Manual J, Manual S, and Manual D are three separate residential HVAC design deliverables. Manual J calculates heating and cooling loads, Manual S selects equipment using manufacturer performance data, and Manual D sizes and lays out ducts for the required airflow. They can inform one another, but ordering one does not automatically include the others. This guide explains what each report does, what project information is needed, and how to decide which service to request.

Key Takeaways

• Treat Manuals J, S, and D as separate deliverables: Request the reports your project needs; Manual J covers loads, Manual S covers equipment selection, and Manual D covers duct sizing and layout.
• Share complete, up-to-date project details: Provide the latest plans or measurements, building specifications, project location, and any equipment or duct information already selected.
• Have the installer verify the final design: The installer verifies site conditions, final equipment selection, and installation decisions.

Manual J vs. Manual D and Manual S: What Does Each Do?

Manual J, Manual S, and Manual D address different parts of residential HVAC design. Manual J determines the home’s heating and cooling needs. Manual S helps select equipment to meet those needs. Manual D plans the ducts that distribute conditioned air.

Each is a separate deliverable. The services are requested separately, and one report does not automatically include the others. The three reports can inform the same residential HVAC design, but the project owner and design team should confirm which reports are required for the project and local documentation requirements.

Explore the separate Manual J load calculation service, Manual S equipment selection service, and Manual D duct design service from Manual J Express. Each service page explains what that report covers and what project information to provide.

Manual J Calculates Heating and Cooling Loads

Manual J calculates the heating and cooling loads for a home, including the needs of individual rooms. The calculation considers details such as room dimensions, window size and orientation, insulation, air leakage, climate, ventilation, and heat from occupants and appliances. This creates a project-specific picture of how much heating and cooling the home requires.

The results give HVAC professionals a basis for equipment selection and duct design. A square-footage estimate alone can miss differences in room layout, windows, and insulation. Manual J Express provides residential Manual J load calculations using building information to determine those loads.

Manual S Selects Equipment to Meet Those Loads

Manual S uses the heating and cooling loads from Manual J to guide equipment selection. The HVAC professional compares the home’s calculated needs with manufacturer performance data to find equipment that can meet the loads under the project’s design conditions.

That comparison matters because a system’s capacity can change with operating conditions. Selecting equipment by square footage or by the size of an existing unit may not reflect the home’s actual requirements. Proper selection helps prevent choosing equipment that is too large or too small for the calculated loads. Manual S equipment selection connects the load calculation to the system’s stated performance.

Manual D Designs Ducts to Deliver Required Airflow

Manual D guides the design and sizing of a home’s duct system. It uses room-by-room airflow needs, along with the selected equipment’s capabilities, to plan supply and return ducts that can distribute conditioned air throughout the home.

The design accounts for factors such as duct length, fittings, layout, and resistance to airflow. These details affect how much air reaches each room. If ducts are not sized and laid out to suit the airflow requirements, some rooms may receive too little or too much air. A Manual D duct design brings the equipment and room-level airflow requirements together in a distribution plan.

How the Three Manuals Work Together

The three procedures can inform one another, but they remain separate deliverables. Manual J calculates the home’s heating and cooling loads. Manual S uses the load results and manufacturer performance data to guide equipment selection. Manual D uses room-by-room airflow needs and selected equipment capabilities to plan duct sizing and layout. A change to plans, equipment, or duct routes may affect another report, so the installer or design team should review the sequence as project details change. Ordering one report does not automatically include the others.

Before You Order: What to Provide and What to Expect

Provide the latest plans or verified measurements, room dimensions and ceiling heights, window information, insulation and construction details, project location, ventilation or air-leakage details, and any equipment or duct-layout information already selected. The calculation uses the information you provide, which Manual J Express does not independently verify.

Your HVAC installer, contractor, or architect should verify site conditions and make the final equipment selection. Manual J Express provides design-support reports, not final architectural or engineering construction documents. The service does not include a PE seal or engineer signature. If a signature is required, confirm with the responsible installer, contractor, architect, or local authority who should sign. A report can support a permit submission, but permit approval is determined by the local authority and is not guaranteed.

How Does Manual J Calculate Heating and Cooling Loads?

Manual J estimates how much heating and cooling a home needs under specific outdoor design conditions. It considers the building’s construction, location, room layout, and how people use the space. The result is a room-by-room load estimate that HVAC professionals can use when selecting equipment and planning a system.

