Alternatives to Traditional HVAC Systems
If you are given a recommendation to replace your existing HVAC due to age, inefficiency, or mold infestation, you should consider newer options that can improve air quality with more efficiency (read: lower energy bills!). With so much information at our fingertips and uncertainty in energy prices, it's time to think out of the box!
1) High-Velocity Mini-Duct Systems: These systems are exciting to me and likely anyone who appreciates historical homes. Instead of running large, cumbersome ducts and vents into rooms, this system runs smaller vents, which can be snaked through walls more easily. There may be several vents in a room, but they are smaller and discreet (think 2-3” round holes) and can be encased with trim that matches the room, such as wood. This system actually removes more humidity than traditional HVAC, so the room feels more comfortable at a higher temperature. In addition, the high velocity of multiple “jets” of air provides more mixing than singular larger vents, so that cold and warm pockets of air are avoided. The system can also be run on “dehumidifier-only” setting just to get the air drier without heating or cooling. Noise attenuators are installed in the ducts so there’s not significant noise with the velocity.
2) Mini-Splits: These have become popular to heat or cool spaces added onto homes, instead of modifying the existing system. They also work well for smaller open floor plans like studios and large master bedrooms. Because there is no “ductwork” in a Mini-Split, there is little space for mold to grow in the system itself and cleaning/replacing the filter regularly goes a long way to maintaining good air quality in the space it serves. Mini-splits are a compact variety of Air Source Heat Pumps (they have heating and cooling capabilities) and are used to upgrade older apartment buildings for energy savings and comfort.
3) Radiant floor heating and cooling: If you have tracked home building trends for some decades, what started as a luxury (stepping out of bed onto a warm floor instead of a cold one!) has turned into an affordable option as materials and technologies evolve. Radiant floor heating and cooling is easiest to install in new builds, but it can also be fitted into existing homes too (see this article on retrofitting). Radiant heat is comfortable and enveloping, does not require ducting that can harbor dust and moisture, and it's more efficient than traditional HVAC. The radiant system does not have to use a large boiler; it can even use an on-demand system (check out this barndominium that uses an on-demand heater for floor heating). If you like this type of heat, why not make the system you pay to install, do double duty as a cooling system too? You can use chilled water in the same lines that use hot water, to cool your home. Using modern humidity sensors and switches, the system can keep condensation from occurring on the floors by monitoring dewpoint conditions. I live in the southeast US, where outside it is continually hot and muggy for 5-6 months, but a test in India gave me the confidence that radiant floor cooling is possible even in such tropical climates (go to the “Conclusion” on this page to read the details). Here's the summary: a leading software company built one-half of a new office building with traditional forced air cooling, and one-half with radiant cooling. “After two years the result was clear. The radiant system had used 34% less energy when compared to the VAV system (traditional forced air). On top of that, the initial cost was also lower in the radiant system and a survey conducted of the building’s occupants found that thermal satisfaction was higher in the section that utilized the radiant cooling system.” Wow!