All-in-One Systems for Heating, Cooling and Ventilation
However, when a house is built with minimal air leakage, it is essential to have an excellent ventilation system to maintain a healthy environment inside.
All-in-one systems are often called "Magic Boxes" because they combine all the functions of an HVAC system in one unit. One of the truly revolutionary systems is the Compact P Heat Pump from Nilan, certified by the Passivhaus Institut in Germany. The Compact P Heat Pump, which functions as a ventilation system with heat recovery, also includes space heating and cooling and provides the household's hot water supply. (Heat recovery means that the heat -- or cooling -- already created for the stale air in the home is not lost. The temperature "magically" is transferred to the incoming fresh air.) This type of system is compact, provides healthy indoor air, and reduces energy costs.
While heat recovery can recapture a portion of space heating energy before stale air is exhausted and replaced with fresh air, the additional heat pump in this system also can warm the fresh air on the coldest days. Separately, the same heat pump also provides 47.5 gallons of hot water for domestic use. This unit has additional options to incorporate a geo-thermal heat pump or outdoor air-to-water heat pump, which can supplement air heating with radiant floor heating. Most of the Compact P units produced are being used in Europe, but some are being tested in recent U.S. projects, including in Vermont, which has some of the more challenging weather conditions in the United States. So far these "boxes" are functioning very well.
Though European countries have led the way, an example of an all-in-one system manufactured by a U.S. company is the CERV (conditioning energy recovery ventilator), developed by Build Equinox. CERV systems, which are UL Listed, incorporate heating, cooling, dehumidification and ventilation. The systems have been incorporated into a 25-unit, moderately priced prefabricated housing complex that HVAC engineer Peter Schneider is working on in Vermont. Schneider, a leader in his field, called the CERV system a "brilliant device," adding that so far he is very pleased with the systems' efficiency, comfort and usage in a location that is high-demand because of the climate.
Other companies around the world making similar systems include Drexel & Weiss in Austria and Daikin in Japan, which produces an all-in-one system that doesn't include a ventilation system. Another company with a strong ventilation business in the United States, Zehnder, produces an all-in-one system called the ComfoBox which is not available in the U.S. market.
Magic Boxes are becoming more popular in Europe, but are still in limited use in North America. The demand has been small, probably because of a lack of awareness of the systems and because of the small number of extremely energy efficient homes being built here. All-in-one units tend to be more expensive than unbundled systems -- although according to Schneider, that additional cost seems small when all HVAC factors are taken into consideration, including energy efficiency, comfort and health. However, one potential disadvantage is that if one of the systems breaks down, all systems are lost -- including heat, cooling, ventilation and water heating. Also, there are not yet enough professionals in this country who are able to fix these systems, but that is likely to change as building codes become stricter and people become more familiar with the optimal building materials available.
Sheri Koones' latest book, "Prefabulous World: Energy-Efficient and Sustainable Homes Around the Globe," includes homes that use magic box systems. She won the prestigious Robert Bruss Real Estate Book Award from NAREE in 2008, 2011, and 2013, and is a columnist, freelance writer and speaker.