An accurate calculation depends on accurate project details. Plans, measurements, window specifications, insulation levels, and ventilation information all help the designer build a more complete picture of the home. Manual J load calculations use these details to estimate heating and cooling needs.

Measure Each Room and Review the Layout

The assessment begins with floor plans or verified measurements. The designer reviews each room’s length, width, and ceiling height, along with the home’s floors and overall layout. Room-by-room information matters: a sunlit bedroom, a shaded basement, and an open living area may have different heating and cooling needs.

The layout also shows which surfaces border the outdoors or unconditioned spaces, such as attics and garages. These details help estimate where heat may enter or leave the home. If construction or renovation plans have changed, make sure the designer has the latest version. Accurate measurements and updated plans give the calculation a dependable foundation.

Account for Climate, Orientation, Insulation, Windows, and Air Leakage

Manual J considers the home’s location and local design weather, including outdoor temperatures and humidity. It also accounts for the home’s orientation and the direction its windows face, since sunlight can add heat differently throughout the day. Window size, type, and shading affect how much heat enters or escapes.

Insulation and air leakage also shape the results. A tightly sealed, well-insulated home generally loses less heat in winter and gains less heat in summer than a draftier home with limited insulation. These features help explain why two homes with similar floor plans can have different loads. MRCOOL’s guide to Manual J inputs covers how climate, orientation, windows, insulation, and airtightness inform the calculation.

Include Ventilation and Internal Heat Gains

Heat moves through more than a home’s walls and windows. Manual J accounts for ventilation and air infiltration, including outdoor air brought in intentionally and air that enters through gaps in the building envelope. Both can affect the amount of heating or cooling needed to maintain indoor conditions.

The calculation also considers heat generated inside the home. People, lights, appliances, and other equipment add warmth, which can affect cooling needs. How many people use the space and how rooms function help put these gains in context. Share unusual ventilation requirements or equipment loads with the designer. The more complete the project information, the more accurately the calculation can represent the home.

Calculate Heating, Cooling, Sensible, and Latent Loads

Manual J estimates the home’s heating load and cooling load under peak design conditions. The heating load reflects heat lost during cold weather, while the cooling load reflects heat gained during warm weather. These estimates help determine the capacity the HVAC system needs to meet the home’s demands. Sobieski Services’ overview of Manual J explains how the calculation accounts for heat loss and heat gain.

Cooling load includes sensible heat, which affects air temperature, and latent heat, which relates to moisture in the air. The system needs to manage both to support indoor comfort. These load results guide later equipment selection and system design. They are not a substitute for proper installation, airflow, and setup, all of which affect how the system performs in the home.

Why Square-Footage Rules of Thumb Can Miss the Mark

A fixed amount of heating or cooling capacity per square foot may seem like a quick estimate, but it leaves out important differences between homes. Window placement, insulation, air leakage, ceiling height, orientation, and occupancy can all affect heating and cooling needs. Two homes with the same floor area may therefore require different system capacities.

Using the existing equipment as a guide can also carry forward an earlier sizing error. A previous system may have been too large or too small, so replacing it with equipment of the same capacity may repeat the problem. A room-by-room Manual J calculation provides a more specific estimate based on the home’s current condition. Before a replacement, tell the designer about changes to the layout, windows, insulation, or other features that could affect the load.

How Does Manual S Use Manual J Results to Select Equipment?

Manual J calculates a home’s heating and cooling loads. Manual S uses those results to select equipment that can meet the home’s needs under local design conditions. Instead of relying on square footage or the capacity of the old system, the selection is based on the home’s calculated loads and the equipment’s documented performance. Manual J Express provides residential Manual J load calculations to support this process.

Match Equipment Capacity to Calculated Loads

The Manual J report provides the heating and cooling loads that guide equipment selection. Manual S compares those loads with available equipment capacities to identify a system that can provide the required heating and cooling. A unit’s nominal capacity is only a starting point, since its actual output can vary depending on operating conditions.

The comparison can also include equipment characteristics such as airflow and static pressure. These details help confirm that the selected system is appropriate for the home and can work with its planned duct design. As Sobieski Services explains, Manual S uses Manual J results alongside equipment performance information to support the selection.

