3-Function Heat Pump: Hot Water, Space Heating and Cooling
Water Heating and Space Conditioning: Three-Function Heat Pump vs. Separate Space Heating, Cooling, and Water Heating
A heat pump system providing residential heating, cooling and domestic water heating.
Item ID: 156
Multiple Energy Systems--Combined Space Conditioning and Water Heating
Technical Advisory Group: 2010 HVAC TAG (#3)
Average TAG Rating: 2.8 out of 5
TAG Ranking Date: 06/29/2010
TAG Rating Commentary:
- Is this the same as one or more of the above?
- Great residential technology, particularly where low grade heat can be used such as in radiant heating systems. We're testing two, maybe three systems and will know more in a year and a half.
- Great option for homes without access to natural gas.
- Sounds like a residential application
Technical Advisory Group: 2009 HVAC TAG (#2)
Technical Advisory Group: 2014 Residential Building TAG (#10)
Average TAG Rating: 3.25 out of 5
TAG Ranking Date: 04/10/2014
TAG Rating Commentary:
Support would be more enthusiastic if the system was less costly.
Looks promising for the future. Some of the other technologies here seem as good an option but might have fewer issues because of the European manufacturing.
This system can be much more complex than conventional HVAC/DHW systems--and we see lots of problems with getting those done well. Not sure this can become much more than a niche market in the foreseeable future. I would suggest looking for the simplest configurations and not limit to the Altherma platform.
The potential efficiencies are much higher than those available on HPWHs. The advantage of having a single device that provides all heat could provide significant initial cost savings compared to installing multiple devices but it's unclear that this is currently the case.
A 3-Function or integrated heat pump (IHP) provides space heating, cooling, and domestic hot water with one heat pump unit rather than requiring separate appliances to meet these functions. This offers the potential for cost savings, energy efficiency improvements, and the opportunity for waste heat recovery. Achieving these goals in an integrated unit at a competitive price is the challenge for developing this technology into a product that will be adopted by the U.S. market.
IHPs can take several different forms.
Air-to-Water heat pumps can provide hot or cool water to a variety of externally connected heat exchange devices (including radiators, air handler coils, or a radiant floor system) for hydronic space heating/cooling and to a hot water storage tank for production of domestic hot water. This type of IHP system tends to be custom designed, built up systems that are expensive.
Multi-split heat pumps are ductless mini-split heat pumps that provide refrigerant to indoor unit for space heating and cooling and provide an additional refrigerant loop to a hot water storage tank for domestic hot water. Prototype development of a multi-split heat pump for the U.S. market is underway.
Packaged IHPs that produce hot water for DHW and space heating (hot water fan coil) and use a refrigerant coil in the air handler for cooling. DOE is partnering with two U.S. manufacturers to develop these IHPs for the U.S. market.
Because packaged, cost-competitive IHPs are not available in the U.S., there is little information about their performance and cost in U.S. homes. Further development and testing of IHPs in the U.S. should provide further insight on whether energy savings of 50% or more can be achieved at initial costs that allow the systems to be cost-effective.
Baseline Description: Electric heat, cooling, and hot water in a single-family home
Baseline Energy Use: 7.1 kWh per year per square foot
The energy use index (EUI) in the Pacific Northwest for single-family homes with electric space heat is 10.87 kWh/sf (Baylon, et. al., 2012 Pg Table 152). This is a prorated value that includes homes with electric resistance heat and heat pumps. According to the Energy Information Agency, space heating accounts for 41.5% of residential energy use, cooling for 6.2% and water heating 17.7% (EIA, 2009). Heating, cooling and water heating thus amounts to a total of 65.4% of total single family home energy use, or 7.1 kWh/sf.
Manufacturer's Energy Savings Claims:
Savings Range: From 35% to 75%
IHPs are an emerging product in the U.S. market. There are few product claims for an IHP that provides space heating, cooling, and domestic hot water (DHW). A brochure for the Trilogy Geothermal IHP shows cost savings ranging from approximately 35% to 70% depending on the comparison heating system.
Best Estimate of Energy Savings:
"Typical" Savings: 50%
Low and High Energy Savings: 30% to 75%
Energy Savings Reliability: 3 - Limited Assessment
Energy savings will vary significantly depending on the type of IHP, the application, and the comparison system. Modeled energy savings estimates by the Alliance for Residential Building Innovation for the Altherma system showed approximately 30% HVAC savings compared to a conventional heat pump, but the measured DHW savings were modest (6%), which may be due to sizing and design issues for the application (Backman, and others, 2013 Pg 52).
