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ac-installation

Installing a New AC Unit? Lower Your Cooling Load First

Published on: July 31, 2012

Air conditioning is an energy intensive system, and during the hot part of the year, it can be responsible for more than 50% of electricity costs. Before you call an HVAC company to arrange a new air conditioning installation, it’s a good idea to think about how you can reduce your cooling load.

Your cooling load determines the size and running costs of the air conditioning portion of your HVAC system. Lowering the cooling load can lower your electricity bills considerably.

These strategies can help:

Take a look at your ducts.

Check to see if your registers are optimally placed for cooling.

Use operable windows.

Limit solar gain.

Use economizers.

Install a zone system.

Think about upgrading the building envelope.

Take a look at your ducts.

Replacing the air conditioner in an existing building usually involves attaching a newly purchased split system to an existing duct system. Flaws in the duct system can increase the cooling load by preventing the system from working at full efficiency.

First, check all of the accessible ducts for leaks and potential blockages. If you can’t access some of your ducts, then it may be worth it to commission a pressure test. Leaking or damaged ducts should be replaced.

Next, check the sections of ductwork that are located in unconditioned areas. This may include basements, lofts, and roofs. It’s especially important that these ducts be well insulated and fully sealed. If possible, replace them with ducts in conditioned areas.

Check to see if your registers are optimally placed for cooling.

Just as a new air conditioning installation makes use of existing ducts, it also makes use of existing air distribution registers or diffusers. Because hot air rises, floor-height air distribution is optimal for heating, and ceiling height air distribution is best for cooling.

If your air distribution is at the floor level, you can add fans to help circulate the air in the rooms. Fans use electricity, but they can easily save you more in energy for air conditioning than they cost to run.

Use operable windows.

Regular sliding, single hung and double hung windows can provide an alternative to air conditioning when the outside temperature isn’t too high.

Older buildings may have operable clearstory windows near the tops of the walls. These are often in the form of hopper or awning windows, and can be opened using a pole. Newer buildings sometimes have a control system for this type of window. They allow hot air to escape the building. If you have them, use them.

Limit solar gain.

Solar gain occurs when the building absorbs heat from solar radiation through windows and walls, and it can significantly increase the air conditioning load. Simply blocking the windows with reflective or light-colored shades or curtains can greatly reduce solar gain. Similarly, planting trees along south-facing walls can reduce the amount of heat that’s absorbed by the walls and passed to the building’s interior.

Use economizers.

Economizers are included with most commercial air conditioning systems today. They replace conditioned air with outside air when it’s cooler outside than it is inside. That can sometimes happen when the building’s occupants and systems are adding heat to the interior. If your current air conditioning system doesn’t have an economizer, then your new one should.

Install a zone system.

If your home or building currently has a single thermostat controlling the HVAC system, then a zone system could save you a great deal of money. With localized the HVAC system controls, conditioned air goes where it’s needed, and you don’t pay to heat and cool areas that aren’t in use. Make sure that your new air conditioning installation includes zone control.

Think about upgrading the building envelope.

Of course, building envelope upgrades can reduce the cooling load, as well. They may include:

draft-proofing;

replacing single glazed windows and doors with double glazed units;

and adding insulation to your walls, roof or attic.

Lowering your HVAC system’s cooling load before commissioning a new air conditioning installation can save you money. An expert HVAC contractor or insulation installer can help you carry our your plan. If you’re replacing your air conditioning system, then now is the time to reduce your cooling load.