Check Manufacturer Data at Local Design Conditions

A system’s performance can change with outdoor and indoor conditions. Its listed capacity may not represent the heating or cooling output available during the local winter or summer design conditions used for the project. Manual S checks manufacturer performance data to see whether a system can meet the home’s Manual J loads under those conditions.

This step helps the designer look beyond the model’s nominal capacity and assess its expected output in the specific application. If the data shows that a system cannot meet the calculated load, another model or configuration may be a better fit. Manufacturer performance data is central to making that comparison.

Consider Airflow, Humidity Control, and System Type

Equipment selection is about more than matching a total heating or cooling number. Manual S considers sensible cooling, which affects air temperature, and latent cooling, which relates to moisture removal. Reviewing both helps determine whether the system can support comfortable indoor conditions, including humidity control.

The selected system must also provide the airflow needed to distribute conditioned air through the home. Its operating characteristics and requirements inform the duct design, which is addressed through Manual D. As MRCOOL’s overview of HVAC design calculations describes, equipment selection accounts for heating needs, sensible and latent cooling, and design conditions.

Avoid Oversized or Undersized Equipment

Undersized equipment may struggle to meet a home’s heating or cooling needs during demanding weather. Oversized equipment can create problems too. It may cycle on and off frequently, contribute to uneven temperatures, or remove less moisture during cooling than the home requires. Incorrect sizing can also affect energy use and place extra wear on system components.

Manual S helps reduce these risks by using the calculated Manual J loads and manufacturer performance data to guide the selection. The best choice is not necessarily the largest unit, but equipment that can meet the home’s documented needs under local design conditions and work with the planned airflow. Hansberger Refrigeration’s explanation of HVAC design manuals outlines how sizing can affect comfort, humidity, energy use, and equipment life.

What Does Manual D Determine About Ductwork?

Manual D determines how a home’s duct system should be laid out and sized to deliver the airflow each room needs. It uses room-by-room heating and cooling loads from Manual J, along with the selected equipment’s airflow and pressure limits, to guide duct sizes and routes. The design accounts for both supply ducts, which carry conditioned air to rooms, and return-air pathways, which bring air back to the HVAC system.

The goal is a duct system that can deliver the required airflow without exceeding the equipment’s available static pressure. Duct dimensions alone do not determine performance: route length, turns, fittings, materials, and equipment location can all affect how easily air moves through the system. A Manual D duct design considers these factors as part of a coordinated residential HVAC plan.

A clear design gives HVAC professionals a practical basis for installing and checking the ductwork. It also helps keep the duct plan consistent with the home’s calculated loads and selected equipment. If room layouts, equipment, or duct routes change, the design may need to be reviewed so the airflow plan still fits the project.

Set Airflow Needs for Each Room

Each room has its own heating and cooling requirements, so the airflow needed in one space may differ from the airflow needed in another. Manual D uses room-by-room load results from Manual J to establish airflow targets, generally measured in cubic feet per minute (CFM). For example, a room with large sun-facing windows may have a different cooling load from a shaded room of similar size.

These targets help determine the ducts serving each room and how those ducts connect to the main system. When airflow is planned around the calculated room loads, the design can better support consistent comfort throughout the home. Bradley Mechanical explains how Manual D uses Manual J results to plan airflow.

Size Ducts Based on Available Static Pressure

Ducts need to carry the required airflow while staying within the HVAC equipment’s available static pressure. Static pressure describes the resistance the blower must work against as air moves through the ducts, filters, coils, and other system components. Manual D accounts for that available pressure when determining suitable duct sizes.

If a duct system creates too much resistance, the equipment may not deliver the airflow needed in each room. Duct sizing therefore needs to balance airflow targets with the capabilities of the selected equipment. A design based on those limits gives installers a more reliable plan than choosing duct dimensions by rule of thumb. Hansberger Refrigeration describes how available static pressure affects duct sizing.

Account for Duct Length, Fittings, and Airflow Resistance

Air encounters resistance as it travels through a duct system. Straight runs, turns, transitions, and other fittings all affect airflow, as can the duct material and the air handler’s location. Manual D considers the full route from the equipment to each room, rather than relying only on the distance between the two.

This matters because a longer or more complex route may require a different duct size or layout to deliver the target airflow. Reviewing these details during design helps identify potential restrictions before installation and gives the HVAC professional a clearer plan to follow. Duct length, fittings, materials, and equipment location are among the factors addressed in duct design.

