Whether you’re a homeowner looking to make your home green, or a REALTOR® trying to market your listings as eco-friendly, the energy efficiency ratio (EER) is an important part of your home energy audit. But what exactly is the EER? In short, it’s a way to sum up how efficiently your home’s HVAC system operates. The higher the EER, the more efficient the system, meaning that you’re spending less on operating costs and maintaining a consistent and comfortable temperature year-round. Here’s a closer look at the EER and what it means for you:
What’s an Energy Efficiency Ratio (EER)?
The energy efficiency ratio is the ratio of the cooling energy to the power input energy of the cooling unit. The cooling energy is always measured in British thermal units (BTU), while the power input energy is always measured in watts (W).
As an example, an HVAC unit that has 10,000 BTU of cooling energy and 1,200 watts of power input energy has an EER of 8.3, or 10,000 divided by 1,200. You can find the EER of any air conditioner as long as you know its BTU and wattage values. Generally, an EER of 12 or above is considered energy efficient.
As a baseline, the EER is calculated using 95°F as the outdoor temperature, 80°F as the indoor temperature, and 50 percent as the relative humidity. The actual, operating efficiency of the unit on a day-to-day basis depends on weather fluctuations, your climate, and the conditions inside your house. A higher difference between the indoor and outdoor temperature leads to less operating efficiency.
What’s a SEER (Seasonal Energy Efficiency Ratio)?
The SEER rating is similar to the EER, but it only takes into account seasonal use rather than year-round use. This is ideal for purchasing HVAC units in countries with strong seasonal changes, for instance, in any climate where you only run air conditioning in the summer. Again, the higher rating is always more efficient, so aim as high as you can.
Most central HVAC units use SEER ratings, while portable air conditioners and window HVAC units use EER.
Why You Should Pay Attention to EER and SEER
Most homeowners are used to buying HVAC units by the BTU rating, but the problem is that the BTU rating alone doesn’t determine energy efficiency, or even operating efficiency. You can have a 12,000 BTU unit that operates on 1,400 watts, which is an EER of 8.5, or the same 12,000 BTUs operating on 800 watts, which works out to an EER of 15: nearly twice as efficient.
When you shop by EER instead of by BTU, you enjoy the benefits of an energy efficient home cooling system. They include:
- Low carbon footprint, reducing the overall energy usage of your household
- High performance, ensuring your comfort through the hot summer months
- Better quality, including quiet operation and longer-lasting hardware
- Lower utility bills due to using less power to run the HVAC system overall
- Smart functionality, such as energy-saving modes and automatic maintenance reminders to help save even more money
Not sure where to find high-EER HVAC systems? It helps to buy from the ENERGY STAR® catalog, as every listed HVAC unit needs to meet certain standards for EER and SEER. Look out for the ENERGY STAR® logo on any unit you’re considering buying.
Understanding your HVAC system’s EER is the first step toward serious savings on your utility bill and minimizing your carbon footprint. Take the time to make smart decisions about your home cooling system today. A home energy audit is the next step!