Research Strategy: Residential Ductless Heat Pumps Research and Evaluation Subcommittee Christian Douglass and Josh Rushton January 8, 2016

Overview This presentation focuses on a Research Strategy related to residential ductless heat pumps (DHPs) Research would affect multiple RTF measures – Residential Heating/Cooling – DHP for Zonal Heat SF (Proven UES) Residential Heating/Cooling – DHP for Zonal Heat SF – Residential Heating/Cooling – DHP for Zonal Heat MH (Small Saver UES) Residential Heating/Cooling – DHP for Zonal Heat MH – Residential Heating/Cooling – DHP for Forced Air Furnace SF and MH (Planning UES) Residential Heating/Cooling – DHP for Forced Air Furnace SF and MH – Any other measures that may require a DHP to be modeled (e.g., ENERGY STAR home with DHP, weatherization in homes with DHPs) Research needed to support savings for higher-performance DHPs Seeking subcommittee feedback/recommendations: Is the outlined research approach reasonable? – Likely to succeed as advertised? – Does estimated cost range match outlined research? – Recommended modifications or alternative approach? Is more research really needed for Proven category? 2

Outline Background – Addition of higher DHP efficiency tiers – Existing data and scope of update – Uncertainty in savings for high-performance DHPs Research Strategy – Objectives – Straw-man approach 3

Background 4 – DHP Background

Proposed Addition of DHP Efficiency Tiers Current RTF DHP measures assume a single, minimum efficiency level of 9.5 HSPF NEEA interested in offering multiple DHP efficiency “tiers”: – Tier 1: HSPF 9.5 to 11 – Tier 2: HSPF 11 to 12.5 – Tier 3: HSPF >12.5 For Tiers 1 and 2, we already have calibrated, reliable savings estimates based on empirical data from the NEEA DHP pilot project (field study 1 and billing analysis 2 ) We do not have empirical in situ data for Tier 3 5 – DHP Background 1 NEEA, Ductless Heat Pump Impact & Process Evaluation: Field Metering Report, prepared by Ecotope, May 2012.Ductless Heat Pump Impact & Process Evaluation: Field Metering Report 2 NEEA, Ductless Heat Pump Impact & Process Evaluation: Billing Analysis Report, prepared by Ecotope, August 2013.Ductless Heat Pump Impact & Process Evaluation: Billing Analysis Report

Existing Data and Scope of Update NEEA pilot project was a major effort that collected many pieces of data, most of which do not need to be updated under this research strategy – Site characteristics data – Pre-/post-billing data – Sub-metering of DHP, resistance heat, DHW – Measurement of fraction of heat load met by DHP – Survey of supplemental fuel use – Measurement of in-situ COP, output capacity 6 – DHP Background Only part that would need updating

Uncertainty in Savings How much uncertainty would we introduce if we estimated Tier 3 savings based on figures published by manufacturers? Published figures suggest 5-7% more energy consumption in first generation Fujistu DHP (top performer in NEEA field study) than third generation Fujitsu (currently available) – Heating COP of first generation unit: 4.39 – Heating COP of third generation unit: 5.33 RTF UES values for DHPs are around 2000 kWh/year for zonal homes and 4000 kWh/year for FAF homes – Published figures therefore suggest about 120 kWh more savings per unit for zonal and 240 kWh for FAF – If we split that uncertainty range in half, uncertainty in savings would be +/60 kWh to 120 kWh per year, per unit (for zonal and FAF, respectively) – 60 kWh/year times 500k potential units plus 120 kWh/year times 225k potential units yields about 7 aMW (range of uncertainty) 7 – DHP Background IMPORTANT: Research strategy states nearly 20%, but we found an error in our math.

Research Strategy 8 – DHP Research Strategy

Research Objective Empirically estimate the in-situ COP and output heating capacity of >12.5 HPSF DHPs over a wide range of outdoor temperatures Not objectives of this research strategy: – Fraction of heating load met by the DHP versus other heating sources (know this well enough from NEEA field study) – Effects of wood heat (known well enough from NEEA billing analysis) 9 – DHP Research Strategy

Straw-man Approach Approach based on detailed metering of small number of units Meter data: Study units equipped with “COP monitoring instruments” same as in NEEA field study, logged at five minute intervals: – DHP power usage, supply air temperature, return air temperature, indoor unit airflow, outside air temperature Analysis: Use interval-level power consumption, heat output, and outdoor temperature to estimate COP as a function of outdoor air temperature – Code this function into SEEM to model >12.5 HSPF DHP systems – UES values then estimated similar to existing DHP for Zonal Heat measures (same baseline and “calibration” factors) 10 – DHP Research Strategy

Straw-man Approach (continued) Metering period: Minimum of 30 days during the winter to capture a wide range of outdoor temperatures Sample size: Staff proposes sampling 5 units – Small sample because we are only after in situ COPs (not after usage patterns, etc.) Sample disposition: No particular needs called out in research strategy Estimated cost range: $25,000 and $100, – DHP Research Strategy

Analyst Recommendation Although estimated range of uncertainty in regional savings potential is not trivial (0-7 aMW), the estimated increment in savings per unit is small and could be difficult to detect Based on this, CAT thinks it is reasonable to: – make a minor extrapolation from the Tier 2 unit consumption to represent Tier 3 unit consumption – propose the Tier 3 DHP measure as Proven 12

Additional Slides 13 – DHP Additional Slides

How Data Feeds into Savings Estimates DHP performance characteristics – Data from NEEA field study: Detailed in situ metering data for 95 DHPs (efficiencies ranging from 8 to 12 HSPF) – Used to estimate COP curves and output capacity – Developed SEEM parameters for three DHP options (8, 10, 12 HSPF) Tie SEEM-modelled savings to differences between pre and post billing data – Data from NEEA field study: Site characteristics and pre- and post-DHP billing data for sample of electrically heated homes (screened to eliminate wood heat) – This step accounts for possible comfort take-back and things like systematic error in SEEM’s estimate of the portion of load being met by the DHP – Idea: Relationship between calibrated-SEEM (DHP) and post-DHP billing data must reflect relationship between calibrated-SEEM (ER-zonal) and pre-DHP billing data Account for effect of wood heat in actual program homes – Data from NEEA billing analysis: Square footage, wood heat indicator, and pre- /post-DHP billing data for ~3000 homes – Idea is to quantify this: When DHP is installed, electric heating kWh/ft 2 decreases a lot in homes without wood heat and only a little in homes with wood heat 14 – DHP Additional Slides Part we propose updating

What is a Research Strategy? Clarifies knowledge gaps in non-Proven measures Focuses on high-priority research objectives – What does the RTF need for the measure to be proven? – Anything researchers should pay special attention to? Outlines a straw-man approach to data collection and analysis – Demonstrates one feasible least-cost research path – Research Sponsors develop final Research Plan Sponsors can work with RTF staff to ensure plan addresses RTF needs RTF reviews final Research Plan later (at Provisional  Planning step) Calls out approaches that probably wouldn’t suffice (optional) Provides a rough cost estimate (based on straw-man approach) Research Strategies try to be BRIEF: Critical items shouldn’t get lost in a sea of helpful suggestions 15 – DHP Additional Slides