Welcome to Lesson 12

In this lesson we will learn what you might expect from a residential home energy audit. You will learn about what things you can do to help reduce your energy costs.  In earlier lessons we learned about your electric use, and how to calculate your usage.  In this lesson we will bring it together with your whole home energy use. 

• Interactive Infographic: U.S. residential energy use breakdown (EIA data) with the End-use Consumption Shares by Type of U.S. Homes, 2015 infographic on this page. Use of energy explained: Energy use in homes
• Read the U.S. Department of Energy Energy Saver “Tips on Saving Money and Energy in your Home""

Learning Objectives

By completing this module, students will be able to:

1. Explain how residential energy use connects to climate change, household budgets, and indoor comfort
2. Identify the three primary pathways of energy loss in buildings (air leakage, insufficient insulation, inefficient equipment)
3. Conduct a no-cost DIY energy audit of their current living space using household items
4. Analyze a utility bill (real or sample) to establish energy consumption baselines
5. Prioritize energy improvements using a simple cost-benefit framework

Even if you don’t want to have a professional energy audit performed, you can still look for ways to save energy in your space. What things can you do to look for energy savings in your home?

1. Hunt for Air Leaks (Your #1 Priority)

Air leaks waste energy year-round—letting heated air escape in winter and cool air escape in summer.

Where to look:

• Around windows and doors (feel for drafts with your hand)
• Electrical outlets and switch plates on exterior walls
• Where pipes or wires enter walls (kitchen, bathroom, basement)
• Attic hatches and fireplace dampers
• Baseboards and crown molding gaps

DIY test: On a windy day, hold a lit incense stick near potential leak spots. If the smoke wavers, you've found a leak!

Quick fix: Apply weatherstripping to doors/windows and foam gaskets behind outlet covers ($5–$20 fixes that can save 10–20% on heating/cooling costs).

2. Check Your Insulation Levels

Poor insulation works against your HVAC system constantly.

Easy inspection spots:

• Attic: If you can see ceiling joists, you likely need more insulation (joists should be covered)
• Basement/crawlspace walls: Look for gaps or compressed insulation
• Exterior walls: Cold spots on interior walls during winter suggest missing insulation

3. Inspect Heating & Cooling Equipment

Your HVAC system works harder (and costs more) when poorly maintained.

Checklist:

• Air filters: Are they dusty/clogged? Replace every 1–3 months ($5–$15 filters)
• Thermostat placement: Is it near a draft, lamp, or sunny window? (False readings cause wasted energy)
• Ductwork: In basements/attics, look for disconnected or crushed ducts
• Programmable/smart thermostat: Can you set back temperatures when sleeping or away? (Saves ~10% annually)

4. Slay "Energy Vampires"

These devices drain power 24/7—even when "off." Anything with a light on it is consuming energy, even when it is off.

Common culprits in student/family homes:

• Phone/laptop chargers left plugged in
• Game consoles on standby
• Coffee makers with clocks
• TVs and sound systems with "instant-on" features
• Desktop computers not set to sleep mode

Action: Plug entertainment centers and chargers into a power strip. Flip the switch off when not in use, it could save you 5–10% on electricity bills.

5. Lighting & Appliances

• Light bulbs: Replace incandescent or CLF lighting with LEDs (use 75% less energy, last 25x longer)
• Refrigerator: Check door seals (close door on dollar bill, if you pull it out easily, seals need replacing)
• Water heater: Set to 120°F (not "hot"). Insulate hot water pipes in unheated spaces.

Imagine having X-ray vision for heat. That’s essentially what an infrared (IR) camera gives energy auditors. These specialized cameras detect infrared radiation—the heat energy emitted by all surfaces—and translate it into a visible image called a thermogram.

• Cooler areas appear blue/purple/black
• Warmer areas appear yellow/orange/red/white

This works best when there is a large temperature difference between inside and outside temps (at least 20^oF). This allows the camera to show bigger contrasts.

Text description of the optical and thermal image.

The image shows a carpeted indoor stairway leading to a white-painted wooden door. The stair has dark brown carpet, and the adjoining walls and door are painted white. There is a significant contrast in temperature depicted through a thermal view inlay within a circular border, occupying the right side of the image. This thermal section shows the stair and door area in vibrant colors ranging from deep blue and purple to orange and yellow, indicating cooler and warmer areas respectively. The temperature readout in the thermal view shows 45.3°F.

