ASHRAE Standards for HVAC Testing

Posted by Maria Martin on

ASHRAE Standards for HVAC Testing

ASHRAE standards are the backbone of HVAC system testing, ensuring systems perform efficiently, maintain indoor air quality, and meet energy use goals. These guidelines cover key areas such as airflow, temperature, humidity, and duct leakage testing. They also establish protocols for inspections, maintenance, and energy audits for both residential and commercial buildings.

Key highlights include:

  • Energy Audits (Standard 211): Three audit levels to assess energy-saving opportunities.
  • Ventilation & IAQ (Standards 62.1 & 62.2): Minimum ventilation rates for commercial and residential spaces.
  • Duct Testing: Updated requirements for low- and medium-pressure ducts to minimize energy loss.

ASHRAE standards also guide system commissioning for new constructions and retrofits for older systems, ensuring compliance with performance and safety benchmarks. Whether for residential or commercial applications, these standards help technicians evaluate, maintain, and optimize HVAC systems effectively.

“An Overview of Ashrae Standard & its Applications”

Main ASHRAE Standards for HVAC Testing

ASHRAE has developed several key standards that form the backbone of professional HVAC testing practices. These standards outline the necessary requirements and procedures to ensure HVAC systems function effectively, delivering the desired levels of thermal comfort, energy efficiency, and indoor air quality in both new and existing commercial buildings. Below is an overview of the primary standards and their specific roles in HVAC testing.

ANSI/ASHRAE Standard 180: Inspection and Maintenance

ANSI/ASHRAE Standard 180 establishes the minimum requirements for inspecting and maintaining HVAC systems. Its goal is to help professionals maintain system performance through a structured maintenance program. This includes creating a detailed inventory of equipment, documenting information such as manufacturer details, location, capacity, and system identifiers. The standard also differentiates inspection tasks – like testing and condition checks – from maintenance tasks, which involve cleaning, aligning, lubricating, adjusting, and making necessary corrections.

Additionally, it emphasizes the importance of regular reviews, such as startup meetings and annual assessments, with more frequent checks if any system degradation is observed. These guidelines ensure that HVAC systems are maintained not only for efficiency but also to meet ventilation and indoor air quality requirements.

ANSI/ASHRAE Standards 62.1 and 62.2: Ventilation and Indoor Air Quality (IAQ)

ANSI/ASHRAE Standard 62.1 focuses on ventilation and indoor air quality requirements for commercial buildings. It defines minimum ventilation rates based on factors like building occupancy and function. The standard also provides methods for calculating outdoor air requirements and evaluating ventilation effectiveness.

For residential applications, ANSI/ASHRAE Standard 62.2 sets guidelines for whole-house ventilation and local exhaust systems. These requirements take into account variables such as home size, occupancy levels, and local climate conditions. Both standards offer performance-based compliance options, giving flexibility while ensuring that essential health and safety standards are upheld.

ANSI/ASHRAE Standards 211 and 100: Energy Audits and Performance

Energy audit and performance standards complement the above by addressing energy consumption and efficiency. Standard 211 outlines three levels of energy audits:

  • Level I: A preliminary assessment to identify quick energy-saving opportunities.
  • Level II: A more detailed analysis, including financial and energy evaluations.
  • Level III: A comprehensive engineering study with detailed project plans and cost estimates.

Meanwhile, Standard 100 focuses on energy performance by setting specific performance targets and establishing baseline energy usage. It also provides guidelines for ongoing commissioning and tracking improvements over time. Together, these standards support continuous efforts to optimize energy use and improve overall building performance.

HVAC Testing Methods Based on ASHRAE Standards

ASHRAE standards provide a framework for testing HVAC systems to confirm they meet design specifications, operate efficiently, and maintain indoor air quality. Certified technicians follow these protocols to evaluate system performance and detect potential issues before they impact a building’s overall efficiency. These testing methods ensure HVAC systems align with ASHRAE guidelines, achieving energy efficiency and air quality goals. Below are the primary testing methods based on these standards.

Airflow and Ventilation Testing

Measuring airflow is a critical step in verifying an HVAC system’s performance. Technicians use specialized instruments to assess airflow at various points in the system, comparing the results to ASHRAE’s recommended outdoor air intake rates. These rates are calculated based on the building’s occupancy and intended use, ensuring proper ventilation and air quality.

Temperature and Humidity Testing

Temperature and humidity levels play a significant role in maintaining indoor comfort, as outlined in ASHRAE Standard 55. Technicians measure these parameters at strategic points, such as supply and return air vents, to confirm the system meets its design specifications. Psychrometric calculations help verify the system’s ability to dehumidify effectively during heating or cooling cycles. In some cases, data loggers are employed to monitor temperature and humidity changes over time, ensuring consistent performance within the desired setpoints.

Additionally, the integrity of air distribution systems must be maintained to prevent inefficiencies.

Duct and Building Leakage Testing

Duct leakage testing has gained importance as energy efficiency standards become more stringent. ASHRAE Standard 189.1 now mandates testing for low- and medium-pressure ducts (3-inch water gauge) in addition to high-pressure ones (4-inch WG). This update addresses a major source of energy loss, as lower-pressure ducts can leak significantly more than their high-pressure counterparts.

“I spearheaded this update because of concerns that it is very rare to have ducts greater than 4-inch pressure class to be used today, while it was very common when the original requirement was to test the leakage of ducts greater than 3-inch WG pressure class. This resulted in much less leak testing today, while standard 189.1 is attempting to reduce energy use.”
– Jeff Boldt, Director of Innovation and Quality, IMEG Corp.

The testing process involves pressurizing the duct system and measuring air leakage rates using advanced tools. ASHRAE SPC215P provides guidelines for calculating both leakage airflow and the percentage of leakage in operating systems. Testing typically begins with 20% of the ductwork, expanding to the entire system if initial results reveal significant issues.

Industry data highlights the prevalence of duct leakage. A 2015 survey by the Building Commissioning Association revealed that 75% of engineers identified leaky ducts as a major source of energy loss in U.S. buildings, with 68% reporting leakage rates of 15% or more. These findings emphasize the importance of thorough duct testing to optimize energy efficiency.

