When you’re in the market for a new HVAC unit, one of the key considerations will be the energy efficiency rating. This is equally true if you’re purchasing an air conditioner or any kind of furnace. When you have heating and cooling equipment with good energy efficiency, you can save a lot of money on your energy bills. But, the core energy efficiency ratings are not the sole factors that will affect the sustainability and performance of your new HVAC unit. In this article, we will explain what the energy efficient ratings mean to help you make an informed purchasing decision.

A Glance at the Label

The best news about energy efficient ratings is that every HVAC unit sold must have the SEER rating displayed on the label. This makes it easy to compare two units to find the one with the best efficiency rating. But, this isn’t the whole story, and there are other factors that you need to look out for when choosing your next HVAC unit. These factors differ depending on whether you’re shopping for a furnace or an air conditioning unit, as you will see below.

The Basics of Energy Efficiency: Air Conditioning

The air conditioning units have different types of energy efficiency ratings compared to a furnace. All modern air conditioners can be rated with two different efficiency ratings, and they are not interchangeable. These are known as the Energy Efficiency Ratio (ERR) and the Seasonal Energy Efficiency Ratio (SEER). The ratings for ERR and SEER progress upwards, and the higher the number, the more efficient they are. As you might expect, the more efficient units cost more to purchase up front. But, the best units with the higher efficiency ratings cost less to run, and this means you can recoup your investment quickly. The next obvious question is, which is the best type of energy efficiency rating? Do you go with the highest ERR or SEER number? Let’s take a closer look at ERR and SEER in more detail.

How is ERR Calculated?

The ERR is calculated by dividing the wattage of the unit by the volume of cool air that it can generate, which is measured in British Thermal Units (BTUs). It’s important to understand that the ERR uses measurements are taken under very specific conditions at 95ºF. So, you can think of an ERR as a kind of brief snapshot of the efficiency of a unit rather than a long term prediction on energy efficiency.

How is SEER Calculated?

The key part of the term SEER when compared to ERR is the addition of the S, which stands for Seasonal. The  SEER rating is calculated as the energy expended to cool a building with an “average” air conditioning system. A better way to express this difference would be that ERR measures the operating efficiency (at 95ºF) and SEER takes temperature fluctuations and weather conditions into account.

Which is the Best Rating System?

The answer to this question will differ depending on where you live, and both ratings can be handy when you’re looking for a new AC unit. But, you may not see both on a unit that you’re looking to buy in the U.S., but the SEER rating must be displayed on the packaging. Some manufacturers show both, and if that is the case, the one you choose to use will depend on an average summer cooling season for your area.

If you live in an area where the summer temperatures fluctuate a great deal, you will need a rating that takes these factors into account. In this case, you would be better served by choosing a unit with the best SEER rating. If you live in a hotter area where the summer conditions don’t tend to change much, an ERR would be a great fit.

The Basics of Energy Efficiency: Heating Equipment

The ERR and SEER ratings mentioned above are not used in furnaces. In fact, the rating system used with furnaces is easier to understand, and the main rating that you need to look for is the Annual Fuel Utilization Efficiency (AFUE) ratio. The AFUE is a calculation of the amount of heat that can be produced from a single dollar of fuel that would be burned to produce it. Again, a higher AFUE rating is better because it represents a system that can produce heat by burning less fuel.

When it comes to heat pumps, a slightly different rating system is used. The Heating Seasonal Performance Factor (HSPF) works in a similar manner to SEER. The HSPF calculates how a heat pump performs during fluctuating conditions during a heating season.

Making Good Efficiency Decisions

When it comes to comparing the efficiency ratings for air conditioning units, furnaces, and heat pumps, the best thing to remember is that higher is better. Too many people get caught up in the comparison between ERR and SEER ratings, but as we’ve shown this is only relevant if you have fluctuating weather conditions. If you choose a unit based on the wrong location, it can be a problem. As an example: a unit with a very high SEER rating will not necessarily have a high ERR rating too (or vice versa). If you take your local conditions into account, it’s easier to choose the right efficiency rating to use.

The Importance of a Professional Installation

Even if you do purchase an air conditioning unit, furnace, or heat pump with a high efficiency rating, the potential energy savings could still be ruined with an amateur installation.

Another key factor to consider is that you can boost your efficiency if you buy units that are matched to work well together. Manufacturers take a great deal of care to get their heating and cooling equipment to work efficiently together. So, if you only have a couple of years left in one unit, it may make good sense to replace both at the same time.

If you’re looking for a high efficiency HVAC unit for your home, contact your local certified specialist for expert help and advice.