The DIY Home Energy Audit: What to Check Before You Call a Pro

A professional blower-door audit is worth the money if you want precise numbers, but a large share of the easy wins are visible without any equipment. The goal of a DIY pass is to find the obvious losses first, so any paid audit that follows is confirming detail rather than starting from zero.

Start with the envelope, not the equipment

Air leaks lose more energy in most houses than an inefficient furnace or an old water heater. On a windy or cold day, walk the house with the back of your hand near likely gaps: window and door frames, electrical outlets on exterior walls, the attic hatch, and where pipes or cables pass through the foundation.

• Attic hatch or pull-down stairs — usually unsealed and uninsulated even in otherwise well-insulated homes.
• Rim joists in the basement, where the foundation meets the wood framing.
• Recessed lighting fixtures in insulated ceilings, especially older non-IC-rated cans.
• Dryer vent flaps and bathroom exhaust fan dampers that fail to close fully.
• Weatherstripping around exterior doors, checked for a visible light gap or a paper-pull test.

Check insulation depth where you can see it

In an unfinished attic, insulation depth is a rough but useful proxy for R-value. Lay a tape measure flat on top of the insulation in two or three spots. If joists are visible above the insulation line, you are under most current recommendations for most climates.

Find phantom electrical loads

Devices left in standby draw power around the clock. A cheap plug-in watt meter, moved between a TV setup, a desktop computer, a game console, and a coffee maker with a clock, usually turns up a few devices drawing 5-15 watts continuously for no active use — small individually, but constant for 8,760 hours a year.

Look at the water heater and HVAC without touching them

• Check the water heater's age against its typical service life; tanks over 10-12 years old are worth budgeting to replace before they fail.
• Look at the furnace or air handler filter — a filter you cannot see through is restricting airflow and raising energy use.
• Note the thermostat setback schedule, if any. A programmable or smart thermostat with no schedule set is providing zero benefit over a manual dial.

When to bring in a professional

A blower-door test quantifies total air leakage in a way a hand-check cannot, and infrared thermal imaging finds hidden insulation gaps inside finished walls. Both are worth paying for if you are about to do major insulation or window work and want to prioritize spending, or if utility bills seem high relative to a similarly sized home and the visible checks above found nothing obvious.

Checking doors and windows for cost-effective sealing wins

Not every drafty window needs replacement. Before assuming a big-ticket fix, test each exterior door and window individually: close a dollar bill or a strip of paper in the frame and pull gently. If it slides out with little resistance, the seal there is weak. This simple test, repeated at several points along each frame, tells you exactly which units need new weatherstripping or fresh caulk rather than guessing based on how a room feels.

• Exterior door thresholds — check for a visible gap under the door with a flashlight held outside at night while someone holds a light inside.
• Storm windows and doors, if present — confirm they close and latch fully, since a storm door left ajar provides none of its intended benefit.
• Caulk lines around window trim, both inside and outside, looking for cracking or separation from the wall surface.

Estimating the payback before you spend money

Once you've logged the leaks, insulation gaps, and phantom loads you found, it helps to rank them by rough cost-to-fix versus expected savings rather than tackling whichever is most visible first. Air sealing and weatherstripping are usually the cheapest fixes with the fastest payback, often under a year. Attic insulation top-ups pay back over a few years depending on climate and current depth. Big-ticket items like window replacement or a new HVAC system have the longest paybacks and are best planned for equipment end-of-life rather than justified by energy savings alone.