenous improvements probably overestimates them, both the energy and cost savings presented in this article represent lower bounds to the true benefits. Cumulative present-valued dollar savings after subtracting out the additional cost of the more efficient equipment are about $30 billion from 1990 to 2010. Each dollar of federal expenditure on implementing the standards will contribute $165 of net present-valued savings to the US economy over the 1990 to 2010 period. Average benefit/cost ratios for these standards are about 3.5 for the US as a whole. Projected carbon reductions are approximately 9 million metric tons of carbon per year in the years from 2000 to 2010. Because these standards save energy at a cost less than the price of that energy, the resulting carbon emission reductions are achieved at negative net cost to society.

Energy Consumption and Structure of the US Residential Sector: Changes Between 1970 and 1985

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