The purpose of an energy audit is to evaluate your home's overall energy usage. A comprehensive audit will consider all aspects of your home's energy efficiency, from your HVAC system to kitchen appliances. However, some areas typically offer greater opportunities for savings than others, and HVAC systems can often be a good target for efficiency improvement.

While every energy audit may include slightly different steps, you can expect a few things from any evaluation. When evaluating your HVAC system, your auditor will typically look at three major factors: 

• Usage
• System Efficiency
• Home Losses

Understanding how these factors affect your home's energy efficiency and utility bills is crucial for making improvements.

How Your Usage Affects Efficiency

Usage refers to how you use your home's HVAC system. For example, keeping your thermostat much colder than the recommended temperature during the summer can reduce efficiency by causing your system to run for too long. An energy auditor will ask about your typical thermostat setpoints and make recommendations that can save you money.

Many people are uncomfortable with instructions to keep their thermostats at temperatures they perceive as uncomfortable, but that's not the purpose of an energy audit. Instead, it's important to understand how your usage impacts your system. You can then use this information to choose thermostat settings that balance a comfortable home with low utility bills.

Why System Efficiency Matters

System efficiency measures the rated efficiency of your HVAC units. For air conditioners, this refers to the SEER (seasonal energy efficiency ratio) rating. On furnaces, it's AFUE (annual fuel utilization efficiency). An energy audit will look at the rated performance of your HVAC equipment and its measured performance.

This part of the audit will allow you to judge whether your system is running as efficiently as it could be and how much you can save by replacing your equipment with newer models. It's rarely worthwhile to replace functional equipment, but the information from your audit can help you make decisions for its eventual replacement.

What You Can Do About Losses

Finally, all energy audits will look at conditioned air losses through windows, doors, and other gaps in your home's envelope. These losses allow conditioned air to escape into the environment, forcing your HVAC equipment to run harder and work longer to keep your home comfortable. Losses due to poor insulation incorrectly installed windows, or other problems can cost you a lot of money.

In many cases, this part of your audit (which may include a blower door test) will be the most actionable. Your auditor will look for areas where your home is losing the most air, allowing you to make cost-effective decisions to seal your home's envelope. These improvements can save you money over the long run while also helping to keep your home more comfortable.

Speak to a contractor to learn more about home energy audits.