The upgrades described above are briefly discussed below in context of the three scenarios and summarized in Table 2-7.
Scenario 1e: AC Solar/Storage Microgrid with EE Retrofits
Scenario 1e focuses on the individual home scale, with on-site generation to offset electrical use. Fossil fuel end uses are converted to electrical end uses to reduce carbon emissions and allow for electrical consumption to be offset by on-site generation. In addition the homes will leverage two types of storage. First, heat pump water heaters will be installed and set points configured to maximize thermal storage, providing hot water through the peak grid period, thereby minimizing energy consumption from the electric grid. Second, the homes will have on-site battery storage to support electrical end uses when solar production is not available. The upgrades are designed to result in zero net energy on an annual basis and a minimum
85 percent reduction in carbon dioxide equivalent (CO2e) emissions.
Scenario 2e: DC Solar/Storage/EV Microgrid with EE Retrofits
Energy retrofit Scenario 2e expands the house scale to include block-level elements. The
additional energy-efficiency features included in this scenario are new windows. The renewable generation is net metered and has the potential to be redistributed among neighbors. The block level effect is achieved with energy storage at block scale, and battery storage is eliminated from the home scale. In addition, EV charging occurs at the block scale. This scenario, with greater storage, is estimated to achieve a 90 percent CO2e reduction, as gas stoves are assumed
Scenario 3e: DC Solar/Storage/EV Microgrid with EE Retrofits
In Scenario 3e, the additional energy features are replacement of the gas stove, therefore eliminating fossil fuel end uses from the homes. In addition, a DC panel and circuit are added to each home to provide reliable energy sources. To maximize the contribution and availability of the DC grid, all commercially available major appliances and lighting will be upgraded. It is assumed that this scenario will provide 100 percent zero net energy on an annual basis, plus a significant reduction of peak demand to the grid.
Table 2-7: Upgrade Measure Summary by Scenario
Measure Description Scenario 1e Scenario 2e Scenario 3e Space Heating / Lighting High-efficacy LED High-efficacy LED DC supply for
high-efficacy LED
Duct Sealing Duct sealing Duct sealing Duct sealing Ventilation Smart ventilation
Phase 2 Energy Analysis Planning
Phase 2 Onsite Assessments and Evaluation
A home energy retrofit must be based on site-specific evaluation of the homes by a qualified energy professional to determine the upgrades and identify installation conditions. The on-site evaluation will include documentation of existing conditions, modeling the home, identification of energy-efficiency improvements, and recommendations for upgrades. In the conceptual phase, the upgrades were based on accessible information from drive-by audits, Zillow data, and assumptions based on vintage of homes and industry experience. In Phase 2, the project team will refine the recommendations through on-site audits and performance testing.
There are several standards for audits of existing buildings (CEC 2008; BPI 2008, 2014; HUD 1998; RESNET, n.d.; Enterprise, n.d.; Build It Green, n.d.) An assessment means visual
evaluation, diagnostic and Combustion Appliance Safety “Test-In” and/or “Test-Out” events, as well as energy software modeling and document submission. It specifically excludes installation or other work performed by participating contractors and/or subcontractors. Based on the assessment/audit, a project-specific scope of work will be developed that meets the project’s technical goals and incorporates the project’s specifications.
The audit will be an equivalent to an ASHRAE Level 2 audit, which is a whole-building model, as defined below (Baechler 2011).
Level 1: Site Assessment or Preliminary Audits identify no-cost and low-cost energy saving opportunities and a general view of potential capital improvements. Activities include an assessment of energy bills and a brief site inspection of your building.
Level 2: Energy Survey and Engineering Analysis Audits identify no-cost and low-cost opportunities, and also provide energy-efficiency measure recommendations in line with your financial plans and potential capital-intensive energy savings opportunities. Level 2 audits include an in-depth analysis of energy costs, energy usage, and building
characteristics, and a more refined survey of how energy is used in your building.