“The industry has resisted testing because of the additional cost involved. But in reality, building owners can either make a relatively small payment upfront to ensure their ducts are operating properly, or they can continue to pay higher operating costs throughout the life of the building. The 189.1 updates to duct testing will help ensure that today’s buildings are operating as efficiently and cost effectively as possible.”
– Bob Reid, Former Chairman of ASHRAE Technical Committee 5.2 and Chief Engineer, SPOT (Spiral Pipe of Texas)

Building envelope leakage testing uses blower door equipment to pressurize the entire structure and measure air infiltration rates. This process identifies areas where conditioned air escapes or unconditioned air enters, allowing targeted sealing efforts. Properly addressing these leaks enhances building performance and reduces long-term operating costs.

HVAC Testing Process: Step-by-Step Guide

The HVAC testing process, as outlined by ASHRAE standards, involves detailed planning, precise fieldwork, and thorough data analysis. These steps ensure accurate results, compliance with industry standards, and actionable insights for system improvements. Professional technicians follow a structured protocol to assess performance, uncover deficiencies, and recommend solutions, all while minimizing errors and maximizing the value of the testing process.

Planning and Documentation Before Testing

Preparation is key to effective HVAC testing. This starts with reviewing system documentation, including design drawings, specifications, maintenance records, and occupancy schedules. These materials provide a baseline understanding of the system and help identify potential problem areas.

Testing schedules are influenced by building occupancy and usage patterns. For example, testing during peak occupancy can reveal how the system performs under real-world conditions, while off-hours testing allows for more controlled measurements. Weather conditions also play a role, particularly for outdoor air intake and building envelope evaluations.

Instrument calibration is another critical step. Tools like digital manometers, airflow measurement devices, and temperature sensors must be regularly calibrated to meet accuracy standards. Calibration certificates ensure that these instruments comply with strict error tolerance requirements, which is essential for reliable results.

Once the planning phase is complete, the process moves seamlessly into field testing.

Field Testing Procedures

Field testing begins with a visual inspection of the system. This step helps identify and address obvious issues, such as damaged ducts, missing insulation, or malfunctioning equipment.

Baseline conditions are established by recording indoor and outdoor temperature, humidity, and barometric pressure. These initial measurements provide context for any performance variations observed during testing.

Airflow testing is conducted using traverse measurements across duct cross-sections. Technicians take readings at specific grid points to calculate average velocities. Properly calibrated tools, such as pitot tube arrays and thermal anemometers, are vital for obtaining accurate airflow data.

Temperature and humidity readings are taken simultaneously at supply, return, and outdoor air locations. Psychrometric analysis is then used to evaluate the system’s ability to condition air according to design specifications. These measurements are compared to ASHRAE standards for comfort and energy efficiency.

Pressure testing assesses the integrity of ductwork and the building envelope. Duct blaster equipment pressurizes individual duct sections to measure leakage rates, while blower door fans create pressure differentials to quantify air infiltration through the building envelope.

Analyzing Results and Creating Reports

Once field measurements are complete, technicians analyze the data to evaluate system performance. Measured airflow and temperature differentials are compared to design specifications to identify any discrepancies.

Statistical analysis, such as confidence interval evaluations, helps distinguish between normal measurement variability and actual performance issues. ASHRAE standards provide guidelines on acceptable tolerance ranges, ensuring that findings are both accurate and meaningful.

Field data is converted into standardized metrics like ventilation effectiveness, energy efficiency ratios, and indoor air quality indicators. This ensures consistency across evaluations and simplifies the interpretation of results.

Reports are then created to document the testing process, measurements, and findings. Executive summaries highlight key issues and recommendations for building owners and facility managers, while technical sections provide detailed data for engineers and maintenance teams.

To help prioritize corrective actions, issues are categorized by severity, cost impact, and compliance requirements. Immediate safety concerns are addressed first, followed by recommendations for improving energy efficiency and occupant comfort. Reports often include cost estimates, implementation timelines, and return on investment calculations to demonstrate the financial benefits of addressing identified deficiencies.

Finally, follow-up testing schedules are established to monitor ongoing performance and compliance with ASHRAE standards. Trending analysis over time can reveal gradual performance declines and help optimize maintenance intervals, ensuring the system continues to operate efficiently.

ASHRAE Standards for Different Building Types

ASHRAE standards customize HVAC testing protocols based on the type of building and the project phase. The complexity of testing depends on whether it’s a new construction project, an upgrade to an existing system, or the differences between residential and commercial applications. Let’s break down how these standards address each scenario.

New Construction and System Commissioning

For new buildings, ASHRAE standards play a key role during the design and installation phases. They guide the selection of equipment, proper system sizing, and ensure compliance with energy efficiency and indoor air quality (IAQ) requirements. Commissioning, as defined by ASHRAE, is a systematic process to confirm that HVAC systems align with the owner’s expectations and function as intended. This involves testing system components under various operating conditions, verifying automatic controls, safety features, and energy management systems. Detailed documentation ensures that the system meets performance, safety, and comfort standards.

Existing Building Upgrades and Retrofits

When it comes to older buildings, ANSI/ASHRAE/IES Standard 100-2024 provides guidelines to improve energy efficiency and system performance. This standard covers all aspects of a building, including the envelope and HVAC systems, with the goal of enhancing thermal performance and reducing energy use. Retrofit testing includes energy audits, equipment efficiency checks, and assessments based on the system’s operational history. It also outlines strategies for creating energy management plans and methods for ongoing performance monitoring, ensuring that upgrades lead to measurable, long-term improvements.

Residential vs. Commercial Testing Requirements

ASHRAE standards take a different approach when comparing residential and commercial applications. For instance, ASHRAE Standard 90.1 sets energy efficiency benchmarks for commercial buildings but excludes low-rise residential properties. Commercial systems face stricter design and testing demands, particularly in large buildings where failures can have serious consequences. Standards like ASHRAE 62.1 (ventilation) and ASHRAE 55 (thermal conditions) apply broadly but are more rigorously enforced in commercial settings. Commercial projects often require detailed performance verification and permits, while residential testing focuses on basic energy efficiency, safety, and comfort.

Aspect Residential Commercial
Energy Standards Excluded from ASHRAE 90.1 Must comply with ASHRAE 90.1
Testing Complexity Basic performance checks Comprehensive testing and documentation
Regulatory Oversight Limited requirements Extensive compliance and permit needs
Documentation Minimal reporting Detailed reports and continuous monitoring

Commercial buildings demand more frequent and detailed testing, along with ongoing monitoring and extensive documentation. On the other hand, residential testing places greater emphasis on safety, comfort, and basic energy efficiency rather than complex regulatory compliance.