Plan Supply and Return Ducts for Balanced Airflow

Supply ducts deliver conditioned air to rooms, while return ducts carry air back to the HVAC system. Manual D plans the supply and return sides together, so the system has a complete path for air to circulate. A supply layout by itself does not show whether air can return to the equipment as intended.

The design considers how air enters and leaves each space, along with how the ducts connect to the air handler. Properly planned return-air pathways support the system’s airflow requirements and can help reduce uneven temperatures. For residential projects, Manual D design services can help align the duct layout with the calculated loads and selected equipment.

How Do Manual J, Manual S, and Manual D Work Together?

Manual J, Manual S, and Manual D form a connected residential HVAC design process. Manual J calculates the heating and cooling loads, Manual S uses those results to select equipment, and Manual D designs ductwork to deliver the required airflow. Each step depends on accurate information from the one before it, so the home, equipment, and duct system work as a coordinated plan.

Start With the Manual J Load Calculation

Manual J establishes how much heating and cooling each room needs. The calculation considers details such as room dimensions, window size and orientation, insulation, air leakage, local climate, and occupancy. Together, these inputs help determine loads for individual rooms as well as the home overall.

Room-by-room results matter because spaces of the same size can have different needs. A sunny room with large windows, for example, may need more cooling than a shaded room. The results also help determine the airflow needed to serve each space, which informs equipment selection and duct design. Review the factors included in Manual J heating and cooling load calculations. Sobieski Services explains how the load calculation provides a foundation for the other HVAC design steps.

Use Manual J Results to Select Equipment With Manual S

After the loads are calculated, Manual S helps identify equipment suited to the home’s heating and cooling needs. It compares the Manual J results with manufacturer performance data, including equipment capacity under relevant operating conditions. This helps the designer choose a system based on the home’s calculated requirements rather than a rough estimate based on square footage.

Equipment selection involves more than matching one capacity number. Airflow, system type, and the unit’s ability to manage cooling and humidity also matter. A system’s performance can vary depending on operating conditions, so its published specifications need to be reviewed carefully. Manual S guidance describes how equipment selection relies on both Manual J results and manufacturer data.

Design Manual D Ductwork for the Loads and Equipment

Once room loads and equipment are established, Manual D guides the design and sizing of the duct system. It helps determine duct sizes and routes that can deliver the required airflow to each room. The design accounts for factors such as duct length, fittings, and resistance to airflow, and includes both supply ducts and return ducts.

The duct system needs to suit the selected equipment as well as the room-by-room requirements. Available static pressure helps determine whether the planned duct paths can carry the needed airflow. Ducts that are poorly matched to the system may contribute to uneven temperatures, excess noise, or inadequate air delivery. MRCOOL’s overview of Manual J, S, and D explains how load calculations, equipment selection, and duct design work together.

Revisit the Design When Plans, Equipment, or Duct Routes Change

HVAC calculations rely on project details, so a change in one area can affect the others. Revised windows or insulation may alter the Manual J loads. A different unit may require a new Manual S equipment review and affect the airflow available for duct design. Changes to framing or duct routes can also mean the Manual D layout needs another look.

Share updated plans and equipment details with the design professional before installation or permit submission. Reviewing changes early helps keep the load calculation, equipment selection, and duct layout aligned. For coordinated residential HVAC reports, Manual J Express’s design services include Manual J load calculations, Manual S equipment selections, and Manual D duct designs.

What Can Go Wrong Without Manual J, Manual S, and Manual D?

Guesswork Can Lead to Incorrect Equipment Sizing

Choosing HVAC equipment based on square footage, an old system’s capacity, or a quick estimate can leave a home with equipment that does not match its heating and cooling needs. An undersized system may struggle to maintain comfortable temperatures during peak conditions. An oversized system may cycle on and off too often, increasing energy use and making temperatures less consistent. Incorrect sizing can also contribute to premature equipment wear, as explained in this overview of Manuals J, S, and D.

Manual J calculates the home’s heating and cooling loads, while Manual S uses those results to select equipment with suitable capacity. Without both steps, a replacement may repeat an earlier sizing mistake. A project-specific Manual J load calculation gives equipment selection a more reliable starting point.

Poorly Designed Ducts Can Restrict Airflow and Create Uneven Temperatures

Even properly selected equipment may not perform as intended if the duct system cannot deliver the airflow each room needs. Ducts that are too small, too long, or routed with excessive resistance can limit airflow. Some rooms may feel warmer or cooler than others, while noisy registers or extra strain on the equipment can signal airflow problems.

