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Inequities in the built environment have long persisted in communities around the world. Prior studies have exposed that energy retrofit programs invest inequitably in residential buildings, leaving racial minorities with disproportionately less energy inefficient homes, regardless of income level. This inequity in energy performance and retrofit investments has yet to be studied for commercial and institutional buildings. Further research has shown that tree canopy coverage and vegetation is less dense in historically disadvantaged communities, contributing to a greater urban heat island effect and corresponding higher energy consumption for cooling compared to historically advantaged communities. Moreover, there is limited albeit emerging research that utilizes granular socioeconomic data with fine temporal scale energy consumption data to help identify energy inequalities among race and income groups. This paper examines the differential impact of energy efficiency retrofit installation on energy performance between advantaged vs. disadvantaged groups using data from U.S. public school buildings. Additionally, it studies how the effect of retrofits is compounded by the presence of vegetation surrounding the building. Utilizing hourly interval smart meter data from primary and secondary school buildings in California, the impact of retrofits are quantified using three energy metrics. Then the disparities in retrofit impact for advantaged vs. disadvantaged groups (as defined by three equity metrics) are evaluated using school-level demographic data. Lastly, regression on the percent change in monthly energy consumption from the pre-retrofit to post-retrofit period is used to quantify the incremental benefits of retrofits compounded by vegetation. Findings show that energy efficiency retrofits can improve energy performance and reduce energy inequities. Specifically, retrofits significantly increase energy efficiency and reduce the energy efficiency equity gap by up to 198%. Evidence shows that vegetation surrounding a building has a synergistic effect with mechanical retrofits for reducing energy consumption in respect to reduced cooling loads, even in cases where mechanical retrofits alone resulted in significant increases in energy consumption. Dense vegetation provides around 6% energy savings, similar in magnitude to savings from mechanical retrofit installation. This validates the effectiveness of retrofits for reducing energy consumption and improving energy equity, and demonstrates the ability of vegetation to provide additional energy savings beyond mechanical interventions. [ABSTRACT FROM AUTHOR]

• Propose a method for embedding demand flexibility into building benchmarking. • Utilizes emerging building characteristics and time-series energy data streams. • Apply method to case study of 306 buildings in Southern California, USA. • Demonstrates ability to cluster buildings by attributes of demand flexibility. • Can inform decarbonization performance-specific policy targeting for buildings. The intermittency of carbon-free renewables and the demand changes associated with the widespread push for electrifying the transportation and building sectors provides an opportunity for buildings to go beyond energy efficiency and push towards providing demand flexibility to the electricity grid. The duality of energy efficiency and demand flexibility is necessary for success in a sustainable and reliable energy transition. Current building energy benchmarking models are limited in their ability to integrate concepts of demand flexibility and/or utilize granular smart meter data. Thus, current benchmarking methods are focused annual energy usage and fail to incorporate how the time of use of energy consumption impacts emissions in a quickly changing energy grid. Without a more comprehensive view of energy usage and associated real-time emissions, current benchmarking methods are unlikely to realize the full decarbonization potential of buildings. New emerging data streams provide an opportunity to develop a new generation of benchmarking energy models that embed dimensions of energy efficiency, grid interactivity, and demand flexibility into their analysis. In this paper, we propose a four-step method for embedding grid interactivity and demand flexibility into building benchmarking models that utilizes emerging building and time-series electricity data streams. We first engineer features to produce a mix-type dataset that encompasses many attributes of grid-interactive and efficient buildings, and then we apply K-medoids using Gower's Distance to produce peer-group clusters. We apply the method to a case study of 306 primary and secondary schools in southern California, USA. The results show that the method effectively clusters buildings by attributes of demand flexibility and energy efficiency. The clustering results reveal patterns in inefficient building operations and demand inflexibility at the building peer group level. The interpretation of clusters can serve as an integrated energy efficiency and demand flexibility benchmarking model and inform performance-specific policy targeting for buildings that go beyond traditional efficiency measures. [ABSTRACT FROM AUTHOR]

• Zero net energy is feasible when clean fuel is combined with electrification. • Building energy consumption valuation method impacts the component sizing. • Time dependent valuation of energy in California reflects its cost and emissions. • Solid oxide fuel cell provides efficient electricity and heat at the building. • Building can go off-grid with optimized operation of battery and fuel cell. California is seeking to mandate Zero Net Energy (ZNE) buildings by 2030 as part of its efforts to combat climate change. A ZNE building is required to compensate its annual energy consumption from the grid (electricity or gas) by injecting clean electricity back to the grid. So far, the most common approach for a ZNE building is utilizing solar photovoltaic (PV) or a PV and battery energy storage system. One key problem is the feasibility of installing PV if the surface area requirement is too large to achieve ZNE; another issue is grid congestion during the off-peak hours of midday when a large number of houses export their excess solar power to the grid. Hence, other ZNE home scenarios need to be evaluated to tackle these restrictions in achieving California's climate goals. In this work, we proposed and evaluated different system arrangements to reduce the required PV installation that is commonly installed as power generation source for ZNE residential units in California. The aim of this technical analysis is to provide a societal level policy guidance to accelerate fulfilling the ZNE home mandate. Due to the availability of the gas grid and potential for having more renewable gas in the grid, we investigated using gas-based heat generation versus only electric-based heat appliances. In addition, we incorporated a residential solid oxide fuel cell (SOFC) on the building site as a micro combined heat and power (mCHP) to facilitate achieving ZNE. The impact and contributions of different components, including energy storage, on grid-dependence, and the overall energy demand are also studied. With analysis of different mix of technologies that could be used for a ZNE home, we propose the potential solutions and discuss their strengths and weakness. In this paper, energy performance and optimal PV capacity are assessed for a ZNE home in all 16 climate zones of California established by California Energy Commission (CEC). The ZNE measurements for all four scenarios are based on three metrics of energy evaluation: (1) site energy (energy measured by the meter used at the building site); (2) source energy (raw fuel consumption at the source of energy generation to account for energy loss in production and distribution); and (3) time dependent valuation (TDV) of energy, which has been developed by the CEC to comply with its building energy efficiency standards. The TDV of each energy type depends on the time of use, climate, grid constraints, and other factors that reflect its societal value at any given hour of the year. The PV size required by each ZNE metric is calculated and compared. The results proved that relying on some gas in addition to electricity improves the practicality of required PV for ZNE homes particularly in regions with high heating demands. It was found that depending on the energy metric (site, source, and TDV), a different arrangement is required for the most efficient ZNE performance. Unlike the site metric, using source and TDV metrics where electricity is more valuable than gas shows that having both gas and electricity significantly reduces the PV size. This encourages investment in introduction of more renewable gas in the grid as one possible solution to achieving ZNE in individual homes. The great impact of an mCHP SOFC on a ZNE home in terms of reliability and feasibility points to the need for research, development, and commercialization to reduce the cost of mCHP SOFCs in residential application. Also, the addition of a battery does not reduce the PV size with site and source metrics; it only reduces the electric grid reliance. However, with TDV, where the time of energy consumption affects its value, not only does it reduce grid reliance during peak hours, but also less PV is required to achieve ZNE. [ABSTRACT FROM AUTHOR]