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Hydrodynamics: HVAC Testing Services

Hydrodynamics

Hydrodynamics has built its reputation on delivering energy-conscious HVAC solutions that meet modern building standards. By adhering to strict testing protocols and prioritizing sustainable practices, the company ensures its services are both effective and environmentally responsible.

HVAC testing plays a critical role in maintaining system performance and ensuring occupant comfort. Hydrodynamics combines time-tested expertise with cutting-edge technologies to align its work with ASHRAE guidelines, addressing the needs of residential, commercial, and industrial clients. Here’s a closer look at how these principles shape their services.

Complete HVAC Services

Hydrodynamics provides a wide range of HVAC services, covering every phase of a system’s lifecycle. From installations and repairs to maintenance and specialized testing, their offerings are designed to adhere to ASHRAE protocols. Their expertise spans:

  • Heating systems, air conditioning, and ductless systems
  • Heat pumps and geothermal heating and cooling solutions
  • Complex industrial systems, including rooftop HVAC units, waste oil systems, and gas, propane, and oil heating installations

Their proactive maintenance programs aim to extend system longevity and sustain peak performance. Beyond HVAC, Hydrodynamics also tackles plumbing, refrigeration, water conditioning systems, and grinder pump services. This comprehensive approach ensures that interconnected systems work together efficiently, enhancing overall building performance and air quality.

Energy Efficiency and Indoor Air Quality Solutions

Hydrodynamics goes beyond basic installations and maintenance by focusing on energy optimization and indoor air quality. They leverage advanced technologies to deliver measurable improvements in efficiency and comfort. One standout offering is their hydronic HVAC systems, which use water instead of air to regulate temperature. These systems are not only quieter and easier to maintain but also significantly more efficient – water can carry nearly six times more heat than air and requires much less space to transport the same amount of thermal energy.

The company also integrates Computational Fluid Dynamics (CFD) into its HVAC design and testing processes. CFD simulations allow for energy savings of 15–30%, far surpassing the 5–10% efficiency gains typical of traditional methods. Additionally, CFD optimization can enhance thermal comfort by 20–35%. Over multiple design iterations, energy consumption reductions of up to 30% are achievable, compared to just 10% with conventional techniques.

Indoor air quality is another key focus area for Hydrodynamics. By adhering to ASHRAE Standards 62.1 and 62.2, the company ensures proper ventilation and healthier indoor environments. Their water conditioning services, such as softeners and UV systems, further enhance HVAC performance by addressing water quality issues that could impact system efficiency and durability.

Conclusion: Why ASHRAE Standards Matter for HVAC Testing

ASHRAE standards are essential for ensuring HVAC systems operate efficiently while prioritizing the health and comfort of occupants. These guidelines serve as a trusted framework, shaping HVAC systems into reliable and effective solutions for indoor environments.

FAQs

How do ASHRAE standards help improve HVAC system energy efficiency?

ASHRAE standards play a key role in boosting the energy efficiency of HVAC systems by establishing minimum efficiency requirements for equipment such as furnaces, air conditioners, and heat pumps. For instance, standards like ASHRAE 90.1 and 90.2 ensure that HVAC systems are built and operated to align with up-to-date energy-saving benchmarks.

Beyond efficiency requirements, ASHRAE also offers detailed guidelines for system design, controls, and maintenance. Take Guideline 36, for example – it provides recommendations for standardized control sequences, which help fine-tune system performance and cut down on energy waste. Following these standards allows HVAC systems to run more efficiently, reducing energy use and utility bills, all while supporting environmentally conscious practices.

What are the main differences between ASHRAE standards for testing residential and commercial HVAC systems?

The Primary Differences Between ASHRAE Standards for Residential and Commercial HVAC Testing

The key differences between ASHRAE standards for residential and commercial HVAC testing lie in the complexity of the systems and their performance demands. Residential standards are designed with smaller, standalone systems in mind, focusing on straightforward inspections, routine upkeep, and energy-saving measures. Meanwhile, commercial standards cater to larger, more intricate systems, requiring detailed protocols for testing, adjusting, and balancing to ensure optimal energy efficiency, air quality, and occupant comfort.

For instance, commercial standards often specify testing methods tailored for advanced equipment and complex systems. Residential standards, by contrast, stick to simpler guidelines aimed at individual units. This approach ensures that each type of system is assessed and maintained according to its specific operational and performance requirements.

Why is duct leakage testing crucial for improving energy efficiency, and how is it performed following ASHRAE standards?

Why Is Duct Leakage Testing Important?

Duct leakage testing plays a key role in improving energy efficiency by pinpointing and reducing air leaks in HVAC systems. Air leaks can cause conditioned air to escape, leading to higher energy bills and wasted resources. When ducts are properly sealed, the air reaches its intended destination, boosting system performance and cutting down on energy waste.

As outlined by ASHRAE standards, the process involves pressurizing the duct system and measuring how much air escapes. This is done using specialized equipment like a duct blaster or blower door. Adhering to these standards helps HVAC systems meet efficiency benchmarks, conserve energy, and deliver better comfort for homes, businesses, and industrial spaces.

Duct Leakage Testing Methods Explained

Posted by Maria Martin on

Duct Leakage Testing Methods Explained

Duct leakage testing helps identify air loss in HVAC systems, which can waste up to 30% of conditioned air and increase energy bills. Testing also improves air quality, boosts HVAC efficiency, and ensures compliance with building codes.

Here are the three main methods:

  • Duct Pressurization Testing: Uses a calibrated fan to measure precise air leakage in ducts. Cost: $150–$500. Ideal for compliance and detailed audits.
  • Blower Door Testing: Measures overall home airtightness, including duct leaks. Cost: $150–$1,000+. Best for whole-house assessments.
  • Visual Inspections: Involves spotting visible leaks or damage. Low-cost but less accurate. Good for initial checks.

Each method fits different goals and budgets. For accurate results and compliance, duct pressurization is the most reliable. Professional testing is often recommended for precise data and long-term savings.

Residential Duct Leakage Test Demonstration

Duct Leakage Testing Methods

When it comes to detecting duct leakage, professionals rely on three main methods, each tailored to specific needs. These approaches vary in accuracy and purpose, helping to evaluate your HVAC system’s efficiency and compliance.