Credit: Adapted from n.a. “How to Look at a House like a Building Scientist (Part 2: Heat)” Building Science Corporation, December 2019.

What Thermography Reveals (With Real Examples)

1. Missing or Settled Insulation
   • What you see: Large cool patches on interior walls/ceilings in winter (warm patches in summer)
   • Why it matters: Heat flows through the path of least resistance—uninsulated cavities become thermal highways 
2. Thermal Bridging (When conductive materials bypass insulation)
   • Classic example: Steel studs in walls (steel conducts heat 300x better than wood!)
     • In winter IR images: Vertical blue lines tracing every stud
     • Real-world consequence: In one infamous Las Vegas case, cool steel studs caused smoke particles to plate out along every stud line, making the entire wall look like a barcode! 
   • Other bridges: Uninsulated concrete slabs, metal window frames, structural beams penetrating insulation layers

3. Air Leaks (Best seen with blower door testing)

• Without depressurization: Subtle temperature differences at leak sites
• With blower door: Dramatic black streaks appear where cold air is being sucked through gaps (windows, outlets, rim joists)
• Pro technique: Auditors first scan the building normally, then depressurize it with a blower door fan and scan again—comparing "before/after" reveals hidden leaks

How Auditors Measure Your Home's "Leakiness"

What Is a Blower Door?

A blower door isn't a door at all, it's a calibrated fan system temporarily mounted in an exterior doorway that deliberately sucks air out of your house to create controlled negative pressure inside.

Text description of the Blower Door image.

The image shows a doorway that leads into a room. An open door is positioned on the left side. The entrance is obscured by a large red plastic barrier that acts as an air seal test setup. The large circular object at the base of the barrier is a blower, which is attached to the barrier for measuring air pressure. There is also a black control panel mounted next to the door, connected by wires, featuring buttons and a digital display.

Credit: Blower Door by The EnergySmart Academy from Flickr (Public Domain). Accessed July 21, 2026.

The physics in action:

When the fan pulls air out, indoor pressure drops below outdoor pressure. Nature hates imbalance, so outdoor air immediately rushes in through every unsealed crack, gap, and hole in the building envelope. The leakier the house, the harder the fan must work to maintain the pressure difference.

Note: A blower door doesn't create leaks—it reveals them by exaggerating natural air movement 20–50x beyond normal conditions.

Why 50 Pascals? Understanding the Standard Test Pressure

Auditors don't just run the fan at random speed. They depressurize the house to a precise 50 Pascals (Pa)—roughly equivalent to a 20 mph wind blowing against all sides of the house simultaneously.

Why this number?

• Strong enough to overcome natural wind/stack effects during testing
• Standardized globally—allows comparison between homes
• Safe for the building structure (won't rip shingles off your roof!)

Blower Door Test (5:34)

The Testing Procedure: Step by Step

Pre-Test Prep

Before the fan even turns on, the auditor must:

1. Close all windows and exterior doors
2. Open all interior doors (bedrooms, closets, bathrooms)
3. Turn off HVAC systems, fireplaces, and exhaust fans (bath/kitchen)
4. Close fireplace dampers and woodstove doors
5. Cover dryer vents and kitchen range hoods (temporarily)

During the Test

1. Mount the blower door frame in an exterior doorway (usually the main entry)
2. Seal the frame edges with nylon panels to prevent bypass air
3. Start the fan and gradually ramp up to 50 Pa depressurization
4. Walk the house with smoke pencil/incense to visually locate leaks as air rushes in
5. Optional but powerful: Pair with IR camera to photograph thermal patterns while depressurized (see connection below)

Post-Test

• Record CFM₅₀ and calculate ACH₅₀
• Generate leakage report with prioritized repair recommendations
• Retest after air sealing to verify improvement (typical goal: 20–40% reduction)

The Power Combo: Blower Door + Thermography

Remember our lesson on IR cameras? Alone, thermography shows where surfaces are cold—but can't distinguish between missing insulation, thermal bridging, or actual air leaks.

Enter the blower door:

When you depressurize the house while scanning with an IR camera, air leaks become dramatically visible as cold streaks being sucked through gaps:

Why This Matters to Homeowners (and Future You)

¹Energy Trust of Oregon has a nice page with information and tips to save money and energy.