Manual D addresses duct sizing and layout, including airflow needs and resistance from duct runs and fittings. A duct design coordinated with the equipment helps plan how conditioned air reaches each room. Design is only part of the picture, though: duct leaks or installation issues can still affect performance. Checking airflow and static pressure after installation helps confirm that the system is operating as intended. Ductwork design and installation both matter for comfort and efficiency.

Excess Capacity or Poor Air Distribution Can Affect Comfort and Humidity

Comfort depends on more than reaching the temperature set on the thermostat. Oversized cooling equipment may satisfy the thermostat quickly and shut off before it has run long enough to remove enough moisture. Poor air distribution can also leave rooms feeling stuffy or uneven, even when the thermostat shows the desired temperature.

An existing system is not a reliable sizing guide on its own. If it was oversized, replacing it with equipment of the same capacity may carry the problem into the next system. Manual J, S, and D calculations help connect the home’s calculated loads, equipment performance, and room-by-room airflow. Considering those elements together supports better decisions about temperature and humidity control.

Missing or Inconsistent Documents Can Complicate Permit Review

Permit requirements vary by location and project, but some local offices request HVAC calculations and design documents for new homes or renovations. If plans, equipment selections, and duct layouts do not agree, a reviewer may request clarification or revisions. That can add time before work moves forward. Local requirements may include Manuals J, S, and D, so it helps to check with the permitting office early.

Complete, consistent reports make it easier to show how the proposed HVAC system fits the home and project plans. Check that details such as room dimensions, insulation, windows, equipment models, and duct routes match across the documents. Manual J Express prepares residential HVAC design reports that include load calculations, equipment selections, duct designs, and related project documentation.

How Can You Keep HVAC Design Calculations Accurate?

Accurate HVAC design depends on reliable project information and careful checks at every stage. Confirm the home’s details, review calculation inputs, and make sure equipment and ductwork are designed to work together. During installation, compare the completed system with the plans and verify airflow and static pressure.

Verify Plans, Measurements, and Building Details

Begin with the latest plans, then confirm that the dimensions and building details match the home or proposed construction. Check room sizes, ceiling heights, window locations and types, exterior doors, insulation levels, and the home’s orientation. Note features that may be missing from the drawings, such as a finished basement, an addition, or changes to the building envelope.

Manual J considers more than square footage. It accounts for details such as windows, insulation, orientation, air leakage, appliances, lighting, and occupants, as outlined in this guide to Manual J, D, and S. If plans or building conditions change, update the calculation so the design reflects the home as it will be built or occupied. A documented Manual J load calculation can provide a reliable starting point for equipment selection and duct design.

Follow Current ACCA Procedures and Review Software Results

Use calculation methods and software that follow current Air Conditioning Contractors of America (ACCA) procedures. Software can organize project details and run calculations, but a qualified reviewer should still check the inputs and results. Confirm that measurements, units, construction details, and local design conditions are entered correctly.

Review results that seem inconsistent with the home’s size or construction. Check the source data and assumptions before using the numbers to select equipment or design ducts. Applying HVAC standards carefully supports system performance and energy use, as Bradley Mechanical explains in its overview of Manual J, S, D, and related procedures. Keep the plans and calculation documents aligned, so everyone working on the project uses the same information.

Check Equipment Performance and Duct Requirements Together

After establishing the Manual J loads, use them to guide equipment selection and duct design. Manual S compares the calculated heating and cooling loads with manufacturer performance data, including capacity and airflow. Check performance at the project’s expected operating conditions, since a model’s nominal capacity may not tell the whole story.

Next, confirm that the Manual D design can deliver the airflow required by the selected equipment. Capacity, airflow, and static pressure are connected, so equipment and ducts should be reviewed as parts of one system. This relationship is described in this guide to Manuals S, D, and J. If equipment, duct routes, or other project details change, review the design again to make sure all calculations remain consistent.

Confirm Airflow and Static Pressure During Installation

Check that the installed equipment, duct sizes, and supply and return locations match the design documents. Once the system is operating, have a qualified HVAC professional measure airflow and static pressure and compare the readings with the equipment requirements and design targets. These checks can help identify restrictions, leaks, or balancing issues that may not be visible during a walk-through.

