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Know Your HVAC Terminology
In order to converse with air conditioning experts, it is essential to be familiar with basic terms used in the description of the various types of cooling equipment. The following questions illustrate some of the key terms that are more commonly used and confused.
- What is a BTU?
- What is the difference between the terms EER and SEER?
- What is a "ton" and how is it used to define air conditioning capacity?
- What is COP?
- What is relative humidity?
1. What is a BTU?
A British Thermal Unit (BTU) is defined as the amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. It is approximately the amount of heat that a lit match will generate.
2. What is the Difference Between EER and SEER?
EER (energy efficiency ratio) is a measure of how efficiently a cooling system will operate when the outdoor temperature is at a specific level (usually 95 F). A higher EER means the system is more efficient. You can figure out kW if you know EER and tons.
EER = BTUs of Cooling @ 95 F / Watts used @ 95 F
In the case of a 10 EER, 2 ton air conditioner:
10 EER = 24,000 BTUs Out / 2,400 Watts In
For the same size unit, but rated at 12 EER:
12 EER = 24,000 BTUs Out / 2,000 Watts In or 20% more efficient.
If you want to calculate kWh, just multiply the "Watts In" by the number of hours that the air conditioning is running. If you'd like to convert watts to kWh, simply divide by 1000.
SEER (seasonal energy efficiency ratio) is a measure of efficiency over an entire cooling season, as opposed to a single outdoor temperature. Residential units are almost always rated in SEER. SEER came into use as a more practical measure, since the temperature outside is not always 95 F. Also, the denominator is in watt-hours, not in watts as is the case for EER. The same relationship holds ... a higher SEER means the system is more efficient. SEER is the total amount of cooling the air conditioner will provide over the entire cooling season divided by the total number of watt-hours it will consume or:
SEER = Seasonal BTUs of cooling / Seasonal watt-hours used
3. What is a "Ton" and How is it Used to Define Air Conditioning Capacity?
A "ton" has come to be defined as the cooling capacity of an air conditioning system. One ton is equal to the BTU's required to melt one ton of ice in a 24 hour period. A one ton air conditioner is rated at 12,000 BTU's, a 2 ton unit at 24,000 BTU's, a 3 ton unit at 36,000 BTU's and so on. It takes 144 BTU's of heat to melt 1 pound of ice in 24 hours, or 288,000 BTU to melt a ton (2,000 pounds) in 24 hours.
Typically residential central heating systems provide from 2 to 5 tons of cooling. Commercial rooftop units are typically 3 to 20 tons each. Chillers can range from 15 tons up to 1,500 tons.
4. What is COP?
COP (coefficient of performance) ratings are more typically found in chiller ratings and on gas cooling equipment, as well as in heat pumps. It is a measure of how efficiently a heating or cooling system will operate at a single outdoor temperature condition. As an example the commonly used outdoor temperature condition for a heat pump calculation in the heating mode is 47 F. As is also the case for EER and SEER, higher COP's mean higher efficiency.
For a heat pump:
COP = BTU of heat produced at 47 F divided by the BTU equivalent of electricity to produce that same amount of heat. The COP rating for a heat pump typically ranges from 3.0 to 5.0.
Where 1 kW = 3,413 BTU/hr
For a chiller:
COP = 3.516 divided by the kW/ton rating of the chiller
Where the kW/ton rating of a chiller is typically in the 0.6 to 1.0kW/ton range. Therefore, the COP rating for an electric chiller will generally fall between 3.0 and 5.0. Gas absorption chillers have COPs from 1.5 to 2.0.
5. What is Relative Humidity?
Relative humidity is a measure of the amount of water in the air compared with the amount of water the air can hold at a particular temperature. Warmer air has more capacity to "hold" water vapor than colder air. Dew point is a measure of how much water vapor is actually in the air.
Take the Next Step
In just minutes, FPLs Online Business Energy Evaluation can provide you with personalized cost-saving recommendations specific to your business.
Air conditioning is usually the largest part of a business' energy bill. And, if you have old or inefficient cooling equipment, your energy costs can be even higher. FPL has many Energy-Efficient Cooling & Heating Incentives. Go to FPL.com to learn more.
Tree Facts
Trees give us oxygen, and what is absolutely amazing is that while giving off oxygen, trees are absorbing carbon dioxide produced from the combustion of various fuels. Trees remove or trap lung-damaging dust, ash, pollen and smoke from the air, in addition to providing shade for people and conserving energy.
One tree that shades your home in the city will also save fossil fuel, cutting CO2 buildup as much as 15 forest trees.
-National Arbor Day Foundation pamphlet #90980005
Planting trees remains one of the cheapest, most effective means of drawing excess CO2 from the atmosphere.
-Prow, Tina., The Power of Trees, Human Environmental Research Laboratory at University of Illinois.
A single mature tree can absorb carbon dioxide at a rate of 48 lbs./year and release enough oxygen back into the atmosphere to support 2 human beings.
-McAliney, Mike. Arguments for Land Conservation:Documentation and Information Sources for Land Resources Protection, Trust for Public Land, Sacramento, CA, December, 1993
Over a 50-year lifetime, a tree generates $31,250 worth of oxygen, provides $62,000 worth of air pollution control, recycles $37,500 worth of water, and controls $31,250 worth of soil erosion.
-USDA Forest Service Pamphlet #R1-92-100
If every American family planted just one tree, the amount of CO2 in the atmosphere would be reduced by one billion lbs annually. This is almost 5% of the amount that human activity pumps into the atmosphere each year.
-American Forestry Association Tree Facts: Growing Greener Cities, 1992
Great detailed explanation of the benefits of heating your water with clean free solar energy! Go Solar NOW! it pays.
Click on the link and get linked to a video that is a wonderful tutorial on a lot of the stuff you need to know about solar systems! (requires Macromedia Flash Player)
Whether you are the rookie who wants to understand how solar-electric systems work, or you are looking for fundamental information that better describes solar to your spouse, friend, or prospective customer, this article explains the guts and bolts of the three most common options in solarelectric systems: grid-intertied, grid-intertied with battery backup, and off-grid (stand-alone).
Understanding the basic components of an RE system and how they function is not an overwhelming task. Here are some brief descriptions of the common equipment used in grid-intertied and off-grid solar-electric systems. Systems varynot all equipment is necessary for every system type. In the diagrams, the numbers in red correspond to the components needed.
This is a quite long and involved explanation of batteries, but contains a lot of good and usable information.
All kinds of tools for all kinds of energy estimating requirements.
Renewable Energy Products are protected in Florida by Statute 163.4
Thoughts on how to pay for it.
The first thing everyone should do is replace their incandescent lights with compact fluorescent lights. It makes a world of difference in your lighting bill.
Here's one for the nerdiest of you solar nerds. If you understand and appreciate this you "r" one!