Energy Audit Types and Procedures
A home energy audit is the first step toward reducing energy consumption and improving comfort. Professional energy auditors use a combination of visual inspections, diagnostic testing, and data analysis to evaluate a home’s energy performance. The two main types of audits are walk-through audits, which provide a basic assessment of major energy systems, and comprehensive audits that use blower door tests, infrared thermography, and detailed modeling.
The blower door test is the primary diagnostic tool for measuring air leakage. A calibrated fan mounted in an exterior door depressurizes the home, drawing outside air through all gaps and cracks. The fan measures the airflow required to maintain a constant pressure difference, providing a quantitative measure of the building envelope airtightness. The results are expressed in air changes per hour at 50 pascals of pressure.
Infrared Thermography
Infrared cameras detect temperature differences on building surfaces, revealing areas of missing insulation, air leakage, and moisture intrusion. The thermal image shows warm areas where heat is escaping in winter or entering in summer. Common findings include voids in wall insulation, gaps around windows and doors, thermal bridging through framing members, and inadequate insulation at attic hatches and rim joists. blower door test procedures. weatherstripping techniques. cellulose insulation.
The best conditions for infrared scanning are a temperature difference of at least 20 degrees Fahrenheit between inside and outside. Winter months provide ideal conditions for detecting heat loss, while summer months reveal heat gain through the building envelope. The auditor scans all exterior walls, ceilings, floors, windows, and doors from the interior side.
Common Findings and Solutions
Air leakage accounts for 25 to 40 percent of the energy used for heating and cooling in a typical home. The most common leakage locations are attic hatches, recessed lighting fixtures, duct connections, window and door frames, plumbing and electrical penetrations, and rim joists. Sealing these leaks with caulk, spray foam, and weatherstripping is the most cost-effective energy improvement.
Insulation deficiencies are found in attics, walls, basements, and crawlspaces. The recommended insulation levels vary by climate zone, with most northern zones requiring R-49 to R-60 in attics and R-19 to R-21 in walls. Adding insulation to an under-insulated attic typically pays back in 2 to 5 years through energy savings.