Duct Pressurization Testing (Duct Blaster)

Duct pressurization testing involves using a calibrated fan to pressurize the duct system to 25 Pascals. The amount of air leakage is measured by determining how much air the fan needs to replace lost air. This method is often used to ensure compliance with standards like the 2015 IECC, which requires no more than 4 CFM of leakage per 100 square feet of conditioned space.

Certified technicians typically perform this test, as the equipment can be costly. Homeowners can expect to pay between $150 and $500 per HVAC system for a professional duct blaster test.

Blower Door Testing

Blower door testing focuses on measuring the overall airtightness of a home. A powerful fan is installed in an exterior door frame to create a 50-Pascal pressure difference. During the test, all windows, doors, and intentional openings are sealed, allowing the fan to be the sole pathway for air movement. An adjustable frame and digital manometer are used to record the results.

This test measures airtightness in ACH50 (air changes per hour at 50 Pascals). Requirements vary based on climate zones and local codes. For instance, the 2015 IECC mandates that homes in Zone 2 achieve 5 ACH50 or less. Blower door tests can also help identify duct leaks in unconditioned spaces like attics or crawlspaces when combined with duct testing. Costs for this method range from $150 to over $1,000, depending on the home’s size and complexity.

Visual Inspection Methods

Visual inspections are the simplest and most affordable way to detect duct leaks, though they lack the precision of pressure-based tests. This method involves examining accessible ductwork for visible leaks, disconnections, or damaged insulation. Tools like smoke pens or video endoscopes can help identify problem areas without measuring exact air loss.

While this approach is excellent for spotting obvious issues, it cannot quantify air leakage and is limited to areas where ducts are accessible. Hidden ductwork in walls or ceilings may harbor small leaks that collectively lead to significant energy loss. Visual inspections are often used as a preliminary step before more detailed testing or to locate specific problem areas after pressure testing confirms leakage.

Testing Method Cost Range Best Used For Limitations
Duct Pressurization (Duct Blaster) Moderate ($150-$500) Code compliance; precise leakage measurement Requires professional equipment
Blower Door Testing Moderate to High ($150-$1,000+) Whole-house airtightness; finding external duct leaks Does not isolate duct-specific issues
Visual Inspection Low Initial checks; identifying obvious problems Limited to accessible areas; no air loss quantification

Together, these methods provide a well-rounded approach to duct leakage assessment. Professionals often begin with visual inspections to address visible issues and then turn to pressure-based tests for precise measurements and verification after repairs.

How to Perform Duct Pressure Testing

This section explains the step-by-step process for duct pressure testing, a crucial method for measuring air leakage in duct systems. Accurate testing requires careful preparation and execution.

Required Tools and Equipment

To get started, you’ll need a duct tester, which combines a calibrated fan with a digital manometer. The fan generates the required 25 Pascal pressure in the duct system, and the manometer measures pressure differences and airflow rates.

You’ll also need materials to seal vents and registers temporarily. Common sealing supplies include tape, plastic sheeting, and foam plugs. If the test reveals significant air leakage, a theatrical smoke machine can help pinpoint problem areas. For permanent fixes, have UL-listed foil mastic tape on hand.

Additional tools like a pressure pan are useful for identifying specific trouble spots. Before beginning, ensure all equipment, especially the duct tester, is calibrated according to the manufacturer’s instructions.

Testing Steps

  1. Turn off the HVAC system: This prevents interference with the test and ensures safety for both the equipment and personnel.
  2. Seal the system: Close off all vents, registers, and access points to create an airtight environment. Any unsealed openings will skew the pressure readings.
  3. Set up the duct tester: Attach the tester securely to a return duct grill. Ensure there’s no air leakage around the connection point. Follow the manufacturer’s setup instructions to connect the manometer and prepare the system for pressurization.
  4. Pressurize the ducts: Turn on the fan and increase the pressure to 25 Pascals. This standardized pressure ensures consistent testing and compliance with building codes. Record the airflow rate in cubic feet per minute (CFM) once the pressure stabilizes.
  5. Test supply ducts: Repeat the procedure for the supply ducts and average the readings for a complete assessment.
  6. Document results: Record all data, including pressure differentials and airflow rates. Accurate documentation is essential for code compliance and future reference.

After completing these steps, you’ll have the data needed to evaluate the system’s performance.

Reading Test Results

The results are expressed as CFM25, which measures airflow loss at 25 Pascals. Higher CFM25 values indicate more significant leakage.

Acceptable leakage limits depend on building codes and the stage of construction. For systems under construction, the standard is typically 4 CFM25 per 100 square feet of conditioned floor area. For finished buildings, the limit ranges between 6 to 8 CFM25 per 100 square feet, depending on local regulations.

The 2012 IECC specifies a maximum leakage of 4 CFM25 per 100 square feet of conditioned space. Under ENERGY STAR Version 3, rough-in tests allow up to 4 CFM25 per 100 square feet (or 40 CFM25 total, whichever is greater), while final tests permit up to 8 CFM25 per 100 square feet (or 80 CFM25 total).

To determine compliance, calculate the allowable leakage for your home by multiplying the conditioned floor area by the applicable CFM25 rate. For example, in a 2,000-square-foot home, the maximum leakage under the 2012 IECC would be 80 CFM25.

Proper sealing is essential for HVAC efficiency, as duct leaks can waste up to 30% of conditioned air. If your system exceeds the acceptable limits, use a smoke machine to locate leaks and perform targeted repairs.

Code Standard Construction Stage Maximum Leakage Alternative Minimum
2012 IECC Final 4 CFM25 per 100 ft² N/A
ENERGY STAR V3 Rough-in 4 CFM25 per 100 ft² 40 CFM25 total
ENERGY STAR V3 Final 8 CFM25 per 100 ft² 80 CFM25 total
2009 IECC Final 8 CFM25 per 100 ft² (to outdoors) 12 CFM25 per 100 ft² (total)

Once repairs are complete, conduct a retest to confirm the system meets code requirements and operates efficiently.

Code Requirements and Standards

Building on the testing methods discussed earlier, ensuring compliance hinges on following strict code standards and maintaining detailed documentation. A solid understanding of duct leakage testing codes is essential for creating efficient and compliant HVAC systems.

U.S. Building Codes and Limits

The International Energy Conservation Code (IECC) serves as the foundation for duct leakage standards across the U.S., with many states adopting these guidelines. Over the years, these standards have become more rigorous.