Bigger picture: The U.S. DOE estimates that air sealing alone can reduce heating/cooling energy use by 15–30% in typical homes—making it one of the highest-return energy upgrades available. Air leakage tests are also done to confirm any sealing or insulation has been properly done. This may be a requirement for some tax credits or incentives.

Combustion Analyzers

A combustion analyzer isn't optional equipment—it's a non-negotiable safety prerequisite. Before an auditor depressurizes your home with a blower door (which can reverse chimney draft), they must verify that fuel-burning appliances (furnaces, water heaters, boilers) aren't producing dangerous carbon monoxide (CO) or at risk of backdrafting flue gases into living spaces.

Combustion analyzers will detect O₂, CO and CO₂ levels to help determine if your appliance is operating efficiently and safely.

Beyond blower doors and combustion analyzers, auditors deploy specialized tools for specific investigations:

• A manometer (precision pressure gauge) measures pressure differentials between ducts and living spaces to quantify duct leakage without full system pressurization;

  

  Text description of the Manometer image.

  The image depicts a person's hand holding a blue digital manometer with a display showing a reading of "20.7." The manometer features several buttons in yellow, including a plus sign, a unit toggle, and min/max settings. The tool is a precision pressure gauge used to measure pressure differentials between ducts and living spaces to quantify duct leakage without full system pressurization.

  Credit: Tosh Lubek. Adobe Stock. Accessed July 21, 2026.

• The Duct Blaster—a calibrated fan that seals directly to the air handler—provides definitive airtightness measurements for the entire duct system, revealing whether 20%, 40%, or even 60% of conditioned air escapes into attics or crawlspaces before reaching rooms.

  

  Text description of the Duct Blaster image.

  The image depicts a man kneeling on a tiled floor in a hallway, working with a duct blaster connected to a ventilation system. In one hand, he holds a digital measuring tool, focused on the screen, while with the other hand, he adjusts the device's wires. The setup includes a flexible, shiny duct attached to an oval-shaped fan. The duct is connected to a wall vent, which is framed by a rectangular opening. 

  Credit: Duct Blaster by ket555 from Wikimedia CC BY-SA 4.0. Accessed July 21, 2026.

• For safety-critical gas systems, a combustible gas detector scans appliance connections, valves, and piping for methane or propane leaks—addressing both explosion/fire hazards and wasted fuel that silently escapes 24/7.

  

  Text description of the Combustible Gas Detector image.

  The image depicts a close-up view of a gas cylinder inside a storage compartment and a person pointing a gas detector towards the connection where a flexible hose leaves the gas cylinder. The gas detector is gray with a green indicator light and an “ON/OFF” button. 

  Credit: Anetlanda. Adobe Stock. Accessed July 21, 2026.

• To make invisible air movement tangible during inspections, a smoke pencil (or incense stick) releases a steady stream of vapor that bends, swirls, or accelerates when crossing leak paths—turning abstract pressure differences into visible evidence students can photograph and annotate.
• Finally, a digital camera or cell phone documents appliance nameplates (for efficiency ratings), installation flaws, insulation gaps, and pre/post repair conditions—creating a permanent visual record essential for reports, contractor bids, and verifying retrofit success.

Together, these tools transform subjective observations ("this room feels drafty") into quantifiable, actionable data.

After completing a home energy audit, the homeowner receives a comprehensive report that synthesizes all collected data and translates it into actionable recommendations. This document serves as a roadmap for improving comfort, safety, and energy efficiency—prioritizing upgrades by cost-effectiveness and impact. Below are two illustrative examples.

Why this matters to you: Even without owning a home, these reports teach financial literacy. Understanding payback periods, benchmark comparisons, and tiered recommendations prepares you to evaluate any efficiency claim—from apartment upgrades to future home purchases. And those no-cost tips? They work in dorms and rentals today.

There are lots of different programs out there to help auditors create the reports. Some free ones include :

• Energy Star Portfolio Manager
• Home Energy Yard Stick (Energy Star)
• Google Energy Assessment

While there are countless paid tools out there as well! Companies often use a template or program to help them while they are doing their audit, which allows them to enter images or data directly into the report while they are in the process of performing the audit. This can allow the customer to receive the audit report almost immediately.

