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August 31st, 2018

Lab Testing Heat Pump Water Heaters to Support Modeling Load Shifting

Heat pump water heaters have the capability to heat water during off-peak times of the day and store hot water for use during times when the demand for electricity is higher. Utilizing this strategy may provide potential cost savings for occupants by reducing energy use during the highest cost periods under TOU rates and offer the potential for demand flexibility to the utility and customer. This laboratory-based project, funded by PG&E’s Codes and Standards Program, focused on the potential impacts of performing load shifting with HWPHs in California’s Building Energy Efficiency Standards (Title 24, Part 6) and supported simulation model enhancement. The project had three objectives:

  1. Support a simulation-based study performed by Ecotope and the National Resources Defense Council (NRDC) using Ecotope’s HPWHsim model;
  2. Demonstrate the feasibility of using HPWHs for load shifting in a laboratory setting; and
  3. Identify issues that should be addressed to maximize the impact of this control strategy.

This project does not compare HPWHs to other water heating technologies in terms of price, energy savings or reductions in customer utility bills.

Three types of tests were performed on HPWHs from four manufacturers.

Selected key lessons learned included:

  • Even under the draw profile with the greatest need for load shifting, all tested HPWHs demonstrated a significant benefit to the builder for compliance with Title 24 relative to an uncontrolled HPWH, reduction in grid stress for the utility, and potential cost savings for occupants by reducing energy use during the highest cost periods under TOU rates.
  • Benefits of load shifting increased when switching from a HPWH with 50 gallons to 66 gallons of rated storage.
  • HPWH control logic is important to maximize benefits of load shifting. HPWHs favoring the compressor over the resistance element were more likely to obtain significant TDV reductions.
  • Strategies designed to improve Title 24 compliance or reduce consumer energy usage during peak TOU rate period can be in conflict with strategies intended to minimize negative grid impacts. For maximum grid benefits, HPWHs must be able to communicate with the utility, and develop load shifting strategies customized to each day based on anticipated load communicated by the utility.
  • There is potential for home builders to benefit from specifying HPWHs that have load shifting control capabilities in the Title 24, Part 6 compliance process.  When the energy system features are entered into the compliance software (CBECC-Res) used to evaluate whether the home design will achieve a passing score, or Energy Design Rating, the HPWHs with this capability will be given more credit towards compliance than those that do not. CBECC-Res currently does not provide credit for these features. Modifying CBECC-Res to provide an appropriate benefit or credit to builders would encourage industry adoption of load shifting controls.

Read this report: loadshifting_hpwhs_final_08312018

August 21st, 2018

Residential Code Readiness Project: G. J. Gardner Site Monitoring Report

PG&E’s Code Readiness subprogram (within PG&E’s Codes and Standards Program) strives to collect data on measures and technologies that will support more robust advocacy in future code cycles rulemakings as well as inform voluntary energy efficiency programs. Additionally, by encouraging residential builders and commercial building owners or developers to enlist in this effort, participants gain first-hand experience with installation, code compliance, and performance characteristics of these advanced measures. For this Code Readiness residential project located in Porterville, CA, the primary objectives of the project were to:

  • document the installed efficiency measures,
  • assess builder response to the installed measures (costs, installation issues),
  • document any commissioning data,
  • report on full year occupied home monitored energy use by end use, and
  • compare annual energy end uses to compliance model projections.

Installed measures in the 2,095 ft2 single-story home included:

  • high efficacy lighting meeting the CAHP lighting specifications,
  • a whole house fan,
  • low glazing areas (~11% of conditioned floor area),
  • a condensing gas tankless water heater located centrally to key use points,
  • high performance attic with R-19 insulation below the roof deck (meeting the recently adopted 2019 Title 24 specification),
  • 2×6 exterior wall construction with R-21 fiberglass batts,
  • a 17 SEER two-stage air conditioner,
  • a two-stage condensing gas furnace,
  • a heat recovery ventilation system for energy-efficient filtered outdoor air.

The latter five measures were supported by the PG&E Code Readiness project.

Key Project Takeaways

The builder was generally pleased with the selected measures (that were incentivized for installation) and found no significant implementation issues, although there are still concerns on whether all the measures can be adopted and marketed in a cost-competitive housing market.

Energy usage for heating and cooling were significantly higher than predicted by a CBECC-Res building simulation for the house using standard (not actual) weather data. For heating, higher indoor setpoints than assumed by the model certainly played a role. For cooling, setpoints were closer in line to the CBECC-Res model assumptions. Very limited usage of the whole house fan by the occupants likely contributed to the increased cooling loads, as would limited window operation for night ventilation.

Read this report: codereadinessmonitoringreport_gjgardner

May 21st, 2018

Energy Savings Potential and Cost-Effectiveness Analysis of High Efficiency Windows in California

High efficiency windows with U-factors below 0.25 Btu/hr-ft2-°F have historically been dismissed in California because most climates zones in the state are relatively mild, and the potential reduction in energy use has not been viewed as significant enough to justify the higher cost.

The focus of this project was on insulated, multi-pane windows with gas fill and passive coatings to control heat and solar gains. The high efficiency options were analyzed in detail to determine their technological, cost, and market readiness. Time Dependent Valuation (TDV) regulated energy savings for each option in each California climate zone was modeled in accordance with Title 24, Part 6 using the California Building Energy Code Compliance (CBECC-Res) software and California Energy Commission approved methods for evaluating potential new code requirements.

The results suggest that none of the high efficiency options are ready for broad deployment in California with the current cost structure. There may still be opportunities for utilities and others to significantly lower the installed cost of high efficiency windows by stimulating demand through financial incentives and education about non-energy benefits, such as noise reduction and improved comfort.

Read this report: Energy Savings and Cost-Effectiveness: High Efficiency Windows

May 18th, 2018

Multifamily Market Analysis

The multifamily market analysis overlays energy savings opportunities with the current and projected state of the multifamily new construction and existing building markets. The analysis provides a descriptive overview of the new construction and existing building multifamily market, including the relative proportion of market segments by location. This report summarizes opportunities for energy savings through codes and standards advancements and methods of utility program intervention that are specific to the trends and barriers for the multifamily market.

Read this report: PGE_MultifamilyMarketAnalysis_TRC_FinalReport_2018-05-18