Earlier IECC versions set rough-in limits between 4–6 CFM per 100 ft², but later versions tightened this to 4 CFM per 100 ft². The 2009 IECC introduced post-construction limits of 8 CFM per 100 ft² for outdoor leakage and 12 CFM per 100 ft² for total leakage.

The 2012 IECC went further, establishing a single post-construction limit of 4 CFM per 100 ft² of conditioned floor area for total leakage.

The 2021 International Residential Code (IRC) retains similar standards but adds more detailed testing requirements. For rough-in tests, leakage must not exceed 4.0 CFM per 100 ft² if the air handler is installed, or 3.0 CFM per 100 ft² if it’s not. Post-construction testing allows up to 4.0 CFM per 100 ft², while ducts entirely within the thermal envelope can have up to 8.0 CFM per 100 ft².

The 2021 IECC also introduced mandatory testing for all air-handling ductwork, regardless of its location.

For commercial systems, the standards are even stricter under the updated ASHRAE 90.1 code. The maximum system leakage rate is now 5%, with ductwork alone limited to 3%. Moreover, supply and return ducts leaking to or from outdoors cannot exceed 2%.

“These updates really reflect the industry’s increased understanding of the critical role that duct performance plays in overall building performance. It also highlights the fact that taking a whole-system approach is vital to achieving maximum energy efficiency”.

States like California, Illinois, and Washington are setting even tougher standards. California’s Title 24, for example, focuses heavily on duct system performance. Many experts believe other states will follow California’s lead.

These codes establish the benchmarks that testing documentation must confirm.

Testing Documentation Requirements

Once the limits are set, proper documentation becomes essential to verify compliance and guide any necessary corrections. Both the 2009 and 2012 IECC require duct tightness verification through either rough-in or post-construction testing.

Certified raters must document leakage levels using RESNET-approved protocols, ensuring consistent and reliable testing procedures.

Timing matters when it comes to testing. If duct leakage is tested at the rough-in stage, a HERS rater must confirm and document compliance with the standard of 4 CFM25 per 100 ft² of conditioned floor area or 40 CFM25 (whichever is greater), using approved testing methods. Additionally, they must perform a final visual inspection to ensure duct boots are sealed correctly to finish surfaces.

Documentation should include leakage results, the conditioned area, and test conditions. For ENERGY STAR Version 3 Rev 11 compliance, testing can occur at rough-in or final stages, with specific limits: 4 CFM25 per 100 ft² or 40 CFM25 (whichever is greater) at rough-in, and 8 CFM25 per 100 ft² or 80 CFM25 (whichever is greater) at final.

As Neal Walsh explains:

“With this new standard, getting it right the first time is critical. Having to re-seal and re-test increasingly larger portions of the duct system can easily turn into a time- and labor-intensive proposition”.

Before starting any project, confirm which version of the IECC your jurisdiction uses to ensure compliance with the applicable duct leakage testing requirements. As regulations continue to evolve, expect tighter leakage limits, increased testing coverage, and broader inclusion of various duct types in testing.

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Pros and Cons of Each Testing Method

Looking at the various testing methods side by side can help clarify how each one fits into different scenarios. Your choice will ultimately depend on factors like your budget, the type of building you’re working with, and your specific goals. Each method has its strengths and weaknesses, which can impact your overall testing strategy.

Method Comparison Chart

Here’s a quick breakdown of the trade-offs for each approach, so you can decide which one aligns best with your needs:

Testing Method Accuracy Best For Main Limitations
Duct Pressurization High Residential & Commercial Requires specialized equipment
Blower Door Testing High Residential buildings Measures entire building, not just ducts
Visual Inspection Lower (~67% accuracy) Initial assessments Labor-intensive; may miss small leaks

The accuracy gap between these methods is worth noting. Pressure-based tests, for example, can achieve up to 97% accuracy, while visual inspections lag behind at about 67% accuracy for detecting and classifying damage. This difference underscores why pressure-based methods are often considered the gold standard.

Duct pressurization testing works by pressurizing the duct system and measuring air leakage rates. This method is particularly effective for identifying areas that need sealing or repair, which directly improves energy efficiency. In fact, the U.S. Department of Energy estimates that air leaks can account for up to 40% of heating and cooling costs, making accurate testing crucial.

Blower door testing evaluates the airtightness of an entire building. It involves sealing all openings except one, where a fan depressurizes the interior to measure overall air leakage. For example, Green Attic offers professional blower door tests starting at $250 for buildings under 3,000 square feet.

“A duct system is an extremely important component of a home’s HVAC (heating, ventilation, air conditioning) system meant to transfer conditioned (heated or cooled) air to various rooms. If it is leaking and not properly sealed, you are paying to heat and cool unconditioned parts of your home… and you may be sacrificing comfort at the same time.” – Knockout Inspections™

Visual inspections, while the easiest to perform, are the least reliable. SMACNA notes that visual checks can suffice for verifying reasonably tight construction, but research shows they often miss smaller leaks and require significant labor.

Which Method to Use When

Selecting the right method depends on the type of building and your specific objectives. Here’s a closer look at when each method works best:

  • Residential systems: Combine duct pressurization with blower door testing for a complete evaluation, as residential systems often suffer from significant air loss.
  • Commercial systems: Use duct pressurization as the primary method. For larger HVAC systems, multiple fans may be necessary. Visual inspections can be used as a secondary measure.
  • Measuring duct efficiency: Duct pressurization is ideal for pinpointing leaks and improving system performance.
  • Assessing overall building airtightness: Blower door testing is the go-to for identifying excess air leakage, which can reduce energy costs and prevent issues like drafts, moisture condensation, and outdoor pollutants.
  • Budget-friendly or initial assessments: Visual inspections can provide a starting point. Improved techniques, such as using colored liquids or tracers, may help, but they lack the precision of pressure-based methods.
  • Industrial applications: A combined approach works well – start with a visual inspection to spot obvious problems, then use duct pressurization for precise measurements. Many codes allow up to 10% leakage and require testing only for high- and medium-pressure ductwork, so thorough evaluation is key.

Professional Testing Services

Trying to test duct leakage on your own often falls short. For accurate results, professional expertise and specialized tools are non-negotiable. With today’s complex HVAC systems and stringent building codes, professional testing plays a key role in ensuring both efficiency and compliance.

When to Call a Professional

Once you’ve familiarized yourself with the basics of duct testing, knowing when to bring in a professional is just as important. These experts use precise methods to meet building code standards and optimize system performance.