Manual D uses airflow needs and equipment information to plan how conditioned air moves through the home. MRCOOL’s explanation of Manual J, S, T, and D describes how these design steps relate. If measurements differ from expectations, investigate the cause and address it before considering the installation complete. Record test results and adjustments so owners and service technicians have useful information for future maintenance.

When Should You Request Manual J, Manual S, and Manual D Reports?

Request these reports early enough for the results to shape equipment choices, duct layouts, and permit documents. Manual J calculates heating and cooling loads, Manual S helps select equipment to meet those loads, and Manual D designs ducts to deliver the required airflow. Coordinating the reports can help your project team make decisions based on the home’s actual design, rather than relying on estimates.

New Homes, Additions, and Major Renovations

For a new home, request the reports while plans are being developed, before equipment is selected and duct routes are set. This gives your HVAC contractor, builder, and design team time to coordinate the load calculation, equipment selection, and duct plan with the home’s layout.

Additions and major renovations can change heating and cooling needs, too. New rooms, replacement windows, added insulation, or changes to the floor plan may affect the loads throughout the home. An existing system may not suit the updated space, even if it worked well before the project. Permit requirements vary by location, so check with the authority reviewing your plans. Manual J Express provides residential load calculations to support design and project documentation.

HVAC Replacements and System Changes

When replacing an HVAC system, request a new load calculation instead of automatically choosing equipment with the same capacity as the old unit. The previous system may have been sized incorrectly, or changes to the home may have altered its heating and cooling needs. Matching its capacity could repeat a sizing problem.

Use Manual J results to guide equipment selection through Manual S. If you are changing system type, relocating equipment, or modifying ductwork, include Manual D in the project planning as well. Reviewing equipment and air distribution together helps the team design a system around the home’s requirements. This overview of Manual J, S, T, and D explains how the calculations support residential HVAC design.

Permit and Project Documentation

Request the reports if your local permitting authority requires HVAC design documents, or if your contractor, builder, or design professional needs calculations to support the proposed system. Requirements depend on the project and location, so confirm which documents are needed before submitting plans.

Clear, consistent reports help reviewers see how the proposed equipment and duct design relate to the home’s calculated loads. The ACCA residential system design review forms reference Manuals J, S, and D in reviewing residential HVAC designs. If your project also requires a REScheck report, verify that separately. REScheck documents energy-code compliance, while Manuals J, S, and D address HVAC loads, equipment selection, and duct design.

Prepare Project Details for an ACCA-Compliant Residential Design Report

Before requesting a report, gather the latest floor plans, room dimensions, ceiling heights, window and door details, insulation values, and exterior wall information. Include the project address because local climate and design conditions affect the calculations. If you have already chosen a system type or have manufacturer and equipment details, share those as well. For published service rates, review the Manual J Express pricing page.

For an existing home, describe changes to the building envelope or HVAC system. If current plans are unavailable, provide clear photos, sketches, or measurements, and note any details that may need confirmation. Complete information helps the designer assess the project and clarify missing items sooner. This guide to the roles of Manuals J, S, and D explains how the reports connect. You can review Manual J Express’s residential HVAC design services to identify the reports your project may need.

Related Articles

• What Are Manuals J, D and S?
• Understanding Calculations for Manual J, S, T, and D
• Manuals S, D and J
• Manual J Load Calculations
• Manual D Duct Design Services

Frequently Asked Questions

Do I need Manual J, Manual S, and Manual D for every HVAC project?
Not necessarily. A new home, major renovation, system replacement, or ductwork change may call for different documents. Check local permit rules and ask your HVAC professional which calculations fit your project.

Can I choose HVAC equipment before completing Manual J?
It’s better to calculate the home’s heating and cooling loads first. Manual J gives Manual S the project-specific information needed to compare equipment options with the home’s requirements.

What information should I provide for an HVAC design report?
Share current floor plans, room measurements, window and insulation details, the project address, and any planned changes to the home. If you have equipment specifications or ductwork plans, include those too.

Do changes to my plans mean the calculations need to be updated?
They might. Changes to room layouts, windows, insulation, equipment, or duct routes can affect loads, equipment selection, or airflow. Ask your designer to review the reports when project details change.

When should I request these reports?
Request them while plans and system choices are still being developed. Early calculations give your project team time to coordinate equipment and ductwork, and to prepare any documents required for permit review.