Previous articles here have looked at green tips for cooling down this summer and discussed a report from August 16, 2010 on how the green building industry in the Portland area is doing a booming business helping to meet some of these needs. Solar assisted air conditioning is one of the methods which have been mentioned for cutting energy costs, but the A/C process is still pretty energy intensive. So, what green technology alternatives exist to the use of A/C?
Green building principles can signficantly reduce cooling needs in homes and buildings, but these practices often work best in new construction, where overall building design can be more easily modified. Many of today’s buildings were built around the assumption of central A/C. However, even in these cases, good energy saving alternatives exist.
Dehumidification is a major issue in marine inland climates like Portland, and many cooling systems rely upon it. A/C units have to chill air to very low temperatures to drive off, or condense moisture. They then must heat the air back up a little so it is not uncomfortably cold. This process is not very energy efficient, so new cooling technologies are focusing on ways to perform dehumidification using less energy.
Dessicant-based cooling, like Energy recovery ventilation systems, use substances such as silica gel, or materials called zeolites, to dry air out more easily than can be done with A/C systems. Energy is still required, because once the dessicant absorbs moisture, it must be heated to drive the moisture off and allow additional dehumidification to continue. But, the energy savings in this process can be considerable over current A/Cs, especially in situations where waste heat or solar energy can be used to help drive this process.
Earlier this summer, the National Renewable Energy Laboratory also announced the development of a process called DEVap cooling, which combines the use of dessicants into an evaporative cooling system. They estimate this process can save 50-90% more energy than today’s A/Cs. However, it is not clear exactly when products based upon this process will be available, so until then, a variety of other technologies are being explored.
In addition to dessicant-based systems and solar assisted air conditioning, a number of additional green cooling technologies exist, including perhaps one of the most promising, solar absorption cooling. There have been challenges in the past to making such system practical and affordable, particular for residential use, but this is now changing.
Stay tuned for future articles on what some have dubbed the holy grail of solar technology: using the heat of the sun to keep you nice and cool.