As California continues to move new buildings towards the goal of more efficient, all-electric, fossil-fuel-free construction, technologies used for decades in other locations - despite feeling new here - will help us reach our goals. Solar panels will power our overall energy needs, while high-efficiency air-source heat pumps (ASHPs) will satisfy the conditioning needs of these buildings and homes.
ASHPs use small amounts of electricity, have relatively few moving parts, and simply move air from one place to another with fans. Utilizing a refrigeration cycle linked to an indoor fan and an outdoor fan via a thin refrigerant line-set, heat in the air is captured by the refrigerant and transferred from inside to outside during cooling mode, or from outside to inside during heating mode. That’s correct: heat pumps do more, with less, and provide both cooling and heating within the same system.
ASHPs have been used since the 1970’s, though these older systems received a bad rap for good reason. Large, inefficient, ugly, and clunky, they moved air across refrigerant coils at one speed - fast - leaving the air inadequately conditioned. Additionally, when outdoor temperatures dropped, they then used resistance electricity to power electric heat strips in an effort to make up for inadequately conditioning that fast moving air. This led to life cycle inefficiency, high electric bills, and unhappy building occupants. Now, it’s time to let go of those grudges.
Today’s high-efficiency ASHPs move air across the refrigerant coils at variable speeds - slow, slower, and slowest (what we might call “Turbo”) - allotting ample time to properly condition. They then efficiently distribute that conditioned air via two methods: ducted and ductless distribution systems.
Ducted and ductless systems use the outdoor unit and the indoor air-distribution unit linked by the refrigerant line-set in the same manner. However, a ducted system distributes air from the indoor unit to multiple rooms via ducts located within a conditioned attic or kneewall, not unlike FAU systems with which we are familiar. In a ductless system, the indoor unit is the solitary air-distribution system. This method of distribution can be incorporated via wall-mount units, floor-mount units, or various forms of ceiling-mounted units manufactured to fit between 16” on-center framing.
Of course, there are advantages and disadvantages to both systems. And just as buildings have personalities, so do their occupants. While some find the interior units of ductless systems to be unsightly, others find beauty in the balance of efficiency, economics, and aesthetics. Without ducting, the installation process for ductless systems is expedient. Ducted systems are more costly - a good rule of thumb is twice as much - though distribution is largely hidden, which some may find desirable and worthy of the added expense.
No matter the distribution method, the benefits of ASHPs are numerous: providing both heating and cooling; reducing envelope penetrations in tighter homes; offering numerous distribution methods; having capacity for multi-zoning; and reducing the energy consumption of what is traditionally the largest consumer of energy in our buildings. ASHPs can eliminate the need for fossil fuel use in our conditioning systems, which becomes icing on the efficiency cake.
Have questions about heat pumps or how to make your building all-electric? Contact us!