(3BL Media/Justmeans) - A sizeable portion (about 5%) of the electricity used in this country is used to produce air conditioning.  That translates into somewhere between 9 and 14 percent of the electricity used in homes and buildings. This has become a cause for concern on a warming planet, given that warming temperatures from energy generation will result in more air conditioning demand requiring more energy generation. This is otherwise known as a positive feedback loop. Some experts are even predicting that the need for air conditioning will exceed the need for heating by the end of this century.

A number of actions are being taken to begin to address this challenge, including, most recently, a move by the Obama administration to raise the standards for commercial air conditioning efficiency. Other innovations include the use of ice for thermal energy storage and evaporative cooling in hot dry climates, as well as continued, incremental improvements in conventional air conditioning systems based on the mechanical vapor-compression principle. While all of these are helpful, it’s not clear that any of them will substantially move the needle.

Another new type of cooling system called radiant cooling is beginning to attract attention in this country. Roughly half the net-zero energy buildings in this country use radiant cooling. The idea is that by cooling walls, ceilings, and floors, a draft-free, comfortable environment can be created. The cooling is produced as radiant heat from your body is absorbed by these cooler surfaces. Water can be used as the cooling fluid, for which it is far more effective than air. Radiant systems still move air for ventilation purposes, but far less air is required (only about 5% of the energy and 20% of the ductwork) for that purpose. That means smaller ductwork, and less fan power.

Radiant cooling systems have been popular in Europe for 25 years, but have been slow to catch on here. One reason why is that forced-air systems are less expensive out the outset, plus they require more space, making them a better fit for the US market. Now, with rising concerns over energy use, Americans are taking a second look, especially in larger commercial buildings where heating and cooling make up 40% of operating costs. They are especially useful in glass buildings that capture solar heat on tile floors. During summer months, cooling coils in the floor can draw that heat away.

Another big advantage of these systems is the inherent storage contained in chilled water. This allows the system to cool the water at night when they can operate more efficiently (discharging heat into cooler night air), at a time when electric rates are typically lower. It also provides a nighttime load for wind turbines which produce more at night. Proponents claim that comfort level is improved with more evenly distributed temperatures. Like forced air systems, both heating and cooling can be provided through the same radiant delivery system.

As this new approach begins to catch on, particularly in large commercial buildings, we can expect to see significant energy reductions being realized by this approach. New connection systems, such as capillary tube mats, that can be embedded in ceilings or floors are reducing installation costs, making this option more attractive than ever.