Watching practitioners in action transforms abstract concepts into tangible careers. The videos below showcase real energy auditors at work—demonstrating the tools, communication skills, and problem-solving approaches you've studied. After viewing, you'll explore how these roles fit into a broader ecosystem of green building careers.

This DOE-produced overview walks through a complete residential audit—from initial homeowner interview to blower door testing and infrared imaging. As you watch, notice:

•  How the auditor explains technical findings in plain language (e.g., translating CFM₅₀ numbers into "this is like leaving a window open year-round")
•  The sequence of tests (why combustion safety comes before depressurization)
•  How recommendations are prioritized by cost-effectiveness, not just technical possibility

Energy 101: Home Energy Assessment (3:30)

This field perspective highlights the human dimension of energy auditing—working with diverse homeowners, navigating tight crawlspaces and attics, and balancing technical accuracy with empathy. Pay attention to:

•  The physical demands of the job (ladders, confined spaces, variable weather)
•  How auditors document findings for contractors who will implement recommendations
•  The blend of technical knowledge (building science) and soft skills (listening to homeowner concerns about drafts or high bills)

A Day In the Life of an Energy Auditor | AEE & Empeq (2:20)

Career Exploration: Map Your Pathway

After watching the video above, explore the Green Buildings Career Map—an interactive tool developed by the U.S. Department of Energy and industry partners that charts 55 careers across four sectors of the energy efficiency industry. 

Your exploration task:

1. Open the Residential & Multifamily Construction & Retrofitting section of the JOBS menu and click on Residential Energy / Auditor
   • Review the information: typical salary ranges, education pathways, and advancement routes
   • Note recognized certifications (e.g., BPI Building Analyst, RESNET HERS Rater) 
2. Go back to the Career Map and click on the Residential Energy/Auditor dot to see adjacent roles you could grow into:
   • Lateral move: Certified Home Energy Rater/Assessor/Inspector
     • Collects and analyzes building data and tests building functions to determine the energy performance/rating, safety, and durability of a home.
   • Advancement: Building Performance Contractor
     • Run businesses that design and install whole-house energy measures to increase the thermal performance of residential buildings, often with a specialization in blower door-guided air sealing and insulation of the building enclosure.
   • Specialization: Indoor Environmental Health Specialist
     • Assess a wide variety of commercial and industrial buildings to identify health and safety risks such as indoor air quality, environmental contaminants, and safety hazards and propose remediation measures.
3. Look at the Entry-Level (bottom three rows on the graphic) to identify positions you could pursue now while in college:
   • Energy Efficiency Technician (residential or commercial)
   • Insulation/Air Sealing Technicians
   • Building Performance Installer

You now hold a powerful lens for seeing the invisible flows that shape our built environment: heat escaping through hidden gaps, air leaking from ducts buried in attics, combustion gases that demand respect, and thermal patterns that tell stories about how buildings actually perform versus how they were designed to perform. Whether you conduct a 30-minute DIY walkthrough with incense and a flashlight or deploy a $10,000 blower door/Infrared camera rig as a certified professional, the core mindset remains the same—curiosity paired with evidence.

Energy auditing bridges three critical domains often taught in isolation:

• Science (thermodynamics, fluid dynamics, building physics)
• Practical skill (diagnosis, measurement, prioritization)
• Human impact (lower bills for families, safer homes, reduced carbon emissions)

This convergence is why auditing isn't just a technical exercise—it's a form of advocacy. When you document a leaky attic hatch wasting $150/year, you're not just noting a defect; you're revealing a solvable injustice for a low-income household. When you catch a backdrafting water heater before it sickens a family, you're practicing public health. And when you help a homeowner cut fossil fuel use by 25%, you're contributing—tangibly—to climate solutions.

Your journey doesn't end here. Start small this semester:

• Audit your own living space using the DIY checklist
• Notice thermal patterns on windows during temperature swings
• Question why a room feels drafty instead of just turning up the thermostat

These habits sharpen the observational skills that separate exceptional auditors—and exceptional problem-solvers in any discipline. And should you choose to pursue certification (via BPI, RESNET, or state programs), you'll enter a growing field where demand for skilled auditors outpaces supply—especially as building electrification and efficiency mandates expand nationwide.