For commercial and industrial HVAC systems, professional testing is almost always necessary. These systems involve intricate designs and require advanced equipment to evaluate larger duct networks effectively.

Another critical consideration is building code compliance. Professionals adhere to established national and state standards, ensuring your system meets all regulatory requirements. In some areas, duct testing is required to obtain a Certificate of Occupancy (CO), making professional services a must rather than an option.

You might need professional help if you notice certain red flags, such as uneven temperatures across rooms, rising utility bills, excessive dust near vents, musty odors, or persistent allergy symptoms indoors. These issues often point to duct leaks, which can reduce HVAC efficiency by as much as 20%.

Experts recommend scheduling professional duct testing every 2–3 years to maintain efficiency. It’s also wise to test after any changes to your heating or cooling system.

The cost of ignoring duct issues can be steep. Leaks can waste up to 30% of the air your HVAC system produces, and more than two-thirds of duct systems have leaks. As SITA-TAB, an industry expert, explains:

“You can’t fix what you don’t measure. Duct leakage testing provides the data you need to seal the system and optimize airflow.” – SITA-TAB

On average, professional duct testing costs around $325, with prices ranging from $115 to $450. While it may seem like an upfront expense, this service often pays for itself by improving energy efficiency and avoiding costly repairs down the line.

Hydrodynamics Inc. HVAC Services

Hydrodynamics Inc

For dependable, code-compliant testing, Hydrodynamics Inc. is a trusted choice. This family-owned company has been serving residential, commercial, and industrial clients since 1994, offering nearly three decades of HVAC expertise.

Hydrodynamics’ certified technicians use advanced tools like ultrasonic and infrared testing to pinpoint leaks, even in areas that are hard to access with a visual inspection. Their thorough approach ensures no inefficiency goes unnoticed.

Their services typically include a full HVAC inspection, sealing of supply and return registers, pressurizing the duct system, collecting data, and providing a detailed report with actionable recommendations. Additionally, they offer air production cost analysis, helping clients understand the financial impact of air leaks.

Hydrodynamics’ commitment to excellence is backed by certifications such as A.S.S.E Backflow Testing Certification, EPA 609 Certification, and Trac Pipe & Gas Tite Certification. These credentials highlight their dedication to industry standards and regulatory compliance.

Beyond testing, Hydrodynamics offers complete HVAC solutions. They seal ducts to prevent future leaks, provide ongoing maintenance, and service a wide range of systems, including heating, air conditioning, ductless setups, heat pumps, and specialized industrial applications. Their preventative maintenance programs are designed to keep systems running smoothly and to help clients avoid higher energy bills, code violations, and frequent repairs.

With decades of experience and state-of-the-art diagnostic tools, Hydrodynamics Inc. delivers the precise results and compliance that modern HVAC systems demand. Whether it’s routine testing or a full system overhaul, they’re a one-stop solution for all your HVAC needs.

Conclusion

This guide highlights key methods like duct pressurization, blower door tests, and visual inspections to identify leaks that can waste up to 30% of conditioned air.

Routine testing plays a crucial role in maintaining efficiency. As Joe Ophoff, Certified HERS Rater, explains:

“In new construction home design, there is a great emphasis on air leakage and distribution. New homes are designed for super performance, so really fine-tuning distribution systems are necessary for comfort throughout the house.”

The same principle applies to older systems, where significant air leakage is common. Addressing these issues not only improves energy performance but also reduces utility costs.

While energy efficiency is often the main motivation for duct testing, the advantages go beyond just saving money. Proper testing helps maintain consistent indoor temperatures, improves air quality, and ensures compliance with building codes.

Tests like duct blaster evaluations at 25 Pascals and blower door assessments provide precise data, enabling targeted repairs and system optimization.

For homeowners and facility managers, deciding between DIY inspections and professional testing often depends on the system’s complexity and code compliance needs. Visual inspections might uncover obvious problems, but achieving peak performance usually requires professional expertise and specialized tools. For guaranteed results and compliance, professional testing is indispensable.

Hydrodynamics Inc., with nearly 30 years of experience, offers comprehensive duct testing services. Their approach combines advanced diagnostic tools with certified expertise, ensuring your HVAC system runs efficiently and meets all regulatory standards. From initial inspections to detailed reports and repair recommendations, their services are designed to optimize performance.

Whether you’re installing a new system, addressing comfort concerns, or maintaining an existing setup, regular duct leakage testing is a wise investment. The upfront cost of professional testing pays off through lower energy bills, extended system lifespan, and the confidence of knowing your HVAC system is operating at its best.

FAQs

What’s the difference between duct pressurization testing and blower door testing, and when should you use each?

Duct pressurization testing zeroes in on air leaks within the ductwork itself. This process involves a duct blaster, which pressurizes the ducts – typically to 25 Pascals – and pinpoints leaks, especially in areas like attics or crawl spaces that aren’t climate-controlled. It’s commonly carried out after the ductwork is installed to confirm everything is properly sealed.

Blower door testing, by contrast, evaluates the airtightness of the entire building. A blower door fan is used to either pressurize or depressurize the structure, helping to locate overall air leakage. This test is often conducted during or toward the end of construction to ensure the building meets energy efficiency standards.

In summary, duct testing is focused on the duct system, while blower door testing examines the airtightness of the entire building.

How can I tell if I need professional duct leakage testing or if a visual inspection is enough?

If you’re trying to figure out whether you need professional duct leakage testing or if a simple visual inspection will suffice, start by evaluating the situation. A visual inspection is a straightforward approach where you check your ductwork for visible signs of damage, such as holes, cracks, disconnected sections, or worn-out seals. It’s quick and can help you identify obvious problems.

But here’s the thing: smaller leaks or hidden issues are often impossible to spot without the right tools. If your HVAC system isn’t performing as it should, your energy bills seem unusually high, or you suspect more serious leaks, professional testing is a smart move. Methods like pressure testing or blower door tests can give you accurate measurements of duct leakage. These tests are invaluable if you’re looking to improve energy efficiency or need to meet local energy regulations.

What happens if duct leaks are not fixed, and how can they affect energy efficiency and air quality?

Why You Shouldn’t Ignore Duct Leaks

Letting duct leaks slide can hit you where it hurts – your wallet and your health. When your ducts have leaks, the conditioned air you’re paying for escapes, making your HVAC system work overtime. This not only spikes your energy bills but also shortens the lifespan of your heating and cooling equipment.