Level 3: Detailed Analysis of Capital-Intensive Modification Audits (sometimes referred to as an “investment grade” audit) provide solid recommendations and financial analysis for major capital investments. In addition to Level 1and Level 2 activities, Level 3 audits include monitoring, data collection, and engineering analysis.
The audit will consist of (1) data collection and diagnostic testing, (2) interviews with the tenants and owners, and (3) energy consumption modeling and utility bill analysis.
The Audit process will:
Conduct a comprehensive analysis that identifies all reasonable opportunities for energy and water conservation savings, including equipment and system retrofits and
replacement, and operations and maintenance improvements.
Gather data from diagnostic field tests and extensive site analysis. This may include visual inspection, building systems testing, spot measurements, and short-term energy monitoring.
Conduct an evaluation of the building’s integrity to identify any deficiencies that could result in health and safety hazards to residents, code violations, and/or degradation of building systems that might jeopardize the long-term viability of the building over a minimum ten-year horizon.
Conduct an intensive engineering and economic analysis to produce reliable estimates of the project’s energy and financial performance with the high confidence needed for major capital projects.
Data Collection and Diagnostic Testing
A whole-building audit is based upon building science principles. Many homes—particularly those built before Title 24 was enacted in 1978, can have leaky building enclosures, causing homeowners to use more heating or air conditioning to maintain a comfortable indoor temperature. The outcome of a whole-building audit can encourage residents to think about their house as a complete system, a “whole house,” rather than focusing on individual elements.
The concept is to seal and insulate the house first, and then install heating and cooling systems that are correctly sized for the upgraded condition of the home.
The auditor will inspect, evaluate, and analyze the home and engage with the homeowners to document existing conditions and refine recommended upgrades consistent with the Building Performance Institute Standard Practice for Basic Analysis of Buildings (BPI 2008, 2017). An audit will include the following: (1) measure the home to determine square footage and conditioned floor area, wall area, and glazing area, (2) document existing conditions of
envelope and equipment and appliances, (3) complete any test-in diagnostics as necessary (i.e., combustion safety, blower door and/or duct leakage), and (4) interview occupants to get insight into operations and maintenance issues. The auditor will use this information to develop an energy consumption model, evaluate energy efficiency recommendations, and produce a report that can be easily read and understood by the residents.
“Test-in” helps define an energy use baseline and comprehensive work scope, including repair of existing health or safety issues discovered. “Test-out” documents that specified
improvements have been properly sized and installed, performance-based measure data are tested and modeled, and safety tests have been successfully completed.
An energy upgrade project can be enhanced by including measures that enhance indoor air quality, water efficiency, and resource conservation, and capitalize on possible environmental advantages based on the home’s location. On average, Americans spend 90 percent of their time indoors, yet the air inside our homes can be 10 times more polluted than the outdoor air, according to the U.S. Environmental Protection Agency (1989). Children are particularly
vulnerable when it comes to air pollution. In addition to combustion safety concerns, airtight homes may present potential hazards as a result of existing building materials which emit toxic particles and can affect occupant health. Low toxicity or low-VOC materials and mechanical ventilation will be integrated into the upgrades.
With California residences using more than 5.6 million-acre feet of applied water annually, lower water consumption also translates to reduced energy required to pump water for distribution and reduced energy and other inputs required at water treatment facilities. A reduction from 232 gallons per day per capita in 1995 to 178 gallons in 2010 (Mount 2016)
demonstrates the impact of lower-flow water fixtures for urban water use. Upgrading older infrastructure in existing homes can continue to drive down water use. Lower hot water consumption translates to lower energy and water bills.
Further, residential remodeling activities consume large quantities of wood, water, metals, fossil fuels, and other resources. These projects will include construction and debris plans for recycling and reuse as construction and demolition waste comprises 21 to 25 percent of the waste stream in California (Cascadia Consulting Group 2015). All upgrades will meet minimum requirements as defined in the appropriate California Green Building Code (California Building Standards Commission 2016). These requirements will be defined in the full specifications documents.