Air Conditioner Unit Ratings: Why Size Matters

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Bigger is not necessarily better when it comes to cooling your commercial building. Having the appropriate air conditioner size for your space will make a huge difference when it comes to efficiency, cost and emissions. It’s estimated that 25% of all existing rooftop HVAC units are too large resulting in increased expenses, less efficiency and a shorter unit life span from constantly cycling on and off. Too small a unit will work too hard and drive energy costs up as well. But size isn’t all that matters. It’s important that you choose an efficient unit with a high air conditioner rating as well. In order to make an informed decision on installing or retrofitting a properly sized and efficient HVAC system it’s important to understand how air conditioner ratings and air conditioning sizing works.

HVAC Load Calculations

The amount of cooling that an HVAC unit will have to perform to sufficiently cool a space is called the cooling load. There are very detailed HVAC load calculation procedures provided to contractors by both the ACCA (Air Conditioning ...
... Contractors of America) and the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). HVAC cooling load calculations take into account a number of factors including; the size and layout of your space, the size, number and position of the windows, the amount of insulation present and the number of occupants. Once the HVAC cooling load calculations are complete you’ll know exactly which air conditioner size you’ll need. Air conditioner size or capacity in the U.S. is measured in BTUs per hour.

Efficiency Ratings

While BTUs per hour measure an air conditioner’s size, SEER (seasonal energy efficiency ratio) and EER (energy efficiency ratio) are the air-conditioner unit ratings that measure efficiency. SEER is determined by dividing the unit’s cooling capacity in BTUs by the energy input in watt-hours. The SEER rating takes into account seasonal changes in usage while EER measures efficiency at a standard outdoor temperature of 95oF. The higher the air conditioner rating the more efficient the unit. While higher SEER or EER ratings will mean higher initial costs you can expect to recoup that investment rather quickly. A SEER rating of at least 10 is required by law for central air conditioner systems.

When choosing a system also be sure to specify to your contractor that you want an Energy Star unit. Energy Star is the government’s seal of approval. An air conditioner that receives the Energy Star rating either meets or exceeds the governments’ standard for efficiency and can expect to be at least 20% more efficient than non Energy Star rated products.

By installing or retrofitting a properly sized and energy efficient HVAC system you can become more competitive in the market place, save on operating costs and increase the resale value of your commercial space. The first step is to understand air conditioning rating and air conditioning sizing to see how your space sizes up.If you have an HVAC system a professional facilities management team can help you to avoid potential catastrophes in your educational building. But just as importantly, with the AC working properly more and more students will start finding school, to be pretty cool.