As Iowa’s dog days approach, are you wondering whether your cooling equipment is up for the challenge? When fans and ventilation can’t keep up with the heat and humidity, what do you do? Have you given any thought to the new heat pumps and mini-splits that are now attracting lots of attention in Iowa? Might they work in your house?
Heat pumps and mini-splits are innovative cooling and heating appliances that, in the summertime, vent heat and humidity to the outdoors and, in the colder months, reverse directions and pull in outdoor air, heating it over coils on the way in. This “inverter” technology is a new way to heat and cool buildings that, partly because of its exceptional energy efficiency and can utilize clean, renewable electricity, is widely regarded the future of the industry. The federal government, through tax incentives and rebates, is strongly promoting it. Many variations exist today — ducted and ductless systems, air-source and ground-source systems, cooling-only versus heating and cooling – and more are undoubtedly in the pipeline. After speaking with local HVAC dealers and educators, we decided to focus first on air-sourced ductless heat pumps, also called mini-splits. Why? Two reasons stand out:
First, their straightforward installation and operation. Ductless heat pumps have only two components — an outside compressor/condenser and an indoor wall or ceiling mounted air-handling unit, also known as a head. They are not tied into a house’s ductwork and do not need to be integrated with an existing furnace.
Second, they are more energy efficient than conventional heating and cooling systems, partly because warm or cool air is transferred directly into an area of the house rather than a leaky duct system, and partly because they support “zoned” temperature control (in contrast to a furnace struggling to keep a whole house at one set temperature). Temperature control in different areas of the house is possible using multiple heads installed with a single compressor, including in spaces not reached by a house’s duct system. Efficiency declines in the coldest months of the year (see below), so make sure your house is well-insulated and air-sealed.
The challenges are upfront costs and our cold climate. Today, upfront costs of a ductless heat pump used only for cooling are comparable to conventional central air conditioners. The dealers we talked to quoted comparable prices for a single indoor head (i.e., one zone of house), but considerably more for additional units to cool other zones. Prices for heat pumps that both heat and cool are more costly, of course. New federal tax credits of 30% (up to an annual limit of $2000 for heat pumps) can help, and, for some households, full or partial rebates will also be available later this year.
The other challenge is our cold climate. Cold climate models can perform with good efficiency in new houses. Our experts acknowledge, however, that using a heat pump to keep an older, drafty house warm efficiently below freezing is challenging. Certainly, for older Midwestern houses, a “a dual fuel” strategy that utilizes a heat pump as primary heating and cooling for 9 months a year, and existing gas furnace as backup to operate during December – February would be necessary. The technicalities and cost-effectiveness of that approach are different for every house.
The applications that do make sense today are: (1) areas outside the reach of ductwork – a garage workshop, an addition, or a small, separate building. According to local dealers we talked to, these are the projects that customers are calling about and purchasing. And (2) new construction, which tends to require lower heating loads than older houses. Every home (and homeowner) is different, however, so if this technology interests you, start learning about it. As the market expands, cost declines and better technology (along with trained installers and repairmen) will improve. If you are looking to buy this year, call two or three reputable HVAC companies to discuss your options. Be sure to specify cold climate and, if you’re interested in federal funding incentives, Energy Star certification.
Final point: The starting point for everyone contemplating upgrading their HVAC systems, is to lessen a building’s heating and cooling loads with better insulation and air sealing. This fact is often missed when we talk about new, clean energy options, but should be the foundation for any energy and electrification planning.
For further reading, here’s a few of many articles online:
- Energy Star “Ductless Heating and Cooling”, information on products, rebates, installation and operating tips
- Energy Star “Heat Pumps / Mini-splits”, product comparisons
- Energy Star “Air Source Heat Pumps Tax Credit”, information on tax credits
- Paul Cutting “Ductless Heat Pumps”, a hands-on (and realistic) perspectivefrom Clean Energy District of Iowa
Read the entire Good Energy Newsletter, Summer 2023