But that’s not all. Leaky ducts can draw in dust, allergens, and even harmful gases from areas like attics or crawl spaces. This can lead to poor indoor air quality, which might trigger respiratory issues or other health concerns. Tackling duct leaks quickly ensures your home stays comfortable, your air stays clean, and your energy use stays efficient.

What Is Duct Leakage Testing?

Posted by Maria Martin on

What Is Duct Leakage Testing?

Duct leakage testing measures how much air escapes your HVAC system due to holes, gaps, or loose connections in the ductwork. This process helps identify inefficiencies that can waste energy, increase utility bills, and lower indoor air quality.

Here’s what you need to know:

  • Why it matters: Up to 30% of heated or cooled air can be lost through leaks, leading to higher energy costs and uneven temperatures.
  • How it works: Technicians pressurize the duct system to detect leaks using specialized equipment like calibrated fans and manometers.
  • Types of tests:
    • Total Duct Leakage (TDL): Measures all air escaping the system.
    • Leakage to Outside (LTO): Focuses on air lost to unconditioned spaces like attics or crawl spaces.
  • Benefits: Sealing leaks can save up to 20% on energy costs, improve indoor comfort, and meet building codes.

Testing costs typically range from $500 to $1,500, but the savings on energy bills and extended HVAC lifespan make it a worthwhile investment.

Want to reduce energy waste and improve home comfort? Duct leakage testing is a simple yet powerful solution.

How Duct Leakage Testing Works

The Testing Process

To start, technicians seal all supply and return registers using specialized materials. This step ensures a closed system, which is essential for accurate testing. Once sealed, a calibrated fan is connected to the air handler or main return vent. The fan either pushes air into the ducts or pulls it out to maintain a consistent pressure of 25 Pascals (equivalent to 0.1 inch water gauge). A manometer monitors this pressure throughout the process [1].

“Just as when you’re testing for airtightness, each cubic foot of air that leaks out (of the duct system in this case) must be made up by a cubic foot of air blown in by the fan. So, once you’ve measured the amount of air moving through the fan, you’ve quantified the duct leakage at the test pressure.” – Energy Vanguard [1]

The amount of air moving through the fan directly reflects how much air is leaking from the ductwork. In an ideal scenario with perfectly sealed ducts, the fan would require minimal effort to maintain the test pressure. However, real-world systems often have leaks, meaning the fan must work harder to sustain the 25 Pascal pressure. To identify specific leakage points, technicians may also use additional methods like smoke testing or pressure pans for visual confirmation.

Compliance with the 2018 and 2021 International Energy Conservation Code (IECC) often mandates duct pressure testing. A common benchmark is achieving less than 4 CFM of leakage per 100 square feet of conditioned floor area [12]. Once the system is sealed and pressurized, calibrated tools are used to measure leakage with precision.

Testing Equipment and Tools

Duct leakage testing relies on specialized tools designed for accurate and reliable results. The primary components of a duct leakage tester include a calibrated fan, a manometer (pressure gauge), and materials to seal HVAC vents [9][11]. Calibrated fans are crucial because they generate the precise airflow needed to pressurize or depressurize the ductwork to the required 25 Pascals. Modern systems can perform both pressurization and depressurization tests, with some advanced models eliminating the need for orifice plates, simplifying the process [8].

High-quality testing setups can be expensive, with advanced models often costing several thousand dollars. To seal vents during testing, technicians use vent caps in various sizes and specialized tools for hard-to-reach areas [6]. Trusted brands like TEC Ductblaster, Oriflow, and Retrotec provide equipment that meets code requirements and offer technical support [10]. Many of these systems also generate reports compliant with SMACNA standards, which are frequently required for inspections and energy efficiency programs [7]. The results are typically presented as both airflow (CFM) and leakage area measurements, offering a detailed evaluation of duct airtightness [11].

Duct Leakage Testing Basics

Benefits of Duct Leakage Testing

Understanding how duct leakage testing works reveals its clear advantages in areas like energy savings, improved indoor comfort, and meeting building codes.

Energy Savings and Lower Costs

Leaky ducts are a hidden drain on energy efficiency, potentially reducing an HVAC system’s performance by up to 20% [13]. When air escapes through leaks, the system has to work harder to maintain desired temperatures, which means higher energy bills and added stress on components like compressors, heat exchangers, and blower motors.

The cost of duct testing typically runs about $275 per system or $250 per test for multiple systems. Comprehensive testing can range from $500 to $1,500 [5][13]. While there’s an upfront cost, identifying and addressing duct leaks not only cuts energy waste but also extends the life of your HVAC system by reducing wear and tear on its parts.

Better Comfort and Air Quality

Duct leakage doesn’t just affect energy use – it also impacts the comfort and health of your indoor environment. Leaks can cause uneven airflow, leading to rooms that are too hot or too cold. Worse, unfiltered air filled with dust, pollen, and other pollutants can enter your home through these leaks, aggravating allergies or respiratory issues [14].

“By minimizing the possibility of contaminants entering through the ducts and circulating throughout your home, duct sealing can enhance indoor air quality.” – Climate Masters [3]

Sealing ducts prevents outside air, allergens, and moisture from infiltrating your HVAC system. This allows your air filtration system to perform better without constantly battling external contaminants. Plus, sealed ducts help maintain consistent humidity, reduce drafts, and even lower system noise, creating a more comfortable and peaceful living environment.

Meeting Building Code Requirements

Building codes set strict standards for duct leakage to promote energy efficiency. For instance, the 2021 IECC caps duct leakage at 4 CFM per 100 square feet for systems outside the building envelope and 8 CFM for ducts within the thermal envelope [15][16].

New construction projects face even tighter restrictions. The 2012 IECC requires leakage limits of 4 CFM per 100 square feet when the air handler is installed, and just 3 CFM when it’s not [15]. These tests are conducted during the rough-in phase, ensuring proper installation before walls are sealed and systems become harder to access.

“In new construction home design, there is a great emphasis on air leakage and distribution. New homes are designed for super performance, so really fine-tuning distribution systems are necessary for comfort throughout the house. Too much duct leakage can indicate a failure in the installation of the duct system, so we can catch a bad install at the ‘rough mechanical’ phase to ensure things are installed correctly. But also, the duct designs are carefully calculated to ensure distribution equilaterally throughout the house, so any significant leakage would affect that.” – Joe Ophoff, Certified HERS Rater [16]

Beyond passing inspections, meeting these requirements can open doors to energy efficiency programs, utility rebates, and certifications like LEED. For businesses, compliance supports sustainability goals and demonstrates a commitment to reducing environmental impact. Regular duct testing ensures systems remain efficient and aligned with these goals, making it a critical step before moving on to repair strategies.

