Ductless Mini-Split Heat Pump for Multi-Family Housing
Ductless Mini-split Heat Pumps in Multi-Family Homes: Variable-Speed Compressors vs. Constant-Speed Compressors
Mini-Split Heat Pumps with Variable Speed Compressors, but this application is designed specifically for use in multi-family homes.
Item ID: 302
Equipment that is capable of operating only as much as needed to meet the load is more efficient than equipment that can only operate at full capacity or off.
HVAC split systems, including ductless split systems, are available with variable speed (inverter-driven) compressors. Constant speed on/off-only compressors are good for locations where the load is constant, such as a small data or server room. However, for most applications, the load changes with the seasons and time of day. For these applications, inverter-driven motors on HVAC compressors can save significant energy.
Variable speed compressors have been available in other countries for many years, commanding more than 80% of the commercial and residential market combined in Japan, Europe, and China. This technology is now available in the U.S. and manufacturers are offering more options to fit the U.S. market.
NEEA conducted a pilot program in 2009, training 900 installers and succeeding in getting 4,000 ductless heat pumps (DHPs) installed. The heat pumps were provided by 5 different manufacturers. By 2011, NEEA indicates that more than 13,000 ductless heat pumps had been installed in residences within the Northwest, savings at least 40,500,000 kWh of energy (3,115 kWh/unit). Research showed that 90% of customers were satisfied with their ductless heat pumps and that customers reported a 25% to 50% reduction in their heating bills.
Baseline Description: Multi-Family with Electric Space Heat
Baseline Energy Use: 2.6 kWh per year per square foot
We can only count in the technical potential those multi-family homes currently heated with electrical energy. According to estimates in the Northwest Energy Efficiency Alliance's (NEEA's) 2013 "Residential Building Stock Assessment (RBSA):Multifamily Characteristics and Energy Use", 81.7% of multi-family homes in the Northwest are heated with baseboard electrical heaters (David Baylon, 9/5/2013). Each multi-family home averages 766 sf with an annual heating energy use of 2,000 kWh/year. This indicates an EUI of 2.6 kWh/sf-year.
Manufacturer's Energy Savings Claims:
Currently no data available.
Best Estimate of Energy Savings:
"Typical" Savings: 41%
Energy Savings Reliability: 5 - Comprehensive Analysis
Energy savings will depend on weather conditions for a given site. As the bulk of the energy used is for heating, a ductless heat pump COP of 3.5 is assumed (Daiken values range from 3.2 to 3.8). This simplistic assumption results in a projected heating energy savings of about 71% relative to electrical baseboard heaters.
Ecotope conducted a study of energy savings due to deploying ductless heat pumps in multi-family buildings in 2012. Participants included two apartment complexes with a total of 188 units. Calculated heating savings due to billing analysis revealed a savings of 736 kWh/year in Richland, WA, versus 912 kWh/year in Eugene, OR. Cooling figures were a savings of 386 kWh/year in Richland, with an increase of 143 kWh/year in Eugene (from Ben Larson, Ecotope, "Ductless Heat Pump Retrofits in Multifamily and Small Commercial Buildings") (Larson, 2012). The analysts decided to drop cooling savings from the analysis as increases in use in mild climates will tend to offset or balance out savings in climates with high cooling loads.
Savings were less than expected due to "takeback" or significant increases in delivered heat in the metered units. The increase in post-installation output heat delivered ranged from 39% at Eugene to 78% in Richland. The final result was an overall savings number of 824 kWh/year per unit. As mentioned previously, each multi-family home averages 766 sf with an annual heating energy use of 2,000 kWh/year. A savings of 824 kWh/year is equivalent to an energy use reduction of 41.2%. This result will be used in our analysis.
Energy Use of Emerging Technology:
1.5 kWh per square foot per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
We can only count in the technical potential those multi-family homes currently heated with electrical energy. According to estimates in the Northwest Energy Efficiency Alliance's (NEEA's) 2013 "Residential Building Stock Assessment (RBSA):Multifamily Characteristics and Energy Use", 81.7% of multi-family homes in the Northwest are heated with baseboard electrical heaters (David Baylon, 9/5/2013). We make the simplifying assumption that electrically-heated multi-family units are the same average size as each category of units with all heating sources, so to get an estimate of square footage, we multiply the total square footage of each type of multi-family unit times the percentage of units that are electrically heated in that category.
Type of Home No. of Homes Avg. Size Total s.f. % Electrically Heated s.f. Electrical
Regional Technical Potential:
Multi-Family 863,104 766 661,137,664 81.7 540,149,471
0.58 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Installed first cost per: square foot
Emerging Technology Unit Cost (Equipment Only): $5.33
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $0.01
Baseline Technology Unit Cost (Equipment Only): $0.56
Installed costs for single zone systems are around $3,500 for a 1-ton system and up to around $8,500 for a 5-ton system. This technology is available in up to eight zones on a single condensing unit, adding about $1,200 per zone. Prices depend on control systems selected, contractor familiarity with this technology, size of building, etc. The total installed cost for a 1.5 ton ductless heat pump (in mid-2014) was about $4800 including wireless programmable controls. These costs are approximately 20% higher than an equivalent constant-speed system. Given that a one-ton unit will serve a residential area of 600 sf, the 1.5 ton unit captures some economies of scale and has a total cost of $5.33/sf. With a 20% price premium over conventional heating equipment, the assumed conventional equipment cost is $4.44/sf.
The assumed baseboard heating cost is $0.56/sf. (From Means, an 8-foot baseboard has a cost of about $193 and has a power output of 2 kW).
Simple payback, new construction (years): 49.7
Simple payback, retrofit (years): 55.7
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
The description of this technology, and the equipment available for this application is essentially the same as technology #300: Ductless Mini-Split Heat Pumps with Variable Speed Compressors, but this is specifically for application in multifamily residential applications. See #300 for more technical detail.
Operations and Maintenance Costs:
No information available.
Currently no data available.