A Navigant report for the USDOE Building Technologies Office estimates that a three-function or integrated heat pump can lower HVAC energy use by about 50% (including water heater savings) when compared to a 13 SEER/7.7 HSPF air-source heat pump and a 0.9 EF electric water heater (Goetzler, 2012). Savings would be higher for a home with electric baseboard heat or a forced air furnace.
Field and lab trials of a prototype Mitsubishi multi-split IHP by NEEA showed HPSF ratings for heating of 10.05 in the lab and 11.3 in the field, SEER ratings of 17.17 and 21.3 in the lab and field, EF for domestic hot water heating of 2.3 and 1.8 in the lab and field (Energy350, 2015 Pg 10). No energy savings for the IHP are given in the report, but using the HSPF, SEER, and EF ratings, estimated savings are on the order of 50% compared to a standard heat pump and electric resistance water heater and on the order of 60%+ compared to electric resistance space heating, window air conditioner and electric resistance water heater.
The Nordyne prototype IHP with the USDOE is completing field tests and results are expected in September 2015. This will provide additional energy savings estimates for IHPs in U.S. applications.
Another challenge for IHPs is achieving optimum performance across all three functions. Some IHPs have had difficulty with providing adequate domestic water heating capacity, particularly during times of the year when space heating is also required. Because domestic hot water demand can have significant spikes during some parts of the day, if the heat pump is not able to meet this demand, back up electric resistance heat is necessary, significantly reducing domestic water heating efficiency.
Energy Use of Emerging Technology:
3.6 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:
This technology applies to homes with electric space heating and cooling with electric water heaters in the Northwest. The NEEA "Northwest Heat Pump Water Heater Market Test Assessment" estimates that 2,149,426 single-family Northwest homes have electric water heaters (Evergreen Economics, 2013). The 2012 NEEA Residential Building Stock Assessment (Baylon, et. al., 2012) estimates that electricity is the primary heating fuel of choice for 34% of the heating systems in the region ((Baylon, et. al., 2012 Pg Table 51). Furthermore, the region holds an estimated 4,023,937 single family homes (Baylon, et. al., 2012 Pg Table 3), leading to an estimate of 1,368,138 single family homes with electric space heat as their primary fuel source . It will be assumed that the electrically heated homes tend to also utilize electric water heaters (due to the lack of natural gas service). Forty-two percent of homes in the Northwest have cooling (Baylon, et. al., 2012 Pg Table 61). Because electric heat pumps provide both heating and cooling, the share of cooling in electrically heated houses is likely higher than the value for all heat sources. For the purposes of this analysis assume 50% of electrically heated houses have air-conditioning. The average square footage for a single-family electrically heated home is 1,854 sf (Baylon, et. al., 2012 Pg Table B3). Thus, the total regional affected floor space amounts to 1,368,138 x 100% x 50% x 1,854 = 1,268,263,926 sf.
The availability of multi-split systems means IHPs can be applied to homes with zonal electric heating systems (baseboard) as well as forced air heating systems (electric resistance and heat pumps). Thus the entire regional electrically heated floor space is a potential market for this technology. In addition, new residential construction is a potential market, although it is not included in the technical potential estimate because the number of units each year is relatively small compared to existing units and a large share of residential new construction has gas heat.
Manufactured housing is also a potential market for IHPs. However, since IHPs tend to currently be an expensive, niche product, manufactured housing is not included in the market potential estimate. Higher-end, new manufactured homes may be the best application for an IHP in the future.
Multi-family homes are not included in the technical potential estimate due to the high cost of IHPs and the relatively lower heating and cooling loads in this application. However, a multi-split system targeted to this application could be viable.
Regional Technical Potential:
4.50 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): $4.75
Emerging Technology Installation Cost (Labor, Disposal, Etc.): $1.50
Baseline Technology Unit Cost (Equipment Only): $1.75
It is difficult to estimate IHP costs because it is an emerging technology and no packaged units are available in the U.S. Packaged three-function heat pumps have been offered in the past by Carrier (the Hydro Tech 2000) and Nordyne (their PowerMiser) with products failing to gain traction due to high up-front costs and lack of sales. Air-to-water heat pump systems from companies like Altherma tend to be custom, built-up systems with high costs. The incremental cost of the Altherma system in a field test by the Davis Energy Group was $19,000 (Backman, and others, 2013 Pg 12) compared to a standard heat pump, electric water heater and ducted system. As noted in this report, the Altherma heat pump is a high cost system. This report estimated a $6,400 cost premium for air-to-water IHPs in a mature market (Backman, and others, 2013 Pg 52). The Trilogy geothermal heat pump from Climate Master had a list price of $14,300 to $16,800 in a 2013 article (EDU, 2013 Pg 6). This did not include the cost for the geothermal loop.