How to Fix Duct Leakage Problems

Once testing has revealed duct leaks, the next step is to fix them quickly. Sealing those leaks can restore system efficiency and potentially lower heating and cooling bills by as much as 30% [20].

Sealing Methods and Materials

One of the most effective ways to seal duct leaks is by using duct mastic. This thick, paste-like material creates an airtight seal when applied to duct seams and joints. It’s known for its durability, making it a better choice than many other sealing options [17][19]. To use mastic, apply it generously over the leak area and spread it evenly with a brush or putty knife, ensuring there are no gaps [23].

For hard-to-reach areas, foil tape is a good alternative, though it’s less durable than mastic [19]. If using mastic tape for larger gaps or connection points, make sure to press it firmly against the duct surface, avoiding wrinkles or bubbles [23]. Avoid regular duct tape – it deteriorates quickly and isn’t suitable for long-term sealing. Always opt for tape specifically designed for HVAC systems [23].

For smaller holes and cracks, duct seal putty is a practical option. It’s flexible, allowing it to move with the duct, and it’s formulated to handle the higher temperatures often found in HVAC systems. Plus, it’s usually more affordable than other sealants, making it a solid choice for minor leaks [22].

In cases where leaks are in areas you can’t reach, aerosol-based sealants can be injected to seal internal leaks. Professional services like Aeroseal use specialized technology to pressurize the duct system and distribute sealant throughout the network [18][19].

Before applying any sealant, clean the area around the leak with a mild cleaning solution and a rag to ensure proper adhesion. Once mastic is applied, allow it to dry for 24 to 48 hours before running your HVAC system. After it’s fully dried, test for any remaining leaks using a smoke pencil or incense stick [23].

These sealing techniques not only fix leaks but also help restore the overall efficiency of your duct system, reducing energy waste.

Regular Maintenance and Inspections

Sealing leaks is just the beginning. To maintain your system’s performance, regular maintenance is essential. Schedule professional inspections every 3–5 years, or annually for newer systems [4][24]. These checkups can catch minor issues before they turn into major problems.

Replacing filters regularly is another key step to prevent strain on your ductwork [4]. Address small issues like obstructions or dirty filters promptly to avoid more significant damage later [4].

Pay attention to warning signs that your ducts may need attention. Reduced airflow from vents, musty odors, visible mold, or an increase in household dust despite frequent cleaning could all indicate duct problems [25]. If you notice these issues, don’t wait for your next scheduled inspection – have a professional check it out right away [24].

While some repairs can be done yourself, professional maintenance offers a more thorough solution. Experts have the tools and knowledge to tackle hidden leaks and can also insulate sealed sections to prevent heat loss [20][21].

“Duct sealing enhances home comfort, energy efficiency, and indoor air quality by ensuring consistent room temperatures, reducing HVAC strain, and preventing pollutants and allergens from circulating.” – Parker & Sons [20]

Investing in regular maintenance pays off in the long run. Professional duct sealing can boost energy efficiency by up to 20%, saving you money while improving the performance of your HVAC system [4].

Conclusion

Duct leakage testing reveals inefficiencies that can cost homeowners hundreds of dollars each year. In fact, most duct systems lose 20% to 30% of conditioned air due to leaks before it even reaches its intended destination [2][3]. Addressing these leaks can lead to noticeable energy savings and a more comfortable home environment.

By sealing ducts properly, you can cut energy use by as much as 20% [26]. Beyond saving money, this process also enhances indoor air quality by keeping dust, allergens, and other unwanted particles out of your living space. When you weigh the financial benefits alongside the health advantages, the case for duct sealing becomes hard to ignore.

“Duct leakage can significantly increase the energy consumption of a building, leading to increased energy bills for the owner. It increases energy costs and can result in occupant discomfort and lower productivity. This combination can transform a building intended to be a high performing building into a building that is not.” – H. Jay Enck, Member ASHRAE, David Cantrill, P.E., Member ASHRAE [27]

While the cost of duct leakage testing for a typical home ranges between $500 and $1,500 [5], it requires precise tools and expertise to measure airflow and pressure accurately. This makes professional assistance essential for reliable results.

That’s where Hydrodynamics Inc. comes in. With over 30 years of experience, they specialize in duct leakage testing and sealing. Their process not only identifies leaks but also includes expert repairs using trusted materials like duct mastic and advanced sealants. Whether for residential, commercial, or industrial systems, their focus on energy-efficient solutions ensures your ductwork meets all necessary codes while delivering peak performance.

FAQs

How can I know if my home’s ductwork has leaks that need testing?

Duct leakage testing is all about finding and measuring air leaks in your home’s ductwork. Common signs that your ducts might be leaking include uneven room temperatures, unexpectedly high energy bills, or weak airflow coming from your vents.

By testing for leaks, you can boost your HVAC system’s efficiency, cut down on wasted energy, and keep your home comfortable no matter the season. If these problems sound familiar, it could be a good idea to look into professional duct leakage testing.

What’s the difference between duct mastic and foil tape for sealing leaks, and when should you use each?

Duct mastic and foil tape are two popular choices for sealing leaks in ductwork, each with its own strengths. Mastic is a thick, paste-like sealant applied with a brush or spatula. It forms an airtight, durable seal, making it perfect for larger gaps or areas where durability is key. Foil tape, by contrast, is easier and faster to apply, which makes it a practical option for smaller repairs or tight spaces.

For most situations, mastic is the go-to option due to its reliable sealing and long lifespan, especially in high-efficiency HVAC systems. However, foil tape still has its place. It works well for quick fixes or as a complement to mastic. In fact, some experts suggest combining the two – starting with foil tape and then adding a layer of mastic over it for an even more secure seal.

Are there government incentives or rebates for duct leakage testing and sealing?

If you’re considering duct leakage testing and sealing, you might be eligible for government incentives or rebates, depending on where you live and your utility provider. These programs aim to promote energy efficiency and help homeowners and businesses cut down on utility expenses.

To see what’s available in your area, reach out to your local utility company or explore energy efficiency initiatives offered by state or federal agencies. Not only can duct sealing lower your energy bills, but it might also open the door to some helpful rebates.