SAVE $100 
Depending on your geography, you'll want the appropriate cooling system for your new home. Read about the many different choices before making your investment:
Central air conditioning
The most popular air conditioning system is central air. This is where a special fluid called a refrigerant circulates between an indoor coil and an outdoor condenser with a compressor. The refrigerant cools and dehumidifies the air and then the air is blown through ducts into the house.
Your climate and cooling loads will dictate the type and size of which air conditioner you'll need. When you start looking for a central air conditioner, look for a SEER (seasonal energy efficiency ratio) rating between 12-20.
If you are planning to have a forced-air heating system, you may be able to tie an air conditioner into your existing ducts, but that will depend on their size and your home's relative heating and cooling loads. Keep in mind that the price tag for cool air using this system is quite costly — not only the system itself, which starts around $5,000 installed, but also your electric bill. For comfort and resale purposes, AC systems are definitely worth the investment.
High-velocity air conditioners
A new technology called high-velocity air conditioning (also know as "mini-duct" systems) uses a standard outdoor compressor to cool the air, combined with a high-pressure blower mounted in the attic. Instead of using bulky metal ductwork, this technology uses two inch flexible tubing, which can be threaded behind walls. Instead of large metal registers or grills, you'll have a two-inch vent in your ceiling and on top of your walls. This system works quickly and quietly to dehumidify the air in your home.
Room air conditioners
Room air conditioners are measured by a simple calculation of EER, or energy efficiency ratio and considered most efficient when the EER is greater than 9.5. They come in two basic styles — a wall or window unit. When purchasing an air conditioner, look for some of these features — sleep settings, filter alerts, remote controls, energy-saving options, timers and noise insulation.
Room air conditioners are generally 5000 - 24,000 Btu's (international measurement of energy). Matching Btu requirements to room size is important because the rooms won't cool efficiently if the Btu rating is too low or too high for the size of the room.
You should always install a window/wall air conditioner in a shady area, because placing it on the sunny side of your house will make it work a lot harder and cut back on its effectiveness. Cost can range from $500 to thousands depending on the brand and size.
Forced air systems
Many new homes are built with forced air systems to satisfy two needs — heating and cooling. The fans in either the furnace or the air conditioner blow air through ducts that are networked throughout the entire house. The ducts are connected to grills or registers in the floor or ceiling which allow the forced air into your home. Most systems run on gas or electricity to power the heating coils, blowers and filter. Choosing the right HVAC (Heating, ventilation and air conditioning) system depends on the size of your house, insulation and the climate of where you live. The bigger the home the bigger system, in fact homes with over 3,000 square feet usually need to have a second HVAC system installed.
Zoned cooling system
In a typical zoning system, sensors are placed in each zone to monitor the temperature and can immediately detect when cold air is needed. The sensors then send information to a central controller that activates the zoning system, adjust the motorized dampers in the ductwork and send the conditioned air to only that zone. By delivering conditioned air only to areas that are in use, a zoning system is very cost effective and helps maintain a comfortable home.
Whole-house fan
A whole-house fan, also known as an attic fan, provides great ventilation, lowers the temperature in your home and most importantly lowers your summer electric bills.
With the flip of a switch, it pulls cooler outside air through open windows and sends hot indoor air out through the attic. It can lower the temperature in your home by five degrees in just a few minutes.
One of the biggest advantages of a whole-house fan is the cost — only $150 to $350, compared to thousands of dollars for a central air conditioner. You can use a whole-house fan by itself, or you can combine it with your central air conditioner to help cool the house more quickly.
Outside temperatures and humidity levels can affect how well a whole-house fan works, so it is advised to only use the fan when temperatures outside are below 85 degrees. Anything above that requires an air conditioning system to cool your home.