The Mitsubishi multi-split system is a prototype undergoing field testing. When available in the market, costs for this system might be expected to be comparable to a multi-head ductless heat pump system with a hot water heater tank (<$10,000). The NEEA field study concluded that the technology has a reasonable likelihood to have a first cost that is competitive or lower than a standalone ductless heat pump and heat pump water heater (Energy350, 2015 Pg 21).
The Nordyne packaged IHP prototype being developed with support from the USDOE is expected to be available in 2016. The USDOE estimated IHPs have a cost premium of $2,500 to $3,500 more than a standard electric heat pump with an electric water heater (Goetzler. et. al., 2012 Pg 228). This appears to be a mature market estimate. It is unknown how close the Nordyne will come to meeting the USDOE cost premium estimate when it is released.
The cost premium of an IHP relative to an electric resistance space heating and water heating system and window air conditioners would be several thousand dollars more than the cost premium relative to a heat pump system.
As IHP technology matures and units enter the market, the cost premium should go down. For the purposes of this analysis, a $5,000 to $10,000 cost premium for IHPs is assumed (use a mid-point of $7,500 for the cost calculations) rather than the higher cost of some current custom-built systems. Time will tell whether IHPs available in the U.S. market become more cost competitive. The baseline technology costs are intended to represent a prorated average between a heat pump system with an electric water heater and an electric resistance heating system with window air conditioners and an electric water heater.
Simple payback, new construction (years): 9.4
Simple payback, retrofit (years): 19.6
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.
A field test and calibrated model analysis of the cost effectiveness of air-to-water IHPs in several climate zones (Backman, and others, 2013 Pg 52) showed a positive cash flow in only one of the three locations (Denver). This analysis assumed an incremental cost of $6,400 and a loan term of 30 years. The other two locations (Sacramento and Tucson) do not have a positive cash flow and presumably would not have a payback of less than 30 years. Mature market products with lower cost premiums in locations with sufficient loads and cost savings should produce more favorable paybacks.
Reference and Citations:
Baylon, et. al.,
2011 Residential Building Stock Assessment: Single-Family Characteristics and Energy Use
Northwest Energy Efficiency Alliance & Ecotope
Performance Assessment of an Advanced Hydronic Heat Pump
Electric Power Research Institute
Daikin Altherma Simulator
Free software download.
Residential Energy Consumption Survey (RECS)
Energy Information Administration
Northwest Heat Pump Water Heater Market Test Assessment
Northwest Energy Efficiency Alliance
One Machine for Heating, Cooling, and Domestic Hot Water: Multi-Function Heat Pumps to Enable Zero Net Energy Homes
Summer Study on Energy Efficiency in Buildings
Goetzler. et. al.,
Energy Savings Potential and Research, Development, & Demonstration Opportunities for Residential Building Heating, Ventilation, and Air Conditioning Systems
Prepared by Navigant Consulting for U.S. DOE Building Technologies Office
Energy Savings and RD&D Opportunities for Residential Building HVAC Systems
U.S. DOE Building Technologies Office
Backman, and others,
Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes
U.S. Department of Energy, Building Technologies Office
Proposed Compliance Option for Altherma Air-to-Water Source Heat Pump for the Residential Energy Efficiency Standards: Final Evaluation Report
California Energy Commission
Advanced Variable Speed Air-Source Integrated Heat Pump: Prototype and Field Test 2011-2015
Oak Ridge National Laboratory
Advanced Variable Speed Air-Source Integrated Heat Pump (AS-IHP)
U.S. Department of Energy, Presented at 2014 Building Technologies Office Peer Review
Pushing Boundaries on Performance & Design: the ClimateMaster Trilogy 40 Q-Mode™ Geothermal Heat Pump (Part 1)
Energy Design Update
Pushing Boundaries on Performance & Design: the ClimateMaster Trilogy 40 Q-Mode™ Geothermal Heat Pump (Part 2)
Energy Design Update
Rice and others,
Development of a Residential Ground-Source Integrated Heat Pump
Oak Ridge National Laboratory, presented at 2013 ASHRAE Winter Conference, Dallas, TX
Heating Water with Multi-Purpose Residential Heat Pumps
Mitsubishi Electric, presented at 2015 ACEEE Hot Water Forum
Combination Ductless Heat Pump & Heat Pump Water Heat Lab and Field Tests
Northwest Energy Efficiency Alliance